HLA-A and neoplasm: This condition is due to a low expression of major histocompatibility class I antigen (HLA-A/B/C) and no expression of major histocompatibility class II antigen (HLA-DR) and β2 microglobulin (Chiavegato et al., 2007; Murphy et al., 2010; Srinivasan et al., 2020); likewise, they do not express HLA-A/B/C costimulatory molecules such as CD80, CD86, and CD40 (Wolbank et al., 2007; Pratama et al., 2011) As such, when hAECs and hAMSCs have been transplanted intravenously into humans, they did not result in hemolysis, allergic reactions, toxicity, or tumor formation (Yang et al., 2018).