Abstract:Biomaterial Mechanical Microenvironment and Tissue Functional Regeneration： From Static Regulation to Dynamic Remodeling

Abstract:Organoid technology has become a highly promising in vitro model in biomedical research, but its traditional culture relies on animal-derived basement membrane matrices, which suffer from batch-to-batch variability, undefined biochemical composition, and poorly controllable mechanical properties. Recent studies have confirmed that matrix stiffness, viscoelasticity, topography, and temporal mechanical dynamics play regulatory roles equally as critical as biochemical signals in stem cell self-organization, lineage specification, and functional maturation of organoids. This review systematically summarizes the progress in understanding how extracellular matrix (ECM) mechanical properties regulate organoid formation. Focusing on the YAP/TAZ factors and the integrin receptors, which engage in crosstalk with biochemical signals to synergistically determine cell fate. We then elaborate how specific mechanical parameters, such as stiffness, viscoelasticity, and topography, influence each distinct stage of organoid development, from initial aggregation and compaction, through proliferative expansion, to lineage-committed differentiation and terminal functional maturation. Appropriate stiffness facilitates efficient aggregation and symmetry breaking, while excessive rigidity impairs proliferation and accelerates cellular senescence. In hepatic organoid expansion where only stiffness matching liver tissue (~6.2 kPa) supported robust growth. Viscoelastic stress relaxation promotes integrin clustering, enhances focal adhesion maturation, and stimulates endogenous ECM deposition, thereby supporting self-organized crypt-villus architecture and basement membrane assembly. Notably, dynamic softening of hydrogels enables optimal crypt budding, whereas rapid stress relaxation permits nephron segment coiling and drives vascular organoid maturation toward arteriole differentiation, highlighting stress relaxation as a key temporal parameter. Topographical cues provide contact guidance that directs polarized outgrowth, lumen formation, and neuronal orientation, all of which are essential for achieving organotypic architecture. The embedded 3D printing of complex neural networks enables precise control over branching geometries, facilitating studies of morphogenesis under spatial constraints. The engineered mechanical microenvironments have been successfully applied to recapitulate disease phenotypes: stiff matrices induce fibrosis and epithelial-mesenchymal transition in liver organoids, promote chemoresistance in cholangiocarcinoma. Furthermore, we summarize engineering strategies for both natural and synthetic hydrogels aimed at creating mechanically defined culture platforms. Natural biomaterial modifications achieve spatial separation of mechanical constraints from biochemical support, enabling self-limited compressive stimulation within a defined time window. Synthetic polymers allow independent tuning of stiffness, ligand density, and viscoelasticity through adjustable crosslinking and dynamic non-covalent interactions, thus providing orthogonal control over multiple mechanical parameters. Dynamic microenvironments that mimic progressive stiffening as observed in development, tumor evolution, or fibrosis can be constructed using composites that undergo spontaneous structural transitions. In the future, critical challenges include deciphering the synergistic rules governing mechanical-biochemical interplay, developing spatiotemporally programmable hydrogels that enable on-demand modulation of local mechanics, establishing comprehensive databases of tissue-specific mechanical parameter windows, and advancing standardized high-throughput screening platforms to accelerate preclinical validation and clinical translation. Moreover, integrating real-time mechanical sensors and non-invasive imaging techniques would allow dynamic monitoring of intracellular forces and tissue-level stress during culture. Ultimately, this review aims to provide a theoretical foundation for deepening our understanding of mechano-biological coupling mechanisms and for rationally designing high-fidelity, physiologically relevant organoid culture platforms that fully harness the regulatory power of mechanical cues.

Abstract:Tissue repair requires the reconstruction of functional vascular networks to restore oxygen and nutrient delivery, eliminate metabolic waste, and maintain tissue homeostasis. Although biochemical factors such as growth factors and cytokines have been extensively studied in vascular regeneration, increasing evidence indicates that mechanical signals from the extracellular matrix (ECM) are equally important regulators of angiogenesis. Matrix stiffness, as a major biomechanical property of the tissue microenvironment, provides critical information that influences endothelial cell (EC) behavior and vascular remodeling through mechanotransduction. However, the biological effects of matrix stiffness are not universally defined as either pro- or anti-angiogenic, but are highly dependent on tissue context, cellular composition, disease progression, and the dynamic changes occurring during tissue repair. Therefore, understanding how matrix stiffness regulates vascular regeneration is essential for developing more precise strategies for tissue engineering and regenerative medicine. In this review, we summarize recent advances in the regulation of angiogenesis by matrix stiffness during tissue repair from multiple perspectives. First, we discuss the direct effects of matrix stiffness on EC behaviors, including differentiation, morphological remodeling, migration, proliferation, barrier maintenance, and vascular network formation. ECs sense mechanical alterations in the surrounding matrix through various mechanosensitive structures, including integrins, focal adhesion complexes, and mechanosensitive ion channels such as Piezo1 and TRPV proteins. These mechanical signals are subsequently transmitted through intracellular pathways involving FAK, RhoA/ROCK, MAPK, and Hippo-YAP/TAZ signaling, leading to cytoskeletal reorganization and transcriptional regulation. Through these mechanisms, matrix stiffness regulates endothelial functional states and determines the balance between regenerative vascular formation and pathological vascular remodeling. Beyond the direct regulation of ECs, we further highlight the importance of stiffness-mediated intercellular communication within the regenerative microenvironment. Matrix stiffness can regulate the behavior and secretory profiles of vascular-associated cells, including mesenchymal stem cells and macrophages, thereby indirectly affecting endothelial function through paracrine mechanisms. Changes in matrix mechanics influence the secretion of angiogenic factors, inflammatory cytokines, and extracellular vesicles from these cells, creating a mechanical regulation network that coordinates vascular regeneration. This perspective extends the traditional concept of matrix stiffness from a physical support structure to an active regulatory signal that integrates multiple cellular responses during tissue repair. Furthermore, we discuss the tissue-specific effects of matrix stiffness in vascular regeneration across different organs, including the aorta, lung, liver, and heart. Although excessive matrix stiffening is frequently associated with fibrosis and vascular dysfunction, the consequences of mechanical changes vary considerably among tissues. Moderate stiffness alterations may support endothelial activation and vascular stabilization in certain regenerative contexts, whereas persistent pathological stiffening can promote inflammation, endothelial dysfunction, and impaired vascular repair. These findings emphasize that the biological meaning of “soft” and “stiff” microenvironments should be interpreted according to specific tissue and experimental conditions rather than as universal mechanical classifications. Finally, we summarize current challenges and future perspectives in this field. A major limitation is the lack of standardized mechanical characterization among different studies, as stiffness measurements are influenced by material properties, testing methods, and experimental conditions, limiting direct comparison across research systems. Moreover, most existing models fail to fully reproduce the dynamic and viscoelastic properties of native ECM during tissue regeneration. Future studies should combine advanced biomaterials with standardized mechanical analysis, organoid models, and multi-omics approaches to establish more accurate mechanical regulatory maps. Overall, this review proposes that matrix stiffness is not merely a structural feature of tissues, but an active biological signal that regulates vascular regeneration through coordinated mechanotransduction and multicellular interactions. A deeper understanding of stiffness-mediated vascular regulation will provide new theoretical insights and therapeutic opportunities for improving tissue repair outcomes.

