Schema of extramedullary bone and marrow generation. MSCs and ECFCs were isolated from heparinized human BM or peripheral blood through an initial adhesion step and subsequently allowed to proliferate in specific media. Cells mixed with Matrigel were subcutaneously injected into the flanks of NOD/SCID/IL-2rγ^null mice, and these cells developed into bonelike tissues with high osteoblastic activity in 8 weeks.