Bone formation in demineralized bone transplants treated with biosynthetic human growth hormone

The influence of local administration of biosynthetic human growth hormone on the bone formation in a rabbit bone defect grafted with demineralized autologous bone was studied and compared to contralateral saline administration. The growth hormone was produced by hybrid DNA-technique and administered locally to the bone defect with the demineralized bone implant by an osmotic pump delivering 5 microliters/h during 14 days. At 14 and 28 days after operation the bone forming process was evaluated by roentgenography, planimetry included, and scintigraphy after injection of 99Tcm-labelled DPD. At 28 days after operation also autoradiography was performed. The roentgenographic and scintigraphic examinations revealed no influence from growth hormone neither 14 nor 28 days postoperatively. Centrally in the remineralized grafts the roentgenograms 28 days after operation showed radiolucent areas which in corresponding autoradiograms showed no uptake of 99Tcm. These areas turned out to be remnants of matrix. It is suggested that growth hormone has no influence on the bone induction process during the first 14 days when administered to bone matrix, probably due to relative lack of osteogenic cells. This study contributes a base for further evaluation of factors pertinent to hormonal stimulation of bone matrix transplants.