Mechanical Properties Of Extracellular Matrix Research Articles

The (un)known crosstalk between metabolism and mechanotransduction: Implications for metabolic syndrome (MetS)-associated neurological complications.

Metabolic syndrome (MetS) has been associated with disruptions in tissue mechanical homeostasis and inflammatory and metabolic derangements. However, the direct correlation between metabolic alterations and changes in tissue stiffness, and whether they could play a role as upstream initiators of disease pathology remains to be investigated. This emerging concept has yet to be put into clinical practice as many questions concerning the interplay between extracellular matrix mechanical properties and regulation of metabolic pathways remain unsolved. This review will highlight key foundational studies examining mutual regulation of cell metabolism and mechanotransduction, and opening questions lying ahead for better understanding MetS pathophysiology.

Transient Receptor Potential Vanilloid 4 Calcium-Permeable Channel Contributes to Valve Stiffening in Aortic Stenosis.

Aortic valve stenosis (AVS) is a progressive disease characterized by fibrosis, inflammation, calcification, and stiffening of the aortic valve leaflets, leading to disrupted blood flow. If untreated, AVS can progress to heart failure and death within 2 to 5 years. Uncovering the molecular mechanisms behind AVS is key for developing effective noninvasive therapies. Emerging evidence highlights that matrix stiffness affect gene expression, inflammation, and cell differentiation. Activation of valvular interstitial cells into myofibroblasts, along with excessive extracellular matrix accumulation and remodeling, are major contributors to AVS progression. Inflammation further exacerbates the disease, as macrophages infiltrate valve leaflets, enhancing inflammation, activating valvular interstitial cells, and driving extracellular matrix remodeling. Our lab and others have shown that the activities of macrophages and fibroblasts are sensitive to matrix stiffness. Previously, we identified mechanosensitive transient receptor potential vanilloid 4 (TRPV4) channels as key regulators of fibrosis and macrophage activation, implicating TRPV4 in AVS as a potential stiffness sensor. Herein, we found elevated levels of TRPV4, α-smooth muscle actin, and cluster of differentiation 68 proteins in human AVS tissues compared with controls. Furthermore, the stiffening of human aortic valve tissue is associated with the levels of myofibroblasts, macrophages, and TRPV4 protein expression. In a mouse model, TRPV4 promoted valve stiffening during hypercholesterolemia-induced AVS. Additionally, TRPV4 mediated intracellular stiffness in valvular interstitial cells in response to transforming growth factor β1, which was blocked by the TRPV4 antagonist GSK2193874. These findings reveal a novel mechanism linking TRPV4 to valve stiffening, providing insights into how extracellular matrix mechanical properties drive inflammation and fibrosis in AVS.

Single-cell Trajectories and Pseudo-time Analysis Reveal Additional Insights into Rheumatoid Arthritis Disease Progression

As the chicken embryo grows, its increasing metabolic demand drives the development of the cardiovascular system, enabling efficient nutrient delivery through complex molecular and structural formation. Key extracellular matrix (ECM) components, such as hyaluronic acid (HA) and collagen type I alpha 1 (COL1A1), play a crucial role in shaping the biomechanical environment of the heart, particularly the sinoatrial node (SAN). These ECM elements regulate cell adhesion, migration, and the maturation of cardiac progenitor cells (CPCs), essential for the heart's electrical conductivity and rhythmicity. Based on the hypothesis that ECM mechanical properties influence the spatial patterning of conduction-related genes, we analyzed spatial transcriptomics data from chicken hearts at different developmental stages. Collagen-related genes associated with a sturdy ECM showed an increasing trend over time, while soft ECM-related genes responsible for producing proteoglycans and breaking down collagen decreased. Although conduction-related genes did not fully align with ECM trends, intriguing patterns were observed, pointing to potential interactions between ECM remodeling and the construction of the cardiac conduction system. Our findings suggest significant ECM r7emodeling between days 4 and 7, which may influence the heart's structural and functional development.

