Scaphocephaly: Premature Closure of the Sagittal Suture: A Localized Disorder of Cellular Metabolism?

Osteoblasts derived from sagittal sutures with premature synostosis, noninvolved coronal sutures, and normal frontal bone were harvested and cultured as cells in an attempt to determine if osteoblasts at the site of premature fusion exhibited altered in vitro cellular dynamics. Basal metabolic parameters of cellular growth and the production of metabolites, including osteocalcin, alkaline phosphatase, platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-β), PDGF-β receptors, epidermal growth factor (EGF) receptors, and fibroblast growth factor (FGF) were characterized. Osteoblasts harvested from sagittal sutures (sagittal osteoblasts) exhibited altered cellular growth and indices of cellular metabolism when compared with osteoblasts derived from patent coronal sutures (coronal osteoblasts) and frontal bone (frontal osteoblasts). Sagittal osteoblasts grew at a significantly increased rate and produced significantly more osteocalcin and less alkaline phosphatase than the coronal and frontal osteoblasts (p < 0.05). Significant variations in the production of EGF receptors were also noted between the sagittal osteoblasts and the coronal and frontal osteoblasts (p < 0.05). The osteoblasts from coronal sutures exhibited similarities in cellular growth and cellular metabolism, with the exception of PDGF receptors (p < 0.05), when compared with the osteoblasts obtained from the normal frontal bone. These results support a hypothesis in which a complex cell signaling mechanism regulates morphogenesis of the cranial vault at the sutural sites rather than a set of biomechanical tension forces that are exerted by the underlying brain.