Age-dependent decline in extracellular matrix-induced local bone differentiation

Implantation of demineralized bone matrix in subcutaneous sites in the rat results in new bone induction. This model system was examined with bone matrix prepared from young (4-month-old) and old (24-month-old) rats. The implants were removed on Days 9, 14 and 21 and examined for alkaline phosphatase activity and 45Ca incorporation. There is a significant decline in the osteo-inductive potential of the bone matrix derived from 24-month-old rats, as quantitated by the enzyme activity and 45Ca incorporation.