[Ectopic bone formation by composite graft of culture-expanded rat marrow cells and porous calcium phosphate ceramicmic].

Bone marrow cells derived from the femora of inbred rats were introduced into tissue culture. The adherent cells were cultivated, mitotically expanded, passaged, harvested, then placed in small cubes of porous calcium phosphate ceramics and finally grafted into subcutaneous sites of syngeneic rats. Primary marrow-derived cultured cells introduced into ceramics showed strong osteogenic potential with bone forming in the pore regions of ceramics as early as 2 weeks after in vivo implantation. Osteogenesis could be observed after 18th passage (over 36 population doublings). With increasing passage number, the initiation of osteogenesis and the apparent rate of bone formation declined and the course of osteogenesis was delayed. These data indicate that porous ceramic provides an excellent delivery vehicle for cells which are capable of osteogenic expression. In the future, it is possible to culture marrow cells as a source for reparative cells for implantation back into autologous in vivo sites.