Species variation in the spontaneous calcification of bone marrow-derived mesenchymal stem cells.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) hold great promise for tissue regeneration. With increasing numbers of clinical trials, the safety of BM-MSCs attracts great interest. Previously, we determined that rat BM-MSCs possessed spontaneous calcification without osteogenic induction after continuous culture. However, it is unclear whether BM-MSCs from other species share this characteristic. In this study, spontaneous calcification of BM-MSCs from rat, goat, and human specimens was investigated in vitro. BM-MSCs were cultured in complete medium, and calcification was determined by morphologic observation and alizarin red staining. It was demonstrated that rat BM-MSCs possessed a typically spontaneous calcification, whereas goat and human BM-MSCs under the same system proliferated significantly but did not calcify spontaneously. The significant species variation in spontaneous calcification of BM-MSCs described in this study provides useful information regarding evaluation of numerous BM-MSC-based approaches for bone regeneration and the safety of BM-MSCs.