P-164 Promoting embryo plating and outgrowth with extracellular vesicles
Authors: Lin Y M , Pangestu M , Yang Y M , Lin J C , Tsai F P 
Published: June 2023

Abstract

Study question
Can extracellular vesicles promote embryo plating and improve embryo outgrowth?

Summary answer
The addition of extracellular vesicles to the media and the use of assisted hatching can promote embryo plating and outgrowth.

What is known already
Effective and synchronous embryo-maternal crosstalk is required for proper implantation of the embryo into the receptive endometrium. Extracellular vesicles (EV) are imperative in embryo-maternal crosstalk and successful implantation (Das and Kale, 2020). Nowadays, embryo implantation still has some unexplainable and unsolvable issues which further leads to implantation failure in the field of reproductive medicine research which may result from the lacking of the EV between the endometrium and the embryo communication.

Study design, size, duration
Total 35 mice with total 176 embryos were utilised. Each run, embryos were cultured to blastocyst stage, total 4 experiment run and 3 control run were conducted. The embryo cell culture was performed on the 96-well cell culture plate coated with matrigel and treated with cleavage media and extracellular vesicles additive. Each run, the size of the embryo outgrowth area were recorded and measured every 24 hours for 4 consecutive days.

Participants/materials, setting, methods
We performed 4 types of assisting hatching (AH) to the embryo: 25%AH, 50%AH, single shot AH (1AH) and with an embryo hatching control (without AH performed) then cultured in 4 different culture treatments: 10% foetal bovine serum (FCS) as culture control and 3 different extracellular vesicles concentrations: 0%EV, 2.5%EV, 5.0%EV. The outgrowth area of plated embryos were measured. The significance in outgrowth size at 4 different time point was estimated by repeated 2-way ANOVA.

Main results and the role of chance
Results are divided based on the treatment and the assisted hatching type, 2.5%EV media additive resulted in significantly larger outgrowth areas at 96 hours post plating (p = 0.0463) which proves that with the addition of the extracellular vesicles in the culturing can promote the embryo outgrowth. And within 4 AH types, all showed significantly larger outgrowth at 96 hours post plating (a.p = 0.0009, b.p&lt;0.0001, c.p&lt;0.0001, d.p&lt;0.0001) which prove that with the use of assisting hatching to the embryo can improve the embryo outgrowth.

Limitations, reasons for caution
Experiment limitation appeared in the embryo orientation, where we could not control the embryo direction when it plated to the matrigel which affected the outgrowth direction, some of our embryo’s outgrowth showed vertical growth rather horizontal growth, which resulted a small outgrowth area when we were measuring it.

Wider implications of the findings
5.0%EV had poorer outcome in the outgrowth. 50% zona breaching caused embryo death. Therefore, further studies can look into finding the most suitable EV and AH for the embryo and look into adding EV to the transfer media in murine model to assess implantation.

Trial registration number
not applicable