Genetic engineering of stent grafts with a highly efficient pseudotyped retroviral vector - Discussion

Purpose: The purpose of this study was first to compare the gene transfer efficiency of amphotrophic murine leukemia vital vector (ampho- MuLV) with the efficiency of MuLV pseudotyped with the vesicular stomatitis virus G glycoprotein (VSVG-MuLV) in tissue of vascular origin. The second purpose of this study was to determine cell retention after the implantation of genetically engineered stent grafts. Methods: Gene transfer efficiency was ascertained with the β-galactosidase assay. The target tissues included endothelial cells (ECs), smooth muscle cells (SMCs), and human saphenous veins (HSVs). Polyurethane stent grafts were suffused with lac Z-transduced ECs and SMCs that were harvested from porcine jugular vein. The grafts were implanted into the iliac artery of each pig whose jugular vein had been harvested. Cell retention was analyzed at 1 and 4 weeks with X-Gal staining. Results: VSVG-MuLV transduction efficiency exceeded that of ampho-MuLV in human ECs (VSVG-MuLV, n = 24, 89% ± 6%; ampho-MuLV, n = 18, 14% ± 6%; P < .001), human SMCs (VSVG-MuLV, n = 5, 92% ± 3%; ampho-MuLV, n = 4, 17% ± 2%; P< .001), pig ECs (VSVG-MuLV, n = 4, 81% ± 2%; ampho-MuLV, n = 4, 13% ± 3%; P < .001), and pig SMCs (VSVG-MuLV, n = 5, 89% ± 3%; ampho-MuLV, n = 4, 16% ± 1%; P < .001). As much as a 10-fold higher transduction efficiency was observed with VSVG-MuLV in HSVs. After the stent graft implantation, the engineered cells were retained and proliferated on the stent membrane, with ingrowth into the underlying intima. Conclusion: VSVG-MuLV significantly increased the gene transfer efficiency in vascular SMCs and ECs and in organ- cultured HSVs. The cells were retained and proliferated on stent grafts for the short term in the pig.