Increased basal fibronectin is sufficient to promote excess endothelial cell matrix assembly causing localized barrier dysfunction.

Endothelial cell behavior is regulated by subendothelial extracellular matrix (ECM). The ECM protein fibronectin (FN) is rare in healthy blood vessels but accumulates in disease accompanied by endothelial dysfunctions. Here, we report that excess assembly of FN disrupts key endothelial functions.

Identification of a fibronectin-binding protein signature associated with idiopathic pulmonary fibrosis.

The extracellular matrix (ECM) is a critical component of tissue where it provides structural and signaling support to cells. Its dysregulation and accumulation lead to fibrosis, a major clinical challenge underlying many diseases that currently has little effective treatment. An understanding of the key molecular initiators of fibrosis would be both diagnostically useful and provide potential targets for therapeutics.

Extracellular matrix composition affects outgrowth of dendrites and dendritic spines on cortical neurons.

The composition of the extracellular matrix (ECM) in nervous tissue plays an important role in controlling neuronal outgrowth and synapse development. Changes in both protein and glycosaminoglycan components of the ECM occur with tissue injury and may affect neuron growth. To investigate neuron responses to alterations in fibronectin (FN), a major component of the wound ECM, we grew cortical neurons on cell-derived decellularized matrices composed of wild type FN (FN) or of a mutant form of FN (FN) from which the III heparin-binding site had been deleted by CRISPR-Cas 9 gene editing.

Open-Spaced Ridged Hydrogel Scaffolds Containing TiO-Self-Assembled Monolayer of Phosphonates Promote Regeneration and Recovery Following Spinal Cord Injury.

The spinal cord has a poor ability to regenerate after an injury, which may be due to cell loss, cyst formation, inflammation, and scarring. A promising approach to treating a spinal cord injury (SCI) is the use of biomaterials. We have developed a novel hydrogel scaffold fabricated from oligo(poly(ethylene glycol) fumarate) (OPF) as a 0.

Nucleation of fibronectin fibril assembly requires binding between heparin and the 13th type III module of fibronectin.

Fibronectin (FN), a critical component of the extracellular matrix, is assembled into fibrils through a cell-mediated process. Heparan sulfate (HS) binds to the III module of FN, and fibroblasts lacking this glycosaminoglycan exhibit reduced FN fibril assembly. To determine if HS depends on III to control FN assembly, we deleted both III alleles in NIH 3T3 cells using the CRISPR-Cas9 system.

A new mechanism of fibronectin fibril assembly revealed by live imaging and super-resolution microscopy.

Fibronectin (Fn1) fibrils have long been viewed as continuous fibers composed of extended, periodically aligned Fn1 molecules. However, our live-imaging and single-molecule localization microscopy data are inconsistent with this traditional view and show that Fn1 fibrils are composed of roughly spherical nanodomains containing six to eleven Fn1 dimers. As they move toward the cell center, Fn1 nanodomains become organized into linear arrays, in which nanodomains are spaced with an average periodicity of 105±17 nm.

Implications of fibrotic extracellular matrix in diabetic retinopathy.

Fibrosis is an accumulation of extracellular matrix (ECM) proteins and fibers in a disordered fashion, which compromises cell and tissue functions. High glucose-induced fibrosis, a major pathophysiological change of diabetic retinopathy (DR), severely affects vision by compromising the retinal vasculature and ultimately disrupting retinal tissue organization. The retina is a highly vascularized, stratified tissue with multiple cell types organized into distinct layers.

Heparan sulfate is necessary for the early formation of nascent fibronectin and collagen I fibrils at matrix assembly sites.

Fibronectin (FN), an essential component of the extracellular matrix (ECM), is assembled via a cell-mediated process in which integrin receptors bind secreted FN and mediate its polymerization into fibrils that extend between cells, ultimately forming an insoluble matrix. Our previous work using mutant Chinese hamster ovary (CHO) cells identified the glycosaminoglycan heparan sulfate (HS) and its binding to FN as essential for the formation of insoluble FN fibrils. In this study, we investigated the contributions of HS at an early stage of the assembly process using knockdown of exostosin-1 (EXT1), one of the glycosyltransferases required for HS chain synthesis.

