Extracellular presence/release of galectins from HTR-8/SVneo extravillous trophoblast cells*

Galectins (gals) are s-galactoside binding lectins, involved in many processes at the fetomaternal interface where they can exert their roles both in and out of cells. The aim of this work was to explore the extracellular presence/release of HTR-8/SVneo extravillous trophoblast cell line galectins. To that end, conditioned medium (CM) from HTR-8/SVneo cell culture was fractionated into a high molecular mass fraction (HMF) and low molecular mass fraction (LMF) using 100 kDa cut-off concentrators. In addition, extracellular vesicles (EVs) were isolated from CM by ultracentrifugation. Size and shape of the EVs were analyzed by transmission electron microscopy and their galectin mRNA content was determined by real-time PCR. The presence of galectins in fractions of HTR-8/SVneo CM and EVs was detected by western blot. All three galectins expressed by HTR-8/SVneo cells (gal-1, gal-3, and gal-8) were detected in the CM, HMF, and EVs, while only gal-1 was found in the LMF. In addition, EVs contained all three galectin mRNAs. These results reveal that free, complexed, and EV-associated forms of galectins were released from extravillous trophoblast cells, suggesting their potential to exert extracellular functions both in their immediate vicinity at the fetomaternal interface and distant locations.