The Efficacy of Recombinant Platelet-Derived Growth Factor on Beta-Tricalcium Phosphate to Regenerate Femoral Critical Sized Segmental Defects: Longitudinal In Vivo Micro-CT Study in a Rat Model

Background and Objectives: Beta-tricalcium phosphate (beta-TCP) has been used for bone regeneration. The objective of this study was to assess longitudinally, the regeneration of critical sized segmental defects (CSSD) in rat femur using beta-TCP with or without recombinant platelet-derived growth factor (PDGF) through in vivo micro-computed tomography (micro-CT). Materials and Methods: Following ethical approval unilateral femoral CSSD measuring 5 mm was surgically created, under general anesthesia, in 30 male Wistar-Albino rats (aged 12-18 months; weighing 450-500 g). CSSD was stabilized using titanium mini-plate (4 holes, 1.0 mm thick with 8 mm bar). Depending upon biomaterial used for regeneration, the animals were randomly divided into: Control group (N = 10): CSSD covered with resorbable collagen membrane (RCM) only; Beta-TCP group (N = 10): CSSD filled with beta-TCP and covered by RCM; Beta-TCP + PDGF group (N = 10): CSSD filled with beta-TCP soaked in recombinant PDGF and covered by RCM. Longitudinal in vivo micro-CT analysis of the CSSD was done postoperatively at baseline, 2nd, 4th, 6th, and 8th weeks to assess volume and mineral density of newly formed bone (NFB) and beta-TCP. Results: Significant increase in NFB volume (NFBV) and mineral density (NFBMD) were observed from baseline to 8-weeks in all groups. Based on longitudinal in vivo micro-CT at 8-weeks, beta-TCP + PDGF group had significantly higher (p < 0.01) NFBV (38.98 +/- 7.36 mm(3)) and NFBMD (3.72 +/- 0.32 g/mm(3)) than the beta-TCP (NFBV-31.15 +/- 6.68 mm(3); NFBMD-2.28 +/- 0.86g/mm(3)) and control (NFBV: 5.60 +/- 1.06 mm(3); NFBMD: 0.27 +/- 0.02 g/mm(3)) groups. Significantly, higher reduction in beta-TCP volume (TCPV) and mineral density (TCPMD) were 1 observed in the beta-TCP + PDGF group when compared to the beta-TCP group. Conclusion: Addition of recombinant PDGF to beta-TCP enhanced bone regeneration within rat femoral CSSD and increased resorption rates of beta-TCP particles.