Abstract:Objective This study aims to investigate the regulatory effects of microcapsules with different matrix stiffness on the survival, proliferation, adhesion, and osteogenic differentiation of mesenchymal stem cells (MSCs), to further explore the relationship between matrix stiffness and MSCs osteogenic behavior, and to evaluate the in vivo histological responses and osteogenic-related protein expression of the microcapsules using an animal subcutaneous implantation model.Methods In this study, three-dimensional carbon nanofiber (CNF)/sodium alginate (SA) microcapsules with different matrix stiffness were constructed. By adjusting the CNF content, three groups of microcapsules with stiffness values of 27.05, 35.90, and 52.40 kPa were prepared, and their physicochemical properties, including morphology, mechanical properties, particle size, chemical structure, and degradation properties, were characterized. The effects of these microcapsules with different stiffness on the survival, adhesion, and osteogenic differentiation of MSCs were evaluated. Live/dead staining was used to observe cell survival and distribution in the microcapsules, while alkaline phosphatase (ALP) activity and the expression of osteopontin (OPN) and osteocalcin (OCN) were examined to assess osteogenic differentiation. Immunofluorescence staining was further performed to observe the expression of Yes-associated protein (YAP) and integrin β1 under different stiffness conditions. In addition, a rat subcutaneous implantation model was used to evaluate the in vivo tissue compatibility of the microcapsules. Histological staining and immunohistochemical analysis were carried out to examine local tissue responses and the expression of osteogenic-related proteins.Results The results showed that all three groups of microcapsules exhibited regular and uniform morphology and similar particle size, and all groups showed good degradability. Except for the differences in mechanical properties, no obvious differences were found in the other physicochemical properties among the three groups. Live/dead staining indicated that all groups of microcapsules had good cytocompatibility. MSCs in the low-stiffness group were mostly round, whereas cells in the medium- and high-stiffness groups showed more obvious spreading. Higher matrix stiffness was more favorable for MSC adhesion, growth, and survival. ALP staining and quantitative analysis showed that ALP activity increased significantly with increasing matrix stiffness. The expression of the osteogenic-related proteins OPN and OCN also increased with increasing stiffness, and the high-stiffness group showed the strongest positive signals. Immunofluorescence results further indicated that YAP and integrin β1 fluorescence signals tended to increase in MSCs with increasing matrix stiffness, suggesting that matrix stiffness may influence MSC osteogenic differentiation through stiffness-related cell adhesion and mechanotransduction. In vivo experiments showed that all three groups of microcapsules exhibited good histocompatibility after subcutaneous implantation, although different degrees of degradation and local tissue response were observed. Immunohistochemical analysis showed that the expression levels of OPN and OCN increased with increasing matrix stiffness, and the high-stiffness group exhibited higher expression of these osteogenic-related proteins.Conclusion CNF endows SA microcapsules with tunable matrix stiffness. While maintaining good biocompatibility, the high-stiffness microenvironment can effectively promote the adhesion and osteogenic differentiation of MSCs, accompanied by increased ALP activity and enhanced OPN and OCN expression. The increased YAP and integrin β1 fluorescence signals in the high-stiffness group further indicate that matrix stiffness is closely related to cellular mechanical responses. These findings provide a three-dimensional cell carrier with potential application value for MSC delivery and bone tissue regeneration based on mechanical microenvironment regulation.

Abstract:Objective Peripheral nerve injury is a common clinical condition that can impair the regulatory function of target organs, leading to functional disability; severe injuries may even result in lifelong disability. Therefore, how to effectively promote the morphological and functional reconstruction of injured peripheral nerves has become a critical scientific issue that urgently needs to be addressed. This study biomimicked the highly oriented structure and electrophysiological properties of peripheral nerves and investigated the feasibility and effectiveness of combining electrical stimulation (ES) with oriented conductive substrates for the repair of injured peripheral nerves at the cellular level.Methods Polydimethylsiloxane (PDMS) substrates with oriented microgroove structures of varying widths (0, 5, 10, and 20 μm) were fabricated using silicon wafers with micropatterned grooves as templates. Graphene-based conductive patterned substrates (GCPSs) with oriented microgrooves were then constructed via soft lithography and designated as GCPS 0, GCPS 5, GCPS 10, and GCPS 20 according to the groove width. The GCPSs were prepared from collagen/polycaprolactone (PCL) matrices containing 1.0 wt% graphene, and their morphology, wettability, and conductivity were characterized. Mesenchymal stem cells (MSCs) viability, proliferation, adhesion, and orientation on the substrates were evaluated before ES treatment. Then, ES at a frequency of 2 Hz and field strengths of 10, 20, or 50 mV/cm were applied to the cells for 10 min daily, over 3 or 7 consecutive days. Neural differentiation was assessed by morphological observation, immunofluorescence staining, and analysis of neural lineage-related markers.Results The oriented microgroove PDMS substrates supported long-term MSCs growth, guided cells to align along the groove direction, and promoted a morphological transition toward neural-like cells, exhibiting the capacity to induce MSCs differentiation toward the neural lineage. Microgroove structures effectively guided the alignment of MSCs and promoted the development of a more elongated, neural-like morphology, with the most pronounced morphological changes observed on grooves of 10 and 20 μm in width. Meanwhile, the incorporation of graphene endowed the GCPSs with favorable electrical conductivity, though the groove width did not significantly affect the conductive performance. The GCPSs showed good cytocompatibility with MSCs, and cell proliferation on these substrates exhibited a time-dependent pattern, with no significant effect observed from groove width. The inductive effect of ES combined with GCPSs on MSCs differentiation toward specific neural lineages was co-regulated by ES intensity (0, 10, 20, and 50 mV/cm) and microgroove width. ES at 10 mV/cm and 20 mV/cm promotes MSCs differentiation toward neurons on microgrooved substrates of various widths (5, 10, and 20 μm); under the same ES intensities, microgrooves with widths of 5 μm and 10 μm are more favorable for MSCs differentiation toward glial cells/SCs. Notably, low-intensity ES (10 or 20 mV/cm) combined with GCPS 10 significantly enhanced the neural differentiation of MSCs. Neurotrophic factor secretion levels by MSCs cultured on various GCPS substrates after 3 d of ES application was further detected. There were no significant differences in nerve growth factor-β (NGF-β) and brain-derived neurotrophic factor (BDNF) concentrations among the GCPS 5, GCPS 10, and GCPS 20 substrates, and these levels were not affected by variations in ES intensity. Under ES at 10 mV/cm, the glial cell line-derived neurotrophic factor (GDNF) concentration in each GCPS substrate was higher than that in the corresponding non-ES group on the same substrate. However, as ES intensity increased, the GDNF concentration decreased to varying degrees.Conclusion This study demonstrates that the combined strategy of “oriented topographical structure+ES” can effectively promote the neural differentiation of MSCs and holds promise for accelerating the repair process of peripheral nerve injuries.

