Potentiation of transforming growth factor (TGF-β1) by natural coral and fibrin in a rabbit cranioplasty model

Abstract

The association of a biodegradable material and a growth factor could be of clinical value for treating bone defects. We therefore tested the association of transforming growth factor β (TGF-β1) in fibrin glue and coral granules to heal skull defects in rabbits. Adult rabbits underwent a double trepanation symmetrically in both parietal bones. Using histomorphometry, we compared bone repair after 1 month in control animals (n=5) and in animals treated with either TGF-β1 as a single injection of 1 μg in methylcellulose (n=5) or in fibrin glue (n=5), or with coral granules in fibrin glue (n=4) or with coral granules and TGF-β1 1 μg in fibrin glue (n=5). We measured the diameter of the remaining defect and the surface of the bone growth. TGF-β1 without coral in either methyl cellulose or fibrin induced a partial closure of the defect as assessed by a significant decrease in the defect diameter, compared with the control group. However, the association of TGF-β1 in fibrin and coral induced an area of the bone growth higher than in any other groups (P<0.05). Two months after surgery, this triple association induced a better healing of the defect than coral alone or control group. In each group treated with TGF-β1, the mineralization rate was increased not only at the treated side but also in the contralateral defect which was untreated, suggesting a diffusion of the growth factor. Indeed, when pooled together, the diameter of the defect at the contralateral side of 14 animals that had received TGF-β1 was reduced compared with the control group. Significant coral granules resorption occurred between month 1 and 2 and was unchanged by the addition of TGF-β1. In conclusion, the triple association of coral granules and TGF-β1 in fibrin could be of interest for treating bone defects.