Extracellular matrix degradation and remodeling in development and disease. Cold Spring Harb Perspect Biol. 2011;3. [PMID: 21917992 DOI: 10.1101/cshperspect.a005058]

Dynamics of inflammatory signals within the tumor microenvironment

Tumor stroma, or tumor microenvironment (TME), has been in the spotlight during recent years for its role in tumor development, growth, and metastasis. It consists of a myriad of elements, including tumor-associated macrophages, cancer-associated fibroblasts, a deregulated extracellular matrix, endothelial cells, and vascular vessels. The release of proinflammatory molecules, due to the inflamed microenvironment, such as cytokines and chemokines is found to play a pivotal role in progression of cancer and response to therapy. This review discusses the major key players and important chemical inflammatory signals released in the TME. Furthermore, the latest breakthroughs in cytokine-mediated crosstalk between immune cells and cancer cells have been highlighted. In addition, recent updates on alterations in cytokine signaling between chronic inflammation and malignant TME have also been reviewed.

The theatrics of collagens in the myocardium: the supreme architect of the fibrotic heart

Heart failure (HF) mediated by cardiac fibrosis (CF) is characterized by an excessive accumulation of collagen-based extracellular matrix (ECM) in the myocardium. CF is a common pathophysiological condition in many heart diseases and can be distinctly categorized into two types: replacement and interstitial. In ischemic heart diseases, sudden loss of cardiomyocytes leads to the replacement of CF to prevent ventricular rupture. In contrast, excessive collagen deposition in the interstitial space between cardiomyocytes (often in response to pressure overload, chronic cardiac stress, hypertension, etc.) is termed interstitial CF. The progression of HF due to cardiac fibrosis is mainly driven by compromised diastolic function, resulting from increased stiffness of the heart wall muscle due to collagen-based scar formation. Increased myocardial stiffness is primarily catalyzed by the differential cross linking of deposited collagens forming the scar in the fibrotic heart. Although collagen deposition remained a hallmark of fibrosis, the pathophysiological progression due to biochemical alterations and mechanistic discrepancy of collagens across cardiac fibrosis subtypes remains elusive. With the advent of next-generation RNA sequencing and high-resolution mass spectrometry, mechanistic insights into collagen-mediated scar maturation have gained impetus. A deeper understanding of the spatiocellular transcriptional heterogeneity and site-specific collagen posttranslational modifications (PTMs) in maneuvering ECM remodeling is gaining attention. The unexplored mechanisms of posttranslational modifications and subsequent collagen cross linking in various cardiac fibrosis may provide the prime target for therapeutic interventions. This review comprehensively summarizes the detailed pattern, role, signaling, and mechanical contributions of different collagens and their PTMs, including cross-linking patterns as newer therapeutic regimens during cardiac fibrosis.

Obesity and type 2 diabetes mellitus: insights from skeletal muscle extracellular matrix remodeling

Obesity and type 2 diabetes mellitus (T2DM) are metabolic diseases at epidemic proportions. The economic burden for these diseases is at an all-time high, and as such, there is an urgent need for advancements in identifying targets for treating these complex disorders. The extracellular matrix (ECM), comprising collagen, fibronectin, laminin, elastin, and proteoglycan, surrounds skeletal muscles and plays a critical role in maintaining tissue homeostasis by providing structural support and facilitating cell-to-cell communication. Disruption of the ECM signaling results in changes to its micro/macroenvironment, thereby modifying tissue homeostasis. Skeletal muscle ECM remodeling has been shown to be associated with insulin resistance, an underlying feature of obesity and T2DM. This narrative review explores the critical components of skeletal muscle ECM and its accumulation and remodeling in metabolic diseases. In addition, we discuss potential treatments to mitigate the effects of ECM remodeling in skeletal muscle. We conclude that targeting ECM remodeling in skeletal muscle represents a promising yet underexplored therapeutic avenue in the management of metabolic disorders.

Extracellular matrix: unlocking new avenues in cancer treatment

The extracellular matrix (ECM) plays a critical role in cancer progression by influencing tumor growth, invasion, and metastasis. This review explores the emerging therapeutic strategies that target the ECM as a novel approach in cancer treatment. By disrupting the structural and biochemical interactions within the tumor microenvironment, ECM-targeted therapies aim to inhibit cancer progression and overcome therapeutic resistance. We examine the current state of ECM research, focusing on key components such as collagen, laminin, fibronectin, periostin, and hyaluronic acid, and their roles in tumor biology. Additionally, we discuss the challenges associated with ECM-targeted therapies, including drug delivery, specificity, and potential side effects, while highlighting recent advancements and future directions. This review underscores the potential of ECM-focused strategies to enhance the efficacy of existing treatments and contribute to more effective cancer therapies.

CXCR4+ mammary gland macrophageal niche promotes tumor initiating cell activity and immune suppression during tumorigenesis

Tumor-initiating cells (TICs) share features and regulatory pathways with normal stem cells, yet how the stem cell niche contributes to tumorigenesis remains unclear. Here, we identify CXCR4+ macrophages as a niche population enriched in normal mammary ducts, where they promote the regenerative activity of basal cells in response to luminal cell-derived CXCL12. CXCL12 triggers AKT-mediated stabilization of β-catenin, which induces Wnt ligands and pro-migratory genes, enabling intraductal macrophage infiltration and supporting regenerative activity of basal cells. Notably, these same CXCR4+ niche macrophages regulate the tumor-initiating activity of various breast cancer subtypes by enhancing TIC survival and tumor-forming capacity, while promoting early immune evasion through regulatory T cell induction. Furthermore, a CXCR4+ niche macrophage gene signature correlates with poor prognosis in human breast cancer. These findings highlight the pivotal role of the CXCL12-CXCR4 axis in orchestrating interactions between niche macrophages, mammary epithelial cells, and immune cells, thereby establishing a supportive niche for both normal tissue regeneration and mammary tumor initiation.

Macromolecular crowding-based biofabrication utilizing unmodified extracellular matrix bioinks

The extracellular matrix (ECM) is the body's natural cell-scaffolding material, and its structure and content are often imitated for applications in tissue engineering and regenerative medicine to promote biocompatibility. One approach toward biomimicking natural ECMs is to utilize decellularized extracellular matrices (dECMs), which involve removing cellular components from native tissues to preserve natural components. Solubilizing dECMs to produce bioinks therefore holds high potential for 3D biofabrication and bioprinting of bioactive scaffolds and tissues. However, solubilized ECMs have low printability owing to their slow gelation times, which necessitates additional artificial modifications (e.g. crosslinking) to facilitate biofabrication applications. In this study, we demonstrate a method utilizing macromolecular crowding (MMC) to confer printability, via rapid gelation, to solubilized unmodified dECMs from a variety of tissue types - heart, muscle, liver, small intestine, and large intestine. We show cell spreading and contractility in cell-laden dECM gels fabricated through MMC, highlighting biocompatibility with our method. Finally, we demonstrate successful extrusion bioprinting of complex 3D structures using unmodified dECM solutions as bioinks, revealing the potential of our MMC-based fabrication method for layer-by-layer building of user-designed bioinks made from wide-ranging fully physiological tissues. STATEMENT OF SIGNIFICANCE: Decellularized extracellular matrix (dECM) bioinks are among the most promising materials for simulating native organ-specific extracellular matrices. However, standard methods for gelling solubilized dECMs are slow and result in poor mechanical and structural characteristics, reducing printability. dECM solutions are typically supplemented with additional crosslinkers for the formation of robust hydrogels. The crosslinkers may be toxic to cells, and they often need UV light for activation. Here, we present a method that allows wide-ranging dECMs to be easily patternable and 3D printable in their unmodified forms. We demonstrate cell spreading and contractility in cell-laden unmodified dECM gels created demonstrating cell viability and bioactivity. We also demonstrated successful extrusion bioprinting of complex 3D structures utilizing low concentration unmodified dECM bioinks and normal healthy lung fibroblasts.

Fibroblasts in immune responses, inflammatory diseases and therapeutic implications

Once regarded as passive bystander cells of the tissue stroma, fibroblasts have emerged as active orchestrators of tissue homeostasis and disease. From regulating immunity and controlling tissue remodelling to governing cell growth and differentiation, fibroblasts assume myriad roles in guiding normal tissue development, maintenance and repair. By comparison, in chronic inflammatory diseases such as rheumatoid arthritis, fibroblasts recruit and sustain inflammatory leukocytes, become dominant producers of pro-inflammatory factors and catalyse tissue destruction. In other disease contexts, fibroblasts promote fibrosis and impair host control of cancer. Single-cell studies have uncovered striking transcriptional and functional heterogeneity exhibited by fibroblasts in both normal tissues and diseased tissues. In particular, advances in the understanding of fibroblast pathology in rheumatoid arthritis have shed light on pathogenic fibroblast states in other chronic diseases. The differentiation and activation of these fibroblast states is driven by diverse physical and chemical cues within the tissue microenvironment and by cell-intrinsic signalling and epigenetic mechanisms. These insights into fibroblast behaviour and regulation have illuminated therapeutic opportunities for the targeted deletion or modulation of pathogenic fibroblasts across many diseases.