Mechanisms of triple‐negative breast cancer extravasation: Impact of the physical environment and endothelial glycocalyx

AbstractCancer metastasis is the leading cause of death for those afflicted with cancer. In cancer metastasis, the cancer cells break off from the primary tumor, penetrate nearby blood vessels, and attach and extravasate out of the vessels to form secondary tumors at distant organs. This makes extravasation a critical step of the metastatic cascade. Herein, with a focus on triple‐negative breast cancer, the role that the prospective secondary tumor microenvironment's mechanical properties play in circulating tumor cells' extravasation is reviewed. Specifically, the effects of the physically regulated vascular endothelial glycocalyx barrier element, vascular flow factors, and subendothelial extracellular matrix mechanical properties on cancer cell extravasation are examined. The ultimate goal of this review is to clarify the physical mechanisms that drive triple‐negative breast cancer extravasation, as these mechanisms may be potential new targets for anti‐metastasis therapy.

Decoupling shear stress and pressure effects in the biomechanics of autosomal dominant polycystic kidney disease using a perfused kidney-on-chip.

Kidney tubular cells are submitted to two distinct mechanical forces generated by the urine flow: shear stress and hydrostatic pressure. In addition, the mechanical properties of the surrounding extracellular matrix modulate tubule deformation under constraints. These mechanical factors likely play a role in the pathophysiology of kidney diseases as exemplified by autosomal dominant polycystic kidney disease, in which pressure, flow and matrix stiffness have been proposed to modulate the cystic dilation of tubules with PKD1 mutations. The lack of in vitro systems recapitulating the mechanical environment of kidney tubules impedes our ability to dissect the role of these mechanical factors. Here we describe a perfused kidney-on-chip with tunable extracellular matrix mechanical properties and hydrodynamic constraints, that allows a decoupling of shear stress and flow. We used this system to dissect how these mechanical cues affect Pkd1 -/- tubule dilation. Our results show two distinct mechanisms leading to tubular dilation. For PCT cells (proximal tubule), overproliferation mechanically leads to tubular dilation, regardless of the mechanical context. For mIMCD-3 cells (collecting duct), tube dilation is associated with a squamous cell morphology but not with overproliferation and is highly sensitive to extracellular matrix properties and hydrodynamic constraints. Surprisingly, flow alone suppressed Pkd1 -/- mIMCD-3 tubule dilation observed in static conditions, while the addition of luminal pressure restored it. Our in vitro model emulating nephron geometrical and mechanical organization sheds light on the roles of mechanical constraints in ADPKD and demonstrates the importance of controlling intraluminal pressure in kidney tubule models.

Matrix stiffening promotes chondrocyte senescence and the osteoarthritis development through downregulating HDAC3

Extracellular matrix (ECM) stiffening is a typical characteristic of cartilage aging, which is a quintessential feature of knee osteoarthritis (KOA). However, little is known about how ECM stiffening affects chondrocytes and other molecules downstream. This study mimicked the physiological and pathological stiffness of human cartilage using polydimethylsiloxane (PDMS) substrates. It demonstrated that epigenetic Parkin regulation by histone deacetylase 3 (HDAC3) represents a new mechanosensitive mechanism by which the stiffness matrix affected chondrocyte physiology. We found that ECM stiffening accelerated cultured chondrocyte senescence in vitro, while the stiffness ECM downregulated HDAC3, prompting Parkin acetylation to activate excessive mitophagy and accelerating chondrocyte senescence and osteoarthritis (OA) in mice. Contrarily, intra-articular injection with an HDAC3-expressing adeno-associated virus restored the young phenotype of the aged chondrocytes stimulated by ECM stiffening and alleviated OA in mice. The findings indicated that changes in the mechanical ECM properties initiated pathogenic mechanotransduction signals, promoted the Parkin acetylation and hyperactivated mitophagy, and damaged chondrocyte health. These results may provide new insights into chondrocyte regulation by the mechanical properties of ECM, suggesting that the modification of the physical ECM properties may be a potential OA treatment strategy.

Mechanical properties, collagen and glycosaminoglycan content of equine superficial digital flexor tendons are not affected by training.

