The Joint Annual Scientific Meetings of the Endocrine Society of Australia and the Society for Reproductive Biology 2018

Defining a human embryo implantation ‘adhesome’ (#143)

Jemma Evans 1 , David Greening 2 , Maree Bilandzic 1 , Sophie Kinnear 1 , Susan Fisher 3 , Lois Salamonsen 1
  1. The Hudson Institute of Medical Research, Clayton, VIC, Australia
  2. La Trobe Institute of Molecular Sciences, La Trobe University, Clayton, VIC, Australia
  3. University of San Francisco, San Francisco, California, USA

Background: Human embryo implantation is considered the ‘black box’ of reproduction. Knowledge of the basic biological processes underpinning initial stages of implantation is important to improve fertility outcomes, particularly in ART cycles where pregnancy rates remain ~30% despite production of high quality embryos. Elucidation of critical molecules involved in implantation could facilitate novel approaches/therapeutics to improve reproductive outcomes.

Aim: Develop a medium/high throughput model of human embryo implantation and interrogate it to provide a proteome of human embryo adhesion.

Methods: Human trophoblast stem cells (‘trophectoderm’) were formed into spheroids (TS), approximating size of human blastocyst, and co-cultured with endometrial epithelial cell-lines/ primary human endometrial epithelial cells (HEEC) to determine i) time course of adhesion; ii) adhesion with hormonal treatments; iii) adhesion to HEEC’s from fertile versus infertile women. Hormonally-treated HEEC/TS co-cultures were subjected to proteomic analysis for proteins involved in embryo adhesion.

Results: The endometrial endometrial cell-lines exhibited differing degrees of adhesion for TS ranging from high (RL95-2 cells), moderate (ECC-1, Ishikawa) to low (Hec-1a). ECC-1 cells exhibited ~50% adhesion after 6-hours of co-culture; timing approximating human embryo adhesion. ECC-1 and HEEC’s demonstrated increased adhesion in response to ‘receptive’ (estrogen/progesterone) and ‘implantation’ (estrogen/progesterone/hCG) versus ‘proliferative’ (estrogen) treatments. Importantly, TS adhered to 95% of HEEC’s derived from fertile women but only 11% of those from infertile women, suggesting TS ‘identify’ endometrial infertility. Proteomic analysis identified 147 up-regulated and 145 down-regulated proteins associated with adhesion; the ‘adhesome’. The most up-regulated proteins included PTGS2, RPL28, CNIH4, SERPINE1 and ATP5I, which have previously been implicated in endometrial receptivity/embryo adhesion, confirming the validity of our model.

Conclusion: The TS-HEEC model provides insight into embryo adhesion and a medium-throughput model for screening pro/anti-implantation factors. Our characterisation of an embryo implantation ‘adhesome’ provides a valuable resource for understanding and more effectively targeting this critical phase of pregnancy.