In vitro mineralization of a three-dimensional collagen matrix by human dental pulp cells in the presence of chondroitin sulphate.

These matrices were used as cell culture substrates to investigate the influence of extracellular molecules on mineralization. Pulp cells seeded in type I collagen or type I collagen-chondroitin-4-sulphate sponges were able to grow and were morphologically similar to cells responsible for reparative dentine formation in vivo. In sponges consisting of collagen only, the cells elaborated an abundant new matrix which became organized with time and consisted of collagen fibres surrounded by fibrillar material, but no mineralization was observed. In collagen-chondroitin sulphate sponges, cells deposited less and poorly organized matrix; in these, calcification occurred, increasing with time, and at the ultrastructural level, small needle-like crystals containing calcium and phosphorus were scattered throughout the sponge fibres. These observations suggest that chondroitin sulphate might influence in vitro calcification induced by pulp cells.