Cancer-associated fibroblasts (CAFs) and plaque-associated fibroblasts (PAFs): Unraveling the cellular crossroads of atherosclerosis and cancer

Atherosclerosis is a complex process involving various cells and molecules within the atherosclerotic plaque. Recent evidence suggests that plaque-associated fibroblasts (PAFs), also known as atherosclerosis-associated fibroblasts (AAFs), might play a significant role in the development and progression of the disease. The microenvironment of the atherosclerotic plaque, resembling the tumor microenvironment (TME), includes various cellular populations like plaque-associated macrophages (PAMs), plaque-associated neutrophils (PANs), vascular smooth muscle cells (VSMCs), myeloid-derived suppressor cells (MDSCs), and PAFs. Similar to cancer-associated fibroblasts (CAFs) in tumors, PAFs exhibits a wide range of characteristics and functions. Their interactions with endothelial cells, smooth muscle cells, and other stromal cells, including adventitial fibroblast precursors, significantly influence atherosclerosis progression. Moreover, the ability of PAFs to express various markers such as alpha-SMA, Desmin, VEGF, and GFAP, highlights their diverse origins from different precursor cells, including vascular smooth muscle cells, endothelial cells, glial cells of the enteric nervous system, adventitial fibroblast precursors, as well as resident and circulating fibrocytes. This article explores the molecular interactions between PAFs, cells associated with atherosclerosis, and other stromal cells. It further examines the role of PAFs in the development and progression of atherosclerosis, and compares their features with those of CAFs. The research suggests that studying tumor-associated fibroblasts can help understand fibroblast subpopulations in atherosclerotic plaque. Identifying specific subpopulations could provide new insight into atherosclerosis complexity and lead to the development of innovative drugs for medical intervention.

Estrogenic control of matrix metalloproteinases: a perspective on breast tumor invasion and metastasis

Metastasis is the major cause of mortality in breast cancer patients, and presents an invincible therapeutic challenge. It is a complex process of dissemination of tumor epithelial cells, which is associated with disruption of tissue homeostasis, and alterations in the tumor microenvironment through extracellular matrix (ECM) remodeling, stromal alteration, and epithelial-mesenchymal transition. Matrix metalloproteinases (MMPs) constitute a group of more than 25 zinc-dependent endopeptidases. By virtue of their ability to degrade a wide variety of ECM-associated proteins, they enable ECM remodelling during development, and disease. A large body of clinical data, and experimental evidences implicate MMPs in the invasion and metastasis of breast tumors. While MMPs are aberrantly expressed in breast tumors, few appear to have a dual role in disease progression; either promoting or inhibiting metastasis. Given the role of estrogen in breast cancer development, it is natural to ask whether this steroid hormone has any role in breast cancer metastasis. This review is a round-up of the prominent literature that presents estrogenic control of MMPs, which in turn implies its influence on the tumor microenvironment and metastasis.

Hydrogel-Based Tumor Tissue Microarchitecture Reshapes Dendritic Cell Metabolic Profile and Functions

The extracellular matrix (ECM) plays a pivotal role in immunomodulation, providing structural and biochemical cues that shape immune cell function. In pathological conditions like cancer and chronic inflammation, dysregulated remodeling often results in altered ECM composition and architecture, with fibrillar alignment being a hallmark linked to disease progression. Here, how ECM alignment influences dendritic cell (DC) behavior using 3D biomimetic collagen matrices with controlled fibril anisotropy is investigated. This results show that immature DCs in aligned matrices exhibited increased expression of CD86 and HLA-DR with elevated secretion of CXCL8 and CCL2 chemokines, which may enhance immune cell recruitment. However, transcriptomic and metabolomic analysis revealed significant downregulation of oxidative phosphorylation and an insufficient compensatory shift toward glycolysis, resulting in reduced ATP production. This metabolic constraint correlated with impaired/reduced DC migratory speed and distance. In contrast, mature DCs displayed minimal sensitivity to ECM alignment, maintaining uniform differentiation and functional profiles across matrix conditions. T-cell coculture experiments revealed that ECM alignment dampens T-cell activation and proliferation, likely through direct modulation of T-cell behavior. These findings highlight the stage-specific effects of ECM alignment on DC function, highlighting its role in DC immunomodulation, with implications for therapeutic development in cancer and other pathological contexts.

Stromal Cells in Early Inflammation-Related Pancreatic Carcinogenesis-Biology and Its Potential Role in Therapeutic Targeting

The stroma of healthy pancreases contains various non-hematopoietic, non-endothelial mesenchymal cells. It is altered by chronic inflammation which in turn is a major contributor to the development of pancreatic adenocarcinoma (PDAC). In PDAC, the stroma plays a decisive and well-investigated role for tumor progression and therapy response. This review addresses the central role of stromal cells in the early inflammation-driven development of PDAC. It focuses on major subpopulations of pancreatic mesenchymal cells, i.e., fibroblasts, pancreatic stellate cells, and multipotent stroma cells, particularly their activation and functional alterations upon chronic inflammation including the development of different types of carcinoma-associated fibroblasts. In the second part, the current knowledge on the impact of activated stroma cells on acinar-to-ductal metaplasia and the transition to pancreatic intraepithelial neoplasia is summarized. Finally, putative strategies to target stroma cells and their signaling in early pancreatic carcinogenesis are reflected. In summary, the current data show that the activation of pancreatic stroma cells and the resulting fibrotic changes has pro- and anti-carcinogenetic effects but, overall, creates a carcinogenesis-promoting microenvironment. However, this is a dynamic process and the therapeutic targeting of specific pathways and cells requires in-depth knowledge of the molecular interplay of various cell types.

Differential cellular origins of the extracellular matrix of tumor and normal tissues according to colorectal cancer subtypes

BACKGROUND

Understanding the proteomic-level heterogeneity of the tumor microenvironment (TME) in colorectal cancer (CRC) is crucial due to its well-known heterogeneity. While heterogenous CRC has been extensively characterized at the molecular subtype level, research into the functional heterogeneity of fibroblasts, particularly their relationship with extracellular matrix (ECM) alterations, remains limited. Addressing this gap is essential for a comprehensive understanding of CRC progression and the development of targeted therapies.

METHODS

24 tissue samples from 21 CRC patients, along with adjacent normal tissues (NAT), were collected and decellularized using a detergent-based method to enrich the ECM component. Proteomic analysis of ECM-enriched samples was performed using tandem mass tag (TMT) spectrometry, followed by statistical analysis including differential expression protein (DEP) analysis. Single-cell RNA sequencing (scRNA-Seq) data from public datasets were integrated and analyzed to delineate cell states within the TME. Bulk tissue RNA-Seq and bioinformatics analysis, including consensus molecular subtype (CMS) classification and single-cell level deconvolution of TCGA bulk RNA-seq data, were conducted to further explore gene expression patterns and TME composition.

RESULTS

Differential cellular origin of the NAT and tumorous ECM proteins were identified, revealing 110 ECM proteins enriched in NAT and 28 ECM proteins in tumor tissues. Desmoplastic and WNT5A+ inflammatory fibroblasts were indicated as the sources of tumor-enriched ECM proteins, while ADAMDEC1+ expressing fibroblasts and PI16+ expressing fibroblast were identified as the sources of NAT-enriched ECM proteins. Deconvolution of bulk RNA-seq of CRC tissues discriminated CMS-specific fibroblast state, reflecting the biological traits of each CMS subtype. Specially, seven ECM genes specific to mesenchymal subtype (CMS4), including PI16+ fibroblast-related 4 genes (SFRP2, PRELP, OGN, SRPX) and desmoplastic fibroblast-related 3 genes (THBS2, CTHRC1, BGN), showed a significant association with poorer survival in patient with CRC.

CONCLUSION

We conducted an extracellular matrix (ECM)-focused profiling of the TME by integrating quantitative proteomics with single-cell RNA sequencing (scRNA-seq) data from CRC patients. We identified the ECM proteins of NAT and tumor tissue, and established a cell-matrisome database. We defined mesenchymal subtype-specific molecules associated with specific fibroblast subtypes showing a significant association with poorer survival in patients with CRC. Our ECM-focused profiling of tumor stroma provides new insights as indicators for biological processes and clinical endpoints.

