Effect of fibrin-targeting on clot lysis with urokinase-type plasminogen activator

Strategies for the Improvement of Thrombolytic Agents

“…We have recently constructed a number of chemical conju gates of scu-PA with a murine monoclonal antibody (MA-15C5) directed against human cross-linked fibrin fragment D-dimer (229)(230)(231)(232). In an in vitro system composed of a 125 I-fibrin labeled whole human plasma clot immersed in citrated human plasma, the fibrinolytic potency of the conjugates with scu-PA or tcu-PA was respectively 6-fold and 2-fold higher than that of the uncon jugated molecules.…”

Enhancement of the thrombolytic potency of plasminogen activators by conjugation with clot-specific monoclonal antibodies

“…In order to reduce the molecular size of the conjugates, a low molecular weight form of rscu-PA, rscu-PA-32k (comprising amino acids Leu144-Leu411), was chemically coupled to F(ab')2 fragments of MA-15C5 (24). This yielded a conjugate, rscu-PA-32k/MA-15C5-F(ab')2, with Mr130 000 and with similar in vitro biochemical properties for its single-chain form and its plasminor thrombinderived two-chain derivatives as compared to intact rscu-PA/M A-15C5 and its two-chain derivatives (24,25). The in vitro fibrinolytic potency of rscu-PA-32k/ MA-15C5-F(ab')2 or of the thrombin-derived rtcu-P A-32k / MA-15C5-F(ab')2/T was respectively increased 5-and 2-fold over that of the corresponding unconjugated counterpart (Table I).…”

Conjugation of plasminogen activators and fibrin-specific antibodies to improve thrombolytic therapeutic agents

“…Fibrin-specific antibodies have been chemically crosslinked to plasminogen activators, among them urokinase (15)(16)(17), tPA (18), and scuPA (19,20). Following the coupling of urokinase to polyclonal rabbit anti-human fibrinogen antibodies, thereby demonstrating the practical feasibility of this approach (15), urokinase and the monoclonal antifibrin antibodies 64C5 and 59D8 were crosslinked (16).…”

“…Dewerchin and colleagues (17,19,20) have cross-linked scuPA with a monoclonal antibody directed to the fragment D dimer of fibrin (Figure 3), rather than against the NH2 terminus of the /3-chain of fibrin. Their rationale for using the anti-D-dimer antibody was based on data suggesting that the /3-chain epitope is lost earlier in thrombolysis than is the D dimer epitope (23,24).…”