Fig. 2
From: Decreased Fibrinolytic Activity in Porcine-to-Primate Cardiac Xenotransplantation
Tissue plasminogen activator and plasminogen activator inhibitor-1 in pig-to-baboon cardiac xenografts. Tissue samples obtained normal porcine hearts and porcine cardiac xenografts were studied by immunofluorescence for expression of tissue plasminogen activator and plasminogen activator inhibitor-1. Fluorescence was graded on an assigned scale of 0–4 (4 = maximum). Average grades for the tissues at various times after transplantation are shown graphically. (A) Tissue plasminogen activator (t-PA). Tissue samples exhibited an initial increase in tissue plasminogen activator 24 hr after transplant, followed by a progressive decrease over time. (B) Plasminogen activator inhibitor-1 (PAI-1). The same biopsy tissues shown in A exhibited increased plasminogen activator inhibitor-1 beginning 1 hr after transplantation (B). These changes in tissue plasminogen activator and plasminogen activator inhibitor expression were seen before the development of histological evidence of acute vascular rejection, suggesting that a defect in fibrinolysis contributes to the pathogenesis of acute vascular rejection.