Effect of age on calcification of poly(hydroxyethyl methacrylate) in animals.

The effect of age on the calcification of biomaterials was studied by the subcutaneous implantation of poly(hydroxyethyl methacrylate) hydrogel in rats. The hydrogel sheets were implanted in rats 6, 12, 24, and 52 weeks (1 year) of age. The retrieved implants were compared and the percentage weight increase by mineralization was determined quantitatively. Significant differences in the rate and amount of calcification were observed between the growing (6 weeks old) and the adult (greater than or equal to 12 weeks of age) rats. The onset of calcification in the adult rats was significantly delayed. The immature rats had deposits three to four times as heavy as the mature rats.