Single-cell RNA sequencing analysis of granulosa cells in preovulatory follicles in normal ovarian reserve patients undergoing progestin-primed ovarian stimulation and GnRH-antagonist

Abstract Study question Could the difference in controlled ovarian stimulation protocol between progestin-primed ovarian stimulation and GnRH-antagonist induce change in the expression genes of human granulosa cells? Summary answer The mitochondrial DNA (mtDNA) gene expression of granulosa cells in patients who underwent progestin-primed ovarian stimulation was significantly higher than the GnRH-antagonist. What is known already The progestin-primed ovarian stimulation (PPOS) protocol has attracted attention and many studies have reported similar pregnancy outcomes for both PPOS and the GnRH-antagonist (GnRH-ant). However, our previous study demonstrated that pregnancy rate was significantly lower in PPOS compared to GnRH-ant (38th Hybrid Annual Meeting of the ESHRE, O-130). In this study, we evaluated the gene expression of granulosa cells (GCs) which affects reproductive outcome. Many studies have shown a close association between the mitochondrial status of GCs and embryo’s quality. To date, the change in gene expression of GCs with different controlled ovarian stimulation protocols have not been investigated. Study design, size, duration From November 2021 to January 2022, all samples were obtained from the patients who provided written informed consent before the inclusion and underwent controlled ovarian stimulation cycles at a single-institution. Single cell RNA-seq (scRNA-seq) was performed on 2,224 cells corresponding to GCs of the MII-oocyte follicles from a total of 16 patients with normal ovarian reserve (aged < 40 years, AMH ≧1.1 ng/mL) undergoing PPOS with chlormadinone acetate (n = 8), or GnRH-ant with cetrorelix (n = 8). Participants/materials, setting, methods The GCs were obtained by follicular aspiration from 16 patients undergoing oocyte retrieval. The follicular fluid (FF) from each follicle was collected and all FF were mixed together in MII-oocyte for sequencing. The GCs were isolated from the blood cells and cellular debris using Percoll gradient centrifugation. Samples for sequencing were prepared using Chromium Next GEM Single Cell V(D)J Reagent Kits. Libraries were sequenced in DNBSEQ-G400, and reads processed with CellRanger and visualized with CellxGene. Main results and the role of chance Two population of GCs were used in this investigation: PPOS and GnRH-ant of MII-oocyte. After the quality control, 1,197 cells for PPOS and 1,027 cells for GnRH-ant, respectively, were analyzed. The GCs of MII-oocyte were clustered into 6 groups based on Leiden algorithm and visualized by UMAP analysis. There was no significant difference in the gene expression and cell distribution in each cluster. In the two population of GCs, we identified 12 differentially expressed genes (DEGs). Interestingly, we observed significant increase in expression of mtDNA genes in PPOS of MII-oocyte as compared to GnRH-ant of MII-oocyte. The data were confirmed by qRT-PCR analysis. Limitations, reasons for caution Our conclusions are limited due to the inclusion of Asian patients at a single-institution. The results need to be validated across different centers and other ethnicities. Due to the small sample size, these results should prompt further study to confirm our findings. Wider implications of the findings These findings describe, for the first time, the DEGs of GCs investigated in different COS protocols at single-cell level. This study suggests that progestin for PPOS induce elevation of the mt DNA gene expression of GCs which may be associated with reproductive outcomes. Trial registration number Not applicable