Transmyocardial laser revascularization limits in vivo adenoviral-mediatedgene transfer in porcine myocardium

Objective: Transmyocardial laser revascularization (TMR) is emerging as a p otential treatment option for patients with end-stage CAD, and adjuvant gen e therapy may be helpful in further improving the results of the procedure. However, the effects of TMR on gene transfer are unknown. Methods: Swine u nderwent left thoracotomy. TMR was performed to create five channels at 2-c m intervals in the anterolateral free wall of the left ventricle (LV) follo wed by injection of 1x10(9) plaque-forming units (pfu) of a replication-def icient adenovirus vector carrying the reporter gene beta-galactosidase (Ad. Pac beta-gal). An additional five direct injections of 1x10(9) pfu Ad.Pac b eta-gal were made at 2-cm intervals in the posterolateral LV of each heart. Control animals underwent TMR alone/vehicle alone (n=3) or empty virus alo ne/no treatment (n=3) of the anterolateral/posterolateral LV, respectively. Results: ELISA revealed significantly greater transgene expression in the direct Ad.Pac beta-gal injection versus TMR plus Ad.Pac beta-gal inject reg ions at both 3 (n=6) (273.0+/-58.5 vs. 133.4+28.1 pg beta-gal/g protein, P= 0.02) and 7 days (n=6) (180.01+59.9 vs. 56.7+18.1 pg beta-gal/g protein, P= 0.02) postoperatively. At 14 days postoperatively (n=2), no transgene expre ssion was detected in either region. No transgene expression was detected i n any of the control regions at 3 days postoperatively. CD-18 staining reve aled significantly greater inflammation in the TMR plus Ad.Pac beta-gal and TMR alone regions as compared to Ad.Pac beta-gal or vehicle (P<0.001). Con clusions: Adenoviral-mediated gene transfer in conjunction with TMR is poss ible, although TMR appears to limit the degree of transgene expression atta ined as compared to direct intramyocardial injection alone, likely due to t he greater immune response observed with the former. These findings may hav e important implications for therapeutic strategies aimed at combining TMR with gene therapy for CAD. (C) 1999 Elsevier Science B.V. All rights reserv ed.