Fig. 1: Engraftment and functional repair of injured lungs by mouse embryonic lung cells. Following lung injury with NA and conditioning with 6Gy TBI, C57BL/6 adult mice were transplanted with syngeneic E16 stage embryonic lung cells from GFP+ donors. (a,b) Representative two-photon microscopy extended focus images of the lungs of transplanted mice 6 weeks after transplantation, showing entire scan depth from top to bottom of chimeric lung, without (a: z-stack 88μm), and with (b) co-staining of blood vessels with Quantum dots (red) (bar=90μm). (c) Two-photon extended focus image, showing entire scan depth from top to bottom of chimeric lung (z-stack 96μm) 16 weeks post-transplantation. (d) Two-photon microscopy of non-transplanted C57BL mouse lung showing background (bar=90μm). (e,f,g) Representative images of chimeric lungs stained with anti-GFP (green) and anti-AQP-5 (red), indicating incorporation of donor-derived type I alveocytes into the gas-exchange surface. (h,i,j) Chimeric lung stained with anti-GFP (green), anti-Sp-C antibodies (blue), demonstrating donor-derived surfactant producing type II alveocytes (bars=20μm). All the individual images shown above are representative of n=10 mice pooled from 3 independent experiments. (m,n) Lung function measurements 6 weeks after transplantation. (k,l) Staining of chimeric lung for CFTR (red) and (GFP), demonstrating CFTR positive donor cells. (m) Lung baseline compliance. Comparison of control intact mice vs mice with lung injury (Student's t-test, P<0.001), and of mice with lung injury vs mice transplanted after injury (Student's t-test, P=0.008). (n) Tissue damping. Comparison of control mice vs mice with lung injury (Student's t-test, P=0.015), and of mice with lung injury vs mice transplanted after injury (Student's t-test, P=0.021). Values are means ± SEM of 10-15 (n=15 control, n=10 injured and n=10 treated) mice in each group pooled from two independent experiments However, while this conditioning was required for enabling effective engraftment of donor lung progenitors in normal mice, we envision that in patients with different lung diseases, the lung niches could be already partially depleted and therefore transplantation might require less severe conditioning.