Immunohistochemical Study of Matrix Metalloproteinase-9 in Medial Collateral Ligament Epiligament in Rat Knee after Grade III Injury.

Background: In the present study, we conduct an immunohistochemical analysis to evaluate the expression of matrix metalloproteinase-9 (MMP-9) in the epiligament (EL) after grade III injury of the medial collateral ligament (MCL) in an experimental model of a rat knee. Methods: Twelve 8-month old male Wistar rats were used in this study. Three animals were used as controls, while the remaining nine underwent grade III injury of the MCL. The MMP-9 immunoreactivity was evaluated on the 8th, 16th and 30th day after injury. Results: We observed an intensive expression of the enzyme in all periods after injury in contrast with the control group. We also discovered that the main source of matrix metalloproteinase-9 was localized in the epiligament tissue. Immunoreactivity was highest and homogeneously distributed on the 8th day and gradually diminished, concentrating on the EL-ligament border and the perivascular zones on the 30th day. Conclusion: We present the first immunohistochemical study of the expression and distribution of the enzyme MMP-9 in the EL of the MCL and track the changes in enzyme activity on the 8th, 16th and 30th day after damage.

Expression of Matrix Metalloproteinase-2 and 9 in the Medial Collateral Ligament Epiligament in Rat Knee.

Background: In this study, we describe and compare the different expression of matrix metalloproteinase-2 and 9 (MMP-2 and 9) in the epiligament (EL) of the medial collateral ligament (MCL) of the rat knee. Methods: Twelve 8-month old male Wistar rats were used in this study. The MCL and the external surface of the surrounded EL were precisely dissected. The description of the structure of EL and the expression of MMP-2 and 9 were implemented by light microscopic and imunohistochemical analysis. Results: In the ligament, a classic morphological structure was found. The expression of the MMP-2 and MMP-9 was fSound in the adventitia of the blood vessels and in the fibroblast in the EL. The reaction of MMP-2 was more intensive in comparison to MMP-9. Conclusion: We present one of the first study of immunohistochemical localization and distribution of the enzyme MMP-2 and 9 in EL tissue and furthermore we describe and compare the enzyme activity of MMP-2 and 9 in the EL.