Impaired lung regeneration after SARS‐CoV‐2 infection

To the Editor, The 2019 coronavirus disease (COVID‐19), caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), has become a global pandemic. [...]13 September 2020, SARS‐CoV‐2 caused more than twenty eight million infections and nine hundred thousand deaths worldwide. SARS‐CoV‐2 uses angiotensin‐converting enzyme 2 (ACE2) for cell entry into various lung cells including endothelial cells and alveolar type 2 (AT2) epithelial stem cells. 1,2 As cell damage usually results in the release of cell‐specific proteins into the circulation, these proteins can be detected to evaluate cellular injury. 3 So far, there is little information on cellular repair in the lung after the clearance of SARS‐CoV‐2. Nonetheless, AT2 cells serve as stem cells for repairing alveolar gas‐exchanging epithelium. 7 Our study, therefore, suggests that insufficient alveolar repair may increase lung vulnerability to inhaled microbes and substances or lead to lung fibrosis especially in discharged male COVID‐19 patients. [...]our data demonstrate that it will take an unexpectedly longer time to recover from SARS‐CoV‐2 infection, which is worth further clinical investigation. 8 ACKNOWLEDGEMENTS We are grateful to Dr Zichuan Liu at Tianjin University for critical review and constructive advice.