Abstract:Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta and abnormal accumulation of α-synuclein. Its pathogenesis involves multiple interconnected processes, including oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, neuroinflammation, and impaired protein homeostasis. Extracellular signal-regulated kinase 1/2 (ERK1/2), a major component of the mitogen-activated protein kinase signaling network, plays an important role in neuronal survival, synaptic plasticity, stress responses, and cell death. However, accumulating evidence indicates that ERK signaling in PD is not unidirectional, as both insufficient activity and sustained overactivation have been associated with neuronal dysfunction and disease progression. In this review, we systematically summarize the evidence for the pathological and protective roles of ERK signaling in PD. Insufficient ERK activity may impair neurotrophic support, synaptic plasticity, mitochondrial homeostasis, and neuronal adaptation to stress, thereby increasing the vulnerability of dopaminergic neurons. In contrast, persistent and excessive ERK activation may promote neuroinflammation, oxidative stress, mitochondrial dysfunction, apoptosis, autophagy-lysosomal impairment, and abnormal α-synuclein accumulation. Conversely, moderate and transient ERK activation induced by neurotrophic factors, bioactive compounds, or exercise may enhance neuronal survival, antioxidant defense, synaptic plasticity, and functional recovery. These apparently contradictory findings suggest that ERK activation itself cannot be simply classified as either neuroprotective or neurotoxic. Based on the available evidence, we propose the concept of an “ERK activity window” to explain the context-dependent effects of ERK signaling in PD. This hypothesis suggests that ERK activity needs to remain within an appropriate dynamic range to maintain neuronal homeostasis and adaptive responses. ERK activity below this range may weaken neurotrophic support and stress resistance, whereas prolonged and high-intensity activation may exceed the adaptive capacity of neurons and glial cells, thereby promoting inflammatory and degenerative processes. Importantly, this functional window should not be regarded as a fixed threshold. Its biological effects are likely determined by the intensity and duration of activation, cell type, subcellular localization, upstream stimuli, interaction with other signaling pathways, and disease stage. This framework may therefore help reconcile the apparently inconsistent findings among different PD models and experimental conditions. From a therapeutic perspective, these findings indicate that ERK should not necessarily be considered a target for simple activation or inhibition. Instead, restoring ERK signaling toward an appropriate functional state may represent a more rational strategy. Exercise is of particular interest because it can simultaneously influence neurotrophic signaling, oxidative stress, inflammation, synaptic plasticity, and ERK activity, potentially promoting adaptive remodeling of ERK signaling according to pathological conditions. Nevertheless, current evidence is predominantly derived from cellular and animal studies, and the dynamic, cell-specific, and spatial characteristics of ERK signaling remain insufficiently defined. Blood-brain barrier penetration, long-term safety, preservation of physiological ERK functions, and the lack of reliable biomarkers for monitoring brain ERK activity also limit clinical translation. Importantly, the “ERK activity window” remains a theoretical framework, and direct clinical evidence that ERK modulation can alter the progression of human PD is currently lacking. Future studies should therefore integrate longitudinal analysis, cell-specific and spatial approaches, and clinical biomarker validation to determine whether precise regulation of ERK signaling can provide a viable strategy for disease-modifying intervention in PD.

Abstract:The abnormal accumulation, structural change, and spread of tau protein in the brain are now considered important factors in the progression of Alzheimer’s disease (AD) and many other tau-related neurodegenerative diseases. Clinical and pathological studies have shown that the amount and distribution of abnormal tau protein are closely related to synaptic damage, neuronal loss, and cognitive decline. Therefore, tau protein has become an important target for disease-modifying therapy. However, tau is difficult to target because it has no fixed structure, lacks a clear active site, undergoes many post-translational modifications, and forms different abnormal structures in different diseases and disease stages. Therefore, the effective and selective removal of harmful tau species is both a major opportunity and a major challenge in drug discovery for neurodegenerative diseases. Proteolysis-targeting chimeras (PROTACs) offer a new strategy to deal with this problem. Unlike traditional inhibitors, PROTACs do not simply block protein function. Instead, they bring the target protein close to an E3 ubiquitin ligase, which leads to ubiquitination and degradation of the target protein by the proteasome. This event-driven mechanism may be especially useful for disease-related proteins such as tau protein, which are hard to inhibit with traditional small molecules. In recent years, tau protein-targeting PROTACs and related degradation strategies have shown promising effects in cell and animal models. These effects include reducing abnormal tau protein levels, lowering synaptic toxicity, regulating disease-related signaling pathways, and improving behavioral or cognitive outcomes. These studies support targeted tau protein degradation as a promising therapeutic approach, although many problems still need to be solved before clinical use. In this review, we summarize recent progress in the development of tau protein-targeting PROTACs and discuss the main factors that affect their design and activity. We focus on the choice of tau protein-binding ligands, their binding sites, and their ability to recognize abnormal tau protein rather than normal tau protein. We also discuss the selection of E3 ligase recruiters, linker length and structure, ternary complex formation, and structure-activity relationships that influence degradation potency and selectivity. In addition, we introduce new strategies beyond traditional proteasomal degradation, including the regulation of tau protein phosphorylation and autophagy-based clearance. These approaches may be more suitable for different tau species or different stages of disease. A major challenge for tau protein-targeting PROTACs is delivery to the central nervous system. Many PROTACs have high molecular mass, large polar surface area, flexible structures, and may be removed by efflux transporters. As a result, they often have poor ability to cross the blood-brain barrier and may not reach enough free drug levels in the brain. Therefore, the therapeutic potential of tau protein-targeting PROTACs depends not only on their ability to degrade tau protein in vitro, but also on whether they can achieve long-lasting, selective, and safe target engagement in important brain regions after practical administration. Future studies should focus on improving selectivity for abnormal tau protein, understanding E3 ligase function in neural cells, designing brain-penetrant molecules, developing better delivery methods, and testing these drugs in models that better reflect human disease. Overall, tau protein-targeting PROTACs are a promising and fast-developing strategy for treating tau-related diseases. However, their successful clinical translation will require progress in chemical biology, medicinal chemistry, neuroscience, drug delivery, and translational medicine.

Abstract:Glycosylation constitutes a critical, highly intricate, and diverse co- and post-translational modification characterized by the covalent attachment of sugar moieties to proteins, lipids, or small RNAs. Complex glycans are ubiquitously present across nearly all living organisms. Despite their prevalence, our comprehension of glycan diversity remains limited, likely due to the inherent challenges associated with elucidating their structural complexity. Among post-translational modifications, protein glycosylation is notably prevalent, involving the enzymatic transfer of oligosaccharides to specific amino acid residues by glycosyltransferases. This modification plays a pivotal role in modulating protein function, including participation in various biological and biochemical recognition processes. G protein-coupled receptors (GPCRs), encoded by approximately one thousand genes, share a conserved architecture comprising seven transmembrane helices interconnected by three intracellular and three extracellular loops. Representing the largest family of human membrane proteins, GPCRs regulate a vast array of physiological and pathological processes, thereby constituting the most extensive class of therapeutic targets. In mammalian systems, the majority of GPCRs undergo glycosylation predominantly at their extracellular N-terminus or extracellular loops, primarily through N-linked and O-linked glycosylation. These covalent carbohydrate modifications exert profound effects on multiple facets of GPCR biology, including endoplasmic reticulum folding and quality control, membrane trafficking and surface expression, receptor internalization and recycling or degradation, ligand binding and signal transduction, biased signaling, and receptor dimerization. Notably, glycosylation can exert both positive and negative regulatory influences on these processes. Dysregulation of GPCR glycosylation has been implicated in a range of pathological conditions, such as cancer, diabetes, and neurological disorders, underscoring its physiological and pathological significance. Aberrant glycosylation patterns may lead to dysfunctional receptor signaling, thereby contributing to disease progression. Consequently, elucidating the precise roles of glycosylation in GPCR function not only enhances fundamental understanding of receptor biology but also facilitates the development of novel therapeutic strategies targeting glycosylation pathways or specific GPCR glycoforms. Although the functional consequences of glycosylation have been investigated for several decades, delineating their exact structural underpinnings has remained challenging due to the intrinsic flexibility and heterogeneity of carbohydrate structures. Recent advances in structural biology, particularly single-particle cryo-electron microscopy (cryo-EM) and X-ray crystallography, have catalyzed a paradigm shift in our understanding of GPCR glycosylation. The integration of these sophisticated structural techniques with biochemical approaches has redefined glycosylation as a complex structural element integral to receptor function. These developments provide a molecular framework for comprehending how glycans influence receptor pharmacology and open new avenues for the rational design of glyco-engineered biologics and allosteric modulators targeting specific extracellular motifs. This mini-review concentrates on glycosylation within the GPCR superfamily, summarizing the impact of glycosylation modifications on receptor function and regulatory mechanisms, recent progress in the structural biology of GPCR glycosylation, and prospective directions for future research in this field.

