Endometrium-on-a-chip reveals the endometrial transcriptome, and protein content of secretome are altered by changes in circulating concentrations of insulin and glucose in vitro.

Abstract

The molecular interactions between the maternal environment and developing embryo that are key for early pregnancy success are known to be influenced by factors such as the metabolic status. We are, however, limited in our understanding of the mechanism by which these individual nutritional stressors alter endometrial function and the in utero environment for early pregnancy success. Here we report for the first time the use of endometrium-on-a-chip microfluidics approach to produce a multi-cellular endometrium in vitro, that is exposed to glucose and insulin concentrations associated with maternal metabolic stressors. Following isolation of endometrial cells (epithelial and stromal) from the uteri of non-pregnant cows in early-luteal phase (Day 4-7 approximately) epithelial cells were seeded into the upper chamber (4-6 104 cells/mL) and stromal cells seeded in the lower chamber (1.5-2 104 cells/mL). Three different concentration of glucose 1) 0.5 mM 2) 5.0 mM or 3) 50 mM or insulin 1) Vehicle, 2) 1 ng/mL or 3) 10 ng/mL were performed in the endometrial cells at a flow rate of 1{micro}L/min for 72 hr to mimic the rate of secretion in vivo. Quantitative differences in the transcriptomic response of the cells and the secreted proteome of in vitro-derived uterine luminal fluid (ULF) were determined by RNA-sequencing and TMT respectively. Changes in maternal glucose altered 21 and 191 protein coding genes in epithelial and stromal cells respectively (p<0.05). While there was a dose-dependent quantitative change in protein secretome (1 and 23 proteins). Insulin resulted in limited transcriptional changes including insulin-like binding proteins that were cell specific (5, 12, and 20) but altered the quantitative secretion of 196 proteins including those involved in extracellular matrix-receptor interaction and proteoglycan signaling in cancer. Collectively, these highlight the potential mechanism by which changes to maternal glucose and insulin alter uterine function.