Purpose: Bone allografting appears to be optimised by in situ stromal cells which have potential to evolve into a bone line. The purpose of this study was to test the bio-compatibility of stromal cells and an allogenic human bone support treated with stromal cells as well as their evolutive potential.

Material and methods: The bone support was a human femoral head allograft harvested during total hip arthroplasty. After validation of the safety of the femoral heads by the bone bank, they were treated using the Osteopure(r) method. Human stromal cells were harvested during cardiac surgery from the sternotomy. The in vitro study was conducted in a sterile atmosphere in an incubator. Different adhesion molecules were used: collagen, gelatin, fibronectin, human serum AB, in addition to an adhesion molecule-free medium. Microscopic qualitative evaluation determined the adhesion of stromal cells and the absence of difference between the morphology of cultured stromal cells and stromal cells found in the bone marrow. Cell counts were made on days 24; 32; 48, and 64. The functional properties of the new cultured stromal cells was evaluated by seeding CD34+ cells on day0 and counting the number of CFC produced on day45 (LTCIC1). This LTCIC1 line was cultured in the different media and re-evaluated at day45 (LTCIC2).

Results: The first microscopic observations showed that the stromal cells oriented naturally in the bone architecture with no particular rejection and that they maintained their adhesion properties with each other and with the bone support. Cell counts showed increased proliferation for the stromal cells cultured on the bone support compared with cultures without bone support. Stromal cultures were favoured by the presence of bone and culture media containing collagen, gelatin, and fibronectin. But the LTCIC2 cultures demonstrated better performance with bone and gelatin.

Discussion: Proliferation of stromal cells cultured in contact with an allograft demonstrated the biocompatibility of stromal cells/treated allografts. After twelve weeks incubation, the first cell counts tended to show that stromal cells cultured in vitro on human bone substitute preserve their functional potential and allow the proliferation of certain cells participating in osteogenesis. Further research to identify the capacity of these cells to induce an osteoblastic line must be conducted to allow in situ graft osteogenesis.