Abstract:Polyamine homeostasis is tightly coupled to tumor-cell proliferation, metabolic reprogramming, stress adaptation, and immune escape. Ornithine decarboxylase antizyme 1 (OAZ1) is a central negative regulator of this network. When intracellular polyamine levels increase, the ribosome shifts one nucleotide downstream and switches to a new reading frame during translation of OAZ1 mRNA, thereby enabling the production of the full-length active OAZ1 protein. OAZ1 then restrains polyamine accumulation through two complementary mechanisms. It binds ornithine decarboxylase (ODC), inhibits enzyme activity, promotes dissociation of the active ODC homodimer, and facilitates ubiquitin-independent proteasomal degradation of ODC, thereby reducing endogenous putrescine synthesis. In parallel, OAZ1 suppresses the polyamine transport system (PTS), limiting the uptake of extracellular polyamines that may compensate for reduced biosynthesis. Recent studies have reshaped the concept of the mammalian PTS. Rather than a single plasma-membrane transporter, it is now viewed as a multicomponent and compartmentalized network involving cell-surface enrichment by heparan sulfate proteoglycans, caveolin-associated endocytosis in selected cellular contexts, endosomal or lysosomal escape mediated by P5B-type ATPases such as ATP13A3 and ATP13A2, vesicular storage mediated by SLC18B1, and acetylation-coupled export mediated by spermidine/spermine N1-acetyltransferase 1 (SAT1) and the SLC3A2-associated diamine exporter pathway. These findings provide a broader framework for understanding how tumor cells maintain high polyamine availability even when synthesis is pharmacologically inhibited. However, several fundamental questions remain unresolved. The direct PTS targets recognized by OAZ1 have not been identified, the structural basis by which polyamine-induced OAZ1 dimerization contributes to transport inhibition is still unclear, and the relationship between dysregulation of the OAZ1-PTS axis and therapeutic responses varies among tumor types. In this review, we summarize the molecular mechanisms of OAZ1 polyamine sensing, programmed frameshift translation, ODC inhibition and degradation, and feedback control of polyamine uptake. We also integrate recent advances on ATP13A2, ATP13A3, ATP13A4, SLC3A2, SLC18B1, SAT1, and related transport or export modules, and compare their alterations in neuroblastoma, lung cancer, prostate cancer, colorectal cancer, hepatocellular carcinoma, breast cancer, pancreatic cancer, leukemia, glioma, and oral squamous cell carcinoma. Particular attention is given to tumor-type specificity. MYCN-driven neuroblastoma appears to depend on both enhanced biosynthesis and compensatory uptake, lung and prostate cancer models provide functional evidence for OAZ1-dependent feedback repression of uptake, hepatocellular carcinoma highlights the immunological role of acetylated-polyamine efflux, and breast and pancreatic cancer studies suggest nonredundant contributions of ATP13 family members. Finally, we discuss translational strategies that aim to mimic or restore the dual negative-feedback function of OAZ1, including difluoromethylornithine (DFMO), AMXT1501-based polyamine blockade therapy, ATP13A3-directed intervention, targeting of AZIN1-OAZ1 antagonism, and modulation of SAT1-SLC3A2-associated acetylated-polyamine export. Future work should combine transport assays, interaction mapping, spatial omics, metabolomics, and immune profiling to define actionable biomarkers, such as OAZ1, AZIN1, ODC, ATP13A3, SLC3A2, SAT1, and tumor polyamine signatures. Such biomarkers will be important for selecting patients, monitoring target engagement, and designing combinations with chemotherapy, targeted therapy, or immune checkpoint blockade. A better understanding of the OAZ1-PTS axis may support biomarker-guided patient stratification and rational combination therapies targeting polyamine dependence and the immunometabolic tumor microenvironment.

Abstract:The α7 nicotinic acetylcholine receptor (α7 nAChR) is a ligand-gated ion channel characterized by high Ca²⁺ permeability, rapid activation, and rapid desensitization. It is widely expressed in the nervous system and various non-neuronal cell types. α7 nAChR is involved in regulating neuronal excitability, synaptic transmission and plasticity, cognitive function, and inflammatory responses. These properties have made α7 nAChR a potential therapeutic target for neuropsychiatric and inflammatory diseases. In recent years, advances in cryo-electron microscopy have provided structural insights into α7 nAChR gating, ligand recognition, allosteric modulation, and allosteric activation. The receptor mainly undergoes transitions among resting, open, and desensitized states. Recent structural studies have further revealed asymmetric conformational changes and multiple intermediate states during receptor activation and recovery from desensitization. Conformational rearrangements in the extracellular domain-transmembrane domain coupling region and the pore-forming M2 helices are closely associated with channel opening and desensitization. However, structural characterization of the α7 nAChR gating cycle still largely depends on pharmacological stabilization. Open-state structures have been resolved in the presence of PNU-120596 or GAT107, whereas a high-resolution structure of the open state induced by acetylcholine alone remains to be determined. These physiological roles underpin the involvement of α7 nAChR in multiple disease processes. In the hippocampus, α7 nAChR regulates local neuronal circuits, theta oscillations, synaptic transmission, and synaptic plasticity, thereby contributing to learning, memory, attention, and other cognitive processes. In macrophages, microglia, and other immune-related cells, α7 nAChR activation regulates inflammatory responses and oxidative stress. These effects involve several signaling pathways, including Janus kinase 2 (JAK2)/STAT3, phosphoinositide 3-kinase (PI3K)/AKT, and NF-κB signaling, as well as regulation of the NLRP3 inflammasome and IL-1β production. Such anti-inflammatory effects may also contribute to α7 nAChR-mediated neuroprotection. Although several compounds targeting α7 nAChR have entered clinical studies, no α7 nAChR-selective drug has been approved for clinical use. Limited clinical translation may be related to rapid receptor desensitization, inconsistent efficacy across clinical studies, insufficient or variable target engagement, patient heterogeneity, and clinical endpoint selection. TC-5619 showed promising effects on cognitive impairment and negative symptoms in an early exploratory study of schizophrenia, but these effects were not confirmed in a subsequent, larger phase II trial. Encenicline (EVP-6124) also showed cognitive improvement in early studies, whereas two global phase III trials in schizophrenia failed to meet their co-primary cognitive and functional endpoints. Pharmacological strategies targeting α7 nAChR have expanded from orthosteric agonists to positive allosteric modulators (PAMs) and allosteric agonist-positive allosteric modulators (ago-PAMs). Orthosteric agonists directly activate the receptor by binding to the orthosteric site, but their effects are limited by rapid receptor desensitization. Type I PAMs mainly enhance agonist-evoked responses with relatively small effects on desensitization, whereas type II PAMs markedly potentiate receptor responses and reduce or delay desensitization. Ago-PAMs such as GAT107 can directly activate α7 nAChR through an allosteric mechanism while also potentiating responses to orthosteric agonists. Together, these findings have broadened the pharmacological approaches to α7 nAChR regulation. In summary, future drug development should focus on precise regulation of α7 nAChR according to receptor structure and disease mechanisms, rather than simply enhancing receptor activation. Further studies are needed to clarify how candidate ligands affect receptor gating, conformational transitions, recovery from desensitization, and downstream signaling. Pharmacological differences between neuronal and non-neuronal α7 nAChRs, between homomeric α7 and heteromeric α7β2 receptors, and between α7 nAChR and other nAChR subtypes also require further investigation. Integrating structure prediction, artificial intelligence-assisted virtual screening, molecular docking, molecular dynamics simulations, and electrophysiological validation may facilitate the discovery and optimization of new α7 nAChR modulators.

