Mesenchymal stem cell (MSC) and endothelial progenitor cell (EPC) growth and adhesion in six different bone graft substitutes

Several different synthetic and allograft bone graft substitutes are used clinically to treat large bone defects. In contrast to the gold standard of autologous bone grafts, these do not contain bone-forming (MSC) or vessel-forming (EPC) cells. In order to achieve the same level of success enjoyed by autologous bone grafts, they must be compatible with mesenchymal stem cells (MSC) and endothelial progenitor cells (EPC). In a previous study, we seeded MSC onto six different bone graft substitutes and then measured the cell adhesion, viability, differentiation, and morphology. In the present study, we seeded both MSC and EPC onto the same six bone graft substitutes and measured the same parameters. In vitro, 125,000 MSC and 125,000 EPC were seeded onto Chronos(A (R)), Vitoss(A (R)), Actifuse(A (R)), Biobase(A (R)), Cerabone(A (R)), and Tutoplast(A (R)). Cell adhesion (fluorescence microscopy) and viability (MTT assay) were measured on days 2, 6, and 10. Osteogenic (cbfa-1, alkaline phosphatase [ALP], osteocalcin, collagen-1 alpha [Col1A]) and endothelial (von Willebrand factor [vWF], vascular endothelial growth factor [VEGF], kinase domain receptor [KDR]) gene expression were analyzed by reverse transcriptase polymerase chain reaction (RT-PCR). Morphology was described by scanning electron microscopy (SEM) at day 2. MSC adhered significantly better to Tutoplast(A (R)), Chronos(A (R)), Actifuse(A (R)), and Biobase(A (R)). EPC adhered better to Actifuse(A (R)), Chronos(A (R)), Biobase(A (R)), and Tutoplast(A (R)). Viability increased over time when seeded on Tutoplast(A (R)) and Chronos(A (R)). Osteogenic and endothelial gene expression were detectable at day 10 in cells seeded on Chronos(A (R)), Actifuse(A (R)), and Tutoplast(A (R)). The best morphology of MSC and EPC was found on Tutoplast(A (R)), Chronos(A (R)), Actifuse(A (R)), and Biobase(A (R)). When bone graft substitutes are used to help fill large defects, it is important that their interaction with these cells be supportive of bone healing.