Microparticles, also known as microcarriers, have gained significance as building blocks for tissue engineering strategies, in bioinks for three-dimensional (3D) bioprinting and for large-scale expansion of anchorage-dependent cells. Microcarrier-expanded mesenchymal stem cells have been reported to show increased osteogenic gene expression and improved subsequent differentiation potential in vivo compared to planar cultures. Understanding the correlation between microparticle-based cues and associated cellular responses is critical to achieve predictable outputs for translational applications. Tailoring surface properties of microparticles to direct differentiation in 3D pro vides the opportunity to transform cell delivery systems from passive mechanical supports to functional components of cell expansion processes and regenerative therapies.
Microparticles with different topological surfaces (smooth, dimpled and angular) were developed by a team from Nottingham University, UK. To test the capability of topographical designs on microparticles to induce osteogenesis, a range of viability and osteo-specific gene, protein and mineralization assays were performed using primary human mesenchymal stem cells (hMSCs) in vitro, and within non-healing murine radial bone defects in vivo. As showed in the study, cell adhesion is mediated by different integrins on varied topographical designs. Altered metabolic profiles of hMSCs were observed on dimpled versus smooth microparticles. Varying histological features were also observed in vivo by different 3D surface topographies.