Platelet-derived growth factor enhancement of a mineral-collagen bone substitute

Background: Anorganic bovine bone-collagen matrix is commercially available for bone regeneration procedures. Platelet-derived growth factor-BE (PDGF- BB) has been demonstrated to stimulate bone formation in vivo and in vitro. It was the aim of these studies to examine 1) the interaction of this mine ral-collagen matrix with PDGF-BB and 2) determine if the adsorption of PDGF -BB to the mineral-collagen matrix stimulates osteoblastic cell proliferati on above that of the untreated matrix. Methods: Measurement of PDGF-BB adsorption and release was accomplished usi ng I-125 radiolabeled growth factor. The PDGF-BB was incubated with the ano rganic bovine bone-collagen matrix and the amount which adsorbed was determ ined. In the release studies, radiolabeled PDGF-BB was adsorbed to the matr ix material, then the samples were incubated in buffer for various time per iods. The amount of PDGF-BS retained on the matrix was measured and the per cent of growth factor released calculated, The biological activity was test ed in an in vitro assay with primary culture neonatal rat osteoblastic cell s, Osteoblastic cells were cultured on bone mineral-collagen matrix with kn own amounts of adsorbed PDGF-BB, Proliferation of the cells was assessed by H-3-thymidine incorporation and cell attachment measured by prelabeling ce lls with H-3-leucine. Results: PDGF-BB adsorbed to the mineralized-collagen matrix material in a rapid, concentration-dependent fashion. The growth factor was slowly releas ed from the matrix such that approximately 30% of the adsorbed protein was liberated over 10 days. PDGF-BB treated mineralized-collagen matrix display ed significantly (P < 0.05, ANOVA) enhanced proliferation of cultured osteo blastic cells compared to the mineralized-collagen matrix alone. Conclusions: These results suggest that PDGF-BB is rapidly adsorbed then sl owly released from the anorganic bovine bone-collagen matrix. PDGF-BB adsor bed to this material is able to stimulate proliferation of the attached ost eoblastic cells, These data suggest that it may be clinically feasible to a dsorb PDGF to this bone-collagen matrix and that this combination of bone g rowth factor and mineral-collagen matrix has the potential for clinical app lications.