Late Breaking Abstract - Ex vivo lung perfusion prolongs donor lung preservation in mice via Hippo signaling-mediated vascular barrier integrity

<bold>Background:</bold> <italic>Ex vivo</italic> lung perfusion (EVLP) is a promising technique that allows organ preservation and repair, increasing the number of marginal donor lungs for lung transplantation. <bold>Aims:</bold> This study aimed to establish a murine EVLP model and to unveil the molecular mechanisms responsible of EVLP beneficial effects. <bold>Methods:</bold> The mouse EVLP system was established and lungs were exposed to: 1) without ischemia or EVLP (control), 2) 45 min EVLP followed by 135 min cold ischemia (EVLP-CI), 3) 135 min cold ischemia followed by 45 min EVLP (CI-EVLP), and 4) 180 min cold ischemia (CI). Increases in lung weight (Δweight) and lung vascular filtration coefficient (ΔK_f), lung compliance and vascular resistance were measured. <bold>Results:</bold> Compared to CI group, either CI-EVLP or EVLP-CI group showed an attenuated Δweight and ΔK_f, vascular resistance, and histological evidence of lung damage. Both transcriptomic and proteomic analyses on mouse lungs revealed that EVLP regulated the Hippo signaling in response to CI. Pharmacological inhibition of Hippo signaling by Yap/Lats inhibitor TDI-011536 and Lats-IN-1, and genetic deletion of Yap or Lats1 specifically in endothelial cells (<italic>Yap^Endo-KO</italic> or <italic>Lats1^Endo-KO</italic>) further increased ischemia-induced Δweight, which was attenuated by Yap phosphorylation activator AICRA or metformin. <italic>In vitro</italic>, barrier function was disrupted in Yap-KO cells or Lats-IN-1 in Ibidi pump system, with a decreased cytoplasmic and junctional localization of Yap. <bold>Conclusions:</bold> We applied the EVLP technique to the research field of mouse donor lung preservation, and found that EVLP prolonged the preservation time <italic>via</italic> Hippo signaling-mediated vascular barrier integrity.