Physical activity can activate extracellular matrix (ECM) protein synthesis and influence the size and mechanical properties of tendon. In this study, we aimed to investigate whether different training histories of horses would influence the synthesis of collagen and other matrix proteins and alter the mechanical properties of tendon. Samples from superficial digital flexor tendon (SDFT) from horses that were either (a) currently race trained (n = 5), (b) previously race trained (n = 5) or (c) untrained (n = 4) were analysed for matrix protein abundance (mass spectrometry), collagen and glycosaminoglycan (GAG) content, ECM gene expression and mechanical properties. It was found that ECM synthesis by tendon fibroblasts invitro varied depending upon the previous training history. In contrast, fascicle morphology, collagen and GAG content, mechanical properties and ECM gene expression of the tendon did not reveal any significant differences between groups. In conclusion, although we could not identify any direct impact of the physical training history on the mechanical properties or major ECM components of the tendon, it is evident that horse tendon cells are responsive to loading invivo, and the training background may lead to a modification in the composition of newly synthesised matrix.

The Effect of Substrate Properties on Cellular Behavior and Nanoparticle Uptake in Human Fibroblasts and Epithelial Cells.

The delivery of nanomedicines into cells holds enormous therapeutic potential; however little is known regarding how the extracellular matrix (ECM) can influence cell-nanoparticle (NP) interactions. Changes in ECM organization and composition occur in several pathophysiological states, including fibrosis and tumorigenesis, and may contribute to disease progression. We show that the physical characteristics of cellular substrates, that more closely resemble the ECM in vivo, can influence cell behavior and the subsequent uptake of NPs. Electrospinning was used to create two different substrates made of soft polyurethane (PU) with aligned and non-aligned nanofibers to recapitulate the ECM in two different states. To investigate the impact of cell-substrate interaction, A549 lung epithelial cells and MRC-5 lung fibroblasts were cultured on soft PU membranes with different alignments and compared against stiff tissue culture plastic (TCP)/glass. Both cell types could attach and grow on both PU membranes with no signs of cytotoxicity but with increased cytokine release compared with cells on the TCP. The uptake of silica NPs increased more than three-fold in fibroblasts but not in epithelial cells cultured on both membranes. This study demonstrates that cell-matrix interaction is substrate and cell-type dependent and highlights the importance of considering the ECM and tissue mechanical properties when designing NPs for effective cell targeting and treatment.

Spatial and Temporal Control of 3D Hydrogel Viscoelasticity through Phototuning.

The mechanical properties of the extracellular environment can regulate a variety of cellular functions, such as spreading, migration, proliferation, and even differentiation and phenotypic determination. Much effort has been directed at understanding the effects of the extracellular matrix (ECM) elastic modulus and, more recently, stress relaxation on cellular processes. In physiological contexts such as development, wound healing, and fibrotic disease progression, ECM mechanical properties change substantially over time or space. Dynamically tunable hydrogel platforms have been developed to spatiotemporally modulate a gel's elastic modulus. However, dynamically altering the stress relaxation rate of a hydrogel remains a challenge. Here, we present a strategy to tune hydrogel stress relaxation rates in time or space using a light-triggered tethering of poly(ethylene glycol) to alginate. We show that the stress relaxation rate can be tuned without altering the elastic modulus of the hydrogel. We found that cells are capable of sensing and responding to dynamic stress relaxation rate changes, both morphologically and through differences in proliferation rates. We also exploited the light-based technique to generate spatial patterns of stress relaxation rates in 3D hydrogels. We anticipate that user-directed control of the 3D hydrogel stress relaxation rate will be a powerful tool that enables studies that mimic dynamic ECM contexts or as a means to guide cell fate in space and time for tissue engineering applications.

Impact of various detergent-based immersion and perfusion decellularization strategies on the novel caprine pancreas derived extracellular matrix scaffold.

