Objective To determine whether antibody perturbation of Tgf-β, delivered in a collagen gel, could inhibit cranial suture fusion. Design Attachment and proliferation of osteoblasts cultured on a collagen gel with or without anti-Tgf-β2 antibody were determined by AlamarBlue dye assay and cell morphology by toluidine-blue staining. In rat calvarial organ culture, collagen gel with and without anti-Tgf-β2 antibody was injected subperiosteally over the posterior frontal suture of postnatal day 15 rat calvariae. A quantitative analysis of suture fusion was used to measure suture bridging in histological serial sections at various time points. Results Attachment and proliferation for cells cultured on collagen gel with anti-Tgf-β2 antibody were similar to collagen gel controls. Although proliferation was lower than on tissue culture plastic, cells treated with anti-Tgf-β2 antibody maintained an osteoblastic morphology. After 7, 10, and 15 days in organ culture, anti-Tgf-β2 antibody treatment caused a reduction in the percent bridging of posterior frontal sutures, compared with controls. Sutures exposed to anti-Tgf-β2 antibody and fibroblast growth factor-2 concurrently did not show an inhibition of bony bridging. Conclusions These results support previous reports suggesting a role for Tgf-β2 in cranial suture fusion. In cell culture the collagen gel, both with and without anti-Tgf-β2 antibody, promoted similar osteoblast attachment, proliferation, and osteoblastic morphology. In organ culture anti-Tgf-β2 antibody was delivered in a bioactive state via a collagen gel to inhibit cranial suture fusion. Also, the results suggest that the inductive effect of fibroblast growth factor-2 is not dependent on Tgf-β2 activity. Together, these results provide further support for the role of Tgf-β2 in cranial suture fusion.
Age-related changes in the biomolecular mechanisms of calvarial osteoblast biology affect fibroblast growth factor-2 signaling and osteogenesis. Vol. 278 (2003) 32005–32013
