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Characterization of ovarian tissue oocytes from transgender men reveals poor calcium release and embryo development,
A Christodoulaki1,2, H He1,2, M Zhou1,2
1Department for Reproductive Medicine, Ghent-Fertility And Stem cell Team (G-FAST), Ghent University Hospital, Ghent, Belgium.
Study Question:
Can spindle transfer (ST) overcome inferior embryonic development of in vitro matured ovarian tissue oocytes (OTO-IVM) originating from testosterone-treated transgender men?
Summary Answer:
ST shows some potential to overcome the embryo developmental arrest observed in OTO-IVM oocytes from transgender men.
What Is Known Already:
OTO-IVM is being applied as a complementary approach to increase the number of oocytes/embryos available for fertility preservation during ovarian tissue cryopreservation in cancer patients. OTO-IVM has also been proposed for transgender men, although the potential of their oocytes remains poorly investigated. Currently, only one study has examined the ability of OTO-IVM oocytes originating from transgender men to support embryo development, and that study has shown that they exhibit poor potential.
Study Design, Size, Duration:
Both ovaries from 18 transgender men undergoing oophorectomy were collected for the purposes of this study, from November 2020 to September 2022. The patients did not wish to cryopreserve their tissue for fertility preservation and donated their ovaries for research. All patients were having testosterone treatment at the time of oophorectomy and some of them were also having menses inhibition treatment.
Participants/Materials, Setting, Methods:
Sibling ovaries were collected in either cold or warm medium, to identify the most optimal collection temperature. Cumulus oocyte complexes (COCs) from each condition were isolated from the ovarian tissue and matured in vitro for 48 h. The quality of OTO-IVM oocytes was assessed by calcium pattern releasing ability, embryo developmental competence following ICSI, and staining for mitochondrial membrane potential. In vitro matured metaphase I (MI) oocytes, germinal vesicle (GV) oocytes, and in vivo matured oocytes with aggregates of smooth endoplasmic reticulum (SERa) were donated from ovarian stimulated women undergoing infertility treatment and these served as Control oocytes for the study groups. ST was applied to overcome poor oocyte quality. Specifically, enucleated mature Control oocytes served as cytoplasmic recipients of the OTO-IVM spindles from the transgender men. Embryos derived from the different groups were scored and analysed by shallow whole genome sequencing for copy number variations (CNVs).
Main Results And The Role Of Chance:
In total, 331 COCs were collected in the cold condition (OTO-Cold) and 282 were collected in the warm condition (OTO-Warm) from transgender men. The maturation rate was close to 54% for OTO-Cold and 57% for OTO-Warm oocytes. Control oocytes showed a calcium releasing ability of 2.30 AU (n = 39), significantly higher than OTO-Cold (1.47 AU, P = 0.046) oocytes (n = 33) and OTO-Warm (1.03 AU, P = 0.036) oocytes (n = 31); both values of calcium release were similar between the two collection temperatures. Mitochondrial membrane potential did not reveal major differences between Control, OTO-Warm, and OTO-Cold oocytes (P = 0.417). Following ICSI, 59/70 (84.2%) of Control oocytes were fertilized, which was significantly higher compared to 19/47 (40.4%) of OTO-Cold (P < 0.01) and 24/48 (50%) of OTO-Warm oocytes (P < 0.01). In total, 15/59 (25.4%) blastocysts were formed on Day 5 in the Control group, significantly higher than 0/19 (0%) from the OTO-Cold (P = 0.014) and 1/24 (4.1%) in OTO-Warm oocytes (P = 0.026). Application of ST rescued the poor embryo development, by increasing the Day 5 blastocyst rate from 0% (0/19) to 20.6% (6/29) (P = 0.034), similar to that in the ICSI-Control group (25.4%, 15/59). A normal genetic profile was observed in 72.7% (8/11) of OTO-Cold, 72.7% (8/11) of OTO-Warm and 64.7% (11/17) of Control Day 3-Day 5 embryos. After ST was applied for OTO-IVM oocytes, 41.1% (7/17) of the embryos displayed normal genetic patterns, compared to 57.1% (4/7) among ST-Control Day 3-Day 5 embryos.