Limited availability of the organs donors has facilitated the establishment of xenogeneic organ sources for transplantation. Numerous studies have decellularized several organs and assessed their implantability in order to provide such organs. Among all the decellularized organs studies for xenotransplantation, the pancreas has garnered very limited amount of research. The presently offered alternatives for pancreas transplantation are unable to liberate patients from donor dependence. The rat and mice pancreas are not of an accurate size for transplantation but can only be used for in-vitro studies mimicking in-vivo immune response in humans, while the porcine pancreas can cause zoonotic diseases as it carries porcine endogenous retrovirus (PERV- A/B/C). Therefore, we propose caprine pancreas as a substitute for these organs, which not only reduces donor dependence but also poses no risk of zoonosis. Upon decellularization the extracellular matrix (ECM) of different tissues responds differently to the detergents used for decellularization at physical and physiological level; this necessitates a comprehensive analysis of each tissue independently. This study investigates the impact of decellularization by ionic (SDS and SDC), non-ionic (Triton X-100 and Tween-20), and zwitterionic detergents (CHAPS). All these five detergents have been used to decellularize caprine pancreas via immersion (ID) and perfusion (PD) set-up. In this study, an extensive comparison of these two configurations (ID and PD) with regard to each detergent has been conducted. The final obtained scaffold with each set-up has been evaluated for the left-over cytosolic content, ECM components like sGAG, collagen, and fibronectin were estimated via Prussian blue and Immunohistochemical staining respectively, and finally for the tensile strength and antimicrobial activity. All the detergents performed consistently superior in PD than in ID. Conclusively, PD with SDS, SDC, and TX-100 successfully decellularizes caprine pancreatic tissue while retaining ECM architecture and mechanical properties. This research demonstrates the viability of caprine pancreatic tissue as a substitute scaffold for porcine organs and provides optimal decellularization protocol for this xenogeneic tissue. This research aims to establish a foundation for further investigations into potential regenerative strategies using this ECM in combination with other factors.

Col1a2-Deleted Mice Have Defective Type I Collagen and Secondary Reactive Cardiac Fibrosis with Altered Hypertrophic Dynamics.

The adult cardiac extracellular matrix (ECM) is largely comprised of type I collagen. In addition to serving as the primary structural support component of the cardiac ECM, type I collagen also provides an organizational platform for other ECM proteins, matricellular proteins, and signaling components that impact cellular stress sensing in vivo. Here we investigated how the content and integrity of type I collagen affect cardiac structure function and response to injury. We generated and characterized Col1a2-/- mice using standard gene targeting. Col1a2-/- mice were viable, although by young adulthood their hearts showed alterations in ECM mechanical properties, as well as an unanticipated activation of cardiac fibroblasts and induction of a progressive fibrotic response. This included augmented TGFβ activity, increases in fibroblast number, and progressive cardiac hypertrophy, with reduced functional performance by 9 months of age. Col1a2-loxP-targeted mice were also generated and crossed with the tamoxifen-inducible Postn-MerCreMer mice to delete the Col1a2 gene in myofibroblasts with pressure overload injury. Interestingly, while germline Col1a2-/- mice showed gradual pathologic hypertrophy and fibrosis with aging, the acute deletion of Col1a2 from activated adult myofibroblasts showed a loss of total collagen deposition with acute cardiac injury and an acute reduction in pressure overload-induce cardiac hypertrophy. However, this reduction in hypertrophy due to myofibroblast-specific Col1a2 deletion was lost after 2 and 6 weeks of pressure overload, as fibrotic deposition accumulated. Defective type I collagen in the heart alters the structural integrity of the ECM and leads to cardiomyopathy in adulthood, with fibroblast expansion, activation, and alternate fibrotic ECM deposition. However, acute inhibition of type I collagen production can have an anti-fibrotic and anti-hypertrophic effect.

Correlation between biological and mechanical properties of extracellular matrix from colorectal peritoneal metastases in human tissues

Peritoneal metastases (PM) are common routes of dissemination for colorectal cancer (CRC) and remain a lethal disease with a poor prognosis. The properties of the extracellular matrix (ECM) are important in cancer development; studying their changes is crucial to understand CRC-PM development. We studied the elastic properties of ECMs derived from human samples of normal and neoplastic PM by atomic force microscopy (AFM); results were correlated with patient clinical data and expression of ECM components related to metastatic spread. We show that PM progression is accompanied by stiffening of the ECM, increased cancer associated fibroblasts (CAF) activity and increased deposition and crosslinking in neoplastic matrices; on the other hand, softer regions are also found in neoplastic ECMs on the same scales. Our results support the hypothesis that local changes in the normal ECM can create the ground for growth and spread from the tumour of invading metastatic cells. We have found correlations between the mechanical properties (relative stiffening between normal and neoplastic ECM) of the ECM and patients’ clinical data, like age, sex, presence of protein activating mutations in BRAF and KRAS genes and tumour grade. Our findings suggest that the mechanical phenotyping of PM-ECM has the potential to predict tumour development.

