In vitro differentiation of osteocytes and adipocytes from human placenta-derived cells.

To investigate the capability of human placenta-derived adherent cells to differentiate into osteocytes and adipocytes. Placenta-derived adherent cells were isolated by type IV collagenase digestion of a single freshly obtained human placenta and cultured under standard conditions. Cell surface markers of adherent cells from passages 3 - 9 were analysed by flow cytometry. Osteocytic differentiation was induced with β-glycerol phosphate, vitamin C and dexamethasone and confirmed by Alizarin red staining. Adipocytic differentiation was induced with dexamethasone and insulin and confirmed by oil red O staining. Placenta-derived adherent cells were positive for high levels of CD44 and CD105 and very low levels of CD29 but were negative for CD34, CD45 and CD19. This pattern of cell surface markers is identical to human mesenchymal stem cells. Alizarin red-positive cells were detected 10 days after the induction of osteocyte differentiation. Oil red O-positive cells were detected 7 days after the induction of adipocyte differentiation. Placenta-derived adherent cells can differentiate into either osteocytes or adipocytes in vitro. The human placenta may provide an alternative source of mesenchymal stem cells for basic research and clinical use.