Self-setting hydroxyapatite cement as a carrier for bone-forming cells.

To investigate the feasibility of using self-setting hydroxyapatite cement as a carrier for marrow cells having a high osteogenic ability, a porous form of this cement was fabricated and combined with cultured marrow cells. Marrow cells were obtained from the femurs of a seven-week-old male Fischer 344 rat and cultured in Eagle's MEM containing 15% fetal bovine serum for ten days before being combined with the porous cement or with Interpore 200 hydroxyapatite as a control. The composites were subcutaneously implanted into syngeneic rats and harvested after six weeks. In both types of implants, active osteoblasts together with bone formation were detected in contact with the pore surfaces. No cartilage formation was observed in any of the pores. Both types of implants with and without marrow cells caused very little foreign body reaction. These results indicate that self-setting hydroxyapatite cement containing marrow cells possesses a high osteogenic ability and may be useful as a bone graft substitute as well as a novel delivery system for bone-forming cells.