Gene transfer of heat shock protein 70 protects lung grafts from ischemia-reperfusion injury

Background. We recently demonstrated that heat stress induction of heat sho ck protein 70 (HSP70) in donor animals before harvest decreases posttranspl ant ischemia-reperfusion injury in preserved rat lung isografts. The purpos e of this study was to investigate the feasibility of HSP70 gene transfecti on into rat lung isografts using an adenoviral vector, and to study the eff ects of gene expression on subsequent ischemia-reperfusion injury. Methods. In preliminary studies to determine the optimal titer, animals wer e injected with various titers of adenovirus-HSP70 (saline, 5 x 10(9), 1 x 10(10), and 2 x 10(10) plaque forming units [pfu]) and sacrificed 5 days af ter injection. To determine the optimal exposure time, animals were sacrifi ced at different times (0, 6, 24, and 72 hours) after intravenous injection of adenovirus-HSP70. In a subsequent series of transplant experiments, don ors were allocated to three groups according to transfection strategy. Grou p 1 (n = 8) donors received 5 x 10(9) pfu adenovirus-HSP70 intravenously, g roup 2 (n = 7) donors received 5 x 10(9) pfu adenovirus-beta-galactosidase (as a virus control), and group 3 (n = 7) donors received saline and served as a negative control. Twenty-four hours after treatment all grafts were h arvested and stored for 18 hours before orthotopic left lung transplantatio n. Twenty-four hours after implantation animals were sacrificed for assessm ent. The expression of HSP70 was assessed by Western blot analysis. Results. In preliminary studies, HSP70 was detectable even at low titers (5 x 10(9) pfu) of adenovirus-HSP70, and was detectable at low levels as earl y as 6 hours after intravenous administration. Heat shock protein 70 expres sion was maximal at 24 hours. In transplant experiments, Western blot analy sis showed that overexpression of HSP70 occurred in the HSP70-transfected l ungs. The mean arterial oxygenation 24 hours after reperfusion in group 1 w as superior in comparison with other groups (p < 0.05). Wet to dry weight r atio (p < 0.05) and myeloperoxidase activity (p < 0.05) were also significa ntly less in group 1 grafts compared with the other groups. Conclusions. This study demonstrates that in vivo, donor adenovirus-mediate d gene transfer of HSP70 decreases subsequent ischemia-reperfusion injury i n rat lung isografts. (Ann Thorac Surg 1999;67:1421-7) (C) 1999 by The Soci ety of Thoracic Surgeons.