Large Scale Data:
N/A.
Limitations, Reasons For Caution:
Due to the limited access to human oocytes and ovarian tissue, our results should be interpreted with some caution, as only a limited number of human oocytes and embryos could be investigated.
Wider Implications Of The Findings:
The results of this study, clearly indicate that OTO-IVM oocytes originating from transgender patients are of inferior quality, which questions their use for fertility preservation. The poor quality is likely to be related to cytoplasmic factors, supported by the increased blastocyst numbers following application of ST. Future research on OTO-IVM from transgender men should focus on the cytoplasmic content of oocytes or supplementation of media with factors that promote cytoplasmic maturation. A more detailed study on the effect of the length of testosterone treatment is also currently missing for more concrete guidelines and guidance on the fertility options of transgender men. Furthermore, our study suggests a potentially beneficial role of experimental ST in overcoming poor embryo development related to cytoplasmic quality.
Study Funding/Competing Interest(S):
A.C. is a holder of FWO grants (1S80220N and 1S80222N). A.B. is a holder of an FWO grant (1298722N). B.H. and A.V.S. have been awarded with a special BOF (Bijzonder Onderzoeksfonds), GOA (Geconcerteerde onderzoeksacties) and 2018000504 (GOA030-18 BOF) funding. B.H. has additional grants from FWO-Vlaanderen (Flemish Fund for Scientific Research, G051516N and G1507816N) and Ghent University Special Research Fund (Bijzonder Onderzoeksfonds, BOF funding (BOF/STA/202109/005)), and has been receiving unrestricted educational funding from Ferring Pharmaceuticals (Aalst, Belgium). The authors declare that they have no conflict of interest.
Trial Registration Number:
N/A.
Insights
Spindle transfer (ST) shows promise for improving embryo development in oocytes from transgender men. This technique may help overcome developmental arrest in in vitro matured ovarian tissue oocytes (OTO-IVM).
Area of Science:
- Reproductive biology
- Assisted reproductive technologies
- Transgender health
Background:
- In vitro matured ovarian tissue oocytes (OTO-IVM) are used for fertility preservation, including in transgender men.
- OTO-IVM oocytes from transgender men have shown poor developmental potential in previous studies.
- The efficacy of spindle transfer (ST) in improving OTO-IVM oocyte quality from transgender men is largely uninvestigated.
Purpose of the Study:
- To investigate whether spindle transfer (ST) can overcome the inferior embryonic development of in vitro matured ovarian tissue oocytes (OTO-IVM) from transgender men.
- To assess the quality and developmental competence of OTO-IVM oocytes originating from transgender men.
- To compare the efficacy of cold versus warm medium collection of ovarian tissue.
Main Methods:
- Ovarian tissues from 18 transgender men undergoing oophorectomy were collected and processed.
- Cumulus oocyte complexes (COCs) were matured in vitro (OTO-IVM) after collection in cold or warm medium.
- Oocyte quality was assessed via calcium release and mitochondrial membrane potential.
- Intracytoplasmic sperm injection (ICSI) was performed, followed by embryo scoring and shallow whole genome sequencing.
- Spindle transfer (ST) was applied to enucleated control oocytes using spindles from OTO-IVM oocytes.
Main Results:
- OTO-IVM oocytes from transgender men exhibited lower calcium releasing ability and fertilization rates compared to controls.
- No blastocysts formed from OTO-IVM oocytes collected in cold medium, and only one from warm medium.
- Spindle transfer (ST) significantly improved blastocyst formation rates from OTO-IVM oocytes (20.6%) compared to non-ST controls (0-4.1%).
- Genetic analysis revealed normal copy number variations in a majority of embryos, with ST showing a trend towards improved normalcy.
Conclusions:
- OTO-IVM oocytes from transgender men demonstrate inferior quality, potentially limiting their use for fertility preservation.
- Spindle transfer (ST) shows potential to rescue poor embryo development in OTO-IVM oocytes from transgender men, likely by addressing cytoplasmic factors.
- Further research should focus on improving cytoplasmic maturation and investigating the impact of testosterone treatment duration on oocyte quality.