Abstract:Steroid-associated osteonecrosis of the femoral head (SANFH) is a progressive osteoarticular disorder associated with prolonged or high-dose glucocorticoid exposure. Its development involves local ischemia, oxidative stress, dysregulated bone metabolism, and disruption of the osteoimmune microenvironment. Macrophages exhibit marked phenotypic plasticity, and their polarization is essential for maintaining the dynamic balance among inflammation, angiogenesis, and bone remodeling. Persistent glucocorticoid stimulation, hypoxia, excessive reactive oxygen species, and damage-associated signals released from necrotic tissues can shift macrophages toward a pro-inflammatory phenotype. Classically activated macrophages (M1 macrophages) predominantly mediate inflammatory responses. By releasing tumor necrosis factor-α, interleukin-1β, interleukin-6, and other mediators, promoting osteoclast activation, suppressing the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), and impairing vascular endothelial function, M1 macrophages accelerate trabecular destruction and expansion of the necrotic lesion. In contrast, alternatively activated macrophages (M2 macrophages) contribute to inflammation resolution, neovascularization, osteogenic repair, and tissue remodeling, thereby supporting regeneration within the necrotic region. Macrophage-derived exosomes further influence disease progression through intercellular communication. Exosomes from different macrophage phenotypes can differentially regulate adipogenic differentiation, neutrophil extracellular trap formation, and endothelial phenotypic transition, thereby affecting the repair capacity of the necrotic area. These findings indicate that macrophage polarization shapes the local microenvironment not only through soluble mediators but also through vesicle-mediated communication with BMSCs, neutrophils, endothelial cells, and other cell populations. At the molecular level, the nucleotide-binding domain leucine-rich repeat and pyrin domain-containing receptor 3(NLRP3) inflammasome, nuclear factor kappa B (NF-κB), Janus kinase/signal transducer and activator of transcription (JAK/STAT), and phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathways jointly regulate macrophage polarization and its downstream osteoimmune effects. Dysregulation of these pathways may sustain inflammatory activation, aggravate oxidative and vascular injury, inhibit osteogenesis, and impair tissue repair. NLRP3 inflammasome activation links danger signals and oxidative stress to inflammatory cytokine maturation and pyroptotic injury; NF-κB signaling promotes pro-inflammatory gene transcription and M1 polarization; JAK/STAT signaling participates in the balance between inflammatory and reparative macrophage programs; and PI3K/Akt/mTOR signaling regulates cellular metabolism, survival, autophagy, and regeneration. Notably, the biological effects of PI3K/Akt/mTOR signaling are cell-type dependent, and Akt-mediated repair signaling should be distinguished from mTOR-related autophagy regulation. The pathological significance of macrophage polarization in SANFH is not determined simply by an increase or decrease in a single phenotype. Rather, disease progression appears to result from an imbalance between persistent pro-inflammatory activity and insufficient reparative responses at different stages of the disease. Such an imbalance disrupts the coordinated coupling of inflammation resolution, vascular regeneration, and bone remodeling, ultimately contributing to structural deterioration of the femoral head. This review summarizes the pathological roles, signaling regulation, and exosome-mediated intercellular communication associated with macrophage polarization imbalance in SANFH. A more precise understanding of these mechanisms may clarify the osteoimmune basis of SANFH and support the development of macrophage-targeted interventions. However, most available evidence is derived from cellular and animal studies, and the temporal evolution of macrophage phenotypes in patients remains insufficiently characterized. Therapeutic strategies should therefore move beyond the simple suppression of M1 macrophages or enhancement of M2 macrophages and instead aim to restore a stage-appropriate balance between inflammatory control and tissue repair while promoting angiogenesis and bone reconstruction.

Abstract:Kynurenine pathway (KP) is a major catabolic route of tryptophan, generating a series of bioactive metabolites including kynurenine, kynurenic acid (KA), quinolinic acid, and 3-hydroxykynurenine. Beyond its fundamental role in amino acid metabolism, KP exerts critical regulatory functions in neurodevelopment, synaptic plasticity, and immune modulation. Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental condition with onset in early childhood, characterized by persistent deficits in social communication and restricted, repetitive behaviors. Despite extensive research, the etiological mechanisms underlying ASD remain highly complex and incompletely understood, involving genetic, environmental, and immunological factors. Emerging clinical evidence has consistently revealed a significant imbalance in KP metabolites in individuals with ASD, often accompanied by altered ratios of neuroprotective versus neurotoxic byproducts. However, the primary drivers of this metabolic dysregulation and its causative contribution to ASD pathogenesis are not yet fully elucidated. In this review, we systematically review the enzymatic steps of KP and the principal physiological functions of its major metabolites, with particular emphasis on their dual roles in neuroprotection and neurotoxicity. We then analyze the potential pathogenic mechanisms through which KP dysfunction may contribute to ASD, focusing on two interconnected etiological dimensions. First, KP imbalance can promote oxidative stress, which in turn triggers chronic inflammatory responses via microglial activation and release of pro-inflammatory cytokines, thereby disrupting neuronal homeostasis. Second, aberrant KP metabolism affects neurotransmitter systems, particularly glutamatergic and dopaminergic signaling, leading to impaired neural circuit development and synaptic pruning. By integrating current findings on the KP-ASD association, this review offers a comprehensive etiological framework and a clinically relevant paradigm. Furthermore, we highlight that specific KP metabolites, such as the KA/quinolinic acid ratio, hold promise as peripheral biomarkers for early diagnosis and disease stratification. Finally, we discuss the therapeutic potential of targeting KP enzymes or receptors for personalized intervention strategies, while acknowledging the challenges in translating these findings into clinical practice.