Temporal evolution of fibroblast responses following salivary gland ductal ligation injury

Extracellular matrix remodeling is a natural response to injury but, excessive extracellular matrix accumulation, or fibrosis, is a causative factor in hundreds of diseases that limit organ function, regenerative responses, and can interfere with regenerative therapies. Fibrosis is closely related to inflammation, both of which occur in the salivary glands of patients treated with radiation for head and neck cancers and in patients suffering from autoimmune conditions, such as Sjögren's Disease. Despite the known involvement of fibrosis in disease and the inhibitory effects of fibrosis on tissue regeneration, the mechanisms through which extracellular matrix is elaborated in the salivary gland are poorly understood. Stromal fibroblasts are the primary matrix-producing cells and are known to drive both fibrosis and inflammation. To define the temporal responses of fibroblasts to injury, we induced a temporary obstructive injury though ligation of the primary submandibular and sublingual salivary gland ducts and then performed single-cell RNA sequencing and pathway analysis at timepoints immediately following the injury. Using bioinformatic approaches, we identified three unique fibroblast groups that dynamically respond to the injury. We characterized the changes in matrisomal and inflammatory gene expression over a 7-day time course and identified one group of fibroblasts to be the primary injury-responsive fibrogenic cell type. Understanding how fibroblasts respond at the early and later injury timepoints, along with defining signaling pathways regulated by fibroblasts, could lead to a better understanding of the contribution of fibroblast to acute injury responses to facilitate the development of therapeutics that minimize fibrosis and promote regenerative gland responses in chronic disease states.

Challenges of in vitro modelling of liver fibrosis

Liver fibrosis has been proposed as the most important predictive indicator affecting prognosis of patients with chronic liver disease. It is defined by an abnormal accumulation of extracellular matrix components that results from necrotic and inflammatory processes and eventually impairs organ function. With no approved therapy, comprehensive cellular models directly derived from patient's cells are necessary to understand the mechanisms behind fibrosis and the response to anti-fibrotic therapies. Primary human cells, human hepatic cell lines and human stem cells-derived hepatic stellate-like cells have been widely used for studying fibrosis pathogenesis. In this paper, we depict the cellular crosstalk and the role of extracellular matrix during fibrosis pathogenesis and summarize different in vitro models from simple monolayers to multicellular 3D cultures used to gain deeper mechanistic understanding of the disease and the therapeutic response, discussing their major advantages and disadvantages for liver fibrosis modelling.

Stiffening of a fibrous matrix after recovery of contracted inclusions

Disordered fibrous matrices in living tissues are subjected to forces exerted by cells that contract to pull on matrix fibers. To maintain homeostasis or facilitate disease progression, contracted cells often push on matrix fibers as they recover their original sizes. Recent advances have shown that matrix geometry encodes loading history into mechanical memory independently of plasticity mechanisms such as inter-fiber cohesion or fiber yielding. Conceptualizing cells as inclusions undergoing sequential contraction and recovery, prior work documented matrix remodeling surrounding a solitary recovered inclusion. However, because the remodeling induced by the contraction of multiple inclusions differs from that caused by a single contracted inclusion, we investigate how matrix remodeling occurs when multiple contracted inclusions recover simultaneously, a scenario that more accurately reflects real tissues containing many closely spaced cells. Using mechanics-based computational models of fibrous matrices embedded with clusters of inclusions, we studied the mechanical remodeling of the matrix during the simultaneous recovery of inclusions after contraction. The results revealed permanent mechanical remodeling of the matrix within the cluster, with stiffening observed in areas of the matrix enclosed by closely spaced inclusions. This stiffening was driven by microstructural changes in matrix geometry and was corroborated in experiments, where collagen matrices permanently remodeled by the contraction and recovery of closely spaced embedded cells also exhibited stiffening. By enriching the understanding of memory formation in fibrous matrices, this study opens new possibilities for estimating cell forces on matrix substrates and refining metamaterial design strategies.

ASTROCYTES AND ALCOHOL THROUGHOUT THE LIFESPAN

Evidence for involvement of astrocytes in several neurodegenerative disorders and in drug addiction has been emerging over the last two decades, but only in recent years have astrocytes been investigated for their roles in alcohol use disorder (AUD). As a result, there is a need to evaluate existing preclinical literature supporting involvement of astrocytes in the effects of alcohol exposure. Here we review emerging evidence about responses of astrocytes to alcohol, and the contributions of astrocytes to the development of AUD. We review studies of single-cell RNA sequencing with a focus on alcohol and astrocyte heterogeneity, astrocyte reactivity, and the role of astrocytes in remodeling the extracellular matrix. Effects of alcohol on astrocyte-modulated synaptic transmission are also discussed emphasizing studies never reviewed before. Since astrocytes play essential roles in brain development, we review recent research on the role of astrocytes in fetal alcohol spectrum disorders (FASD) which may also shed light on fetal development of psychiatric disorders that have a high prevalence in individuals affected by FASD. Finally, this review highlights gaps in knowledge about astrocyte biology and alcohol that need further research. Particularly, the dire need to identify astrocyte subpopulations and molecules that are susceptible to alcohol exposure and may be targets for therapeutic intervention.

Targeting tumor extracellular matrix with nanoparticles to circumvent therapeutic resistance

Each stage of tumor development is intrinsically linked to the tumor microenvironment (TME), wherein the extracellular matrix (ECM) serves as a vital and abundant component in tumor tissues. The ECM is a non-cellular, three-dimensional macromolecular network scaffold that provides structural support to cells, stores bioactive molecules, and mediates signaling pathways through specific binding to cell surface receptors. Moreover, the ECM in tumor tissues plays a crucial role in impeding drug diffusion and resisting apoptosis induced by conventional anti-cancer therapies that primarily target cancer cells. Therefore, directing attentions towards the tumor ECM can facilitate the identification of novel targets and the development of new therapies. This review aims to summarize the composition, structure, remodeling, and function of tumor ECM, its association with drug resistance, and current targeting strategies, with a specific emphasis on nanoparticles (NPs).

Copper Complexes with New Glycyl-l-histidyl-l-lysine-Hyaluronan Conjugates Show Antioxidant Properties and Osteogenic and Angiogenic Synergistic Effects

In recent years, hyaluronic acid (HA) and the natural tripeptide glycyl-l-histidyl-l-lysine (GHK), especially its copper(II) complex (GHK-Cu), individually have been shown to exert helpful properties for bone protection and regeneration. However, they are not strong enough to handle oxidative stress, hydrolytic attack, or environmental conditions. Being aware that conjugation chemistry has recently emerged as an appealing approach for generating new molecular entities capable of preserving the molecular integrity of their moieties or delaying their degradation, herein we present the synthesis of conjugates of HA with GHK (GHK-HA), at different loadings of the tripeptide. GHK-HA binds copper(II) ions and potentiates the chemical and biological properties of the two components in in vitro assays. The results highlight copper's role in promoting the expression and release of certain trophic, angiogenic, and osteogenic factors, including brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), as well as bone morphogenetic protein-2 (BMP-2). The protective and regenerative activities of the metal ion are related to the translocation of its intracellular chaperones Copper Chaperone for Superoxide Dismutase (CCS) and Antioxidant-1 (Atox1) to the nucleus where they act as transcription factors.

Matrix metalloproteinase-driven epithelial-mesenchymal transition: implications in health and disease

Epithelial-mesenchymal transition (EMT) is a process in which epithelial cells, defined by apical-basal polarity and tight intercellular junctions, acquire migratory and invasive properties characteristic of mesenchymal cells. Under normal conditions, EMT directs essential morphogenetic events in embryogenesis and supports tissue repair. When dysregulated, EMT contributes to pathological processes such as organ fibrosis, chronic inflammation, and cancer progression and metastasis. Matrix metalloproteinases (MMPs)-a family of zinc-dependent proteases that degrade structural components of the extracellular matrix-sit at the nexus of this transition by dismantling basement membranes, activating pro-EMT signaling pathways, and cleaving adhesion molecules. When normally regulated, MMPs promote balanced ECM turnover and support the cyclical remodeling necessary for proper development, wound healing, and tissue homeostasis. When abnormally regulated, MMPs drive excessive ECM turnover, thereby promoting EMT-related pathologies, including tumor progression and fibrotic disease. This review provides an integrated overview of the molecular mechanisms by which MMPs both initiate and sustain EMT under physiological and disease conditions. It discusses how MMPs can potentiate EMT through TGF-β and Wnt/β-catenin signaling, disrupt cell-cell junction proteins, and potentiate the action of hypoxia-inducible factors in the tumor microenvironment. It discusses how these pathologic processes remodel tissues during fibrosis, and fuel cancer cell invasion, metastasis, and resistance to therapy. Finally, the review explores emerging therapeutic strategies that selectively target MMPs and EMT, ranging from CRISPR/Cas-mediated interventions to engineered tissue inhibitors of metalloproteinases (TIMPs), and demonstrates how such approaches may suppress pathological EMT without compromising its indispensable roles in normal biology.

