Extracellular Matrix Structure Research Articles

Perineuronal nets are phagocytosed by MMP-9 expressing microglia and astrocytes in the SOD1G93A ALS mouse model.

Perineuronal nets (PNNs) are an extracellular matrix structure that encases excitable neurons. PNNs play a role in neuroprotection against oxidative stress. Oxidative stress within motor neurons can trigger neuronal death, which has been implicated in amyotrophic lateral sclerosis (ALS). We investigated the spatio-temporal timeline of PNN breakdown and the contributing cellular factors in the SOD1G93A strain, a fast-onset ALS mouse model. This was conducted at the presymptomatic (P30), onset (P70), mid-stage (P130), and end-stage disease (P150) using immunofluorescent microscopy, as this characterisation has not been conducted in the SOD1G93A strain. We observed a significant breakdown of PNNs around α-motor neurons in the ventral horn of onset and mid-stage disease SOD1G93A mice compared with wild-type controls. This was observed with increased numbers of microglia expressing matrix metallopeptidase-9 (MMP-9), an endopeptidase that degrades PNNs. Microglia also engulfed PNN components in the SOD1G93A mouse. Further increases in microglia and astrocyte number, MMP-9 expression, and engulfment of PNN components by glia were observed in mid-stage SOD1G93A mice. This was observed with increased expression of fractalkine, a signal for microglia engulfment, within α-motor neurons of SOD1G93A mice. Following PNN breakdown, α-motor neurons of onset and mid-stage SOD1G93A mice showed increased expression of 3-nitrotyrosine, a marker for protein oxidation, which could render them vulnerable to death. Our observations suggest that increased numbers of MMP-9 expressing glia and their subsequent engulfment of PNNs around α-motor neurons render these neurons sensitive to oxidative damage and eventual death in the SOD1G93A ALS model mouse.

Modification of extracellular matrix proteins by oxidants and electrophiles.

The extracellular matrix (ECM) is critical to biological architecture and determines cellular properties, function and activity. In many situations it is highly abundant, with collagens and elastin being some of the most abundant proteins in mammals. The ECM comprises of multiple different protein species and sugar polymers, with both different isoforms and post-translational modifications (PTMs) providing a large variety of microenvironments that play a key role in determining tissue structure and health. A number of the PTMs (e.g. cross-links) present in the ECM are critical to integrity and function, whereas others are deleterious to both ECM structure and associated cells. Modifications induced by reactive oxidants and electrophiles have been reported to accumulate in some ECM with increasing age. This accumulation can be exacerbated by disease, and in particular those associated with acute or chronic inflammation, obesity and diabetes. This is likely to be due to higher fluxes of modifying agents in these conditions. In this focused review, the role and effects of oxidants and other electrophiles on ECM are discussed, with a particular focus on the artery wall and atherosclerotic cardiovascular disease. Modifications generated on ECM components are reviewed, together with the effects of these species on cellular properties including adhesion, proliferation, migration, viability, metabolic activity, gene expression and phenotype. Increasing data indicates that ECM modifications are both prevalent in human and mammalian tissues and play an important role in disease development and progression.

Non-TGFβ profibrotic signaling in ulcerative colitis after in vivo experimental intestinal injury in humans.

Although impaired regeneration is important in many gastrointestinal diseases including ulcerative colitis (UC), the dynamics of mucosal regeneration in humans are poorly investigated. We have developed a model to study these processes in vivo in humans. Epithelial restitution (ER) and extracellular matrix (ECM) regulation after an experimental injury of the sigmoid colonic mucosa was assessed by repeated high resolution endoscopic imaging, histologic assessment, RNA sequencing, deconvolution analysis, and 16S rDNA sequencing of the injury niche microbiome of 19 UC patients in remission and 20 control subjects. Human ER had a 48-hour lag before induction of regenerative epithelial cells (WAE and TA cells) along with increase of fibroblast derived stem cell growth factor Gremlin 1 mRNA (GREM1). However, in UC deconvolution data showed aby rapid induction of inflammatory fibroblasts, and upregulation of major structural ECM collagen mRNAs and along with tissue inhibitor of metalloproteinase 1 (TIMP1) suggesting increased profibrotic ECM deposition. No change was seen in transforming growth factor β (TGFβ) mRNA whereas and the profibrotic cytokines interleukin 13 (IL13) and IL11 were upregulated in UC suggesting that human post injury responses could be TGFβ-independent. In conclusion, we found distinct regulatory layers of regeneration in the normal human colon and a potential targetable profibrotic dysregulation in UC that could lead to long-term end organ failure - i.e., intestinal damage.

