Comparative thrombolytic properties of tissue-type plasminogen activator and of a plasminogen activator inhibitor-1-resistant glycosylation variant, in a combined arterial and venous thrombosis model in the dog.
rt-PA-K, a variant of recombinant tissue-type plasminogen activator (rt-PA) with substitution of amino acids 296 to 299 with alanine (KHRR296-299AAAA) has increased fibrin-specificity and reduced sensitivity to plasminogen activator inhibitor-1; rt-PA-T, with threonine 103 replaced by asparagine has an additional glycosylation site and a reduced clearance; and rt-PA-N, with asparagine 117 mutagenized to glutamine lacks the high mannose carbohydrate side chain. We have investigated whether combination of these properties in a single molecule might yield an improved thrombolytic agent. The thrombolytic potency and fibrin-specificity of the combination mutant rt-PA-TNK was compared with that of rt-PA in a combined venous whole blood clot model and platelet-rich arterial eversion graft thrombosis model in dogs given intravenous heparin and aspirin. Infusion of 0.125 to 1.0 mg/kg over 60 min in groups of 4 to 5 dogs produced dose-dependent fibrin-specific venous clot lysis. The thrombolytic potency (percent lysis per mg compound administered per kg body weight) of rt-PA-TNK was significantly higher than that of rt-PA as evidenced by a higher maximal rate of lysis of 480 +/- 100% versus 140 +/- 40% within the 2 h observation period per mg of compound administered per kg body weight (mean +/- SEM, p = 0.004) and a significantly lower dose of 0.08 +/- 0.01 versus 0.21 +/- 0.04 mg/kg body weight at which the maximal rate of lysis was obtained (p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)
Collen
D
D
Center for Molecular and Vascular Biology, University of Leuven, Belgium.
Stassen
J M
JM
Yasuda
T
T
Refino
C
C
Paoni
N
N
Keyt
B
B
Roskams
T
T
Guerrero
J L
JL
Lijnen
H R
HR
Gold
H K
HK
D000595:Amino Acid Sequence; D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D004351:Drug Resistance; D005263:Femoral Artery; D005268:Femoral Vein; D006031:Glycosylation; D006083:Graft Occlusion, Vascular / Q000188:drug therapy; D006801:Humans; D008969:Molecular Sequence Data; D017395:Plasminogen Activator Inhibitor 1 / Q000494:pharmacology; D010976:Platelet Count; D011994:Recombinant Proteins / Q000627:therapeutic use*; D015912:Thrombolytic Therapy; D013927:Thrombosis / Q000188:drug therapy*; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use*
D017395:Plasminogen Activator Inhibitor 1; D011994:Recombinant Proteins; D010959:Tissue Plasminogen Activator