Modulation of HOXA10 and other markers of endometrial receptivity by age and human chorionic gonadotropin in an endometrial explant model

Objective

To characterize the endometrial response to human chorionic gonadotropin (hCG), as influenced by uterine age, using endometrial receptivity markers including HOXA10, vascular endothelial growth factor (VEGF), and glycodelin in an endometrial explant culture system.

Design

In vitro molecular biology research.

Setting

Academic infertility clinic and molecular biology laboratory.

Patient(s)

Fourteen prospective recipients of egg donation (mean age, 44 ± 8 years).

Intervention(s)

Subjects received cyclical estrogen (E₂) and progesterone (P₄) and underwent an endometrial biopsy on day 7 of P₄. Endometrial biopsy samples were cut into 1-mm³ pieces and cultured in Dulbecco's modified Eagle's medium/Ham's F-12 with E₂ and P₄, without (control) or with hCG (400, 4000, and 40,000 mIU/mL) on Millicell-CM inserts for 24 hours.

Main Outcome Measure(s)

Explant viability was assessed using immunohistochemistry (IHC). Semiquantitative polymerase chain reaction was performed to evaluate relative gene expression via mRNA levels of HOXA10, VEGF, and glycodelin.

Result(s)

Explant viability was confirmed on IHC by histology and Ki-67 staining, a marker of proliferation. HOXA10, VEGF, and glycodelin gene expression increased at all concentrations of hCG over those of controls. HOXA10 gene expression was inversely correlated with age (−0.08- ± 0.03-fold decrease in gene expression/year of age).

Conclusion(s)

The endometrial explant culture system is a promising model for the study of endometrial response as it maintains interactions among the stroma, glands, and epithelium. HOXA10, VEGF, and glycodelin all demonstrated increased gene expression in response to increasing hCG concentrations, supporting the role of hCG as a candidate protein for blastocyst-endometrial communication. Statistically significant associations between age and expression of HOXA10 provide novel evidence that uterine age may play a role in endometrial response on a molecular level.

Key Words: Endometrial receptivity, HOXA10, glycodelin, vascular endothelial growth factor, embryo implantation