Cyclic amplification of remodeling bone regeneration process via cerium-energized spinning hydrogel biomembrane for rescuing osteoporotic bone defects

The heightened activity of osteoclasts and diminished function of osteoblasts observed in individuals with osteoporosis present additional complexities in the management of critical bone defects. Consequently, an improved approach is urgently required to enhance bone regeneration in patients with osteoporosis. Our effective strategy involves the integration of hydrogels with spinning membrane technology, and accurately replicates the composition and structure of the native extracellular matrix found in periosteum tissues. Cerium, as a substitute for conventional protein growth factors, facilitates osteogenic differentiation and angiogenesis in stem cells, concurrently impeding bone resorption. In this study, we successfully synthesized a biomimetic electrospun hydrogel periosteum, grafted cerium ions onto the membrane via non-covalently bound phosphate, and achieved cyclic amplification of bone regeneration. This approach represents a pioneering and efficient utilization of tissue-engineered bionic periosteum to address osteoporotic bone defects.

Collagen peptides affect collagen synthesis and the expression of collagen, elastin, and versican genes in cultured human dermal fibroblasts.

Collagen is one of the major proteins of the skin and it is particularly important for its strength and resilience. Skin aging is a natural process that is characterized by the decrease and fragmentation of collagen in the dermis. Oral supplementation with collagen peptides has been clinically shown to have a positive effect on the skin condition. However, the mechanisms of aging-related changes synthesized by cells exposed to collagen are currently not well understood. Therefore, in this in vitro study, the mechanisms associated with collagen, elastin, and versican in human dermal fibroblasts were investigated after exposure to collagen peptides. The effects of different concentrations of collagen peptides on cell viability and metabolism were analyzed. For gene expression analysis, human dermal fibroblasts were treated with collagen peptides. This was then followed by RNA extraction and DNA synthesis. Gene expressions of collagen type 1 (COL1A1), elastin (ELN), and versican (VCAN) were quantified by quantitative reverse transcription polymerase chain reaction (RT-qPCR). In addition, collagen levels were analyzed by confocal scanning laser microscopy using immunostaining. Collagen peptides tested in the study increased the expression of the relevant COL1A1, ELN, and VCAN genes in human dermal fibroblasts (p < 0.005). Furthermore, confocal microscopy showed increased collagen expression in the dermal fibroblast culture after treatment with the collagen peptides (p < 0.005). These data provide cell-based evidence for the beneficial effects of exposure to collagen peptides on the skin's collagen content and on the molecules that provide firmness and elasticity. This may support the hypothesis that collagen peptides are important for maintaining extracellular matrix (ECM) structure and skin regeneration.

Viable Vitreous Grafts of Whole Porcine Menisci for Transplant in the Knee and Temporomandibular Joints.

