Poster Presentation: Andrew Tsao

ABSTRACT

Autoperfused Ex Vivo Murine Heart-Lung En Bloc for Cellular Imaging of Ventilation-Perfusion Mechanics

Andrew Tsao¹, Ling Shi¹, Byungjun Kang¹, Lauren Castle¹, Jessica Daher¹, Hadi Nia¹

¹Department of Biomedical Engineering, Boston University

Statement of Objectives: Understanding lung-heart mechanobiology requires simultaneous access to ventilation and perfusion mechanics. In our previously developed crystal ribcage platform, the ex vivo lung is driven by mechanical pumps, which lack physiological cardiopulmonary interactions driven by an intact heart, limiting study of ventilation-perfusion matching and pulmonary vascular mechanics. Here, we present a novel heart-lung block extension of the crystal ribcage. By restoring physiological cardiac auto-perfusion while maintaining optical access, this platform enables paired interrogation of alveolar deformation, microvascular flow, and cardiopulmonary coupling under controlled ventilation and perfusion.

Methods: Murine heart-lung blocks were harvested under deep anesthesia with anticoagulation. After tracheal cannulation and ventilation, a median thoracotomy was performed, and animals were chilled in cold PBS. The inferior vena cava and aorta were catheterized, and the superior vena cava was ligated. Perfusion was initiated retrograde via aorta in a Langendorff-like mode to perfuse coronary vasculature. As contractions emerged, flow transitioned to anterograde, and the preparation was warmed to 37°C. Perfusate consisted of nutrient buffer with ~20% packed bovine red blood cells, oxygenated through the ventilated lung. Aortic pressure, flow, venous pressure, tidal volume, and temperature were controlled and recorded continuously. Future experiments will mount the heart-lung block in the crystal ribcage for ultrafast confocal imaging in reporter mice to capture cardiomyocyte and alveolar deformation during coordinated heart beating and lung ventilation and how these dynamics change with aging.

 Results: During anterograde perfusion, heartbeats were evident from aortic pressure (~200 bpm). Cardiac and pulmonary functions remained stable for over 2 hours, validating feasibility of the heart-lung block.

 Conclusions: The heart-lung block restores physiological pumping and perfusion while enabling optical access, enabling studies of ventilation-perfusion coupling, pulmonary vascular mechanics, and cardiopulmonary interactions. Future work will utilize confocal imaging to quantify cellular responses in the heart and lungs during injury, infection, and aging, linking organ-scale physiology to cellular mechanobiology.