Optical Coherence Tomography Angiography, Elastography, and Attenuation Imaging for Evaluation of Liver Regeneration

Background/Objectives: As a result of metabolic changes and the disruption of tissue architecture and microcirculation, the regenerative potential of the liver decreases with violations at both micro and macro levels. The development of intraoperative approaches for assessing its regenerative potential is important for reducing the risk of the occurrence of post-resection liver failure. In this study, we used multimodal optical coherence tomography (MM OCT), a combination of three optical coherence tomography modalities-OCT-angiography (OCTA), attenuation coefficient mapping, and OCT-elastography (OCE) to provide real-time three-dimensional and label-free assessment of changes in microcirculation, and in the structure and stiffness of the liver during regeneration. Methods: In our study, the regeneration of a healthy liver was induced by 70% partial hepatectomy. Monitoring of changes was carried out on the 0 (normal liver), 3rd and 7th day of regeneration using modalities of MM OCT. OCT offers the benefits of higher resolution and specificity compared with other clinical imaging modalities, and can be used, even intraoperatively. Results: By the 3rd day of liver regeneration, a decreased density of all observable vessels, together with increased values of the liver tissue's attenuation coefficient and stiffness, was revealed compared to their initial state. However, by the 7th day, the studied parameters tended to return to their normal values, except that the density of large-caliber vessels continued to increase further. Histological and biochemical blood analysis methods were used to verify the MM OCT data. Conclusions: Such data are a first step towards further investigation of liver regeneration in pathology, and, taken in perspective, this should serve as a basis for predictive intraoperative assessment of the regenerative potential of the liver in a clinical setting.

Fibre tracing in biomedical images: An objective comparison between seven algorithms

Obtaining the traces and the characteristics of elongated structures is an important task in computer vision pipelines. In biomedical applications, the analysis of traces of vasculature, nerves or fibres of the extracellular matrix can help characterise processes like angiogenesis or the effect of a certain treatment. This paper presents an objective comparison of six existing methodologies (Edge detection, CT Fire, Scale Space, Twombli, U-Net and Graph Based) and one novel approach called Trace Ridges to trace biomedical images with fibre-like structures. Trace Ridges is a fully automatic and fast algorithm that combines a series of image-processing algorithms including filtering, watershed transform and edge detection to obtain an accurate delineation of the fibre-like structures in a rapid time. To compare the algorithms, four biomedical data sets with vastly distinctive characteristics were selected. Ground truth was obtained by manual delineation of the fibre-like structures. Three pre-processing filtering options were used as a first step: no filtering, Gaussian low-pass and DnCnn, a deep-learning filtering. Three distance error metrics (total, average and maximum distance from the obtained traces to the ground truth) and processing time were calculated. It was observed that no single algorithm outperformed the others in all metrics. For the total distance error, which was considered the most significative, Trace Ridges ranked first, followed by Graph Based, U-Net, Twombli, Scale Space, CT Fire and Edge Detection. In terms of speed, Trace Ridges ranked second, only slightly slower than Edge Detection. Code is freely available at github.com/youssefarafat/Trace_Ridges.

The Atherosclerotic Plaque Microenvironment as a Therapeutic Target

PURPOSE OF REVIEW

Atherosclerosis is traditionally viewed as a disease triggered by lipid accumulation, but growing evidence underscores the crucial role of the plaque microenvironment in disease progression. This review explores recent advances in understanding how cellular and extracellular components of the plaque milieu drive atherosclerosis, with a focus on leveraging these microenvironmental factors for therapeutic intervention. This review highlights recent advances in cell-cell crosstalk and matrix remodeling, offering insights into innovative therapeutic strategies for atherosclerotic cardiovascular disease.

RECENT FINDINGS

While atherosclerosis begins with the subendothelial retention of apolipoprotein B (ApoB)-containing lipoproteins​, its progression is increasingly recognized as a consequence of complex cellular and extracellular dynamics within the plaque microenvironment. Soluble factors and extracellular matrix proteins shape mechanical properties and the biochemical landscape, directly influencing cell behavior and inflammatory signaling. For instance, the deposition of transitional matrix proteins, such as fibronectin, in regions of disturbed flow primes endothelial cells for inflammation​. Likewise, impaired clearance of dead cells and chronic extracellular matrix remodeling contribute to lesion expansion and instability, further exacerbating disease severity. Targeting the plaque microenvironment presents a promising avenue for stabilizing atherosclerotic lesions. Approaches that enhance beneficial cellular interactions, such as boosting macrophage efferocytosis to resolve inflammation while mitigating proatherogenic signals like integrin-mediated endothelial activation, may promote fibrous cap formation and reduce plaque vulnerability. Harnessing these mechanisms may lead to novel therapeutic approaches aimed at modifying the plaque microenvironment to combat atherosclerotic cardiovascular disease.

Intracranial Aneurysm Biomarkers: A Convergence of Genetics, Inflammation, Oxidative Stress, and the Extracellular Matrix

Intracranial aneurysm (IA) is a common cerebrovascular disease in which sacral aneurysms occurring in the Wills ring region can lead to devastating subarachnoid hemorrhage. Despite advances in research, the underlying mechanisms of IA formation and rupture remain incompletely understood, hindering early diagnosis and effective treatment. This review comprehensively summarizes the current landscape of IA biomarkers, encompassing genetic markers, DNA, RNA, inflammatory molecules, oxidative stress proteins, and extracellular matrix (ECM) components. Accumulating evidence suggests that various biomarkers are associated with different stages of IA pathogenesis, including initiation, progression, and rupture. Aberrant ECM composition and remodeling have been observed in IA patients, and extracellular matrix-degrading enzymes are implicated in IA growth and rupture. Biomarker research in IA holds great potential for improving clinical outcomes. Future studies should focus on validating the existing biomarkers, identifying novel ones, and investigating their underlying mechanisms to facilitate the development of personalized preventive and therapeutic strategies for IA.

Understanding Merkel Cell Carcinoma: Pathogenic Signaling, Extracellular Matrix Dynamics, and Novel Treatment Approaches

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine skin cancer, driven by either Merkel cell polyomavirus (MCPyV) integration or ultraviolet (UV)-induced mutations. In MCPyV-positive tumors, viral T antigens inactivate tumor suppressors pRb and p53, while virus-negative MCCs harbor UV-induced mutations that activate similar oncogenic pathways. Key signaling cascades, including PI3K/AKT/mTOR and MAPK, support tumor proliferation, survival, and resistance to apoptosis. Histologically, MCC consists of small round blue cells with neuroendocrine features, high mitotic rate, and necrosis. The tumor microenvironment (TME) plays a central role in disease progression and immune escape. It comprises a mix of tumor-associated macrophages, regulatory and cytotoxic T cells, and elevated expression of immune checkpoint molecules such as PD-L1, contributing to an immunosuppressive niche. The extracellular matrix (ECM) within the TME is rich in proteoglycans, collagens, and matrix metalloproteinases (MMPs), facilitating tumor cell adhesion, invasion, and interaction with stromal and immune cells. ECM remodeling and integrin-mediated signaling further promote immune evasion and therapy resistance. Although immune checkpoint inhibitors targeting PD-1/PD-L1 have shown promise in treating MCC, resistance remains a major hurdle. Therapeutic strategies that concurrently target the TME-through inhibition of ECM components, MMPs, or integrin signaling-may enhance immune responses and improve clinical outcomes.

Investigation of mesenchymal stem cell secretome on breast cancer gene expression: A bioinformatic approach to identify differentially expressed genes, functional networks, and potential therapeutic targets

The mesenchymal stem cell (MSC) secretome plays a pivotal role in shaping the tumor microenvironment, influencing both cancer progression and potential therapeutic outcomes. In this research, by using publicly available dataset GSE196312, we investigated the role of MSC secretome on breast cancer cell gene expression. Our results raveled differentially expressed genes, including the upregulation of Phosphatidylinositol-3,4,5-Trisphosphate Dependent Rac Exchange Factor 1 (PREX1), C-C Motif Chemokine Ligand 28 (CCL28), and downregulation of Collagen Type I Alpha 1 Chain (COL1A1), Collagen Type I Alpha 3 Chain (COL1A3), Collagen Type III Alpha 1 Chain (COL3A1), which contributing to extra cellular matrix (ECM) weakening and promoting cell migration. Functional enrichment analyses also highlighted suppression of ECM remodeling pathways, and activation of calcium ion binding and Rap1 signaling pathway. We proposed that Ca2 + medicated activation of Ras-related protein 1 (Rap1) through its its downstream pathways such as Matrix Metalloprotease (MMP), PI3K/Akt, and MEK/ERK signaling pathway contribute to promotion of cell migration. However, the co-culture model by reducing Fibronectin 1 (FN1) and Secreted Protein Acidic and Cysteine Rich (SPARC) gene expression in cancer cells, emphasized on therapeutical aspects of MSC secretome. These findings emphasize on the dual edge sword nature of MSC secretome on cancer cell behaviors, while our major results emphasize on the cancer progression through ECM remodeling, the therapeutic aspects should not be underscored.