The shortage of suitable donor meniscus grafts from the knee and temporomandibular joint (TMJ) impedes treatments for millions of patients. Vitrification offers a promising solution by transitioning these tissues into a vitreous state at cryogenic temperatures, protecting them from ice crystal damage using high concentrations of cryoprotectant agents (CPAs). However, vitrification's success is hindered for larger tissues (>3 mL) due to challenges in CPA penetration. Dense avascular meniscus tissues require extended CPA exposure for adequate penetration; however, prolonged exposure becomes cytotoxic. Balancing penetration and reducing cell toxicity is required. To overcome this hurdle, a simulation-based optimization approach is developed by combining computational modeling with microcomputed tomography (µCT) imaging to predict 3D CPA distributions within tissues over time accurately. This approach minimizes CPA exposure time, resulting in 85% viability in 4-mL meniscal specimens, 70% in 10-mL whole knee menisci, and 85% in 15-mL whole TMJ menisci (i.e., TMJ disc) post-vitrification, outperforming slow-freezing methods (20%-40%), in a pig model. The extracellular matrix (ECM) structure and biomechanical strength of vitreous tissues remain largely intact. Vitreous meniscus grafts demonstrate clinical-level viability (≥70%), closely resembling the material properties of native tissues, with long-term availability for transplantation. The enhanced vitrification technology opens new possibilities for other avascular grafts.

Oct4 controls basement membrane development during human embryogenesis

Basement membranes (BMs) are sheet-like structures of extracellular matrix (ECM) that provide structural support for many tissues and play a central role in signaling. They are key regulators of cell behavior and tissue functions, and defects in their assembly or composition are involved in numerous human diseases. Due to the differences between human and animal embryogenesis, ethical concerns, legal constraints, the scarcity of human tissue material, and the inaccessibility of the invivo condition, BM regulation during human embryo development has remained elusive. Using the post-implantation amniotic sac embryoid (PASE), we delineate BM assembly upon post-implantation development and BM disassembly during primitive streak (PS) cell dissemination. Further, we show that the transcription factor Oct4 regulates the expression of BM structural components and receptors and controls BM development by regulating Akt signaling and the small GTPase Rac1. These results represent a relevant step toward a more comprehensive understanding of early human development.

Abstract 1505: Unraveling diepafitaxis: Investigating ECM stiffness and microarchitecture in tumor spheroid migration

Abstract Background: Metastasis, accounting for up to 90% of cancer-related deaths, remains one of the least understood aspects of cancer progression. Recent research has shifted focus from solely biological hallmarks to the physical characteristics of cancer, such as the stiffness and microarchitecture of the extracellular matrix (ECM), which play pivotal roles in metastatic advancement. We previously introduced the concept of 'diepafitaxis' to describe a unique mechanism driving the interface-mediated tropism of tumor spheroids at matrix-surface boundaries. This phenomenon suggests that cancer cells preferentially migrate along a 2D 'interfacial' track formed by heterogeneous 3D ECM structures, facilitating invasion and dispersion. However, the exact mechanisms by which interfacial components, stiffness, and structural attributes influence cell movement remain debated. To investigate this, we have developed a microfluidic chip with a precisely controlled stiffness of the hydrogel matrix-matrix interface (MMI), aiming to shed light on specific diepafitatic behaviors. Method: We developed a polydimethylsiloxane (PDMS)-based microfluidic chip using a traditional photolithographic process. This chip features three channels, with the center channel designed to precisely control various MMI stiffness combinations: stiff vs soft (t-o), stiff vs stiff (t-t) and soft vs soft (o-o). MDA-MB-231 breast cancer spheroids (BCS), representing an in vitro tumor model, were embedded in the top gel. We observed the dynamic behavior of these cancer spheroids over a 24-h period using differential interference contrast (DIC) microscopy. Result: The study revealed that BCS exhibited more pronounced dispersion in a soft homogeneous ECM compared to a stiff ECM in 3D environments. Interestingly, when BCS were near an MMI, a stiffer MMI (t-t) significantly enhanced BCS invasiveness and single-cell migration, more so than t-o, and notably more than o-o. We previously described this phenomenon as '2.5D migration,' where cells migrate in a ventral 2D manner within a sandwiched 3D gel structure. This diepafitatic behavior was further analyzed for its response to gravitational effects and the influence of chemotaxis, induced by introducing VEGF on one side of the microfluidic channel. Conclusion: Conclusively, our study demonstrates that the stiffness and structure of the ECM, particularly at MMI, significantly influence the invasive behavior and migration patterns of BCS, underscoring the critical role of mechanical microenvironments in cancer metastasis. Citation Format: Hsiang-Pei Chen, Ya-Chu Tsai, Ting-Yuan Tu. Unraveling diepafitaxis: Investigating ECM stiffness and microarchitecture in tumor spheroid migration [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1505.

