P-472 Endometrial stimulation with culture medium containing granulocyte macrophage colony-stimulating factor promotes embryo implantation after vitrified-warmed blastocyst transfer
Authors: Tomari H , Kato M , Kunitake K , Uchimura K , Shimose H , Kuboyama K , Kitaoka A , Tanibata R , Ninomiya M , Seki H , Saito K , Gondo S , Sano Y , Honjo K , Nagata Y 
Published: June 2023

Abstract

Study question
Does endometrial stimulation with culture medium containing granulocyte macrophage colony-stimulating factor (GM-CSF) promote implantation potential of vitrified-warmed blastocysts?

Summary answer
Endometrial stimulation with culture medium containing GM-CSF prior to transfer of vitrified-warmed blastocysts may promote embryo implantation and improve pregnancy continuation.

What is known already
Human embryonic development and implantation in vivo is precisely regulated by various cytokines, including growth factors. GM-CSF is a cytokine that plays an important role in reproductive function. We reported the possibility that the use of culture medium containing GM-CSF in cleavage stage vitrified-warmed embryo transfers (ETs) promotes embryo implantation (ESHRE2018). However, it has been reported that endometrial stimulation with culture supernatant up to blastocyst stage (SEET method) improves embryo implantation, but the effect of endometrial stimulation with culture medium containing GM-CSF (G-SEET method) on embryo implantation is not clear.

Study design, size, duration
This study was conducted at a single in vitro fertilization (IVF) center from June 2020 to February 2022. The G-SEET procedure was performed at each patient’s request. All study participants provided informed consent, and the study design was approved by the ethics committee of IVF Nagata Clinic, Fukuoka, Japan.

Participants/materials, setting, methods
We examined 702 cycles of vitrified-warmed blastocyst transfer. Warmed blastocysts were incubated in recovery culture for several hours and transferred on day 5 (control group). For the G-SEET method, only culture medium containing GM-CSF was injected into the uterus two days before ET, which was performed as in the control group (G-SEET group). The human chorionic gonadotropin (hCG) positive, clinical pregnancy, miscarriage, and ongoing pregnancy rates were compared between the two groups.

Main results and the role of chance
Of the 702 cycles of single vitrified-warmed blastocyst transfers, the control and G-SEET groups had 459 and 243 cycles, respectively. The G-SEET group had a higher patient age (37.5±4.2 vs. 36.2±3.8, p &lt; 0.01), a thinner endometrial thickness (10.3±1.9 vs. 10.9±2.0, p &lt; 0.01), a lower percentage of good blastocyst transfers (65.4% vs. 79.5%, p &lt; 0.01), and a higher cumulative number of implantation failures (3.6±2.5 vs. 1.9±1.9, p &lt; 0.01) than the control group. The G-SEET method was performed at the patient’s request, so the number of cycles and patient background varied. Multivariate analysis was performed using female age, male age, number of miscarriages, endometrial thickness, presence of good blastocysts, and cumulative number of implantation failures as confounding factors. Compared with the control group, the G-SEET group exhibited the following: hCG positivity rate [odds ratio (OR): 1.14, 95% confidence interval (CI): 0.79–1.64, p = 0.481], clinical pregnancy rate (OR: 1.81, 95% CI: 1.21–2.71, p = 0.003), miscarriage rate (OR: 0.735, 95% CI: 0.30–1.76, p = 0.491), and ongoing pregnancy rate (OR: 1.79, 95% CI: 1.20–2.69, p = 0.004). Clinical pregnancy and ongoing pregnancy rates were significantly higher in the G-SEET group compared with the control group.

Limitations, reasons for caution
The study was limited by the study size and lack of data about live birth rates after ET. In addition, intrauterine infusion of GM-CSF-free culture medium should be used as a control, but this was difficult in the private clinic setting.

Wider implications of the findings
This study suggests that endometrial stimulation with culture media containing GM-CSF prior to transfer of vitrified-warmed blastocysts promotes embryo implantation and enhances the ongoing pregnancy. The G-SEET method may be clinically useful as a new ET method.

Trial registration number
not applicable