Enhanced biological performance of human adipose-derived stem cells cultured on titanium-based biomaterials and silicon carbide sheets for orthopaedic applications.

It is well known that the surface properties of biomaterials may affect bone-healing processes by modulating both cell viability and osteogenic differentiation. In this study we evaluated proliferation and osteogenic differentiation of human adipose-derived stem cells (hASCs) cultured on three prototypes of titanium disks and on thin layers of silicon carbide (SiC-PECVD), a material characterized by a high hardness and wear resistance. Our data indicated that all the tested surfaces supported cell growth, in particular, hASCs seeded on both titanium treated by a double-step etching process (TIT) and titanium modified by two Anodic Spark Deposition processes (TAA) grew better respect to the ones cultured on titanium obtained by KOH alkali etching process on TAA (TAAK). Furthermore, hASCs well colonized SiC-PECVD surface, showing a quite similar viability to cells cultured on plastic (PA). TIT and TAA better supported osteogenic differentiation of hASCs compared to PA, as shown by a marked increase of both alkaline phosphatase activity and calcified extracellular matrix deposition; in contrast TAAK did not positively affect hASCs differentiation. SiC-PECVD did not alter osteogenic differentiation of hASC cells: indeed, ALP and calcium deposition levels were comparable to those of cells cultured on plastic. Furthermore, we observed similar results testing hASCs either pre-differentiated for 14 days in osteogenic medium or directly differentiated on biomaterials. Our study suggests that modifications of titanium surface may improve osteo-integration of implant devices and that SiC-PECVD may represent a valid alternative for the coating of prosthetic devices to reduce wear and metallosis events.