Cardiopulmonary bypass induces the synthesis and release of matrix metalloproteinases

Background. A number of cellular and molecular events can be induced after cardiac procedures requiring cardiopulmonary bypass (CPB). The matrix metal loproteinases (MMPs) are a recently discovered family of enzymes that degra de the extracellular matrix, but expression during and after CPB is unknown . Methods. Systemic plasma MMP levels were measured in patients (n = 28, 63 /- 1 years) undergoing elective coronary revascularization requiring CPB at baseline, termination of CPB, and 30 minutes, 6 and 24 hours after CPB. Re presentative classes of MMP species known to degrade matrix and basement me mbrane components were selected for study. Specifically, the interstitial c ollagenases MMP-8 and MMP-13, and the gelatinases MMP-2 and MMP-9 were dete rmined by internally validated enzyme-linked immunosorbent assay. Results. The MMP-8 levels increased by fourfold at separation from CPB, and returned to within normal values within 30 minutes after CPB. The proenzym e forms of MMP-13 and MMP-9 increased by more than twofold at cross-clamp r elease and returned within normal limits within 6 hours after CPB. The pref orm of MMP-2 increased from baseline values at 6 and 24 hours postoperative ly; likely indicative of de novo synthesis. Conclusions. A specific portfolio of MMPs are released and synthesized duri ng and after CPB. Because MMPs can degrade extracellular proteins essential for maintaining normal cellular architecture and function, enhanced MMP re lease and activation may contribute to alterations in tissue homeostasis in the early postoperative period. (Ann Thorac Surg 2001;71:1518-23) (C) 2001 by The Society of Thoracic Surgeons.