Tumor Microenvironment: A Complex Landscape of Cancer Development and Drug Resistance

Cancer is responsible for nearly one in six global fatalities, making it a major health issue worldwide. Despite advancements in early detection, surgery, and targeted therapies, effective treatment remains challenging due to the complexity and heterogeneity of the disease. A key factor in cancer progression and resistance to treatment is the tumor microenvironment (TME). It is a complex ecosystem comprising cancer cells, stromal cells, immune cells, extracellular matrix (ECM), and soluble factors like cytokines and chemokines. These components interact dynamically to influence tumor growth, metastasis, immune evasion, and treatment resistance. Cancer cells drive the formation of the TME by releasing signaling molecules, while stromal cells, such as fibroblasts and endothelial cells, support tumor metabolism, angiogenesis, and invasion. Immune cells within the TME can either suppress or promote tumor progression, depending on their activation state. Additionally, the TME can promote the growth of immunosuppressive cells that aid cancer cells in evading immune surveillance, such as regulatory T-cells and myeloid-derived suppressor cells. The TME also impedes drug delivery by creating defective blood vessels, contributing to drug resistance. Recent technological advancements have deepened our understanding of the TME, revealing its role in immune modulation, metabolism, and extracellular matrix remodeling. As a result, targeting the TME has become a promising strategy to overcome treatment resistance and improve cancer therapy outcomes.

Deciphering the Matrisome: Extracellular Matrix Remodeling in Liver Cirrhosis and Hepatocellular Carcinoma

Liver cirrhosis and hepatocellular carcinoma (HCC) are major public health concerns due to their high morbidity and mortality rates. The liver, a vital organ for metabolism, detoxification, and homeostasis, depends on the matrisome, a complex and dynamic network of extracellular matrix (ECM) components for maintaining structural and functional integrity. Chronic liver inflammation, induced by factors such as alcohol abuse, viral hepatitis, and non-alcoholic fatty liver disease, leads to fibrosis and cirrhosis, progressing to HCC. The matrisome, composed of ECM proteins including collagen, fibronectin, and laminin, plays a critical role in regulating tissue homeostasis, cell signaling, and tissue repair. Dysregulation of ECM components contributes to the pathogenesis of both liver cirrhosis and cancer. In cirrhosis, matrisome alterations are characterized by excessive ECM deposition and fibrosis, which disrupt the liver's architecture and impair its function. Activated hepatic stellate cells (HSCs) are the principal mediators of fibrosis, producing large quantities of ECM components. In liver cancer, matrisome remodeling facilitates tumorigenesis by promoting cancer cell proliferation, invasion, and metastasis. The tumor microenvironment, shaped by ECM alterations, further supports tumor growth and dissemination. Matrix metalloproteinases (MMPs) play a pivotal role in ECM degradation, fibrosis progression, and tumor invasion, while tissue inhibitors of metalloproteinases (TIMPs) modulate MMP activity. A comprehensive understanding of the molecular mechanisms that link matrisome alterations with the progression from cirrhosis to liver cancer is essential for identifying novel diagnostic and therapeutic targets. This review highlights the dynamic responses of the hepatic matrisome to both acute and chronic insults, emphasizing the complex interplay between ECM components, cellular behavior, and disease progression. Elucidating these interactions may inform strategies aimed at improving clinical outcomes for patients with liver cirrhosis and HCC.

Interpenetrating Polymer Network Hydrogels with Tunable Viscoelasticity and Proteolytic Cleavability to Direct Stem Cells In Vitro

The dynamic nature of cellular microenvironments, regulated by the viscoelasticity and enzymatic cleavage of the extracellular matrix, remains challenging to emulate in engineered synthetic biomaterials. To address this, a novel platform of cell-instructive hydrogels is introduced, composed of two concurrently forming interpenetrating polymer networks (IPNs). These IPNs consist of the same basic building blocks - four-armed poly(ethylene glycol) and the sulfated glycosaminoglycan (sGAG) heparin - are cross-linked through either chemical or physical interactions, allowing for precise and selective tuning of the hydrogel's stiffness, viscoelasticity, and proteolytic cleavability. The studies of the individual and combined effects of these parameters on stem cell behavior revealed that human mesenchymal stem cells exhibited increased spreading and Yes-associated protein transcriptional activity in more viscoelastic and cleavable sGAG-IPN hydrogels. Furthermore, human induced pluripotent stem cell (iPSC) cysts displayed enhanced lumen formation, growth, and pluripotency maintenance when cultured in sGAG-IPN hydrogels with higher viscoelasticity. Inhibition studies emphasized the pivotal roles of actin dynamics and matrix metalloproteinase activity in iPSC cyst morphology, which varied with the viscoelastic properties of the hydrogels. Thus, the introduced sGAG-IPN hydrogel platform offers a powerful methodology for exogenous stem cell fate control.

Microenvironment-based immunotherapy in oral cancer: a comprehensive review

Oral cancer, a prevalent form of head and neck malignancy, accounts for 4% of global cancer cases. The most common type, oral squamous cell carcinoma (OSCC), has a survival rate of about 50%. Even though emerging molecular therapies show promise for managing oral cancer, current treatments like surgery, radiotherapy, and chemotherapy have significant side effects. In addition, the complex tumor microenvironment (TME), involving the extracellular matrix (ECM) and cells like fibroblasts and stromal cells like immune cells, promotes tumor growth and inhibits immune responses, complicating treatment. Nonetheless, immunotherapy is crucial in cancer treatment, especially in oral cancers. Indeed, its effectiveness lies in targeting immune checkpoints such as PD-1 and CTLA-4 inhibitors, as well as monoclonal antibodies like pembrolizumab and cetuximab, adoptive cell transfer methods (including CAR-T cell therapy), cytokine therapy such as IL-2, and tumor vaccines. Thus, these interventions collectively regulate tumor proliferation and metastasis by targeting the TME through autocrine-paracrine signaling pathways. Immunotherapy indeed aims to stimulate the immune system, leveraging both innate and adaptive immunity to counteract cancer cell signals and promote tumor destruction. This review will explore how the TME controls tumor proliferation and metastasis via autocrine-paracrine signaling pathways. It will then detail the effectiveness of immunotherapy in oral cancers, focusing on immune checkpoints, targeted monoclonal antibodies, adoptive cell transfer, cytokine therapy, and tumor vaccines.

Pathological Changes in Extracellular Matrix Composition Orchestrate the Fibrotic Feedback Loop Through Macrophage Activation in Dupuytren's Contracture

Dupuytren's contracture belongs to a group of fibrotic diseases that have similar mechanisms but lack effective treatment and prevention options. The excessive accumulation of connective tissue in Dupuytren's disease leads to palmar fibrosis that results in contracture deformities. The present study aimed to investigate how the tissue microenvironment in Dupuytren's contracture affects the phenotypic differentiation of macrophages, which leads to an inflammatory response and the development of chronicity in fibrotic disease. We utilized a decellularization-based method combined with proteomic analysis to identify shifts in extracellular matrix composition and the surrounding tissue microenvironment. We found that the expression of several matricellular proteins, such as MFAP4, EFEMP1 (fibulin-3), and ANGPTL2, was elevated in Dupuytren's tissue. We show that, in response to the changes in the extracellular matrix of Dupuytren's contracture, macrophages regulate the fibrotic process by cytokine production, promote myofibroblast differentiation, and increase the fibroblast migration rate. Moreover, we found that the extracellular matrix of Dupuytren's contracture directly supports the macrophage-to-myofibroblast transition, which could be another contributor to Dupuytren's disease pathogenesis. Our results suggest that interactions between macrophages and the extracellular matrix should be considered as targets for novel fibrotic disease treatment and prevention strategies in the future.