Abstract 4275: Targeting tumor extracellular matrix to improve response to therapy

Abstract Introduction. Building on our previous findings that tumor extracellular matrix (ECM) composition associates with immune cell phenotype (Pearce et al, Cancer Disco, 2018), and ECM can directly educate tumor-associated immune phenotypes (Puttock et al, Nat Commun, 2023), we present here the identification of specific ECM components that associate with tumor immune phenotype, and discuss our approach to target these components as a way to improve anti-tumor immunity and immunotherapy response. Methods. We use a combination of transcriptomics, proteomics, glycomics, and spatial tissue analysis to identify correlations between ECM composition and the immune landscape in breast and ovarian cancers. Correlations are tested within a decellularized tumor model made from patient samples which allow immune cell movement, interaction with ECM, and tumor killing to be measured in real-time. Results. Through our analysis pipeline we have identified a specific ECM molecule that appears to regulate the spatial location of tumor infiltrating CD8 T-cell populations via post-translational modifications that are present on the molecule. Deletion of this molecule in injectable orthotopic murine models dramatically alters the immune landscape within the tumor. Within an in vitro decellularized tumor tissue model the in situ deletion of the ECM molecule drives tumors into an inflamed phenotype which is more responsive to cell-based cancer therapy. Conclusions. Tumor ECM can direct immunity in two ways. These are educating or stimulating immune cells to develop specific phenotypes that tend to be immunosuppressive, and secondly directing the movement of cells within the tissue. These immunosupressive effects can be overcome through small modifications to ECM structure, indicating therapeutics that make subtle changes to ECM composition may be used in combination with current cell-based therapies to improve tumor response. Citation Format: Oliver Matthew Pearce. Targeting tumor extracellular matrix to improve response to therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4275.

Genetic contribution to microglial activation in schizophrenia.

Several lines of evidence indicate the involvement of neuroinflammatory processes in the pathophysiology of schizophrenia (SCZ). Microglia are brain resident immune cells responding toward invading pathogens and injury-related products, and additionally, have a critical role in improving neurogenesis and synaptic functions. Aberrant activation of microglia in SCZ is one of the leading hypotheses for disease pathogenesis, but due to the lack of proper human cell models, the role of microglia in SCZ is not well studied. We used monozygotic twins discordant for SCZ and healthy individuals to generate human induced pluripotent stem cell-derived microglia to assess the transcriptional and functional differences in microglia between healthy controls, affected twins and unaffected twins. The microglia from affected twins had increased expression of several common inflammation-related genes compared to healthy individuals. Microglia from affected twins had also reduced response to interleukin 1 beta (IL1β) treatment, but no significant differences in migration or phagocytotic activity. Ingenuity Pathway Analysis (IPA) showed abnormalities related to extracellular matrix signaling. RNA sequencing predicted downregulation of extracellular matrix structure constituent Gene Ontology (GO) terms and hepatic fibrosis pathway activation that were shared by microglia of both affected and unaffected twins, but the upregulation of major histocompatibility complex (MHC) class II receptors was observed only in affected twin microglia. Also, the microglia of affected twins had heterogeneous response to clozapine, minocycline, and sulforaphane treatments. Overall, despite the increased expression of inflammatory genes, we observed no clear functional signs of hyperactivation in microglia from patients with SCZ. We conclude that microglia of the patients with SCZ have gene expression aberrations related to inflammation response and extracellular matrix without contributing to increased microglial activation.

