Evaluation of bone allograft processing methods : Impact on decellularization efficacy, biocompatibility and mesenchymal stem cell functionality
The outcome of this study shows a higher efficacy in decellularization for sonication- based processed allografts (SPAs) over chemically processed allografts (CPAs) based on DNA quantification, histological and scanning electron microscopy (SEM) evaluation. Moreover, the decellularization efficacy of SPAs was comparable to two commercial grafts, Tutoplast® processed allografts (TPAs) and Bio-Oss® processed 44 xenografts (BPXs), used as additional reference, also in terms of commercially standardized products. Biocompatibility assessment based on extracts derived from decellularized grafts showed a decrease in mesenchymal stem cell (MSC) viability for SPAs and CPAs, as well as for the commercially available BPXs. In contrast, biocompatibility was not impaired for TPAs, which also showed a better performance after reseeding with MSCs as indicated by confocal laser scanning microscopy (CSLM) and DNA assessment in order to monitor cellular proliferation. Here, a significant increase in DNA throughout a two-week time frame could be shown. BPXs induced a tentative increase in alkaline phosphatase (ALP) activity and mineralization in MSCs potentially associated with the high calcium content. Even though SPAs extracts showed a noticeable reduction of in vitro biocompatibility, results after reseeding with MSCs were comparable to commercially available grafts used in this study. Nevertheless, in this present study, TPAs combined the best in vitro biocompatibility and performance in terms of proliferation and osteogenic differentiation after reseeding with MSCs.