Chondrogenic stimulation of embryonic chick limb mesenchymal cells by factors in bovine and human dentine extracts.

Extracts of bovine or human dentine when incorporated into the medium bathing embryonic chick-limb mesenchymal cells caused the stimulation of chondrogenesis. Such extracts were prepared from demineralized bovine or human dentine by suspension in a 4 M guanidinium hydrochloride (GuHCl) solution. After stepwise dialysis down to distilled water to remove the GuHCl, the protein extracts were separated chromatographically on DEAE resin. The crude and separated extracts from both dentines produced morphological changes in the cultured mesenchymal cells similar to those reported for bovine and human adult bone extracts, as well as metachromatic staining with toluidine blue indicating that they stimulated chondrogenesis. Measurements of [35S]-SO4 incorporation and DNA content in the cultures also indicated that the extracts stimulated chondrogenesis but not cell proliferation. The similarity between silver-stained patterns on sodium dodecyl sulphate polyacrylamide gel electrophoresis of corresponding fractions of the bovine and human dentine suggests that they may contain similar or identical proteins.