GROWTH-HORMONE STIMULATES THE DEGRADATION OF CALCIUM-PHOSPHATE BIOMATERIAL BY HUMAN MONOCYTES MACROPHAGES IN-VITRO

This study investigated the effects of human growth hormone (hGH) on t he monocyte/macrophage lineage, the first cell population involved in degradation of calcium phosphate ceramic after in vivo implantation. M onocytes isolated from human blood were cultured on biphasic calcium p ellets (200 mg) for 8 days in the presence of lipopolysaccharides (LPS , 0.5 mu g/mL), hGH (10 and 50 ng/mL), or an association of LPS with h GH (10 and 50 ng/mL). Unlike LPS, hGH significantly decreased (about 2 5%) the total number of lacunae formed by monocytes. However, hGH indu ced the formation of lacunae with a greater surface area (about a 90% increase) as compared to the control. Finally, intense upmodulation (a bout a 250% increase) of lacuna surface area was observed in the prese nce of both soluble factors, suggesting that hGH and LPS act synergist ically. In view of the development of a drug delivery system for hGH b one release, this study shows that hGH not only stimulates bone cells implicated in the synthesis of the extracellular matrix but also those involved in the early degradation of calcium phosphate biomaterial. ( C) 1998 John Wiley & Sons, Inc.