Comparison of human stem cells derived from various mesenchymal tissues: superiority of synovium as a cell source.

OBJECTIVE To compare the properties of human mesenchymal stem cells (MSCs) isolated from bone marrow, synovium, periosteum, skeletal muscle, and adipose tissue. METHODS Human mesenchymal tissues were obtained from 8 donors during knee surgery for ligament injury. After collagenase digestion or gradient-density separation, nucleated cells were plated at an appropriate density for expansion at the maximum rate without colony-to-colony contact. Yield, expandability, differentiation potential, and epitope profile were compared among MSCs from the 5 different tissue sources. RESULTS Colony number per 10(3) nucleated cells was lower, and cell number per colony was higher, in bone marrow than in other mesenchymal tissues. When the cells were replated at low density every 14 days, bone marrow-, synovium-, and periosteum-derived cells retained their proliferation ability even at passage 10. In chondrogenesis studies in which the cells were pelleted and cultured in vitro, pellets from bone marrow-, synovium-, and periosteum-derived cells were shown to be larger and stained more extensively for cartilage matrix. Synovium-derived cells, in particular, had the greatest ability for chondrogenesis. In adipogenesis experiments, the frequency of oil red O-positive colonies was highest in synovium- and adipose tissue-derived cells. In studies of osteogenesis, the rate of alizarin red-positive colonies was highest in bone marrow-, synovium-, and periosteum-derived cells. For epitope profiling, 15 surface antigens were measured. Most appeared to have similar epitope profiles irrespective of cell source. CONCLUSION Our findings indicate that there are significant differences in MSC properties according to tissue source, beyond donor and experimental variation. Superiority of synovium as a potential source of MSCs for clinical applications was demonstrated.