Bone Abstracts

Constant remodeling of extracellular matrix is a hallmark during physiological conditions, such as stem cell differentiation, embryogenesis and tissue repair. Matrix metalloproteinases (MMPs) play a key role in these processes. MMPs and MMP-inhibitors (TIMPs) are responsible for bone formation and bone matrix remodeling and, probably, determinate the level of its turnover. Mesenchymal stem cells derived from dental pulp are multipotent and have the capacity to differentiate, at least, into mesenchymal tissues, such as bone, fat and cartilage, under inductive conditions in vitro. However, few is known about MMPs and their inhibitors role in stem cell biology and the relevance of their gene and protein modulation during osteoblastic differentiation in vitro. In this study, we evaluated protein expression of MMPs and their inhibitors (TIMPs and RECK) during osteogenic differentiation induction from DPSCs in vitro by western blot. DPSCs (n=3) isolated from extracted human third molars were grown in clonogenic medium (α-MEM+10% FBS+50 μg/ml ascorbate – used as negative control of differentiation) and differentiation stimulated by osteogenic medium (α-MEM+10% FBS+10 mM β-glycerophosphate+1 μM dexamethasone+50 μg/ml ascorbate) for 35 days. Several MMPs/inhibitors are expressed by DPSCs and we observed a progressive up-regulation of protein levels from 14 to 35 days after differentiation induction in comparison to their controls. This coincides to onset of mineralization when we detected maximal alkaline phosphatase activity and beginning of calcium nodules staining by alizarin red. Our preliminary results suggest that MMP and their inhibitors may be important to onset to mineralization during osteogenic differentiation in vitro from DPSCs.

Keywords: dental pulp stem cells, MMP, TIMP, RECK, osteoblast differentiation, and mineralization.

Financial Support: FAPESP.