PTGS2 and hydrops fetalis: Thus, a relationship with PTGS2 upregulation in both bCSC and bEEL after incubation of LF-EXO (Figs. 2C and 3C) and the low fertile origin of sEV may elucidate through PGE2 stimulation and immune suppression by inhibition of TLR4, in contrast to HF-EXO.