[Influence of human tissue factor pathway inhibitor gene transfection on neointima formation in vein grafts]

To reduce restenosis in vein grafts after coronary artery bypass grafting, to investigate the effect of human tissue factor pathway inhibitor (TFPI) gene delivery on neointima formation.

The eukaryotic expressed plasmid vector pCMV-(Kozak) TFPI was constructed. Forty-eight Japanese white rabbits were randomly divided into 3 groups with 16 rabbits in each group: TFPI group, empty plasmid control group and empty control group. Animal model of common carotid artery bypass grafting was constructed. Before anastomosis, vein endotheliocytes were transfected with cationic liposome containing the plasmid pCMV-(Kozak) TFPI (400 microg) by pressurizing infusion (30 min) in TFPI group. In empty plasmid control group, vector pCMV-(Kozak) TFPI was replaced by empty plasmid pCMV (400 microg). In empty control group, those endotheliocytes were not interfered. After operation, vein grafts were harvested at 3 days for immunohistochemical, RT-PCR and Western-blot analyses of exogenous gene expression and at 30 days for histopathology measurement of intimal areas, media areas and calculation of intimal/media areas ratio. Luminal diameter and vessel wall thickness were also measured by vessel Doppler ultrasonography and cellular category of neointima was analyzed by transmission electron microscope at 30 days after operation.

Human TFPI mRNA and protein were detected in TFPI group. The mean luminal diameter of the TFPI group, empty plasmid control group and empty control group was (2.68 +/- 0.32) mm, (2.41 +/- 0.23) mm and (2.38 +/- 0.21) mm respectively. There were statistically significant differences between TFPI group and control groups (P < 0.05). The vessel wall thickness of the TFPI group, empty plasmid control group and empty control group was (1.09 +/- 0.11) mm, (1.28 +/- 0.16) mm and (1.34 +/- 0.14) mm respectively. There were statistically significant differences between TFPI group and other control groups (P < 0.01). The mean intimal areas, the ratio of the intimal/media areas of the TFPI group were (0.62 +/- 0.05) mm2 and 0.51 +/- 0.08 respectively,whichwere reduced compared withthose of the two control groups (P < 0.05). The mean media areas had no significant differences among three groups (P > 0.05). Through transmission electron microscope analyses,no smooth muscle cells were seen in neointima of TFPI group in many visual fields,but smooth muscle cells were found in neointima of two control groups.

Human TFPI gene transfection reduced intimal thickness in vein grafts.