Reduction of early vein graft thrombosis by tissue plasminogen activator gene transfer.
Vein grafts are used to bypass coronary arterial stenosis, but many grafts thrombose soon after surgery. A model was developed in the pig to allow continuous measurement of blood flow and production of flow-restricting thrombi (cyclic flow reductions; CFRs). Saphenous vein lumen was exposed to adenovirus ex vivo, to over-express human tissue plasminogen activator (h-tPA), with beta-galactosidase adenovirus as a control. The vein segments were engrafted into carotid arteries and examined 0, 1 or 3 days later (4-7 animals/group). Untransduced grafts examined on the day of surgery developed repeated CFRs at both normal and restricted flow, but their frequency declined in grafts examined after 3 days. Adenovirus transduction was evident as beta-galactosidase or h-tPA expression 1 day after engraftment. Blood flow was increased 1.4-fold in h-tPA transduced grafts after 1 day [control 390 (280-510), h-tPA 550 (450-660) ml/min; p=0.02 (expressed as mean (95% confidence intervals)]. CFRs were less severe (p=0.002) in the h-tPA transduced grafts than beta-galactosidase-transduced grafts. CFRs were also less frequent in unstenosed undamaged h-tPA grafts [control 17 (6.1-29), h-tPA 7.6 (1.7-14) CFR/hr; p=0.02], but this difference was reduced after damage or stenosis. CFRs formed faster in h-tPA than in beta-galactosidase-transduced grafts [control 14 (11-17), h-tPA 23 (19-27) ml/min(2); p<0.001], and resolved twofold faster [control 25 (22-30), h-tPA 48 (39-60) ml/min(2); p<0.001]. Hence, in this model, local gene therapy with h-tPA increased graft blood flow and decreased measures of early graft thrombosis, namely quicker CFR resolution and decreased frequency and severity.
Thomas
Anita C
AC
Bristol Heart Institute, University of Bristol, Bristol, United Kingdom. a.thomas@bristol.ac.uk
Wyatt
Marcella J
MJ
Newby
Andrew C
AC
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002339:Carotid Arteries / Q000601:surgery; D004195:Disease Models, Animal; D015316:Genetic Therapy / Q000379:methods*; D006083:Graft Occlusion, Vascular / Q000628:therapy*; D006801:Humans; D012039:Regional Blood Flow; D012501:Saphenous Vein / Q000637:transplantation; D034421:Sus scrofa; D013927:Thrombosis / Q000628:therapy*; D010959:Tissue Plasminogen Activator / Q000235:genetics*; D014161:Transduction, Genetic / Q000379:methods; D001616:beta-Galactosidase / Q000235:genetics
D001616:beta-Galactosidase; D010959:Tissue Plasminogen Activator