Conditioned bio-interfaces of silicon/porous silicon micro-patterns lead to the chondrogenesis of hMSCs

The interaction between cells and materials is of scientific and technological interest for the development of new biomaterials with improved functional properties. In this work the chondrogenesis (CG) of human mesenchymal stem cells (hMSCs) derived from the bone marrow of healthy donors has been achieved on Si/PSi surfaces after pre-treatment with a conditioned medium derived from hMSCs (CM). The chondrogenic process was analyzed in fixed-cell preparations by immune fluorescence, determining the cellular localization of beta-catenin and the transcription factors STAT-5, Runx2 and vitamin D receptor (VDR). In a week of CG on Si/PSi or CM-Si/PSi, b-catenin showed cell-cell contacts priming a preferential chondrogenic process on a PSi surface, in contrast with the preferential proliferation and migration processes observed on hexagonal/triangular micro-designed Si areas. Interestingly, the presence of a CM bio-interface improves this differentiation process with respect to a control PSi surface. The chondroinductive effect was also observed in STAT-5, which was highly expressed and is involved in intracellular signaling of many differentiation receptors related to development and tissue repair. In good agreement with the above results, the co-localization of transcription factors Runx2/VDR at nuclei supports active transcription of chondrogenic genes. Considering these observations, we propose that the combination of a rough PSi surface and the components of the CM-hMSCs bio-interface boosts the chondrogenesis of hMSCs. These findings suggest that the tailoring of Si/PSi scaffolds with appropriate bio-interface combinations improves their therapeutic potential.