DSG1 and chronic obstructive pulmonary disease: Notably, human DSG-2 mutations are associated with cardiac arrhythmia (Schinner et al., 2020), and genetic deletion of DSG-2 leads to arrhythmogenic cardiomyopathy and heart failure in mice (Pilichou et al., 2009); thus, whether the exosome-mediated transfer of DSG-1 to cardiomyocytes contributes to the benefit of MSC therapy warrants continued investigation, particularly since MSC exosomes appear to reduce the arrhythmogenicity of human cardiomyocytes (Sattayaprasert et al., 2020).