Abstract:Alzheimer’s disease (AD) is pathologically characterized by cerebral amyloid β-protein (Aβ) aggregation, neurofibrillary tangles and progressive cognitive deterioration. There is an urgent clinical demand for targeted therapeutic agents against AD, whereas the blood-brain barrier (BBB) acts as a critical physical barrier that blocks over 98% small-molecule drugs and nearly all biomacromolecules from entering brain parenchyma. Nanomedicine-based drug delivery systems (NDDSs) with tunable physicochemical properties can cross the BBB via multiple transcytosis pathways including adsorptive-mediated, receptor-mediated and transporter-mediated routes, opening a promising avenue for targeted AD treatment. A core academic viewpoint proposed herein is that robust in vitro endothelial penetration of nanocarriers cannot guarantee effective accumulation in brain target cells. Comprehensive evaluation of BBB-crossing delivery efficiency should not merely rely on in vitro permeability tests, but cover the full multi-step transcytosis cascade, cellular tropism in brain tissues and in vivo therapeutic outcomes. This review systematically sorts out diverse nanoplatforms applicable to BBB penetration for AD intervention. Inorganic nanomaterials such as gold and ceria nanoparticles possess large specific surface areas and intrinsic antioxidant capacity, which eliminate reactive oxygen species and hinder Aβ fibrillization. Liposomal formulations and solid lipid nanoparticles exhibit superior biocompatibility with biomimetic phospholipid bilayer architectures, capable of co-loading hydrophilic nucleic acids for Tau regulation and lipophilic Aβ inhibitors; relying on receptor-mediated transcytosis, they achieve sustained drug retention in the brain. Polymeric nanocarriers including nanogels and polyamidoamine dendrimers enable multi-target combinatorial therapy, and can be engineered to release cargo in response to inflammatory microenvironments, thereby suppressing excessive microglial activation and protecting neuronal mitochondria. Beyond conventional nanocarriers, this work elaborates two cutting-edge BBB-crossing delivery platforms: biomimetic nanosystems and metal-organic frameworks (MOFs). Biomimetic nanoparticles camouflaged with erythrocyte, platelet or macrophage membranes, as well as natural exosomes, evade immune clearance, prolong systemic circulation and inherently home to inflammatory lesions. Serving as “nano-decoys”, they neutralize Aβ neurotoxins and remodel cerebral inflammatory microenvironments simultaneously. MOFs feature high porosity and customizable pore channels for co-delivery of multiple therapeutics, and can be integrated with near-infrared photothermal and photooxidation modalities to facilitate focal brain lesion therapy. This review highlights a transformative paradigm shift in the field of BBB-targeted AD therapy: research focus has shifted from simply maximizing cerebral drug penetration toward active modulation and functional restoration of the BBB. Impaired BBB transporters intrinsically impede endogenous Aβ clearance. Accordingly, BBB-regulating nanocarriers are designed to remodel the low-density lipoprotein receptor-related protein 1 (LRP1) trafficking cascade, redirecting endocytic vesicles from lysosomal degradation to non-degradable transcytosis and restoring the intrinsic Aβ efflux capacity of the BBB. Distinct from conventional strategies that only exert local lesion inhibition, this systemic clearance strategy eliminates cerebral Aβ deposits by accelerating peripheral excretion.

Abstract:CRISPR-Cas-based biosensing systems have become important platforms for rapid nucleic acid detection because of their programmable sequence recognition and high specificity. In many diagnostic workflows, the CRISPR reaction is coupled with polymerase chain reaction or isothermal pre-amplification to enrich low-abundance targets before readout. This design improves sensitivity, but it also introduces additional primers and enzymes, requirements for temperature control and reaction compatibility, and a higher demand for contamination management. These factors make the whole assay less convenient for integrated and field-deployable point-of-care testing. Developing pre-amplification-free CRISPR assays is therefore not simply a pursuit of shorter protocols, but a way to simplify molecular diagnosis at the system level, especially in settings where rapid decisions, closed workflows, and minimal manual operation are required. Microfluidic devices provide an important engineering route for this purpose. Their small reaction volumes, precise fluid manipulation, high-throughput partitioning, and compatibility with portable readout make it possible to integrate target confinement, reaction control, signal acquisition, and quantitative analysis on a chip. Droplet microfluidics and microwell arrays can divide a sample into large numbers of independent microreactors, enabling digital counting of rare recognition events. Continuous-flow, centrifugal, and paper-based microfluidic formats further provide options for automated operation, low-cost fabrication, and on-site use. In this context, microfluidics is not only a signal-enhancement method, but also a platform that connects CRISPR molecular recognition with practical assay implementation. This review summarizes recent progress in microfluidic-based pre-amplification-free CRISPR-Cas biosensing for rapid detection. We focus on four related technical directions. crRNA engineering, including spacer-length tuning, multi-crRNA design, chemical modification, and allosteric regulation, can improve recognition kinetics, nuclease stability, and mismatch discrimination. Digital microfluidic detection based on droplets or microwell arrays converts single-molecule recognition events into countable positive partitions, thereby improving quantitative capability without target pre-amplification. Physical signal transduction interfaces couple CRISPR activity to electrochemical, electrochemiluminescent, fluorescent, or surface-enhanced Raman scattering readouts, making weak molecular signals easier to detect with portable instruments. On-chip cascade signal amplification strategies further enhance output intensity through enzymatic reactions, DNA circuits, nanomaterials, or cross-domain amplification modules while avoiding direct amplification of the target nucleic acid. Together, these strategies show that the performance of a pre-amplification-free assay depends not only on biochemical recognition, but also on how the reaction is confined, amplified, transduced, and operated. In addition to describing these mechanisms, this review compares different strategies in terms of sensitivity improvement, operational complexity, cost, and suitability for point-of-care testing. Representative applications in food authenticity identification and rapid pathogen screening are also discussed to illustrate how these platforms perform in practical scenarios. Finally, we analyze the remaining challenges, including the detection of low-abundance targets in complex matrices, on-chip sample preparation, device-to-device reproducibility, long-term reagent storage, and standardization. Future development will likely depend on tighter integration of sample processing, CRISPR reaction, signal readout, and data interpretation, ultimately moving pre-amplification-free CRISPR diagnostics toward automated and user-friendly sample-to-answer systems.

Abstract:Objective To explore the mechanism by which aerobic exercise improves hippocampal neuroinflammation and learning and memory ability in brain-aged mice via interferon regulatory factor 7 (IRF7).Methods A total of 60 male specific pathogen-free (SPF) C57BL/6J mice were enrolled in the experiment, including 30 young mice (2 months old) and 30 naturally aging mice (12 months old). Young mice and old mice were respectively randomly assigned to four groups: young control group (group C, n=15), young exercise group (group CE, n=15), and aging control group (group A, n=15), aging exercise group (group AE, n=15). Mice in the exercise groups received an 8-week continuous treadmill aerobic exercise intervention, while control mice were kept under routine feeding without exercise intervention. After the intervention, Barnes maze and Y-maze behavioral tests were performed to comprehensively assess the learning and memory abilities of each group of mice. Transmission electron microscopy was used to observe the ultrastructural morphological changes of hippocampal synapses. Western blot assay was utilized to detect the protein expression and phosphorylation levels of Janus kinase 1 (JAK1), signal transducer and activator of transcription 1 (STAT1), as well as the expression of postsynaptic density protein 95 (PSD95). Immunofluorescence staining was applied to quantify the fluorescence intensity of ionized calcium-binding adapter molecule 1 (IBA1) in hippocampal tissues. The expression levels of inflammatory cytokines including interferon-α (IFN-α), interferon-β (IFN-β), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured by enzyme-linked immunosorbent assay (ELISA). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the mRNA expression level of IRF7, and DNA methylation assay was further conducted to analyze the methylation level of the IRF7 gene in mouse hippocampus.Results At the molecular level, compared with group C, the protein expression levels of JAK1, STAT1, p-JAK1, and p-STAT1 in group A were significantly increased (P<0.05), whereas PSD95 expression was decreased (P<0.05). ELISA assays showed that the levels of IFN-α, IFN-β, TNF-α, and IL-1β were significantly elevated in group A (P<0.001). RT-PCR analysis revealed that, compared with group C, the mRNA expression of IRF7 in group A was markedly upregulated (P<0.000 1), while the CpG methylation rate of the IRF7 promoter was significantly reduced (P<0.05). In contrast, all the above parameters in the AE group showed improvements reletive to those in group A. Immunofluorescence staining indicated positive IBA1 expression in the brain tissues of group A mice. Exercise intervention reversed these abnormal changes.Conclusion In aged mice, aerobic exercise induces hypermethylation of the IRF7 promoter region, suppresses IRF7 expression and activation of the downstream IFN-I/JAK1/STAT1 signaling pathway, accompanied by alleviated neuroinflammation, improved learning and memory, and ameliorated brain aging-related phenotypes.