Regulation of AMPK activation by extracellular matrix stiffness in pancreatic cancer

The adenosine monophosphate (AMP)-activated protein kinase (AMPK) sits at a central node in the regulation of energy metabolism and tumor progression. AMPK is best known to sense high cellular ADP or AMP levels, which indicate the depletion of energy stores. Previous studies have shown that the low expression of phosphorylated AMPK is associated with a poor prognosis of pancreatic cancer. In this study, we report that AMPK is also highly sensitive to extracellular matrix (ECM) stiffness. We found that AMPK is activated in cells when cultured under low ECM stiffness conditions and is functionally required for the metabolic switch induced by ECM stiffness. This regulation of AMPK requires the Hippo kinases but not LKB1/CaMKKβ. Hippo kinases directly phosphorylate AMPKα at Thr172 to activate AMPK at low ECM stiffness. Furthermore, we found AMPK activity is inhibited in patients with pancreatic ductal adenocarcinoma (PDAC) with high ECM stiffness and is associated with a poor survival outcome. The activation of Hippo kinases by ROCK inhibitor Y-27632 in combination with the mitochondrial inhibitor metformin synergistically activates AMPK and dramatically inhibits PDAC growth. Together, these findings establish a novel model for AMPK regulation by the mechanical properties of ECMs and provide a rationale for simultaneously targeting the ECM stiffness–Hippo kinases–AMPK signaling and low glucose–LKB1–AMPK signaling pathways as an effective therapeutic strategy against PDAC.

Preprint Highlight: Constriction forces imposed by basement membranes regulate developmental cell migration

Extracellular matrix (ECM) stiffness affects many processes of ECM-associated cells, such as migration and differentiation. Whether ECM mechanical properties also affect distant cell populations remains largely unexplored. This preprint studies migration of border cells within Drosophila ovarian follicles as a model system. Border cells migrate toward the center of the follicle by moving between nurse cells, which are surrounded by follicle cells that are themselves encased by the basement membrane ECM. Decreasing stiffness of the follicle ECM reduced cortical tension of follicle cells, and of nurse cells indirectly, accelerating border cell migration. Increasing follicle cell cortical tension slowed border cell migration. These results may inform how ECM stiffness affects cell migration within other complex tubular tissues, such as blood vessels. This preprint has been assigned the following badges: New Hypothesis, New Materials, Cross-Validation Read the preprint on bioRxiv ( Molina López et al., 2022 ): https://doi.org/10.1101/2022.12.19.520983 .

Effects of matrix viscoelasticity and geometrical constraint on cell migrations: A multiscale bio-chemo-mechanical model

Cells actively sense the extracellular matrix (ECM) biophysical properties and respond by changing migration phenotypes. The regulatory roles of the ECM viscoelasticity and geometrical constraint were separately validated in different experimental studies. However, the extension of the study to more complex microenvironments that combines all these biophysical factors is challenging due to the difficulty of manipulating 3D ECM scaffolds. In this study, we proposed a multiscale model that enabled the sensing of the ECM mechanical properties and contact interactions between a highly deformed cell with the constricted wavy microchannels. The model is validated against experimental data and quantitatively replicates the effects of ECM viscoelasticity and confinement on cell area and speed. We observe a linearly increasing migration speed on stiff substrates with increasing cell aspect ratios in the narrower channels. The reason can be attributed to the increasing net propulsive force as traction forces become progressively polarized and the decreasing viscous drag resulting from the suppressing spreading. Notably, we predict that, on soft viscoelastic substrates, cells concurrently achieve the maximum speed and the largest spreading in which the substrate relaxation time is comparable to the clutch binding timescale. The model also shows the influence of contact guidance by the geometric curvature at the sidewall boundary on cell spreading, morphology, and migration speed. Together, our multiscale model captures varying mechanosensitive migration phenotypes with the underlying mechanism explained from the sub-cellular dynamics and provides experimentally testable predictions on cell migrations in a microenvironment that better mimic the tissue microenvironment.

