Efficacy of a Novel Osteogenic Biomaterial, OG-PLG: A Pilot Study

Recently we reported the development of a novel osteotropic biomaterial, osteogenic-poly[lactide-co-glycolide] (OG-PLG) made by attaching simvastatin to PLG, with slow sustained degradation-controlled release kinetics for bone regeneration. OBJECTIVE: To conduct a pilot study to determine the efficacy of OG-PLG in vivo. METHODS: Films made with PLG (n=6) or OG-PLG (n=8) were implanted subcutaneously above the calvaria of 6-month old inbred LEWIS rats with the periosteum removed. After 8 weeks, the film, calvaria and surrounding tissue were removed, and histomorphometry was done on Goldner Trichrome and tetracycline-stained sections to assess new bone formation. RESULTS: Histomorphometry on Goldner Trichrome-stained sections revealed that total new bone areas were 1.22 ± 0.55 mm2 and 1.73 ± 0.82 mm2 for PLG and OG-PLG groups, respectively (p=0.2, two-tailed t-test). Power analysis of these results revealed that an n=22 was needed for statistical significance. Most probably explanations for the lack of statistical significance include the following. First, most of the new bone was formed at the edge of the films where the periosteum was still intact, and since most of the periosteum was removed, the amount of new bone formation on the calvaria was reduced. Second, since the removal of the periosteum was not carefully controlled and some areas were near the film while other areas were not, there was an increase in the variability of the results. CONCLUSIONS: This pilot study indicates that OG-PLG seems to enhance bone formation but the results were not statistically significant due to most of the new bone forming where the intact periosteum was. Further in vivo studies are being conducted using a different model, the rat calvarial critical-sized defect model.