The solid tumor microenvironment and related targeting strategies: a concise review

The malignant tumor is a serious disease threatening human life. Increasing studies have confirmed that the tumor microenvironment (TME) is composed of a variety of complex components that precisely regulate the interaction of tumor cells with other components, allowing tumor cells to continue to proliferate, resist apoptosis, evade immune surveillance and clearance, and metastasis. However, the characteristics of each component and their interrelationships remain to be deeply understood. To target TME, it is necessary to deeply understand the role of various components of TME in tumor growth and search for potential therapeutic targets. Herein, we innovatively classify the TME into physical microenvironment (such as oxygen, pH, etc.), mechanical microenvironment (such as extracellular matrix, blood vessels, etc.), metabolic microenvironment (such as glucose, lipids, etc.), inflammatory microenvironment and immune microenvironment. We introduce a concise but comprehensive classification of the TME; depict the characteristics of each component in TME; summarize the existing methods for detecting each component in TME; highlight the current strategies and potential therapeutic targets for TME; discuss current challenges in presenting TME and its clinical applications; and provide our prospect on the future research direction and clinical benefits of TME.

Extracellular Matrix Reorganization During Endometrial Decidualization

Extracellular matrix reorganization, a concurrent process of endometrial decidualization, has garnered widespread recognition. However, our understanding of this process remains limited. In this study, we aimed to investigate the expression, spatial distribution, and reorganization of fibrillar collagens, elastin, and lysyl oxidases within the decidua. Using second harmonic generation imaging, we successfully recorded fibrillar collagen reorganization between preimplantation and decidualized endometrium. Upon embryo implantation, the fibrillar collagens align themselves parallel to the direction of embryo invasion. Furthermore, we employed confocal imaging analysis to reveal distinct expression and spatial distribution patterns of elastin and lysyl oxidase-like enzymes. Elastin expression begins to manifest surrounding the implanting embryo, extends into the decidua, and exhibits a high concentration in the mesometrial region after gestation day 8. All lysyl oxidase-like enzymes are localized within the decidua, although they exhibit varying expression patterns. To gain further insights, we utilized an in vitro stromal cell decidualization model and provided compelling evidence that stromal cells serve as the primary source of the extracellular matrix components during endometrial decidualization. Additionally, we demonstrated that the genes encoding factors involved in the synthesis, processing, and assembly of fibrillar collagen and elastic fibers exhibit differential expression patterns during in vitro decidualization. Genes such as asporin, decorin, thrombospondin 2, fibulin 2, fibulin 5, and lysyl oxidase show significant induction during in vitro decidualization. In summary, our comprehensive analysis provides a detailed evaluation of the expression, spatial distribution, and reorganization of fibrillar collagens, elastin, and lysyl oxidases during the process of endometrial decidualization.

Revealing the impact of Pseudomonas aeruginosa quorum sensing molecule 2'-aminoacetophenone on human bronchial-airway epithelium and pulmonary endothelium using a human airway-on-a-chip

Pseudomonas aeruginosa (PA) causes severe respiratory infections utilizing multiple virulence functions. Our previous findings on PA quorum sensing (QS)-regulated small molecule, 2'-aminoacetophenone (2-AA), secreted by the bacteria in infected tissues, revealed its effect on immune and metabolic functions favouring a long-term presence of PA in the host. However, studies on 2-AA's specific effects on bronchial-airway epithelium and pulmonary endothelium remain elusive. To evaluate 2AA's spatiotemporal changes in the human airway, considering endothelial cells as the first point of contact when the route of lung infection is hematogenic, we utilized the microfluidic airway-on-chip lined by polarized human bronchial-airway epithelium and pulmonary endothelium. Using this platform, we performed RNA-sequencing to analyse responses of 2-AA-treated primary human pulmonary microvascular endothelium (HPMEC) and adjacent primary normal human bronchial epithelial (NHBE) cells from healthy female donors and potential cross-talk between these cells. Analyses unveiled specific signaling and biosynthesis pathways to be differentially regulated by 2-AA in epithelial cells, including HIF-1 and pyrimidine signaling, glycosaminoglycan, and glycosphingolipid biosynthesis, while in endothelial cells were fatty acid metabolism, phosphatidylinositol and estrogen receptor signaling, and proinflammatory signaling pathways. Significant overlap in both cell types in response to 2-AA was found in genes implicated in immune response and cellular functions. In contrast, we found that genes related to barrier permeability, cholesterol metabolism, and oxidative phosphorylation were differentially regulated upon exposure to 2-AA in the cell types studied. Murine in-vivo and additional in vitro cell culture studies confirmed cholesterol accumulation in epithelial cells. Results also revealed specific biomarkers associated with cystic fibrosis and idiopathic pulmonary fibrosis to be modulated by 2-AA in both cell types, with the cystic fibrosis transmembrane regulator expression to be affected only in endothelial cells. The 2-AA-mediated effects on healthy epithelial and endothelial primary cells within a microphysiological dynamic environment mimicking the human lung airway enhance our understanding of this QS signaling molecule. This study provides novel insights into their functions and potential interactions, paving the way for innovative, cell-specific therapeutic strategies to combat PA lung infections.

Novel multiple focal point technique for laser-induced shear wave generation in deep tissue: simulation insights

Purpose. Laser applications in biomedical imaging have several decades of history; however, some unexplored corners remain for study. While previous studies contain massive data on photoacoustic imaging, optical coherence imaging/elastography, and surface acoustic waves, the generation of shear waves in bulk by laser remained rarely investigated. Here, we study the applicability of multipoint laser exposure to generate deep tissue shear waves, which have potential applications in dynamic elastography.Method. Previous studies used single shots of laser to induce shear waves and create weak waves. Based on this, we suggest a multipoint approach to enhancing the amplitude of the shear wave in bulk. These approaches contain supersonic exposure, overlay Mach 1, and comb-push exposure in a finite element simulation environment.Result. Although the results showed a linear relationship between laser power and shear wave amplitude, the supersonic and overlay exposure increased the amplitude from 15 nm to over 60 nm and 230 nm, respectively.Conclusion. Our approaches showed a potentially successful increase in shear wave amplitude in the simulation environment. However, experimental data still need to be investigated before these techniques can be suggested for laser-induced shear wave elastography in the deep medium.

Pharmacological Inhibition of Microglial Proliferation Supports Blood-Brain Barrier Integrity in Experimental Autoimmune Encephalomyelitis

Blood-brain barrier dysfunction (BBB) is a primary characteristic of experimental autoimmune encephalomyelitis (EAE), an experimental model of multiple sclerosis (MS). We have previously shown that blocking microglial proliferation using GW2580, a selective inhibitor of CSF1R (Colony stimulating factor 1 receptor), reduced disease progression and severity and prevented the relapse phase. However, whether this was due to effects of GW2580 on the functional integrity of the BBB was not determined. Therefore, here, we examine BBB properties in rats during EAE under GW2580 treatment. Our data suggest that blocking early microglial proliferation through selective targeting of CSF1R signaling has a therapeutic effect in EAE by protecting BBB integrity and reducing peripheral immune cell infiltration. Taken together, our results identify a novel mechanism underlying the effects of GW2580, which could offer a novel therapy for MS.

Liver Extracellular Matrix in Colorectal Liver Metastasis

The liver is the most common site of metastasis of colorectal cancer (CRC), and colorectal liver metastasis is one of the major causes of CRC-related deaths worldwide. The tumor microenvironment, particularly the extracellular matrix (ECM), plays a critical role in CRC metastasis and chemoresistance. Based on findings from clinical and basic research, this review attempts to offer a complete understanding of the role of the ECM in colorectal liver metastasis and to suggest potential ways for therapeutic intervention. First, the ECMs' role in regulating cancer cell fate is explored. We then discuss the hepatic ECM fingerprint and its influence on the metastatic behavior of CRC cells, highlighting key molecular interactions that promote metastasis. In addition, we examine how changes in the ECM within the metastatic niche contribute to chemoresistance, focusing on ECM remodeling by ECM stiffening and the activation of specific signaling pathways. Understanding these mechanisms is crucial for the development of novel strategies to overcome metastasis and improve outcomes for CRC patients.

Advances in Extracellular Matrix-Associated Diagnostics and Therapeutics

The extracellular matrix (ECM) is the common denominator of more than 50 chronic diseases. Some of these chronic pathologies lead to enhanced tissue formation and deposition, whereas others are associated with increased tissue degradation, and some exhibit a combination of both, leading to severe tissue alterations. To develop effective therapies for diseases affecting the lung, liver, kidney, skin, intestine, musculoskeletal system, heart, and solid tumors, we need to modulate the ECM's composition to restore its organization and function. Across diverse organ diseases, there are common denominators and distinguishing factors in this fibroinflammatory axis, which may be used to foster new insights into drug development across disease indications. The 2nd Extracellular Matrix Pharmacology Congress took place in Copenhagen, Denmark, from 17 to 19 June 2024 and was hosted by the International Society of Extracellular Matrix Pharmacology. The event was attended by 450 participants from 35 countries, among whom were prominent scientists who brought together state-of-the-art research on organ diseases and asked important questions to facilitate drug development. We highlight key aspects of the ECM in the liver, kidney, skin, intestine, musculoskeletal system, lungs, and solid tumors to advance our understanding of the ECM and its central targets in drug development. We also highlight key advances in the tools and technology that enable this drug development, thereby supporting the ECM.

