Amongst them, haMSC-Exos was well tolerated in the treatment of COVID-19 severe disease, with a significant remission of lung lesions after 7 days (NCT04276987).250 Zou et al. designed a method using exosomes to deliver IFN-induced transmembrane protein 3 (IFITM3) to fetuses for treating ZIKV infection.251 In their study, exosomes effectively transported IFITM3 across the placental barrier into late-stage fetal cells or lysosomes. The gene discussed is IFITM3; the disease is COVID-19.