In vitro degradation and angiogenesis of the porous calcium silicate-gelatin composite scaffold

Calcium silicate-based materials have attracted a great deal of interest due to their osteogenesis and have been used as implant materials for bone repair and regeneration. The purpose of this study was to use gelatin with and without genipin cross-linking for controlling degradation, improving mechanical properties, and enhancing angiogenesis of calcium silicate bioceramics. The in vitro degradation of gelatin-containing scaffolds was analysed in a simulated body fluid (SBF) solution. Human mesenchymal stem cells (hMSCs) were used to examine angiogenesis. The results indicated that the gelatin-containing scaffolds showed a diametral tensile strength of about 2 MPa and a porosity of about 60% falling within the range of values reported for the cancellous bone. Apatite precipitation occurred on all scaffold surfaces after soaking in SBF for 1 week. The gelatin-containing scaffold without cross-linking exhibited a greater weight loss and porosity than the control without gelatin. The cross-linking agent, genipin, significantly improved the mechanical stability of the composite scaffold. The gelatin enhanced the viable cell populations. More importantly, gelatin actively promoted the secretion of angiogenic factors such as von Willebrand factor and angiopoietin-1 in hMSCs. It is concluded that combination of calcium silicate and gelatin may synergistically enhance clinically desirable functions in terms of controlled degradation, improved mechanical properties, and enhanced angiogenesis.