Thromboresistance of Balloon-Injured Porcine Carotid Arteries After Local Gene Transfer of Human Tissue Factor Pathway Inhibitor

Abstract

Background-Tissue factor pathway inhibitor (TFPI) is an endogenous inhibitor of factor Xa and the coagulant initiator complex tissue factor/factor VIIa. Methods and Results-To study the effects of TFPI gene transfer on thrombus formation, balloon-injured porcine carotid arteries were treated locally with an adenovirus encoding human TFPI (Ad-TFPI) or control virus. Gene transfer of TFPI was confirmed by detection of human TFPI in the conditioned medium of porcine carotid arteries kept in culture after in vivo transduction. When carotid flow was measured with Doppler probe 5 days after surgery, cyclic flow variations (CFVs) developed in 7 of 8 control pigs after constriction of the injured carotid artery by 40%, and all control-treated arteries occluded after 70% constriction. In contrast, CFVs were observed in only 1 of 8 Ad-TFPI-treated pigs after 40% constriction, and only 3 of 8 occluded after constriction by 70% (Pϭ0.0027 and Pϭ0.007, respectively).

Local gene transfer of tissue factor pathway inhibitor regulates intimal hyperplasia in atherosclerotic arteries

“…After local gene transfer of TFPI, we observed no derangements in hemostasis. This finding agrees with shortterm studies in thrombosis models indicating a normally functioning hemostatic systemic at 5 and 6 days after local TFPI gene therapy (24,27). Taken together, these findings warrant reconsideration of systemic anticoagulant and antithrombotic approaches to the problem of recurrent thrombosis and restenosis.…”

“…We found that overexpression of TFPI markedly inhibited intimal hyperplasia, as reflected by a 43% reduction in the intima͞media ratio of carotid segments examined 4 weeks after balloon injury. No impairment of systemic hemostasis or excess bleeding was observed in this or previous studies of adenoviral TFPI gene transfer in vivo (24,27), indicating the potential of locally overexpressed TFPI to inhibit Fig. 3.…”

“…Previous studies of adenoviral TFPI gene transfer in domestic pigs (24) and normal rabbits (27) detected no impairment of hemostatic variables at a time when antithrombotic protection was observed (respectively 5 and 6 days after injury). We further investigated the integrity of the hemostatic system after local adenoviral gene transfer of TFPI.…”

“…Construction of the replication-deficient adenoviral vector, which encodes a fulllength human TFPI (23) driven by the cytomegalovirus immediate͞early promoter͞enhancer (Ad-TFPI), has been previously described (24). Ad-TFPI was plaque purified from 293 cells and further purified according to published procedures (24). Purified virions were suspended in sucrose (2% w͞vol) and MgCl 2 (2 mM) in PBS, desalted by Sepharose CL4B chromatography (Pharmacia & Upjohn), supplemented with 5% glycerol, and stored at Ϫ80°C.…”

Prevention of restenosis by a herpes simplex virus mutant capable of controlled long-term expression in vascular tissue in vivo

“…9,11,20,[26][27][28][29] Furthermore, the dose of HSV-1 required to achieve prolonged gene expression (approximately 10 9 p.f.u./ml) was several orders of magnitude less than traditional strategies using adenovirus. 8,9,13,20,[27][28][29][30][31][32][33][34][35][36][37][38] Although the safety profile of the current vector is largely unknown, no toxicity or immunostimulation was detected using this dosing regimen.…”