The Study of Sodium-Hyaluronate to the Expression of MMP-2 during Healing Process of the Acute Rotator Cuff Tear in Rats

Purpose: To evaluate the effect of HA on the MMP-2 expression level during the healing process of an acute rotator cuff tear in rats by immunohistochemistry and RT-PCR. Materials and Methods: Mature Sprague-Dawley rats were used in this animal study. In each rat, 22 mm partial thickness defect of the rotator cuff was made. The rats were assigned to receive either subacromial injection of HA (HA group) or saline (saline group). The rotator cuff was examined by immunohistochemistry and RT-PCR at 4 weeks after surgery and the results were compared the results. Results: A gross inspection showed that the defects were covered with granulation tissue, which were similar in both groups. The histopathological findings from the HA group revealed collagen bundles with a more dense regular arrangement and small number of inflammatory cells. Semi-quantitative RT-PCR for MMP-2 in the HA group demonstrated a higher expression level than in the saline group. Conclusion: A subacromial injection of extrinsic HA increased MMP-2 expression level during the healing process of a rotator cuff tear in rats and might play a key role in the acute healing process of an injured rotator cuff.