Collagen-chondroitin sulphate-hydroxyapatite porous composites: a histochemical and electron microscopy approach

In this study the structure of collagen-chondroitin sulphate-hydroxyapatite porous composites is investigated by histochemical (Von Kossa staining), immunohistochemical, and transmission electron microscopy. Examination of composites on picrosirius red stained sections showed that polarization colors of collagen were generally in the range of orange-red. Immunofluorescence data indicate that chondroitin sulphate was either chemically incorporated into the bulk structure of collagen scaffolds or attached on surfaces of collagen bundles. Depending on the ratio between collagen:chondroitin sulphate:hydroxyapatite, von Kossa histochemical staining showed a progressive loading of collagen-chondroitin sulphate bundles with hydroxyapatite. Transmission electron microscopy studies have shown that composites contain mostly collagen fibrils aggregated with random orientation with very few collagen fibers showing the 67-nm banding pattern. Hydroxyapatite deposits of various sizes occurred among the collagen fibrils.