The Glyoxalase System Is a Novel Cargo of Amniotic Fluid Stem-Cell-Derived Extracellular Vesicles

Abstract

The glyoxalase system is a ubiquitous cellular metabolic pathway whose main physiological role is the removal of methylglyoxal (MG). MG, a glycolysis byproduct formed by the spontaneous degradation of triosephosphates glyceraldehyde-3-phosphate (GA3P) and dihydroxyacetonephosphate (DHAP), is an arginine-directed glycating agent and precursor of the major advanced glycation end product arginine-derived, hydroimidazolone (MG-H1). Extracellular vesicles (EVs) are a heterogeneous family of lipid-bilayer-vesicular structures released by virtually all living cells, involved in cell-to-cell communication, specifically by transporting biomolecules to recipient cells, driving distinct biological responses. Emerging evidence suggests that included in the EVs cargo there are different metabolic enzymes. Specifically, recent research has pointed out that EVs derived from human amniotic fluid stem cell (HASC-EVs) contain glycolytic pay-off phase enzymes, such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Since GAPDH catalyzes the sixth step of glycolysis using as a substrate GA3P, from which MG spontaneously origins, we wanted to investigate whether MG-derived MG-H1, as well as glyoxalases, could be novel molecule cargo in these EVs. By using immunoassays and spectrophotometric methods, we found, for the first time ever, that HASC-EVs contain functional glyoxalases and MG-H1, pioneering research to novel and exciting roles of these eclectic proteins, bringing them to the limelight once more.

Immersed in a reservoir of potential: amniotic fluid-derived extracellular vesicles

“…Stem cells were most commonly isolated from AF by fluorescence activated cell sorting for c-Kit expression [47,48,52,[56][57][58] or for CD44/CD105 expression [59]. Other researchers cultured cells from AF and separated the colonies based on the fibroblast morphology of the cells [60,61]. Whether these different methods impact EV biogenesis and secretion pathways differently in stem cells is yet to be understood.…”

“…Used both centrifugation (~ 10,000g spin) and filtration in tandem to separate larger vesicles prior to isolating smaller vesicles isolated from semen of multiple species (human, canine, equine, and bovine origin) produced ATP intrinsically through the glycolytic pathway [78,79]. Presence of active metabolic enzymes, particularly glyoxalases and MG-H1, in AFSC-EVs cargo [61] adds up to this concept. AF-EVs contain anti-inflammatory, immunomodulatory, and free radical scavenging properties [39].…”