Vitronectin regulates lung tissue remodeling and emphysema in chronic obstructive pulmonary disease

Vitronectin (VTN) is an important extracellular matrix protein in tissue remodeling, but its role in chronic obstructive pulmonary disease (COPD) is unknown. We show that VTN regulates tissue remodeling through urokinase plasminogen activator (uPA) signaling pathway in COPD. In human COPD airways and bronchoepithelial cells and the airways of mice with cigarette smoke (CS)-induced experimental COPD, VTN protein was not changed, but downstream uPA signaling was altered (increased plasminogen activator inhibitor-1) that induced collagen and airway remodeling. In the parenchyma, VTN levels were decreased, uPA signaling pathway differentially altered and collagen reduced in lung fibroblasts from human and lung parenchyma in experimental COPD. Vtn inhibition with siRNA in mouse fibroblasts altered uPA signaling increased matrix metalloproteinase-12, and reduced collagen, whereas over-expression restored collagen production after CS extract challenge. Vtn-/- and Vtn small interfering RNA-treated mice had exaggerated inflammation, emphysema, and impaired lung function compared with controls with CS-induced COPD. Restoration of VTN in the parenchyma may be a therapeutic option for emphysema and COPD.

Mechanical interaction between a hydrogel and an embedded cell in biomicrofluidic applications

Thanks to their softness, biocompatibility, porosity, and ready availability, hydrogels are commonly used in microfluidic assays and organ-on-chip devices as a matrix for cells. They not only provide a supporting scaffold for the differentiating cells and the developing organoids, but also serve as the medium for transmitting oxygen, nutrients, various chemical factors, and mechanical stimuli to the cells. From a bioengineering viewpoint, the transmission of forces from fluid perfusion to the cells through the hydrogel is critical to the proper function and development of the cell colony. In this paper, we develop a poroelastic model to represent the fluid flow through a hydrogel containing a biological cell modeled as a hyperelastic inclusion. In geometries representing shear and normal flows that occur frequently in microfluidic experiments, we use finite-element simulations to examine how the perfusion engenders interstitial flow in the gel and displaces and deforms the embedded cell. The results show that pressure is the most important stress component in moving and deforming the cell, and the model predicts the velocity in the gel and stress transmitted to the cell that is comparable to in vitro and in vivo data. This work provides a computational tool to design the geometry and flow conditions to achieve optimal flow and stress fields inside the hydrogels and around the cell.

Cancer stem cells: Masters of all traits

Cancer is a heterogeneous disease, which contributes to its rapid progression and therapeutic failure. Besides interpatient tumor heterogeneity, tumors within a single patient can present with a heterogeneous mix of genetically and phenotypically distinct subclones. These unique subclones can significantly impact the traits of cancer. With the plasticity that intratumoral heterogeneity provides, cancers can easily adapt to changes in their microenvironment and therapeutic exposure. Indeed, tumor cells dynamically shift between a more differentiated, rapidly proliferating state with limited tumorigenic potential and a cancer stem cell (CSC)-like state that resembles undifferentiated cellular precursors and is associated with high tumorigenicity. In this context, CSCs are functionally located at the apex of the tumor hierarchy, contributing to the initiation, maintenance, and progression of tumors, as they also represent the subpopulation of tumor cells most resistant to conventional anti-cancer therapies. Although the CSC model is well established, it is constantly evolving and being reshaped by advancing knowledge on the roles of CSCs in different cancer types. Here, we review the current evidence of how CSCs play a pivotal role in providing the many traits of aggressive tumors while simultaneously evading immunosurveillance and anti-cancer therapy in several cancer types. We discuss the key traits and characteristics of CSCs to provide updated insights into CSC biology and highlight its implications for therapeutic development and improved treatment of aggressive cancers.

Identifying Circulating Protein Mediators in the Link Between Smoking and Abdominal Aortic Aneurysm: An Integrated Analysis of Human Proteomic and Genomic Data

Background

Smoking is a well-established risk factor for abdominal aortic aneurysm (AAA). However, the molecular pathways underlying this relationship remain poorly understood. This study aimed to identify circulating protein mediators that may explain the association between smoking and AAA.

Methods

We conducted a network Mendelian randomization (MR) study utilizing summary-level data from the largest available genome-wide association studies. Our primary smoking exposure was the lifetime smoking index, with smoking initiation and cigarettes per day included as supplementary traits. The AAA dataset comprised 39,221 cases and 1,086,107 controls. Protein data were sourced from two large cohorts: UKB-PPP, where proteins were measured using the Olink platform in 54,219 individuals, and deCODE, where proteins were measured using the SomaScan platform in 35,559 individuals. Two-sample MR was employed to estimate the association between smoking and AAA (βtotal) and between smoking and circulating protein levels (β1). Summary data-based MR was then used to assess the association between smoking-related proteins and AAA risk (β2). Mediation pathways were identified based on the directionality of effect estimates, and the corresponding mediation effects were quantified.

Results

Genetically predicted smoking traits were consistently associated with an increased risk of AAA. The lifetime smoking index was associated with the levels of 543 out of 5,764 unique circulating proteins, with 470 of these associations replicated in supplementary analyses using additional smoking traits and protein sources. Among the smoking-related proteins, genetically predicted levels of 22 were associated with AAA risk. Eight mediation pathways were identified accounting for 42.7% of the total smoking-AAA association and with mediation effects >4% for ADAMTS15, IL1RN, MMP12, PGF, PCSK9, and UXS1.

Conclusion

This study identified numerous circulating proteins potentially causally linked to smoking, and eight of these proteins were found to mediate the association between smoking and AAA risk.

PTX3-assembled pericellular hyaluronan matrix enhances endochondral ossification during fracture healing and heterotopic ossification

Endochondral ossification (EO) is a pivotal process during fracture healing and traumatic heterotopic ossification (HO), involving the cartilaginous matrix synthesis and mineralization. Unlike the extracellular matrix, the hyaluronan (HA)-rich pericellular matrix (PCM) directly envelops chondrocytes, serving as the frontline for extracellular signal reception and undergoing dynamic remodeling. Pentraxin 3 (PTX3), a secreted glycoprotein, facilitates HA matrix assembly and remodeling. However, it remains unclear whether PTX3 affects EO by regulating HA-rich PCM assembly of chondrocytes, thereby impacting fracture healing and traumatic HO. This study demonstrates that PTX3 deficiency impairs fracture healing and inhibits traumatic HO, but dose not affect growth plate development in mice. PTX3 expression is up-regulated during chondrocyte matrix synthesis and maturation and is localized in the HA-rich PCM. PTX3 promotes the assembly of HA-rich PCM in a serum- and TSG6-dependent manner, fostering CD44 receptor clustering, activating the FAK/AKT signaling pathway, and promoting chondrocyte matrix synthesis and maturation. Local injection of PTX3/TSG6 matrix protein mixture effectively promotes fracture healing in mice. In conclusion, PTX3-assembled HA-rich PCM promotes chondrocyte matrix synthesis and maturation via CD44/FAK/AKT signaling. This mechanism facilitates EO during fracture healing and traumatic HO in mice.

Remodeling of extracellular matrix collagen IV by MIG-6/papilin regulates neuronal architecture

Neuronal architecture established embryonically must persist lifelong to ensure normal brain function. However, little is understood about the mechanisms behind the long-term maintenance of neuronal organization. To uncover maintenance mechanisms, we performed a suppressor screen in sax-7/L1CAM mutants, which exhibit progressive disorganization with age. We identified the conserved extracellular matrix protein MIG-6/papilin as a key regulator of neuronal maintenance. Combining incisive molecular genetics, structural predictions, in vivo quantitative imaging, and cutting-edge Brillouin microscopy, we show that MIG-6/papilin remodels extracellular matrix collagen IV, working in concert with the secreted enzymes MIG-17/ADAMTS and PXN-2/peroxidasin. This remodeling impacts tissue biomechanics and ensures neuronal stability, even under increased mechanical stress. Our findings highlight an extracellular mechanism by which MIG-6/papilin supports the integrity of neuronal architecture throughout life. This work provides critical insights into the molecular basis of sustaining neuronal architecture and offers a foundation for understanding age-related and neurodegenerative disorders.

