Effective gene transfer in the rat myocardium via adenovirus vectors usinga coronary recirculation model

Background: Gene therapy promises to play an important role in the treatmen t of heart disease and in transplantation. The limited effectiveness of gen e transfer, however, remains an unresolved problem. The aim of the study wa s to create a model for more effective gene transfer using adenovirus vecto rs carrying the lacZ-reporter gene (AdV-lacZ). Methods: Beating Lewis rat h earts perfused with oxygenated Krebs-Henseleit solution were harvested, aft er which an atrial septal defect (ASD) was created. All vessels were tied a nd AdV-lacZ was injected into the aortic root. The solution was recirculate d through the ASD to the left side of the heart and pumped back to the coro nary arteries by the left ventricle. Incubation was allowed for 20 min at 1 5 degrees C and the hearts were subsequently transplanted heterotopically i n syngeneic rats. This method was compared to AdV-lacZ injection into cardi oplegic hearts. The hearts were harvested after 2, 7, or 14 days and evalua ted histologically for expression of the lacZ gene. Results: Maximal gene e xpression was achieved after 7 days by the recirculation model. There was l ess efficient gene expression at day 2 and at day 14. No evidence of ischem ic injury of the myocardium was noticed histologically. Almost no successfu l gene expression was seen in the arrested hearts. Conclusion: This novel r ecirculation method lets the vector be repeatadly exposed to the endotheliu m, resulting in an effective gene expression after 7 days incubation time r ather than after 14, when a decline has set in presumably due to immunologi c response.