OBJECTIVETo evaluate the effect of insulin-like growth factor 1 for the bone induction and the regulation for the fusion of the sagittal cranial sutures.

METHODSThe cells, derived from cranial sutures in the newborn SD rats and the sagittal suture from the mice, were cultured with a serum-free medium and treated with and without insulin-like growth factor 1. The osteoblast phetotypes (osteocalcin, alkaline, osteoponcin and type-1 collagen) were measured with the RT-PCR and ELISA, and the explanted sagittal sutures were then evaluated under light microscopy.

RESULTSThe cells, treated with the insulin-like growth factor 1, significantly produced more osteocalcin, alkaline, osteoponcin and type-1 collagen than those without insulin-like growth factor 1. The fusion of the sagittal suture explants will delay till to 30 days when it was not treated with IGF1. However, in the group with IGF1 the fusion was observed to start in 8 days, and a small amount of the sagittal suture fusion was found at the 20th day while a large amount was at the 30th day.

CONCLUSIONThe IGF1 has a direct effect on the fusion of cranial suture due to enhancing bone induction of cranial suture cell.