Efficient transduction and seeding of human endothelial cells onto metallic stents using bicistronic pseudo-typed retroviral vectors encoding vascular endothelial growth factor.

BACKGROUND: Stents seeded with genetically modified endothelial cells (EC) may provide an attractive therapeutic modality for treating vascular diseases by combining the mechanical properties of the metallic stent with the biologic activity of native or genetically engineered ECs. The clinical feasibility of implanting seeded stents depends on the ability to achieve adequate stent coverage within a clinically applicable time frame. We tested the hypothesis that this goal could be achieved by seeding stents with human ECs overexpressing vascular endothelial growth factor (VEGF) and by using an efficient gene transfer system. METHODS AND RESULTS: Efficiency of gene transfer to human ECs using an amphotropic retroviral vector and a gibbon ape leukemia virus (GALV) pseudo-typed retroviral vector was examined and compared. For assessment of transduction rates, LacZ-encoding vectors were used and beta-galactosidase activity was determined 48 h after gene transfer. The transduction rate of primary human ECs using the amphotropic retroviral vector encoding the LacZ gene was low (2.9+/-2% of cells). Under the same conditions, the GALV pseudo-typed vector encoding LacZ transduced 94+/-2% of cells (P<.001). To test the effect of VEGF gene transfer on stent coverage, we transduced ECs using a bicistronic GALV pseudo-typed retroviral vector encoding either GFP alone or both VEGF and GFP. Since all transduced cells expressed GFP, stent coverage by ECs could be assessed by fluorescent inverted microscopy, which demonstrated that stent coverage by ECs overexpressing VEGF was more rapid and effective than coverage by ECs overexpressing GFP. Progressively increasing quantities of VEGF protein were detected in the conditioned medium of stents seeded with endothelia cells expressing VEGF 2, 3, and 5 days after seeding. CONCLUSIONS: High-rate gene transfer to human primary ECs was observed 48 h after transduction with GALV pseudo-typed retroviral vectors, eliminating the need for the time-consuming process of cell selection. Seeding with ECs overexpressing VEGF improved stent coverage and was associated with continuing secretion of the protein. The findings provide support for the feasibility of implanting genetically engineered biologically active cellular-coated stents.

Cardiac resynchronization therapy: a potential option for congenitally corrected transposition of the great vessels.

The use of cardiac resynchronization therapy in patients with QRS prolongation (left-sided interventricular conduction delay) and symptomatic (New York Heart Association class III and IV) heart failure despite optimal medical therapy is well established. This case report describes the use of cardiac resynchronization therapy to treat symptomatic congestive heart failure in 2 patients with congenitally corrected transposition of the great vessels.

Right-sided prepectoral implantation of an implantable cardioverter defibrillator in a right pneumonectomized patient.

Right-sided prepectoral implantation of an ICD is performed in unusual circumstances only, like in patients with abnormal venous drainage and preexisting left-sided devices. This case report describes a 42-year-old man who had undergone previous right pneumonectomy and who required ICD implantation for symptomatic inducible nonsuppressable hemodynamically unstable ventricular tachycardia. To avoid the small but real possibility of inadvertent iatrogenic left-sided pneumothorax in a patient with previous right pneumonectomy, a dual chamber ICD with an active can was implanted in the right prepectoral position.