Orthotopic Transplantation and Engraftment of Human Induced Pluripotent Stem Cell-Derived Alveolar Progenitor Cells into Murine Lungs

Humanized mice possessing human cells, tissues, or organ systems provide an unparalleled platform for preclinical studies in oncology, immunology, and infectious diseases. While the lungs are a vital organ subject to a wide variety of pathologies, exemplified by the ongoing COVID-19 pandemic, discrete differences in murine and human lungs can obfuscate interpretation of murine models of lung disease. Here we provide proof-of-concept methodology for the potential humanization of murine lungs via orthotopic transplantation of human NKX2.1+ progenitor cells and alveolar type 2 cells derived from induced pluripotent stem cells. We show that these cells engraft readily into highly immunocompromised mice after pharmacological injury with bleomycin, which presumably generates "space" for human cells to access denuded basement membrane and engraft. Transplanted cells stably retain their pulmonary lineage restriction and persist as superficially differentiated alveolar type 2 and type 1 cells. Future work should focus on strategies to promote xenorepopulation of most / all of the murine lung with human cells while retaining appropriate regio-specific epithelial differentiation and normal physiological function.