Adventitial delivery of platelet-derived endothelial cell growth factor gene prevented intimal hyperplasia of vein graft.
BACKGROUND
Platelet-derived endothelial cell growth factor (PD-ECGF), also known as thymidine phosphorylase (TP) reportedly inhibits vascular smooth muscle cells (VSMCs) migration and proliferation. We hypothesized that adventitial administration of the PD-ECGF/TP gene will suppress intimal hyperplasia and prevent vein graft failure.


METHODS
The study used 68 female rabbits. Rabbit jugular vein was autogenously transplanted into carotid artery with a cuff anastomotic technique. To define vascular wall gene transfer efficiency, poloxamer hydrogel (20%) containing plasmid vector encoding the LacZ gene and different concentrations of trypsin (0%, 0.1%, 0.25%, and 0.5%, n = 5 for each group) was applied to the adventitia of the vein graft. Gene transfer efficiency was evaluated 7 days later by X-gal staining. An additional 48 rabbits received poloxamer hydrogel (20%) containing 0.25% trypsin and the human PD-ECGF/TP gene, LacZ gene, or saline. Intima thickness was evaluated at 2 and 8 weeks after grafting (n = 8 for each group at each time point). Transgene expression was examined by reverse transcriptase-polymerase chain reaction, immunoblotting assay, and immunohistochemical staining. Immunohistochemical staining was also used to determine VSMC proliferation, heme oxygenase-1 expression, and macrophage infiltration.


RESULTS
Incorporation of trypsin into the poloxamer hydrogel significantly increased vessel wall gene transfer. Trypsin at 0.25% and 0.5% resulted in higher gene transfer at the same level without effecting intimal hyperplasia and inflammation; thus, trypsin at 0.25% concentration was used for subsequent experiments. Compared with the LacZ and saline groups, grafts receiving the PD-ECGF/TP gene significantly reduced intimal thickness at 2 and 8 weeks after treatment. The ratio of proliferative VSMC was lower in PD-ECGF/TP treated grafts. Histologic examination of the PD-ECGF/TP transgene grafts demonstrated high expression of heme oxygenase-1, which has been reported to inhibit VSMC proliferation, suggesting that heme oxygenase-1 may be important in the inhibition effect of PD-ECGF/TP on VSMC. No neoplastic or morphologic changes were found in the remote organs.


CONCLUSIONS
A safe and highly efficient gene transfer method was developed by using poloxamer hydrogel and a low concentration of trypsin. Neointimal hyperplasia was significantly reduced by adventitial application of the PD-ECGF/TP gene to the vein graft. Our data suggest that adventitial delivery of the PD-ECGF/TP gene after grafting may be promising method for preventing vein graft failure.
Division of Cardiothoracic Surgery, Second Departments of Surgery, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
Mitsuteru
M
Handa
Wei
W
Li
Kouichi
K
Morioka
Atsushi
A
Takamori
Narihisa
N
Yamada
Akio
A
Ihaya
D000818:Animals; D003238:Connective Tissue; D004247:DNA / Q000235:genetics; D004195:Disease Models, Animal; D005260:Female; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D006083:Graft Occlusion, Vascular / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D006965:Hyperplasia / Q000473:pathology / Q000517:prevention & control; D015151:Immunoblotting; D007601:Jugular Veins / Q000378:metabolism / Q000473:pathology / Q000637:transplantation*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000473:pathology*; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013939:Thymidine Phosphorylase / Q000096:biosynthesis / Q000235:genetics*; D016896:Treatment Outcome
D004247:DNA; D013939:Thymidine Phosphorylase