Hydroxyapatite coated with insulin-like growth factor 1 (IGF1) stimulates human osteoblast activity in vitro.

We studied the effects of a hydroxyapatite-tricalcium phosphate material coated with Insulin-like Growth Factor 1 (IGF1) on cell growth, collagen synthesis and alkaline phosphatase activity (ALP) of human osteoblasts in vitro. Cell proliferation was stimulated when osteoblasts were incubated with untreated hydroxyapatite (HA) and it was further increased by exposure to IGF1-coated HA. 3H-Proline uptake was significantly increased by treatment with either HA or IGF1-coated HA but no significant differences were found between these two groups. ALP activity was enhanced by exposure to HA, with respect to the control, and further increased by treatment with IGF1-coated HA. Our findings suggest that HA is useful for promoting osteoblast activity and IGF1 may help to improve its biological characteristics.

Parathyroid hormone-related peptide in the human fetal uro-genital tract.

Using a polyclonal antiserum raised against the first 34 amino acids of human parathyroid hormone-related peptide (PTHrP), we have localized PTHrP throughout the uro-genital tract of the human fetus aged between 8 and 40 weeks. Staining was present in the developing mesonephros, metanephros, gonads and in both the adrenal cortex and medulla. In particular, the developing mesonephric and metanephric renal tubules were intensely positive. Using Northern hybridization analysis we have detected a complex pattern of PTHrP mRNA transcripts ranging in size from 1.4 to 4.5 kb in early second trimester human fetal kidney. The presence of PTHrP in the mesonephros and metanephros provides evidence for a role for PTHrP in the regulation of fetal calcium metabolism. However, its presence in the gonad and adrenal gland invites the possibility of a wider role for PTHrP.