Collagen IV deficiency causes hypertrophic remodeling and endothelium-dependent hyperpolarization in small vessel disease with intracerebral hemorrhage.

Background: Genetic variants in COL4A1 and COL4A2 (encoding collagen IV alpha chain 1/2) occur in genetic and sporadic forms of cerebral small vessel disease (CSVD), a leading cause of stroke, dementia and intracerebral haemorrhage (ICH). However, the molecular mechanisms of CSVD with ICH and COL4A1/COL4A2 variants remain obscure.

Methods: Vascular function and molecular investigations in mice with a Col4a1 missense mutation and heterozygous Col4a2 knock-out mice were combined with analysis of human brain endothelial cells harboring COL4A1/COL4A2 mutations, and brain tissue of patients with sporadic CSVD with ICH.

An In Vitro Model of the Blood-Brain Barrier for the Investigation and Isolation of the Key Drivers of Barriergenesis.

The blood-brain barrier (BBB) tightly regulates substance transport between the bloodstream and the brain. Models for the study of the physiological processes affecting the BBB, as well as predicting the permeability of therapeutic substances for neurological and neurovascular pathologies, are highly desirable. Existing models, such as Transwell utilizing-models, do not mimic the extracellular environment of the BBB with their stiff, semipermeable, non-biodegradable membranes.

Mind the Viscous Modulus: The Mechanotransductive Response to the Viscous Nature of Isoelastic Matrices Regulates Stem Cell Chondrogenesis.

The design of hydrogels as mimetics of tissues' matrices typically disregards the viscous nature of native tissues and focuses only on their elastic properties. In the case of stem cell chondrogenesis, this has led to contradictory results, likely due to unreported changes in the matrices' viscous modulus. Here, by employing isoelastic matrices with Young's modulus of ≈12 kPa, variations in viscous properties alone (i.

Controlling the formation and alignment of low molecular weight gel 'noodles'.

We show how to control the formation and alignment of gel 'noodles'. Nanostructure alignment can be achieved reproducibly by extensional deformation as the filaments form. Using a spinning technique, very long and highly aligned filaments can be made.

You Talking to Me? Cadherin and Integrin Crosstalk in Biomaterial Design.

While much work has been done in the design of biomaterials to control integrin-mediated adhesion, less emphasis has been put on functionalization of materials with cadherin ligands. Yet, cell-cell contacts in combination with cell-matrix interactions are key in driving embryonic development, collective cell migration, epithelial to mesenchymal transition, and cancer metastatic processes, among others. This review focuses on the incorporation of both cadherin and integrin ligands in biomaterial design, to promote what is called the "adhesive crosstalk.

ChondroGELesis: Hydrogels to harness the chondrogenic potential of stem cells.

The extracellular matrix is a highly complex microenvironment, whose various components converge to regulate cell fate. Hydrogels, as water-swollen polymer networks composed by synthetic or natural materials, are ideal candidates to create biologically active substrates that mimic these matrices and target cell behaviour for a desired tissue engineering application. Indeed, the ability to tune their mechanical, structural, and biochemical properties provides a framework to recapitulate native tissues.

The creatine-phosphagen system is mechanoresponsive in pancreatic adenocarcinoma and fuels invasion and metastasis.

Pancreatic ductal adenocarcinoma is particularly metastatic, with dismal survival rates and few treatment options. Stiff fibrotic stroma is a hallmark of pancreatic tumours, but how stromal mechanosensing affects metastasis is still unclear. Here, we show that mechanical changes in the pancreatic cancer cell environment affect not only adhesion and migration, but also ATP/ADP and ATP/AMP ratios.

Material-driven fibronectin assembly rescues matrix defects due to mutations in collagen IV in fibroblasts.

Basement membranes (BMs) are specialised extracellular matrices that provide structural support to tissues as well as influence cell behaviour and signalling. Mutations in COL4A1/COL4A2, a major BM component, cause a familial form of eye, kidney and cerebrovascular disease, including stroke, while common variants in these genes are a risk factor for intracerebral haemorrhage in the general population. These phenotypes are associated with matrix defects, due to mutant protein incorporation in the BM and/or its absence by endoplasmic reticulum (ER) retention.

