The artificial placenta: Continued lung development during extracorporeal support in a preterm lamb model

Purpose: An artificial placenta (AP) utilizing extracorporeal life support (ECLS) could avoid the harm of mechanical ventilation (MV) while allowing the lungs to develop. Methods: AP lambs (n = 5) were delivered at 118 days gestational age (GA; term = 145 days) and placed on venovenous ECLS (VV-ECLS) with jugular drainage and umbilical vein reinfusion. Lungs remained fluid-filled. After 10 days, lambs were ventilated. MV control lambs were delivered at 118 (early MV; n = 5) or 128 days (late MV; n = 5), and ventilated. Compliance and oxygenation index (OI) were calculated. After sacrifice, lungs were procured and H&E-stained slides scored for lung injury. Slides were also immunostained for PDGFR-a and a-actin; alveolar development was quantified by the area fraction of alveolar septal tips staining double-positive for both markers. Results: Compliance of AP lambs was 2.79 +/- 0.81 C-dyn compared to 0.83 +/- 0.19 and 3.04 +/- 0.99 for early and late MV, respectively. OI in AP lambs was lower than early MV lambs (6.20 +/- 2.10 vs. 36.8 +/- 16.8) and lung injury lower as well (1.8 +/- 1.6 vs. 6.0 +/- 1.2). Double-positive area fractions were higher in AP lambs (0.012 +/- 0.003) than early (0.003 +/- 0.0005) and late (0.004 +/- 0.002) MV controls. Conclusions: Lung development continues and lungs are protected from injury during AP support relative to mechanical ventilation. (c) 2018 Elsevier Inc. All rights reserved.