Inhibition of Hydroxyapatite Growth In Vitro by Glycosaminoglycans

Abstract

Hydroxyapatite (HAP) crystal growth was found to be inhibited by glycosaminoglycans in vitro. The major effect was produced by hyaluronan and of the sulphated glycosaminoglycans by chondroitin-4-sulphate. Chondroitin-6-sulphate did have a minor effect, while oversulphated chondroitin did not inhibit growth of HAP crystals. Chemically desulphated chondroitin sulphate still retains its inhibitory ability. Fragmented glycosaminoglycans by testicular hyaluronidase behaved in a manner similar to the respective intact molecules, even in the case in which the size of the fragments was in the tetrasaccharide range. Constituents of the monosaccharide of the glycosaminoglycans, were also examined with respect to their effect on HAP crystal growth; N-acetylglucosamine being the most potent inhibitor. The results clearly suggest that the chemical structure of the glycosaminoglycans determines their behavior in inhibiting HAP crystal growth. The presence of N-acetylglucosamine, and of only one sulphate ester group in the axial position, seemed to be the most prominent.