T-Cell-Derived miRNA-214 Mediates Perivascular Fibrosis in Hypertension.

Rationale: Despite increasing understanding of the prognostic importance of vascular stiffening linked to perivascular fibrosis in hypertension, the molecular and cellular regulation of this process is poorly understood.

Objectives: To study the functional role of microRNA-214 (miR-214) in the induction of perivascular fibrosis and endothelial dysfunction driving vascular stiffening.

Methods And Results: Out of 381 miRs screened in the perivascular tissues in response to Ang II (angiotensin II)-mediated hypertension, miR-214 showed the highest induction (8-fold, =0.

The Plot Thickens: The Emerging Role of Matrix Viscosity in Cell Mechanotransduction.

Cell mechanotransduction is an area of intense research focus. Until now, very limited tools have existed to study how cells respond to changes in the extracellular matrix beyond, for example, mechanical deformation studies and twisting cytometry. However, emerging are a range of elastic, viscoelastic and even purely viscous materials that deform and dissipate on cellular length and timescales.

3D gelatin-chitosan hybrid hydrogels combined with human platelet lysate highly support human mesenchymal stem cell proliferation and osteogenic differentiation.

Bone marrow and adipose tissue human mesenchymal stem cells were seeded in highly performing 3D gelatin-chitosan hybrid hydrogels of varying chitosan content in the presence of human platelet lysate and evaluated for their proliferation and osteogenic differentiation. Both bone marrow and adipose tissue human mesenchymal stem cells in gelatin-chitosan hybrid hydrogel 1 (chitosan content 8.1%) or gelatin-chitosan hybrid hydrogel 2 (chitosan 14.

Nanoscale Coatings for Ultralow Dose BMP-2-Driven Regeneration of Critical-Sized Bone Defects.

While new biomaterials for regenerative therapies are being reported in the literature, clinical translation is slow. Some existing regenerative approaches rely on high doses of growth factors, such as bone morphogenetic protein-2 (BMP-2) in bone regeneration, which can cause serious side effects. An ultralow-dose growth factor technology is described yielding high bioactivity based on a simple polymer, poly(ethyl acrylate) (PEA), and mechanisms to drive stem cell differentiation and bone regeneration in a critical-sized murine defect model with translation to a clinical veterinary setting are reported.

Functionalization of PLLA with Polymer Brushes to Trigger the Assembly of Fibronectin into Nanonetworks.

Poly-l-lactic acid (PLLA) has been used as a biodegradable polymer for many years; the key characteristics of this polymer make it a versatile and useful resource for regenerative medicine. However, it is not inherently bioactive. Thus, here, a novel process is presented to functionalize PLLA surfaces with poly(ethyl acrylate) (PEA) brushes to provide biological functionality through PEA's ability to induce spontaneous organization of the extracellular matrix component fibronectin (FN) into physiological-like nanofibrils.

The strength of the protein-material interaction determines cell fate.

Unlabelled: Extracellular matrix (ECM) proteins are key mediators of cell/material interactions. The surface density and conformation of these proteins adsorbed on the material surface influence cell adhesion and the cellular response. We have previously shown that subtle variations in surface chemistry lead to drastic changes in the conformation of adsorbed fibronectin (FN).

Vitronectin as a Micromanager of Cell Response in Material-Driven Fibronectin Nanonetworks.

Surface functionalization strategies of synthetic materials for regenerative medicine applications comprise the development of microenvironments that recapitulate the physical and biochemical cues of physiological extracellular matrices. In this context, material-driven fibronectin (FN) nanonetworks obtained from the adsorption of the protein on poly(ethyl acrylate) provide a robust system to control cell behavior, particularly to enhance differentiation. This study aims at augmenting the complexity of these fibrillar matrices by introducing vitronectin, a lower-molecular-weight multifunctional glycoprotein and main adhesive component of serum.

Molecular clutch drives cell response to surface viscosity.

Cell response to matrix rigidity has been explained by the mechanical properties of the actin-talin-integrin-fibronectin clutch. Here the molecular clutch model is extended to account for cell interactions with purely viscous surfaces (i.e.

