POTENTIATION OF TRANSFORMING GROWTH-FACTOR (TGF-BETA-1) BY NATURAL CORAL AND FIBRIN IN A RABBIT CRANIOPLASTY MODEL

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 beta (TGF-beta 1) 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-beta 1 as a single injection of 1 mu g 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-beta 1 1 mu g in fibrin glue (n = 5). We measured the diameter of the remaining defect and the surface of the bone growth. TGF-beta 1 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-beta 1 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-beta 1, 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-beta 1 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-beta 1. In conclusion, the triple association of coral granules and TGF-beta 1 in fibrin could be of interest for treating bone defects.