Development and Ex Vivo Functional Evaluation of Bioengineered Lungs

Abstract

Purpose Creation of bioengineered lungs (BL) through decellularization of porcine lungs followed by recellularization of the scaffold with human cells has been identified as a promising strategy for increasing the number of lungs suitable for transplant. Here, we report our progress developing a BL based on this combination decell/recell strategy. Methods Left lungs were dissected from porcine heart-lung blocks and decellularized. The left main pulmonary artery (PA), left atrial cuff (LA), and left main bronchus were then cannulated and attached to a bioreactor. Epithelial cells (EP) were instilled into the airway, followed by instillation of endothelial cells (EC) through the PA and LA. The grafts were then cultured for 7 to 16 days, followed by functional assessment by modified ex vivo lung perfusion (EVLP) techniques. Mock recells (MR) were also performed using the same dissection and perfusion scheme, but seeding steps were also omitted. Results After recellularization, 42 BLs received functional evaluation. Overall, the mean ΔPaO2/FiO2 ratio of BLs was 233 mmHg (Figure 1A), compared to an average of 102mmHg for MR and 395 mmHg for native porcine lungs (NL). Tidal volume and PIP in BL averaged 42ml and 24 cmH2O, respectively, compared to 25ml and 23 cmH2O in MR and 93ml and 17 cmH2O in NL. Additionally, vascular resistance (VR) in BL averaged 18,040 dyn*s*cm-5 at an average PA pressure (PAP) of 9 mmHg (Figure 1B). This was higher than decellularized scaffold, which averaged 17,600 dyn*s*cm-5 at 6 mmHg and NL, which averaged 3960 dyn*s*cm-5 at an average PAP of 17 mmHg. Conclusion We report positive progress toward production of functional BL grafts. Our results detail BL grafts that have perfusable vasculature and are capable of moderate gas exchange. While more development is required, considerable progress has been made, bringing bioengineered lungs closer to reality.