Engineered microenvironments for synergistic VEGF - Integrin signalling during vascularization.

We have engineered polymer-based microenvironments that promote vasculogenesis both in vitro and in vivo through synergistic integrin-growth factor receptor signalling. Poly(ethyl acrylate) (PEA) triggers spontaneous organization of fibronectin (FN) into nanonetworks which provide availability of critical binding domains. Importantly, the growth factor binding (FNIII) and integrin binding (FNIII) regions are simultaneously available on FN fibrils assembled on PEA.

Material-driven fibronectin assembly for high-efficiency presentation of growth factors.

Growth factors (GFs) are powerful signaling molecules with the potential to drive regenerative strategies, including bone repair and vascularization. However, GFs are typically delivered in soluble format at supraphysiological doses because of rapid clearance and limited therapeutic impact. These high doses have serious side effects and are expensive.

Protein Adsorption as a Key Mediator in the Nanotopographical Control of Cell Behavior.

Surface nanotopography is widely employed to control cell behavior and in particular controlled disorder has been shown to be important in cell differentiation/maturation. However, extracellular matrix proteins, such as fibronectin (FN), initially adsorbed on a biomaterial surface are known to mediate the interaction of synthetic materials with cells. In this work, we examine the effect of nanotopography on cell behavior through this adsorbed layer of adhesive proteins using a nanostructured polycarbonate surface comprising 150 nm-diameter pits originally defined using electron beam lithography.

Lateral Chain Length in Polyalkyl Acrylates Determines the Mobility of Fibronectin at the Cell/Material Interface.

Cells, by interacting with surfaces indirectly through a layer of extracellular matrix proteins, can respond to a variety of physical properties, such as topography or stiffness. Polymer surface mobility is another physical property that is less well understood but has been indicated to hold the potential to modulate cell behavior. Polymer mobility is related to the glass-transition temperature (Tg) of the system, the point at which a polymer transitions from an amorphous solid to a more liquid-like state.

Different Organization of Type I Collagen Immobilized on Silanized and Nonsilanized Titanium Surfaces Affects Fibroblast Adhesion and Fibronectin Secretion.

Silanization has emerged in recent years as a way to obtain a stronger and more stable attachment of biomolecules to metallic substrates. However, its impact on protein conformation, a key aspect that influences cell response, has hardly been studied. In this work, we analyzed by atomic force microscopy (AFM) the distribution and conformation of type I collagen on plasma-treated surfaces before and after silanization.

A material-based platform to modulate fibronectin activity and focal adhesion assembly.

We present a detailed characterization of fibronectin (FN) adsorption and cell adhesion on poly(ethyl acrylate) (PEA) and poly(methyl acrylate) (PMA), two polymers with very similar physicochemical properties and chemical structure, which differ in one single methyl group in the lateral chain of the polymer. The globular solution conformation of FN was retained following adsorption onto PMA, whereas spontaneous organization of FN into protein (nano) networks occurred on PEA. This distinct distribution of FN at the material interface promoted a different availability, measured via monoclonal antibody binding, of two domains that facilitated integrin binding to FN: FNIII10 (RGD sequence) and FNIII9 (PHSRN synergy sequence).

A fractal nature for polymerized laminin.

Polylaminin (polyLM) is a non-covalent acid-induced nano- and micro-structured polymer of the protein laminin displaying distinguished biological properties. Polylaminin stimulates neuritogenesis beyond the levels achieved by ordinary laminin and has been shown to promote axonal regeneration in animal models of spinal cord injury. Here we used confocal fluorescence microscopy (CFM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) to characterize its three-dimensional structure.

Design and functional testing of a multichamber perfusion platform for three-dimensional scaffolds.

Perfusion culture systems are widely used in tissue engineering applications for enhancing cell culture viability in the core of three-dimensional scaffolds. In this work, we present a multichamber confined-flow perfusion system, designed to provide a straightforward platform for three-dimensional dynamic cell cultures. The device comprises 6 culture chambers allowing independent and simultaneous experiments in controlled conditions.