Recombinant irisin enhances the extracellular matrix formation, remodeling potential, and differentiation of human periodontal ligament cells cultured in 3D.

Irisin is expressed in human periodontal ligament (hPDL), and its administration enhances growth, migration and matrix deposition in hPDL cells cultured in monolayers in vitro. To identify whether irisin affects the gene expression patterns directing the morphology, mechanical properties, extracellular matrix (ECM) formation, osteogenic activity and angiogenic potential in hPDL cell spheroids cultured in 3D. Spheroids of primary human hPDL cells were generated in a rotational 3D culture system and treated with or without irisin. The gene expression patterns were evaluated by Affymetrix microarrays. The morphology of the spheroids was characterized using histological staining. Mechanical properties were quantified by nanoindentation. The osteogenic and angiogenic potential of spheroids were assessed through immunofluorescence staining for collagen type I, periostin fibronectin and von Willebrand factor (vWF), and mRNA expression of osteogenic markers. The secretion of multiple myokines was evaluated using Luminex immunoassays. Approximately 1000 genes were differentially expressed between control and irisin-treated groups by Affymetrix. Several genes related to ECM organization were differentially expressed, and multiple deubiquitinating enzymes were upregulated in the irisin-exposed samples analyzed. These represent cellular and molecular mechanisms indicative of a role for irisin in tissue remodeling. Irisin induced a rim-like structure on the outer region of the hPDL spheroids, ECM-related protein expression and the stiffness of the spheroids were enhanced by irisin. The expression of osteogenic and angiogenetic markers was increased by irisin. Irisin altered the morphology in primary hPDL cell-derived spheroids, enhanced its ECM deposition, mechanical properties, differentiation and remodeling potential.

Aging-related structural change in 3D extracellular matrix affects its mechanics.

Aging induces marked alterations in the structural, mechanical, and transport properties in the extracellular matrix (ECM). To provide computational data on the impact of aging-related changes on ECM mechanical quantities and transport properties, we developed a computational model for the aging-related ECM fibrous network. A finite volume method was utilized to calculate the velocity field, pressure loss, hydraulic conductivity and drag force. Our results quantitatively demonstrated that the hydraulic conductivity in most of the aging ECM-mimetic fibrous networks tends to be significantly lower than young ECM-mimetic fibrous networks, while pressure loss and drag force show the opposite trend. All these findings highlight that such altered mechanical quantities and transport properties during aging can be important biological cues to assess the aging process and eventually provide insights in treating aging-related diseases.

FRESH 3D Bioprinted Collagen‐based Resistance Vessels and Multiscale Vascular Microfluidics