A single laccase acts as a key component of environmental sensing in a broad host range fungal pathogen

Secreted laccases are important enzymes on a broad ecological scale for their role in mediating plant-microbe interactions, but within ascomycete fungi these enzymes have been primarily associated with melanin biosynthesis. In this study, a putatively secreted laccase, Sslac2, was characterized from the broad-host-range plant pathogen Sclerotinia sclerotiorum, which is largely unpigmented and is not dependent on melanogenesis for plant infection. Gene knockouts of Sslac2 demonstrate wide ranging developmental phenotypes and are functionally non-pathogenic. These mutants also displayed indiscriminate growth behaviors and enhanced biomass formation, seemingly as a result of their inability to respond to canonical environmental growth cues, a phenomenon further confirmed through chemical stress, physiological, and transcriptomic analyses. Transmission and scanning electron microscopy demonstrate apparent differences in extracellular matrix structure between WT and mutant strains that likely explain the inability of the mutants to respond to their environment. Targeting Sslac2 using host-induced gene silencing significantly improved resistance to S. sclerotiorum, suggesting that fungal laccases could be a valuable target of disease control. Collectively, we identified a laccase critical to the development and virulence of the broad-host-range pathogen S. sclerotiorum and propose a potentially novel role for fungal laccases in modulating environmental sensing.

Perineuronal Nets in the CNS: Architects of Memory and Potential Therapeutic Target in Neuropsychiatric Disorders.

The extracellular matrix (ECM) within the brain possesses a distinctive composition and functionality, influencing a spectrum of physiological and pathological states. Among its constituents, perineuronal nets (PNNs) are unique ECM structures that wrap around the cell body of many neurons and extend along their dendrites within the central nervous system (CNS). PNNs are pivotal regulators of plasticity in CNS, both during development and adulthood stages. Characterized by their condensed glycosaminoglycan-rich structures and heterogeneous molecular composition, PNNs not only offer neuroprotection but also participate in signal transduction, orchestrating neuronal activity and plasticity. Interfering with the PNNs in adult animals induces the reactivation of critical period plasticity, permitting modifications in neuronal connections and promoting the recovery of neuroplasticity following spinal cord damage. Interestingly, in the adult brain, PNN expression is dynamic, potentially modulating plasticity-associated states. Given their multifaceted roles, PNNs have emerged as regulators in the domains of learning, memory, addiction behaviors, and other neuropsychiatric disorders. In this review, we aimed to address how PNNs contribute to the memory processes in physiological and pathological conditions.

Single-cell RNA sequencing reveals critical modulators of extracellular matrix of penile cavernous cells in erectile dysfunction

Erectile dysfunction (ED) is a common and difficult to treat disease, and has a high incidence rate worldwide. As a marker of vascular disease, ED usually occurs in cardiovascular disease, 2–5 years prior to cardiovascular disease events. The extracellular matrix (ECM) network plays a crucial role in maintaining cardiac homeostasis, not only by providing structural support, but also by promoting force transmission, and by transducing key signals to intracardiac cells. However, the relationship between ECM and ED remains unclear. To help fill this gap, we profiled single-cell RNA-seq (scRNA-seq) to obtain transcriptome maps of 82,554 cavernous single cells from ED and non-ED samples. Cellular composition of cavernous tissues was explored by uniform manifold approximation and projection. Pseudo-time cell trajectory combined with gene enrichment analysis were performed to unveil the molecular pathways of cell fate determination. The relationship between cavernous cells and the ECM, and the changes in related genes were elucidated. The CellChat identified ligand-receptor pairs (e.g., PTN-SDC2, PTN-NCL, and MDK-SDC2) among the major cell types in the cavernous tissue microenvironment. Differential analysis revealed that the cell type-specific transcriptomic changes in ED are related to ECM and extracellular structure organization, external encapsulating structure organization, and regulation of vasculature development. Trajectory analysis predicted the underlying target genes to modulate ECM (e.g., COL3A1, MDK, MMP2, and POSTN). Together, this study highlights potential cell–cell interactions and the main regulatory factors of ECM, and reveals that genes may represent potential marker features of ED progression.

