Multipotential mesenchymal stem cells from femoral bone marrow near the site of osteonecrosis.

Stem cell-based therapies for degenerative disorders and injuries are promising in the new era. Multipotential mesenchymal stem cells (MSCs) from bone marrow (BM) are on the leading edge because they are easy to expand in culture while maintaining their multilineage potential. In vitro assessment of the chondrogenic and osteogenic potentials of cultured MSCs has been established, and the BM used in those experiments was exclusively from healthy donors via iliac crest aspiration. It is unknown whether human marrow obtained from femurs also contains these multipotential MSCs. We collected marrow from proximal femurs of two patients undergoing total hip replacement surgery for femoral head osteonecrosis and isolated and culture expanded MSCs to about 20 population doublings. These cells were homogeneously positive for beta1-integrin. When pelleted into aggregates and cultured in a medium containing transforming growth factor-beta3 for 14 days, the cells began to express mRNA for aggrecan and collagen type II and to deposit immunoreactive collagen type II and sulfated proteoglycans in the matrix, hallmarks of chondrogenic differentiation. These MSCs could also be differentiated into osteocytic lineage in vitro, as shown by increased expression of alkaline phosphatase activity and deposition of mineral content onto culture plates. These results indicate that femoral BM obtained during hip surgeries also contained multipotential MSCs. These data imply that direct replacement therapy using MSCs from in situ marrow may be possible in the future and that an MSC bank may be established by using marrow from this approach, bypassing the necessity for iliac marrow aspiration from healthy donors.