The effect of local methylprednisolone on granulation tissue formation. II. Mechanisms of action

The mechanism of action of a locally applied depot preparation of methylprednisolone on the granulation tissue was studied. Various connective tissue components were analysed in the developing granulation tissue induced by subcutaneously implanted viscose cellulose sponges in rats. Methylprednisolone treatment at the time of sponge implantation reduced the content of both hydroxyproline and hemoglobin and caused a clearly reduced RNA/DNA ratio in the new connective tissue. The total number of cells infiltrating the sponge was not affected by the treatment, but there were significantly fewer lymphocytes, monocytes and macrophages 4 and 7 days post-implantation. In the non-treated sponges there were significantly more fibroblastoid cells, which sticky cells usually died during the releasing procedure. When the corticosteroid was given after the third postoperative day it did not affect the developing granulation tissue. These results indicate that methylprednisolone mainly affects the initial inflammatory phase of granulation tissue formation and wound healing.