Macrophages in degradation of collagen/hydroxylapatite(CHA), beta-tricalcium phosphate ceramics (TCP) artificial bone graft. An in vivo study.

The macrophages mediated biodegradation of two biomaterials, collagen/hydroxylapatite (CHA) and beta-tricalcium phosphate ceramics (TCP), was studied in 24 male Kunming mice and 20 male C57BL/6 mice with histopathologic, histochemical and ultrastructural observation. It was demonstrated that macrophages infiltrated after CHA, TCP were implanted. The macrophages could be differentiated from fibroblasts and the other infiltrated cells for special cellular profile and strong acid phosphatase activity. Morphologically, monocyte-macrophages and infused multinuclear giant cell degraded CHA and TCP by phagocytosis and extracellular resorption. The carbonic anhydrase activity of macrophages was demonstrated by histochemical technique. It suggested that macrophages secreted H+ and accomplished the decalcification of calcium phosphate compound of CHA and TCP. We conclude that macrophages are the main mediating cells which degraded CHA and TCP intracellularly and extracellularly.