Differential Regulation of Neurite Outgrowth and Growth Cone Morphology by 3D Fibronectin and Fibronectin-Collagen Extracellular Matrices.

The extracellular matrix (ECM) plays a critical role in development, homeostasis, and regeneration of tissue structures and functions. Cell interactions with the ECM are dynamic and cells respond to ECM remodeling by changes in morphology and motility. During nerve regeneration, the ECM facilitates neurite outgrowth and guides axons with target specificity.

The Proteome of Preretinal Tissue in Proliferative Vitreoretinopathy.

Background And Objective: Proliferative vitreoretinopathy (PVR) is the leading cause of retinal detachment repair failure. However, the molecular pathogenesis remains incompletely understood. Determining the proteome of PVR will help to identify novel therapeutic targets.

Promoting Neuronal Outgrowth Using Ridged Scaffolds Coated with Extracellular Matrix Proteins.

Spinal cord injury (SCI) results in cell death, demyelination, and axonal loss. The spinal cord has a limited ability to regenerate, and current clinical therapies for SCI are not effective in helping promote neurologic recovery. We have developed a novel scaffold biomaterial that is fabricated from the biodegradable hydrogel oligo(poly(ethylene glycol)fumarate) (OPF).

Fibronectin fibril alignment is established upon initiation of extracellular matrix assembly.

The physical structure of the extracellular matrix (ECM) is tissue-specific and fundamental to normal tissue function. Proper alignment of ECM fibers is essential for the functioning of a variety of tissues. While matrix assembly in general has been intensively investigated, little is known about the mechanisms required for formation of aligned ECM fibrils.

Elevated glucose alters global gene expression and tenascin-C alternative splicing in mesangial cells.

Mesangial cells are the major extracellular matrix (ECM)-producing cells in the kidney glomerulus and, when exposed to elevated glucose levels, they up-regulate assembly of fibronectin (FN) and other ECM proteins. Increases in glucose concentration are known to alter gene expression; here we investigated the connection between increased ECM production and changes in gene expression in mesangial cells. Comparison of mesangial cells grown in normal or high glucose conditions by RNA-sequencing showed significant expression changes in over 6000 genes and, when grouped by KEGG pathway analysis, identified the ECM-receptor interaction and focal adhesion pathways among the top 5 upregulated pathways.

A multilayered scaffold for regeneration of smooth muscle and connective tissue layers.

Tissue regeneration often requires recruitment of different cell types and rebuilding of two or more tissue layers to restore function. Here, we describe the creation of a novel multilayered scaffold with distinct fiber organizations-aligned to unaligned and dense to porous-to template common architectures found in adjacent tissue layers. Electrospun scaffolds were fabricated using a biodegradable, tyrosine-derived terpolymer, yielding densely-packed, aligned fibers that transition into randomly-oriented fibers of increasing diameter and porosity.

Stimulation of Fibronectin Matrix Assembly by Lysine Acetylation.

Diabetic nephropathy, a devastating consequence of diabetes mellitus, is characterized by the accumulation of extracellular matrix (ECM) that disrupts the kidney's filtration apparatus. Elevated glucose levels increase the deposition of a fibronectin (FN) matrix by mesangial cells, the primary matrix-producing cells of the kidney, and also increase acetyl-CoA leading to higher levels of lysine acetylation. Here, we investigated the connection between acetylation and the ECM and show that treatment of mesangial cells with deacetylase inhibitors increases both acetylation and FN matrix assembly compared to untreated cells.

Fibronectin matrix as a scaffold for procollagen proteinase binding and collagen processing.

The extracellular matrix (ECM) proteins fibronectin (FN) and type I collagen (collagen I) are codistributed in many tissues, and collagens have been shown to depend on an FN matrix for fibrillogenesis. Microscopic analysis of a fibroblast ECM showed colocalization of procollagen I with FN fibrils, and proteolytic cleavage of procollagen to initiate fibril formation was significantly reduced with inhibition of FN matrix assembly. We examined the role of FN matrix in procollagen processing by the C-propeptide proteinase bone morphogenetic protein 1 (BMP-1).

Controlling the Surface Chemistry of a Hydrogel for Spatially Defined Cell Adhesion.

