Effect of solubilized bone matrix components on cultured fibroblasts derived from neonatal rat tissues

Summary Decalcified rat bone matrix was extracted with 4M guanadinium chloride. Extensive dialysis of the solution yielded material which could be, in part, further solubilized in isotonic salt solution and which was particularly enriched in glycoprotein compared to whole bone matrix. The addition of this solubilized material to tissue culture media in concentrations of 25 to 100 g dry weight per milliliter of medium resulted in characteristic morphologic and metabolic alterations of fibroblasts from neonatal rats. These alterations in glycosaminoglycan synthesis were similar to those we had previously reported, resulting from the addition of whole, particulate bone matrix to such cultures. The most prominent change was an increase in hyaluronic acid synthesis and a smaller increase in chondroitin sulfate synthesis. Both intracellular synthesis and secretion into the medium were stimulated, and the magnitude of this stimulation was related to the concentration of the solubilized material in the medium. However, the age of the rat bone appeared to be also an important determinant of the amount of biological activity that could be solubilized. Bone appears to be greatly enriched in this biological activity compared to skin, and fibroblasts derived from neonatal rat muscle are relatively more responsive than fibroblasts derived from neonatal rat skin.