Our recent study has shown that resting primary HPBCs harbor abundant cytoplasmic angiotensin-converting enzyme 2 (ACE2) protein and that circulating exosomes contain ACE2, the surface expression of which is indispensable for SARS-CoV2 infection of circulating monocytes/macrophages [140], highlighting the potential of exosome-based and/or exosome-targeted immunotherapies against COVID-19. Here, ACE2 is linked to COVID-19.