Biology subjects

Fenu, M.

Publications and source records attributed to Fenu, M..

3 recordsLinked to original sources

bioRxiv2023

The Impact of the Local Mechanical Environment on Cell Shape and Chondrogenesis of Mesenchymal Stromal Cells in 3D Biomimetic Composite Materials

Efforts to model and repair connective tissue through engineered tissue constructs have generated great interest in culturing cells in 3d polymer network environments. It has been shown that the polymer environment is influential in determining cellular responses such as differentiation, migration and morphology. Hydrogels are used to mimic the cellular microenvironment, but in most cases hydrogels consisting of one polymeric component are used whereas tissues are composites of different polymers. A clear understanding of how different extracellular components and their mechanical characteristics influence cell behaviour is lacking. Here we developed and characterised composite hydrogels of hyaluronan and fibrin and evaluated their use for cartilage tissue engineering. We demonstrate that these cartilage-mimicking composites have a higher stiffness relative to the individual constituents. Next, we cultured human mesenchymal stromal cells in these 3D hydrogels with chondrogenic media and revealed marked differences in cell morphology, gene expression and cartilage-like matrix deposition depending on the specific extracellular composition. We found that, despite evidence for strong adhesion of the cells to fibrin networks in 2D systems, in 3D systems the primary determinant of cellular morphology is the significantly denser hyaluronan network. Dense hyaluronan hydrogels cause local cell confinement evidenced by rounder cell morphologies, independent of the presence of fibrin. While the composite fibrin-hyaluronan hydrogels led to lower expression of chondrogenic genes than hyaluronan alone, the larger linear modulus and resistance to cell-mediated contraction due to the composite nature of the matrix provides a strong advantage in terms of macroscopic mechanical stability. These findings highlight the potential of multi-component hydrogels for controlling cellular behaviour and bulk mechanical properties of cell-hydrogel constructs independently, therefore opening avenues for better understanding the complex interplay between cells and their extracellular environment and thus improve the biofabrication of connective tissues for disease modelling and tissue regeneration. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/555478v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@151962org.highwire.dtl.DTLVardef@1358890org.highwire.dtl.DTLVardef@198dcedorg.highwire.dtl.DTLVardef@d04f80_HPS_FORMAT_FIGEXP M_FIG C_FIG

biophysics↗

bioRxiv2023

Rational positioning of 3D printed micro-bricks to realize high-fidelity, multi-functional soft-hard interfaces

AO_SCPLOWBSTRACTC_SCPLOWLiving organisms have developed design principles, such as functional gradients (FGs), to interface hard materials with soft ones (e.g., bone and tendon). Mimicking such design principles can address the challenges faced when developing engineered constructs with soft-hard interfaces. To date, implementing these FG design principles has been primarily performed by varying the ratio of the hard phase to that of the soft phase. Such design approaches, however, lead to inaccurate mechanical properties within the transition zone. That is due to the highly nonlinear relationship between the material distribution at the microscale and the macroscale mechanical properties. Here, we 3D print micro-bricks from either a soft or a hard phase and study the nonlinear relationship between their arrangements within the transition zone and the resulting macroscale properties. We carry out experiments at the micro- and macroscales as well as finite element simulations at both scales. Based on the obtained results, we develop a co-continuous power-law model relating the arrangement of the micro-bricks to the local mechanical properties of the micro-brick composites. We then use this model to rationally design FGs at the individual micro-brick level and create two types of biomimetic soft-hard constructs, including a specimen modeling bone-ligament junctions in the knee and another modeling the nucleus pulposus-annulus fibrosus interface in intervertebral discs. We show that the implemented FGs drastically enhance the stiffness, strength, and toughness of both types of specimens as compared to non-graded designs. Furthermore, we hypothesize that our soft-hard FGs regulate the behavior of murine preosteoblasts and primary human bone marrow-derived mesenchymal stromal cells (hBMSCc). We culture those cells to confirm the effects of soft-hard interfaces on cell morphology as well as on regulating the expression of focal adhesion kinase, subcellular localization, and YAP nuclear translocation of hBMSCs. Taken together, our results pave the way for the rational design of soft-hard interfaces at the micro-brick level and (biomedical) applications of such designs.

bioengineering↗

bioRxiv2021

Species variations in tenocytes' response to inflammation require careful selection of animal models for tendon research

For research on tendon injury, many different animal models are utilized; however, the extent to which these species simulate the clinical condition and disease pathophysiology has not yet been critically evaluated. Considering the importance of inflammation in tendon disease, this study compared the cellular and molecular features of inflammation in tenocytes of humans and four common model species (mouse, rat, sheep, and horse). While mouse and rat tenocytes most closely equalled human tenocytes low proliferation capacity and the negligible effect of inflammation on proliferation, the wound closure speed of humans was best approximated by rats and horses. The overall gene expression of human tenocytes was most similar to mice under healthy, to horses under transient and to sheep under constant inflammatory conditions. Humans were best matched by mice and horses in their tendon marker and collagen expression, by horses in extracellular matrix remodelling genes, and by rats in inflammatory mediators. As no single animal model perfectly replicates the clinical condition and sufficiently emulates human tenocytes, fit-for-purpose selection of the model species for each specific research question and combination of data from multiple species will be essential to optimize translational predictive validity.

molecular biology↗