Stem cells osteogenic differentation and cytokine release induced by a composite biomaterial

Bone defects or atrophy may arise as a consequence of injury, inflammation, traumatic processes or as a result of surgical procedures. Regenerative medicine offer novel treatment modalities for such defects, including bone augmentation and repair procedures using osteoinductive scaffolds. The mechanisms by which bone marrow mesenchymal stem cells (BMMSCs) and inflammation interact during physiological and pathological processes to regulate bone turnover are still poorly understood. In the present study, the effects of a composite biomaterial (Geistlich Bio-Oss® Collagen), employed in maxillo-facial surgery, was evaluated using human bone marrow mesenchymal stem cells (BMSCs). The biomaterial is made up of 90% hydroxyapatite (granules) and 10% collagen of porcine origin. A qRT-PCR array was employed to evaluate the expression of genes (n=84) involved in MSCs osteogenic differentiation and osteogenic proteins, osteocalcin (OCN) and osteopontin (OPN) were evaluated by immunofluorescence. Cytokine/chemokine proteins released into BMSCs were analyzed using Bio-Plex Pro Human Cytokine 27-plex Assay. Several genes involved in BMSCs osteogenic signalling (i.e BMP1, COL1A1, TWIST1) and ECM remodelling (ITGA1/A2, MMP2) tested dysregulated in BMSCs grown on biomaterial and OPN and OCN proteins were expressed in BMSCs grown on material at day 7. In BMSCS was observe a significant decrease of proinflammatory interleukin (IL)-6 protein while anti-inflammatory/pro-angiogenic factor IL-4 and endothelial growth factor (VEGF) protein were up-regulated. Platelet-derived growth factor-BB (PDGF-BB), a key molecule for angiogenesis and osteogenesis coupling regulatory factor was increased in BMSCS by scaffold. Our data demonstrate that anti-inflammatory innate immunemediated responses associated to stem cells differentiation are induced by the composite biomaterial investigated herein.