Cells and Materials


Rat bone marrow cells were cultured on solid commercially pure titanium discs. Extracellular matrix (ECM) formed by the cells and the ECM/metal interface developed were examined by both scanning and transmission electron microscopy. The ECM most intimately associated with the substratum comprised afibrillar calcium phosphate globular accretions produced by the colonizing osteoblasts. The presence of calcium and phosphorus was confirmed by energy dispersive X-ray analysis. This initial layer acted as a site of anchorage for collagen fibres, produced by the osteoblasts. However, flaps of tissue elaborated during the culture period and manually reflected created a tissue division immediately above the afibrillar layer which indicated that the latter was adherent to the underlying metal oxide surface. The collagen matrix, consisting of networks of fibres, became mineralized with time in culture and also enveloped osteocytes which possessed radiating cell processes to form a bone nodule. This in vitro study suggests that while a calcified matrix layer, produced by osteoblasts, may adhere to titanium surfaces, subsequently formed bone is separated from this layer by a zone rich in both proteoglycans (as demonstrated by ruthenium red staining) and collagen fibres.