A Simple Framework for Agent-Based Modeling with Extracellular Matrix

Extracellular matrix (ECM) is a key component of the cellular microenvironment and critical in multiple disease and developmental processes. Representing ECM and cell-ECM interactions is a challenging multiscale problem as they span molecular-level details to tissue-level dynamics. While several computational frameworks exist for ECM modeling, they often focus on very detailed modeling of individual ECM fibers or represent only a single aspect of the ECM. Using the PhysiCell agent-based modeling platform, we developed a framework of intermediate detail with the ability to capture bidirectional cell-ECM interactions. We represent a small region of ECM, an ECM element, with three variables describing its local microstructure: anisotropy, density, and overall fiber orientation. To spatially model the ECM, we use an array of ECM elements. Cells remodel local ECM microstructure and in turn, local microstructure impacts cellular motility. We demonstrate the utility of this framework and reusability of its core cell-ECM interaction model through examples in cellular invasion, wound healing, basement membrane degradation, and leader-follower collective migration. Despite the relative simplicity of the framework, it is able to capture a broad range of cell-ECM interactions of interest to the modeling community. Furthermore, variables representing the ECM microstructure are accessible through simple programming interfaces. This allows them to impact cell behaviors, such as proliferation and death, without requiring custom code for each interaction, particularly through PhysiCell's modeling grammar, enabling rapid modeling of a diverse range of cell-matrix biology. We make this framework available as a free and open source software package at https://github.com/PhysiCell-Models/collective-invasion .

Remodeling of extracellular matrix collagen IV by MIG-6/papilin regulates neuronal architecture

Neuronal architecture established embryonically must persist lifelong to ensure normal brain function. However, little is understood about the mechanisms behind the long-term maintenance of neuronal organization. To uncover maintenance mechanisms, we performed a suppressor screen in sax-7 / L1CAM mutants, which exhibit progressive disorganization with age. We identified the conserved extracellular matrix protein MIG-6/papilin as a key regulator of neuronal maintenance. Combining incisive molecular genetics, structural predictions, in vivo quantitative imaging, and cutting-edge Brillouin microscopy, we show that MIG-6/papilin remodels extracellular matrix collagen IV, working in concert with the secreted enzymes MIG-17/ADAMTS and PXN-2/peroxidasin. This remodeling impacts tissue biomechanics and ensures neuronal stability, even under increased mechanical stress. Our findings highlight an extracellular mechanism by which MIG-6/papilin supports the integrity of neuronal architecture throughout life. This work provides critical insights into the molecular basis of sustaining neuronal architecture and offers a foundation for understanding age-related and neurodegenerative disorders.

Three-Dimensional Models: Biomimetic Tools That Recapitulate Breast Tissue Architecture and Microenvironment to Study Ductal Carcinoma In Situ Transition to Invasive Ductal Breast Cancer

Diagnosis of ductal carcinoma in situ (DCIS) presents a challenge as we cannot yet distinguish between those lesions that remain dormant from cases that may progress to invasive ductal breast cancer (IDC) and require therapeutic intervention. Our overall interest is to develop biomimetic three-dimensional (3D) models that more accurately recapitulate the structure and characteristics of pre-invasive breast cancer in order to study the underlying mechanisms driving malignant progression. These models allow us to mimic the microenvironment to investigate many aspects of mammary cell biology, including the role of the extracellular matrix (ECM), the interaction between carcinoma-associated fibroblasts (CAFs) and epithelial cells, and the dynamics of cytoskeletal reorganization. In this review article, we outline the significance of 3D culture models as reliable pre-clinical tools that mimic the in vivo tumor microenvironment and facilitate the study of DCIS lesions as they progress to invasive breast cancer. We also discuss the role of CAFs and other stromal cells in DCIS transition as well as the clinical significance of emerging technologies like tumor-on-chip and co-culture models.

Relaxation of mucosal fibronectin fibers in late gut inflammation following neutrophil infiltration in mice

The continuously remodeled extracellular matrix (ECM) plays a pivotal role in gastrointestinal health and disease, yet its precise functions remain elusive. In this study, we employed laser capture microdissection combined with low-input proteomics to investigate ECM remodeling during Salmonella-driven inflammation. To complement this, we probed how fibronectin fiber tension is altered using a mechanosensitive peptide probe. While fibronectin fibers in healthy intestinal tissue are typically stretched, many lose their tension in intestinal smooth muscles only hours after infection, despite the absence of bacteria in that area. In contrast, within the mucosa, where Salmonella is present starting 12 h post infection, fibronectin fiber relaxation occurred exclusively during late-stage infection at 72 h and was localized to already existing clusters of infiltrated neutrophils. Using N-terminomics, we identified three new cleavage sites in fibronectin in the inflamed cecum. The unique, tissue layer-specific changes in the molecular compositions and ECM fiber tension revealed herein might trigger new therapeutic strategies to fight acute intestinal inflammation.

An eGFP-Col4a2 mouse model reveals basement membrane dynamics underlying hair follicle morphogenesis

Precisely controlled remodeling of the basement membrane (BM) is crucial for morphogenesis, but its molecular and tissue-level dynamics, underlying mechanisms, and functional significance in mammals remain largely unknown due to limited visualization tools. We developed mouse lines in which the endogenous collagen IV gene (Col4a2) was fused with a fluorescent tag. Through live imaging of developing hair follicles, we reveal a spatial gradient in the turnover rate of COL4A2 that is closely coupled with both the BM expansion rate and the proliferation rate of epithelial progenitors. Epithelial progenitors are displaced with directionally expanding BMs but do not actively migrate on stationary BM. The addition of a matrix metalloproteinase inhibitor delays COL4A2 turnover, restrains BM expansion, and increases perpendicular divisions of epithelial progenitors, altering hair follicle morphology. Our findings highlight the spatially distinct dynamics of BM and their key roles in orchestrating progenitor cell behavior and organ shape during development.

Metabolite pathway alterations identified by magnetic resonance metabolomics in a proximal tubular epithelial cell line treated with TGF-β1

Tubulointerstitial fibrosis is a characteristic hallmark of chronic kidney disease (CKD). Metabolic perturbations in cellular energy metabolism contribute to the pathogenesis of CKD, but the chemical contributors remain unclear. The aim of this investigation was to use two dimensional 1H-nuclear magnetic resonance (2D-COSY) metabolomics to identify the chemical changes of kidney fibrogenesis. An in vitro transforming growth factor-β1 (TGF-β1)-induced model of kidney fibrogenesis with human kidney-2 (HK-2) proximal tubular epithelial cells (PTEC) was used. The model was validated by assaying for various pro-fibrotic molecules, using quantitative PCR and Western blotting. 2D-COSY was performed on treated cells. Morphological and functional changes characteristic of tubulointerstitial fibrosis were confirmed in the model; expression of fibronectin, collagen type IV, smooth muscle actin, oxidative stress enzymes increased (p < 0.05). NMR metabolomics provided evidence of altered metabolite signatures associated with glycolysis and glutamine metabolism, with decreased myo-inositol and choline, and metabolites of the oxidative phase of the pentose phosphate pathway with increased glucose and glucuronic acid. The altered PTEC cellular metabolism likely supports the rapid fibrogenic energy demands. These results, using 2D-COSY metabolomics, support development of a biomarker panel of fibrosis detectable using clinical magnetic resonance spectroscopy to diagnose and manage CKD.

Early and late postnatal lung distribution of collagen type VI in preterm and term infants

Collagen type VI (COL6) is an important component of the extracellular matrix (EM) and may have a major role in lung development and disease. Studies on COL6 expression during lung development are mainly based on animal models. The aim of the study was to define COL6 expression pattern in lung parenchyma in infants with different lung maturational stages. COL6 expression in 115 lung samples from deceased newborn infants (21-41 weeks' gestational age; 0-228 days' postnatal age) was studied by immunohistochemistry combined with digital image analysis. The distribution of COL6 expression was generally heterogeneous in the lung parenchyma of preterm and term infants. The size of the high-density and low-density areas appeared with logarithmic correlation and COL6 defined the basement membrane (BM) with a prominent expression around the air spaces in the canalicular stage during the first postnatal week. Infants at the alveolar stage showed linear correlation and a fine filamentous appearance during the first week of postnatal life, similarly to adults. COL6 is condensed to areas corresponding to the BM during the first postnatal week of the canalicular stage of lung development. After the first postnatal week COL6 expression changes to a microfibrillar appearance in the ECM, similar to the pattern that characterizes the later alveolar stage and adults. The localization of COL6 during the canalicular and saccular stages might have a higher impact on lung development than the amount of COL6.