The pursuit of an ideal model system to study the pathophysiology of vascular disease has included the use of tissue engineered blood vessels (TEBV), vascularizing engineered volumetric tissue, silicone‐based “organ‐on‐a‐chip” platform, and tissue decellularization; yet we are still far from generating engineered vascular tissue that recapitulate native physiology. Despite advances such as 3D bioprinting that have led to new approaches for creating fluidic channels, it remains challenging to produce continuous networks with vessels ranging from large (>6 mm) to small (<1 mm) using native‐like extracellular matrix (ECM) that recapitulates the mechanical properties, geometric organization, and complexity of the cellular and extracellular microenvironment. An ideal engineering strategy would combine the controlled fluid flow achieved by organ‐on‐a‐chip platforms with the ECM structure, composition, and biomechanics of decellularized tissue. Here, using Freeform Reversible Embedding of Suspended Hydrogels (FRESH) 3D bioprinting, we spatially define ECM composition and vascular geometry to create collagen‐based microfluidics and an engineered resistance artery scaffold to study how ECM composition, mechanical properties, and fluid flow contribute to vascular disease. A 3D vascular microfluidic CAD model was designed with a hierarchically branching network containing a single inlet and outlet of 1 mm that branched down to 250 µm channels embedded within a collagen scaffold. This model was FRESH printed with 24 mg/mL collagen‐I and yielded a high‐fidelity scaffold with patent internal vasculature. 3D imaging and gauging analysis of the CAD model compared to the collagen scaffold revealed an average positive deviation of 9.9 µm and an average negative deviation of 56.3 µm. To interface with and perfuse the soft collagen microfluidic scaffold we 3D printed a custom bioreactor chamber for long‐term culture capable of >1‐week perfusion under physiological conditions. In addition to embedded vascular networks, FRESH bioprinting allows for direct fabrication of suspended vessels. We designed an ECM scaffold scaled to match a resistance vessel consisting of a collagen‐I frame and suspended vessel (inner diameter of 300 µm, outer diameter of 500 µm). The collagen frame provides overall scaffold stability and allows interfacing to the custom perfusion bioreactor. Using multimaterial FRESH printing, we varied the ECM composition by patterning fibronectin along the inner lumen and collagen‐I within the outer adventitial wall. Biomechanical evaluation using pressure and wire myography revealed a burst pressure >140 mmHg and an average peak tension of 600 mg, comparable to mouse mesenteric resistance arteries. Together, this work highlights the exciting potential for ECM‐based microfluidic scaffolds and vascular tissue engineering that will set the foundation for future work to replicate a healthy and hypertensive vessel microenvironment. In addition to vascular biology, the collagen‐based microfluidics are amenable to other organ systems, and can be utilized to study cell proliferation, metastasis, and ECM remodeling in a 3D environment.

Decellularization of Wharton’s Jelly Increases Its Bioactivity and Antibacterial Properties

The field of regenerative medicine has recently seen an emerging trend toward decellularized extracellular matrix (ECM) as a biological scaffold for stem cell-delivery. Human umbilical cord represents a valuable opportunity from both technical and ethical point of view to obtain allogenic ECM. Herein, we established a protocol, allowing the full removal of cell membranes and nuclei moieties from Wharton’s jelly (WJ) tissue. No alterations in the ECM components (i.e., collagen, GAG content, and growth factors), physical (i.e., porosity and swelling) and mechanical (i.e., linear tensile modulus) properties were noticed following WJ processing. Furthermore, no effect of the tissue processing on macromolecules and growth factors retention was observed, assuring thus a suitable bioactive matrix for cell maintenance upon recellularization. Based on the in vitro and in vivo biodegradability and stromal cell homing capabilities, decellularized WJ could provide an ideal substrate for stromal cells adhesion and colonization. Interestingly, the tissue processing increased the antibacterial and antiadhesive properties of WJ against Staphylococcus aureus and Staphylococcus epidermidis pathogens. Altogether, our results indicate that decellularized WJ matrix is able to limit Staphylococcus-related infections and to promote stromal cell homing, thus offering a versatile scaffold for tissue regenerative medicine.

Mechanically Tunable Extracellular Matrix of Genipin Crosslinked Collagen and Its Effect on Endothelial Function.

Mechanical rigidity of a matrix, to which cells adhere, plays a significant role in regulating phenotypic cellular behaviors such as spreading and junction formation because vascular cells sense and respond to changes in their mechanical environment. Controlling mechanical properties of extracellular matrix by using a crosslinker is important for cell and tissue mechanobiology. In this paper, we explored genipin, a natural plant extract, to crosslink collagen-I in order to enhance mechanical properties with low cytotoxicity. We characterized the effects of genipin concentration on the mechanical properties, color change, degradation, structure, cell viability, and endothelial function such as transendothelial electrical resistance (TEER). Through the analysis of both material properties and endothelial response, it was found that genipin-based glycation caused an increase in viscoelastic moduli in collagen hydrogels, as well as increased fiber density in their structural morphology. Endothelial cells were found to form better barriers, express higher levels of tight junction proteins, and exhibit better adhesion on stiffer matrices.