Abstract:Objective Colorectal cancer (CRC) is a highly heterogeneous malignancy, and traditional Chinese medicine (TCM) syndrome differentiation is widely used in its clinical management. However, the biological basis underlying different TCM syndromes remains insufficiently understood. This study aimed to investigate the proteomic differences between qi-blood deficiency syndrome (QBDS) and damp-heat syndrome (DHS) in CRC patients and to establish a “syndrome-differential protein-herbal component” network for exploring potential molecular mechanisms and therapeutic targets associated with syndrome-specific treatment strategies.Methods Tumor tissue samples were collected from 10 patients with pathologically confirmed CRC, including 5 patients diagnosed with QBDS and 5 with DHS according to standardized TCM syndrome differentiation criteria. Tandem mass tag (TMT)-based quantitative proteomics was employed to identify differentially expressed proteins (DEPs) between the two syndrome groups. Functional enrichment analyses, including Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, were performed to characterize the biological functions and signaling pathways associated with the identified DEPs. Least absolute shrinkage and selection operator (LASSO) regression analysis was further applied to screen key syndrome-related proteins and construct a core protein prediction model. Subsequently, molecular docking was conducted to evaluate the binding affinities between representative herbal compounds, astragaloside IV and berberine, and the identified core proteins. Finally, cell counting kit-8 (CCK-8) assays were performed in HCT 116 and HT-29 colorectal cancer cell lines to validate the anti-proliferative activities of these compounds in vitro.Results A total of 44 DEPs were identified between QBDS and DHS tissues, including 21 upregulated and 23 downregulated proteins in the QBDS group relative to the DHS group. Functional enrichment analyses revealed that these proteins were primarily associated with antiviral immune responses, regulation of inflammatory signaling, NF-κB signaling pathways, cholesterol metabolism, and other biological processes relevant to tumor progression and host immune regulation. LASSO regression analysis identified eight core proteins with potential syndrome-specific significance. Among them, ST7, GPCPD1, and PODXL were closely associated with QBDS, whereas FAT1, GRB7, KRT7, MAFF, and MMP8 were associated with DHS. Molecular docking demonstrated favorable interactions between astragaloside IV and QBDS-related proteins, with binding energies lower than -5 kcal/mol, indicating stable binding activity. Berberine exhibited even lower binding energies and stronger binding specificity toward DHS-related core proteins. In vitro experiments further confirmed that both compounds inhibited CRC cell proliferation, while berberine displayed significantly greater anti-proliferative efficacy. The lowest 48 h IC₅₀ value of berberine reached 15.21 mg/L in CRC cells, indicating a stronger growth-inhibitory effect than astragaloside IV.Conclusion CRC patients with QBDS and DHS exhibit distinct proteomic characteristics, suggesting that different TCM syndromes possess unique molecular signatures. The identified core proteins may serve as potential biomarkers for syndrome differentiation, while astragaloside IV and berberine may exert therapeutic effects through targeting syndrome-specific molecular networks. These findings provide preliminary proteomic evidence supporting syndrome-guided precision integrative medicine in CRC and offer new insights into the biological basis of TCM syndrome differentiation and individualized therapeutic strategies.

Abstract:Objective To address the key challenges in breast electrical impedance tomography (EIT) reconstruction including the severe ill-posedness of the inverse problem, limited measurement information from the electrodes, low contrast of small lesions, as well as the common drawbacks of traditional reconstruction methods such as boundary blurring, low spatial resolution, and weak small-target detection capability, and to overcome the limitations of existing deep learning approaches namely low training efficiency, insufficient physical consistency, and substantial information loss during the low-to-high dimensional mapping process, this study proposes a multi-scale attention and dynamic sparse mask fusion network (MADS-Net). The proposed method aims to enhance high-resolution reconstruction accuracy, small-lesion detectability, noise robustness, and computational efficiency in breast-screening-oriented EIT, thereby providing a feasible solution for the application of EIT in breast functional imaging.Methods The proposed network adopts a strategy of “locate first, reconstruct later”. It realizes adaptive allocation of computational resources through a dynamic mask module, alleviates information loss in the low-to-high dimensional mapping process via a multi-scale attention mechanism, and embeds physical constraints to improve the physical rationality of reconstruction results. The performance of the proposed method was validated through systematic numerical simulations, agar phantom experiments, and porcine tissue experiments. Comparisons were made with mainstream methods including the Gauss-Newton algorithm, convolutional neural networks, U-Net, and Deep D-Bar. The image correlation coefficient (ICC), root mean square error (RMSE), and peak signal-to-noise ratio (PSNR) were adopted as quantitative evaluation metrics. Furthermore, lesion-level evaluation metrics were introduced to assess the capability of different methods in reconstructing abnormal target boundaries and small-sized target regions.Results Experimental results demonstrate that MADS-Net outperforms all comparison methods across all test scenarios. In numerical simulations, it achieves higher accuracy in target morphology and spatial location recovery as well as better background suppression. In agar phantom experiments, its detection and imaging reliability for small targets is significantly superior to the comparison methods. In porcine tissue experiments, the model maintains good generalization performance and can adapt to complex biological tissue imaging scenarios. Quantitative results show that MADS-Net achieves an average ICC of 0.917 6±0.048 8, an RMSE as low as 0.060 6±0.031 6, and a PSNR of (23.893 9±2.685 3) dB. It successfully detects tiny targets as small as 5 mm within a 100 mm diameter sensing field, reduces the total training duration by 23.5% compared with the baseline method, and maintains stable reconstruction performance even under strong noise interference.Conclusion The results demonstrate that MADS-Net achieves favorable EIT reconstruction performance in numerical simulations, agar phantom experiments, and porcine tissue experiments, even under common practical imaging challenges including low signal-to-noise ratio and blurred tissue boundaries. This study provides a methodological reference for further research on EIT in breast-screening-related scenarios and other medical functional imaging tasks, and also offers a low-cost, radiation-free alternative for breast lesion screening that aligns with the clinical demand for non-invasive diagnostic tools. It should be noted that real clinical breast data have not yet been used for validation in this study, and the clinical applicability of the proposed method requires further investigation. Future work will prioritize collecting multi-center real clinical breast datasets, and further optimize the model’s generalization ability to adapt to individual differences in breast tissue composition to promote its clinical application.

