Differentiation of Bone Marrow Mesenchymal Stem Cells Induced by Indirectly Co-cultured Tooth Germ Cells

14 Volume 10, Number 1, 2007 Bone marrow mesenchymal stem cells (BM-MSCs) are a type of adult stem cells that have been recognised for many years1. When provided with appropriate inductive factors, including cytokines and growth factors, these clonal, plastic adherent cells are capable in vitro of differentiating into many kinds of cells, such as osteoblasts, adipocytes, chondrocytes, myoblasts, and also various non-mesenchymal tissue lineages, including hepatocytes and possibly neural cells2-8. It seems that the fate of BM-MSCs is determined by their surroundings5. Studies of BM-MSCs in tooth-tissue-engineering have generated a great deal of excitement9-11. They indicate that BM-MSCs could give rise to ameloblast-like cells and dental mesenchymal cells, and participate in tooth formation by the induction of early embryonic oral epithelium. Recent advances, including direct cell pellet implantation9,10,12,13 and tissue engineering in combination with biocompatible scaffolds14, have allowed us to contemplate new and promising strategies for hard tissue repair, especially for tooth regeneration. To investigate whether the signals produced from tooth germ cells (TGCs) can determine the final differentiation of BM-MSCs, an indirect co-culture system between BM-MSCs and TGCs was established, and the differentiation of BM-MSCs was evaluated according to molecular and tissue characteristics. Objective: To study the differentiation of bone marrow mesenchymal stem cells (BM-MSCs). When co-cuttured with tooth germ cells (TGCs). Methods: The BM-MSCs were isolated from tibiae and fibula of Sprague-Dawley (SD) rats aseptically and cultured. The fist molar tooth buds were isolated from E17 SD foetus and processed to obtain TGCs. The BM-MSCs were co-cultured with TGCs indirectly. The differentiation potentiality of BM-MSCs and the tooth-forming potentiality of TGCs were assessed. Results: The BM-MSCs started to express odontogenic markers, dentin sialoprotein (DSP) and dentin matrix protein 1 (DMP1) after 7 days co-culture with TGCs. Implants of co-cultured pellets formed osteoid dentin under renal capsules, while control groups self-differentiated into osseous tissue. Conclusion: BM-MSCs could be differentiated by co-cultured with TGCs into dental tissues, although the molecular mechanism requires further study.