Quantitative evaluation of fibrinolytic enzymes in a simulated human system

Abstract

A simple in vitro system for the assay of fibrinolytic enzymes intended for therapeutic use has been described. The system employs small quantities of human plasma from outdated bank blood as perfusing medium and purified human fibrin clots labeled with radioactive iodine. Thus, it is possible to follow the dissolution of a human clot without the intervention of reactions of the vascular system (e.g., release of activators). It was shown that the simulated system compares favorably with the in vivo assay. In the assay of a urokinase-activated human plasmin preparation, substitution of human plasma with dog plasma as a perfusing medium resulted in a decrease of the fibrinolytic response. In the case of two preparations, data from the simulated human system correlated well with results of preliminary clinical testing. In using this system as an initial screen for fibrinolytic agents, one must be aware of the fact that in vitro systems represent only part of the mechanisms involved in physiologic or pathologic processes. fibrinolysin system; plasmin; urokinase; thrombolysis; plasma Submitted on December 6, 1963