Gelatin-/Alginate-Based Hydrogel Scaffolds Reinforced with TiO2 Nanoparticles for Simultaneous Release of Allantoin, Caffeic Acid, and Quercetin as Multi-Target Wound Therapy Platform.

This study proposes synthesis and evaluation of gelatin-/alginate-based hydrogel scaffolds reinforced with titanium dioxide (TiO2) nanoparticles which, through their combination with allantoin, quercetin, and caffeic acid, provide multi-target therapy directed on all phases of the wound healing process. These scaffolds provide the simultaneous release of bioactive agents and concurrently support cell/tissue repair through the replicated structure of a native extracellular matrix. The hydrogel scaffolds were synthesized via a crosslinking reaction using EDC as a crosslinker for gelatin. Synthesized hydrogel scaffolds and the effect of TiO2 on their properties were characterized by structural, mechanical, morphological, and swelling properties, and the porosity, wettability, adhesion to skin tissue, and simultaneous release features. The biocompatibility of the scaffolds was tested in vitro on fibroblasts (MRC5 cells) and in vivo (Caenorhabditis elegans) in a survival probe. The scaffolds revealed porous interconnected morphology, porosity of 88.33 to 96.76%, elastic modulus of 1.53 to 4.29 MPa, full hydrophilicity, favorable skin adhesivity, and biocompatibility. The simultaneous release was investigated in vitro indicating dependence on the scaffold's composition and type of bioactive agents. The novel scaffolds designed as multi-target therapy have significant promise for improved wound healing in a beneficial and non-invasive manner.

Exploring Extracellular Matrix Crosslinking as a Therapeutic Approach to Fibrosis.

The extracellular matrix (ECM) provides structural support for tissues and regulatory signals for resident cells. ECM requires a careful balance between protein accumulation and degradation for homeostasis. Disruption of this balance can lead to pathological processes such as fibrosis in organs across the body. Post-translational crosslinking modifications to ECM proteins such as collagens alter ECM structure and function. Dysregulation of crosslinking enzymes as well as changes in crosslinking composition are prevalent in fibrosis. Because of the crucial roles these ECM crosslinking pathways play in disease, the enzymes that govern crosslinking events are being explored as therapeutic targets for fibrosis. Here, we review in depth the molecular mechanisms underlying ECM crosslinking, how ECM crosslinking contributes to fibrosis, and the therapeutic strategies being explored to target ECM crosslinking in fibrosis to restore normal tissue structure and function.

Microenvironment with NIR-Controlled ROS and Mechanical Tensions for Manipulating Cell Activities in Wound Healing.

The extracellular matrix (ECM) orchestrates cell behavior and tissue regeneration by modulating biochemical and mechanical signals. Manipulating cell-material interactions is crucial for leveraging biomaterials to regulate cell functions. Yet, integrating multiple cues in a single material remains a challenge. Here, near-infrared (NIR)-controlled multifunctional hydrogel platforms, named PIC/CM@NPs, are introduced to dictate fibroblast behavior during wound healing by tuning the matrix oxidative stress and mechanical tensions. PIC/CM@NPs are prepared through cell adhesion-medicated assembly of collagen-like polyisocyanide (PIC) polymers and cell-membrane-coated conjugated polymer nanoparticles (CM@NPs), which closely mimic the fibrous structure and nonlinear mechanics of ECM. Upon NIR stimulation, PIC/CM@NPs composites enhance fibroblast cell proliferation, migration, cytokine production, and myofibroblast activation, crucial for wound closure. Moreover, they exhibit effective and toxin removal antibacterial properties, reducing inflammation. This multifunctional approach accelerates healing by 95%, highlighting the importance of integrating biochemical and biophysical cues in the biomaterial design for advanced tissue regeneration.

Molecular analysis of the extracellular microenvironment: from form to function.

