Pulmonary alveolar regrowth in an adult COVID-19 patient

We detected active alveolar regrowth in the lung of a 58-year-old COVID-19 patient who underwent lung transplantation due to severe lung hemorrhage. Specifically, immunohistological and scanning electronic microscopy analyses revealed that alveolar type II epithelial cells (AT2 cells) accumulate in response to viral pneumonia and that these AT2 cells actively proliferate and differentiate into squamous AT1-like alveolar epithelial cells. Thus, our work establishes that alveolar regrowth does occur in post-COVID-19 injury adult human lungs.