Biology subjects

Fage, F.

Publications and source records attributed to Fage, F..

4 recordsLinked to original sources

bioRxiv2026

Collagen-based bilayered biomimetic tubular materials for vascular and airway applications

Biomimetic tubular scaffolds hold great promise for tackling unmet clinical needs thanks to their biocompatibility and recapitulation of cellular microenvironments, conferring the ability to promote regeneration. Potential applications include small-diameter vascular implants and grafts for airway repair, for which no viable off-the-shelf solutions currently exist. The tubular materials (4 and 8 mm internal and external diameters) presented here consist purely of type I collagen, contain no chemical crosslinkers, and reproduce the multi-scale architecture of the native tissue including the presence of collagen fibrils. A novel two-step protocol provides materials with distinct concentric layers. A porous external structure, obtained by means of ice templating combined with collagen topotactic fibrillogenesis, favours oriented cell colonization. A smooth and much less porous internal layer provides mechanical and water-tightness properties relevant for in vivo implantation and promotes the formation of an endothelial monolayer under both static and flow conditions. The compliance of the double-layered materials under physiological pressure is close to that of piglet carotid arteries. The materials are also determined to be sufficiently flexible to provide the ability to perform ex vivo anastomosis with bronchi, although the relatively low value of suture retention strength remains a limitation for in vivo suturing.

bioengineering↗

bioRxiv2024

Disentangling the contributions of stress fibres and the unbundled actin meshwork to the anisotropy of cortical tension in response to cell shape

Many fundamental biological processes, in particular development and morphogenetic movements, involve tissue and cell deformation, as well as the generation of anisotropic mechanical stresses. They are often accompanied by the appearance of oriented contractile actomyosin structures resembling the stress fibres (SF) observed in vitro. Here, we investigate, at the single cell level, how cell shape -- by itself -- could control the structure and tension of the actomyosin cortex. Using a unique combination of 3D micropatterning, single peripheral SF (PSF) tension measurement, laser ablation and image analysis, we show that cell shape anisotropy, e.g. its 2D aspect ratio, is indeed sufficient to induce anisotropy of the cortical structure and tension. In particular, taking into account the experimentally measured anisotropy of the cortical meshwork, we could quantify cortical tension and decouple the contribution originating from bundled actin (oriented cortical stress fibres, CSF) and the contribution of the unbundled actin meshwork (UAM). We show that the increase of cortical tension anisotropy with the cells aspect ratio depends on the CSF alignment and orientation, the contribution of the isotropic mesh being independent of cell shape. Remarkably, while experimental data from single stress fibre measurements and laser ablation were analysed through different theoretical frameworks, namely that of negative pressure in nematics and hole drilling in prestressed materials, we found quantitatively the same composite material behaviour. In sum, we decipher here the very material properties of the actomyosin cortex, and its sensitivity to cell shape which is at the root of many mechanobiological processes, in particular morphogenesis.

biophysics↗

bioRxiv2023

Tunable biomimetic materials elaborated by ice templating and self-assembly of collagen for tubular tissue engineering

Synthetic tubular grafts currently used in clinical context fail frequently, and the expectations that biomimetic materials could tackle these limitations are high. However, developing tubular materials presenting structural, compositional and functional properties close to those of native tissues remains an unmet challenge. Here we describe a combination of ice templating and topotactic fibrillogenesis of type I collagen, the main component of tissues extracellular matrix, yielding highly concentrated yet porous tubular collagen materials with controlled hierarchical architecture at multiple length scales, the hallmark of native tissues organization. By modulating the thermal conductivity of the cylindrical molds, we tune the macroscopic porosity defined by ice. Coupling the aforementioned porosity patterns with two different fibrillogenesis routes results in a new family of materials whose textural features and the supramolecular arrangement of type I collagen are achieved. The resulting materials present hierarchical elastic properties and are successfully colonized by human endothelial cells and alveolar epithelial cells on the luminal side, and by human mesenchymal stem cells on the external side. The results reported here demonstrate the relevance of the proposed straightforward protocol, likely to be adapted for larger graft sizes, to address ever-growing clinical needs such as peripheral arterial disease or tracheal and bronchial reconstructions.

bioengineering↗

bioRxiv2021

Optineurin links Hace1-dependent Rac ubiquitylation to integrin-mediated mechanotransduction to control bacterial invasion and cell division

Extracellular matrix (ECM) elasticity is perceived by cells via focal adhesion structures, which transduce mechanical cues into chemical signalling to conform cell behaviour. Although the contribution of ECM compliance to the control of cell migration or division has been extensively studied, little has been reported regarding infectious processes. We have studied how mechanical properties of the ECM impact invasion of cells by the extraintestinal Escherichia coli pathogen UTI89. We show that UTI89 takes advantage, via its CNF1 toxin, of integrin mechanoactivation to trigger its invasion into cells. We identified OPTN as a protein regulated by ECM stiffness whose function is required for bacterial invasion and integrin mechanical coupling and for stimulation of HACE1 E3 ligase activity towards the Rac1 GTPase. We showed that OPTN knockdown cells display enhanced Rac1 activation, strong mechanochemical adhesion signalling and increased cyclin D1 translation, together with enhanced cell proliferation independent of ECM stiffness. Despite such features, OPTN knockdown cells displayed defective traction force buildup associated with limited cellular invasion by UTI89. Together, our data indicate that OPTN, through a new role in mechanobiology, supports CNF1-producing uropathogenic E. coli invasion and links HACE1-mediated ubiquitylation of Rac1 to ECM mechanical properties and integrin mechanotransduction.

cell biology↗