The extracellular matrix (ECM) proteome represents an important component of the tissue microenvironment that controls chemical flux and induces cell signaling through encoded structure. The analysis of the ECM represents an analyticalchallenge throughhigh levels of post-translational modifications, protease-resistant structures, and crosslinked, insoluble proteins. This review provides a comprehensive overview of the analytical challenges involved in addressing the complexities of spatially profiling the extracellular matrix proteome. A synopsis of the process of synthesizing the ECM structure, detailing inherent chemical complexity, is included to present the scope of the analytical challenge. Current chromatographic and spatial techniques addressing these challenges are detailed. Capabilities for multimodal multiplexing with cellular populations are discussed with a perspective on developing a holistic view of disease processes that includes both the cellular and extracellular microenvironment.

Perineuronal net in the extrinsic innervation of the distal colon of mice and its remodeling in ulcerative colitis.

The perineuronal net (PNN) is a well-described highly specialized extracellular matrix structure found in the central nervous system. Thus far, no reports of its presence or connection to pathological processes have been described in the peripheral nervous system. Our study demonstrates the presence of a PNN in the spinal afferent innervation of the distal colon of mice and characterizes structural and morphological alterations induced in an ulcerative colitis (UC) model. C57Bl/6 mice were given 3% dextran sulfate sodium (DSS) to induce acute or chronic UC. L6/S1 dorsal root ganglia (DRG) were collected. PNNs were labeled using fluorescein-conjugated Wisteria Floribunda (WFA) l lectin, and calcitonin gene-related peptide (CGRP) immunofluorescence was used to detect DRG neurons. Most DRG cell bodies and their extensions toward peripheral nerves were found surrounded by the PNN-like structure (WFA+), labeling neurons' cytoplasm and the pericellular surfaces. The amount of WFA+ neuronal cell bodies was increased in both acute and chronic UC, and the PNN-like structure around cell bodies was thicker in UC groups. In conclusion, a PNN-like structure around DRG neuronal cell bodies was described and found modulated by UC, as changes in quantity, morphology, and expression profile of the PNN were detected, suggesting a potential role in sensory neuron peripheral sensitization, possibly modulating the pain profile of ulcerative colitis.

High-intensity interval training enhances mRNA expression of IGF1Ea in rat Achilles tendon.

High-intensity interval training (HIIT) reportedly enhances the functional properties of the musculoskeletal system. However, the effects of HIIT on tendons remain unclear. Sixteen male rats were randomly assigned to the control (Con) or HIIT group (n = 8 in each group). Rats in the HIIT group executed the HIIT program consisting of 2.5min treadmill running and 4.5min rests between the bouts, 5days per week for 9weeks. Running speed, number of sets, and inclination were incrementally increased during the training period. Histological analysis revealed no apparent morphological changes in the extracellular matrix structure or nuclei of tenocytes between the groups. Real-time reverse transcription polymerase chain reaction analysis revealed thatIgf1EamRNA expression was enhanced in the HIIT group. Furthermore,Igfbp5mRNA expression tended to be higher in the HIIT group. The 9-week HIIT program enhanced tenogenic Igf1Ea mRNA expression.

Aligned Nanofibers Promote Myoblast Polarization and Myogenesis through Activating Rac-Related Signaling Pathways.

The extracellular matrix (ECM) plays a crucial role in regulating cellular behaviors and functions. However, the impact of ECM topography on muscle cell adhesion and differentiation remains poorly understood from a mechanosensing perspective. In this study, we fabricated aligned and random electrospun polycaprolactone (PCL) nanofibers to mimic the structural characteristics of ECM. Mechanism investigations revealed that the orientation of nanofibers promoted C2C12 polarization and myogenesis through Rac-related signaling pathways. Conversely, cells cultured on random fibers exhibited spreading behavior mediated by RhoA/ROCK pathways, resulting in enhanced stress fiber formation but reduced capacity for myogenic differentiation. Our findings highlight the critical role of an ECM structure in muscle regeneration and damage repair, providing novel insights into mechanosensing mechanisms underlying muscle injury diseases.