The Effect of Glucose on the Release and Bioactivity of Exosomes From First Trimester Trophoblast Cells

Hyperglycemia and hypoxia are risk factors of metabolic complication during pregnancy. The interactions between oxygen and glucose-sensing pathways that regulate exosome bioactivity from placental cells, however, have not been established.

The aim of this study was to test the hypothesis that exosomal signaling by placental cells (defined as the number of exosomes released per unit time and their bioactivity) is responsive to extracellular glucose concentration.

First-trimester primary trophoblast cells were incubated with D-glucose (5 mM or 25 mM) under 1%, 3%, or 8% O2 for 48 hours. Exosomes were isolated from cell-conditioned media by differential and buoyant density centrifugation. The total number of exosome vesicles was determined by quantifying immunoreactive exosomal CD63. The effect of exosomes on cytokine (granulocyte macrophage colony-stimulating factor, IL-2, IL-4, IL-6. IL-8, IL-10, interferon-γ, and TNF-α) release from endothelial cells was established by a protein solution array analysis.

Glucose (25 mM) significantly increased the release of exosomes from trophoblast cells at all oxygen tensions tested (by approximately 2-fold when compared with controls, P < .001). Exosomes (100 μg/mL exosomal protein) released from trophoblast cells significantly increased (P < .05) the release of all cytokines from human umbilical vein endothelial cells when compared with the control (ie, cells without exosomes), with the exception of IL-2 and IL-10 (P > .05).

The effects of high glucose on exosomes bioactivity may be recapitulated in vivo and is of clinical relevance in association with maternal insulin resistance (resulting in hyperglycemia) and preeclampsia (associated with placental insufficiency and hypoxia).