EMD differently modulates mesenchymal stem cells proliferation and differentiation

A number of clinical studies confirms the benefit of Enamel Matrix Derivative (EMD) in the therapy of periodontal disease. Furthermore, in vitro investigations suggest that EMD can act stimulating the proliferation of the cells involved in periodontal regeneration. Little is known about the effects of EMD on human bone marrow mesenchymal stem cells (MSC), that are mutipotential and can give rise to precursors for bone tissue. Objectives: The aim of this study was to investigate whether EMD could modulate MSC proliferation and differentiation. Methods: Primary cultures of MSC were obtained and expanded from bone marrow samples of healthy donors. Early passages of MSC were incubated with or without EMD. Cell proliferation was measured by means of 3H-thymidine incorporation. Early and late osteogenic markers were also evaluated. In particular, alkaline phosphatase (AP) activity and calcium content were assessed by spectrophotometric assay, osteocalcin (OC) level by enzyme-linked immunosorbent assay (ELISA) and in vitro mineralization by von Kossa staining. Results: Incubation of MSC with EMD (12.5-25-50 µg/ml) for 72 h resulted in a dose-dependent cell growth stimulation, with a maximum value of 1.8-fold of control. A fixed concentration of EMD (25 µg/ml) was followed over time at 24, 48 and 72 h. The highest proliferation effect was found at 24 h, with a value of 3.4-fold of control. The osteoblastic markers were differently affected by EMD incubation. In fact, AP activity as well as in vitro mineralization and calcium content were reduced up to 50 % of control, while OC level was increased by EMD of 1.5-fold of control. Conclusion: The obtained results indicate a complex in vitro biologic behaviour of MSC in response to EMD. Further studies are required to more precisely clarify the molecular mechanisms of this interaction. This research was supported by Institut Straumann AG (Switzerland).