A two-step synthesis is described for activating the surface of a fully hydrated hydrogel that is of interest as a possible scaffold for neural regeneration devices. The first step exploits the water content of the hydrogel and the hydrophobicity of the reaction solvent to create a thin oxide layer on the hydrogel surface using a common titanium or zirconium alkoxide. This layer serves as a reactive interface that enables rapid transformation of the hydrophilic, cell-nonadhesive hydrogel into either a highly hydrophobic surface by reaction with an alkylphosphonic acid, or into a cell-adhesive one using a (α,ω-diphosphono)alkane.

Impact of Acellular Dermal Matrix on Postsurgical Wound Fluid Biomarkers in Prosthetic Breast Reconstruction.

Background: Despite the widespread practice of using biologic scaffolds for soft tissue reinforcement over prosthetic implants, the impact of acellular dermal matrix (ADM) on surgical wound fluid biomarkers over the initial postoperative period after prosthetic breast reconstruction remains poorly understood.

Methods: Patients undergoing prosthetic breast reconstruction surgery where ADM was likely to be used were consented to have fluid samples collected from surgical drains after surgery. Sample collections occurred at an "Early" time point at 24 to 48 hours after surgery and then a "Late" time point approximately 1 to 2 weeks after surgery.

Cell-derived decellularized extracellular matrices.

The ability to create cell-derived decellularized matrices in a dish gives researchers the opportunity to possess a bioactive, biocompatible material made up of fibrillar proteins and other factors that recapitulates key features of the native structure and composition of in vivo microenvironments. By using cells in a culture system to provide a natural ECM, decellularization allows for a high degree of customization through the introduction of selected proteins and soluble factors. The culture system, culture medium, cell types, and physical environments can be varied to provide specialized ECMs for wide-ranging applications to study cell-ECM signaling, cell migration, cell differentiation, and tissue engineering purposes.

Perforation Does Not Compromise Patterned Two-Dimensional Substrates for Cell Attachment and Aligned Spreading.

Polymeric sheets were perforated by laser ablation and were uncompromised by a debris field when first treated with a thin layer of photoresist. Polymer sheets perforated with holes comprising 5, 10, and 20% of the nominal surface area were then patterned in stripes by photolithography, which was followed by synthesis in exposed regions of a cell-attractive zirconium oxide-1,4-butanediphosphonic acid interface. Microscopic and scanning electron microscopy analyses following removal of unexposed photoresist show well-aligned stripes for all levels of these perforations.

Heparin-fibronectin interactions in the development of extracellular matrix insolubility.

During extracellular matrix (ECM) assembly, fibronectin (FN) fibrils are irreversibly converted into a detergent-insoluble form which, through FN's multi-domain structure, can interact with collagens, matricellular proteins, and growth factors to build a definitive matrix. FN also has heparin/heparan sulfate (HS) binding sites. Using HS-deficient CHO cells, we show that the addition of soluble heparin significantly increased the amount of FN matrix that these cells assemble.

Development of hybrid scaffolds with natural extracellular matrix deposited within synthetic polymeric fibers.

A major challenge of tissue engineering is to generate materials that combine bioactivity with stability in a form that captures the robust nature of native tissues. Here we describe a procedure to fabricate a novel hybrid extracellular matrix (ECM)-synthetic scaffold biomaterial by cell-mediated deposition of ECM within an electrospun fiber mat. Synthetic polymer fiber mats were fabricated using poly(desamino tyrosyl-tyrosine carbonate) (PDTEC) co-spun with poly(ethylene glycol) (PEG) used as a sacrificial polymer.

Minireview: Fibronectin in retinal disease.

Retinal fibrosis, characterized by dysregulation of extracellular matrix (ECM) protein deposition by retinal endothelial cells, pigment epithelial cells, and other resident cell-types, is a unifying feature of several common retinal diseases. Fibronectin is an early constituent of newly deposited ECM and serves as a template for assembly of other ECM proteins, including collagens. Under physiologic conditions, fibronectin is found in all layers of Bruch's membrane.

Nerve Guidance by a Decellularized Fibroblast Extracellular Matrix.

Spinal cord and peripheral nerve injuries require the regeneration of nerve fibers across the lesion site for successful recovery. Providing guidance cues and soluble factors to promote neurite outgrowth and cell survival can enhance repair. The extracellular matrix (ECM) plays a key role in tissue repair by controlling cell adhesion, motility, and growth.