Abstract:Objective Oxygen partial pressure (pO₂) is a critical indicator of the tumor microenvironment and plays an essential role in regulating tumor progression and therapeutic response, particularly for oxygen-dependent treatments such as photodynamic therapy (PDT). Although photoacoustic imaging (PAI) has shown great potential for functional and molecular imaging, conventional oxygenation imaging approaches based on hemoglobin absorption mainly provide relative oxygen saturation information and cannot directly quantify tissue oxygen partial pressure. Therefore, this study aimed to develop a fast laser sequence-based pump-probe photoacoustic tomography (PP-PAT) system for quantitative, non-invasive, and dynamic monitoring of oxygen partial pressure in tumor tissues.Methods The proposed PP-PAT system was developed based on the oxygen-sensitive triplet-state lifetime characteristics of methylene blue (MB). Upon optical excitation, MB molecules undergo transitions from the ground state to an excited state and subsequently form metastable triplet states through intersystem crossing. The lifetime of the triplet state is strongly affected by surrounding oxygen concentration due to dynamic oxygen quenching, providing a direct correlation between triplet-state kinetics and local oxygen partial pressure. A dual-wavelength pump-probe excitation scheme was implemented to selectively interrogate MB triplet-state dynamics. The pump pulse was used to initiate the triplet-state population, while the delayed probe pulse was applied to detect the transient triplet-state response. By optimizing the temporal interval between the pump and probe pulses, transient triplet-state differential (TTD) signals were extracted to enhance the specificity of oxygen-dependent molecular information and suppress background interference from conventional photoacoustic signals. The performance of the PP-PAT system was systematically evaluated through phantom and in vivo experiments. First, a single-tube phantom containing MB solution was used to investigate signal stability, reproducibility, and the influence of signal averaging on imaging quality. Subsequently, a dual-tube phantom model was established to simulate oxygen consumption during PDT, where one MB-containing tube was exposed to laser irradiation and the other served as a control. Finally, in vivo experiments were performed using a subcutaneous tumor model in nude mice. MB was locally injected into the tumor region before imaging to evaluate the feasibility of tumor oxygen partial pressure mapping using the proposed PP-PAT system.Results Phantom experiments demonstrated that the extracted TTD signals exhibited high stability and effectively reflected MB triplet-state dynamics while reducing non-specific background contributions. Signal averaging significantly improved the signal-to-noise ratio, and 50 repeated acquisitions provided an optimal compromise between image quality and acquisition efficiency. In the dual-tube phantom experiments, continuous PDT irradiation induced progressive oxygen depletion in the treated sample. The corresponding TTD decay rate gradually decreased, accompanied by an increase in the calculated triplet-state lifetime, indicating reduced oxygen quenching and decreased oxygen partial pressure. In contrast, the control sample showed relatively stable TTD kinetics and oxygenation levels during the same period. These results demonstrated that PP-PAT could quantitatively characterize oxygen consumption dynamics associated with photochemical reactions. In vivo experiments further demonstrated the capability of PP-PAT for spatially resolved oxygen partial pressure imaging in MB-injected tumor tissues. The reconstructed pO₂ maps revealed heterogeneous oxygen distributions within tumors, showing relatively hypoxic regions in the tumor core and higher oxygenation levels near the tumor boundary. This spatial oxygen distribution pattern was consistent with the typical physiological characteristics of solid tumors, where abnormal vascular structures and limited oxygen diffusion result in intratumoral oxygen gradients.Conclusion This study presents a fast laser sequence-based PP-PAT system capable of quantitative and non-invasive imaging of tissue oxygen partial pressure. By utilizing the oxygen-dependent triplet-state lifetime of MB and extracting TTD signals, the proposed method provides molecularly specific information related to oxygen dynamics beyond conventional photoacoustic oxygenation imaging. The system enables dynamic monitoring of oxygen consumption during PDT and reveals spatial oxygen heterogeneity within tumors. This technique provides a promising imaging approach for tumor hypoxia characterization, evaluation of oxygen-dependent therapeutic responses, and precision-guided cancer treatment.

Abstract:Enhancer-promoter communication is fundamental to the spatial and temporal control of gene expression. Cohesin-mediated loop extrusion has long been considered a major structural mechanism that brings distal regulatory elements into proximity with their target promoters. Recent findings from Aboreden et al. refine this view by showing that depletion of Nipped-B-like protein (NIPBL), a key regulator of cohesin loading and loop extrusion, markedly disrupts architectural chromatin loops, whereas many cis-regulatory contacts and broad post-mitotic transcriptional reactivation are only modestly affected. These observations suggest that loop extrusion is important, but not sufficient, for explaining productive regulatory communication. In this Comment, we discuss how transcriptional condensate-like assemblies may provide an additional biochemical and kinetic layer that helps convert regulatory proximity into transcriptional output. By locally enriching transcription factors, coactivators, mediator and RNA polymerase II (Pol II) around active loci, such regulatory hubs may stabilize productive enhancer-promoter encounters and modulate transcriptional activity. We further propose that transcriptional bursting provides a useful framework for understanding this conversion, because gene expression can be decomposed into burst frequency, burst duration and burst size. Integrating chromatin architecture, condensate organization and bursting dynamics may therefore provide a more complete view of how enhancer-promoter communication is re-established after mitosis and how regulatory proximity is converted into transcriptional output through mechanisms beyond loop extrusion.

Abstract:While pooled CRISPR screens have revolutionized functional genomics by enabling genome-scale interrogation, they have long faced a fundamental compatibility challenge with high-resolution microscopy-based phenotypes. The core issue lies in the technical disconnect between pooled screening formats, where cells are typically analyzed in bulk populations, and microscopy approaches that require spatial resolution and single-cell visualization. This limitation has created a significant blind spot in functional genomics, preventing researchers from systematically linking genetic perturbations to detailed subcellular architectural changes. To bridge this critical technological gap, a recent landmark study published in Developmental Cell has unveiled an integrated microscopy-based CRISPR screening platform that represents a paradigm shift in the field. The most innovative breakthrough of the platform involves extending photoactivation-based labeling techniques to fixed, immunostained cells, thereby overcoming a key limitation of prior approaches that were restricted exclusively to live-cell reporter systems. This methodological advancement allows researchers to capture transient cellular states and preserve delicate subcellular structures that would otherwise be lost in live-cell imaging scenarios. By seamlessly integrating this enhanced labeling approach with sophisticated automated imaging workflows and high-content analysis pipelines, the system enables unprecedented high-throughput, organelle-level phenotypic profiling at true single-cell resolution. The platform’s capabilities were demonstrated through its application to a comprehensive genome-wide screen for regulators of cilium assembly, a complex cellular process involving intricate cytoskeletal dynamics and membrane remodeling events. The screening results validated the platform’s robustness by successfully recapitulating known ciliary machinery components while simultaneously uncovering novel regulatory factors. Most notably, the study identified SMIM27/TZMP1, a conserved transition zone microprotein, as a previously unrecognized regulator of ciliary function. This discovery provides crucial insights into the molecular mechanisms governing ciliary transition zone barrier formation and selectivity. This accessible and versatile framework effectively overcomes longstanding bottlenecks in microscopy-based screening technologies, offering a generalizable strategy for dissecting organelle biology and cellular architecture at scale. The platform’s ability to combine genome-wide screening power with detailed morphological analysis opens new avenues for investigating cellular responses to genetic perturbations across diverse biological contexts.

Abstract:Regulated cell death (RCD) has long been conceptualized as an elaborate program orchestrated by the nucleus and mitochondria in eukaryotic cells. However, this paradigm was fundamentally changed in 2025 by two independent studies published in Cell. One revealed that mature, enucleated erythrocytes execute a cytoskeletal disintegration-driven lysis via a miniNLRP3-ASC-caspase-8-β-spectrin axis, termed spectrin-dependent death (spectosis), wherein caspase-8 undergoes a functional switch from an initiator to an executioner, reflecting an evolutionary adaptation in protein economy. The other uncovered mitoxypterilysis, a modality in which metabolic distress and innate immune signals converge to trigger mTORC2-mediated aberrant mitochondrial-plasma membrane contacts, culminating in localized lipid peroxidation and membrane rupture. Mitoxypterilysis shows a logic defined by dual metabolic-immune regulation. This paper systematically dissects the molecular architectures of both modalities, and through comparative analysis, delineates their distinctions from classical RCD pathways as well as their divergent dependencies on organellar integrity, triggering contexts, and executional programs. In parallel, we integrate the recent discovery of reductive death, which underscores a central metabolic checkpoint to contextualize these findings within an emerging framework. Finally, we evaluate their therapeutic implications in hemolytic diseases, oncology, and inflammatory pathologies, while critically reflecting on current limitations and future directions, with the aim of providing a renewed conceptual foundation for targeted intervention strategies.