P-705 Telomere length of white blood cells is a non-invasive marker of reproductive aging in women
Authors: Lara Molina E  E , Franasiak J  M , Tao X , Garrigos V , Florensa M , Vazquez A , Sebastian P , Ballesteros A , Pellicer A , Diaz-Gimeno P 
Published: July 2024

Abstract

Study question
Can leukocyte telomere length be a marker of ovarian decline?

Summary answer
The significant correlation found between leukocyte and cumulus cell telomere lengths supports the use of leukocyte telomere length (TL) as a marker of ovarian aging.

What is known already
The telomere-based theory of reproductive aging proposes that age-related ovarian dysfunction is a consequence of progressive telomere shortening from fetal oogenesis to the adult ovary, compromising genome stability and proper chromosome segregation. Telomere length in cumulus cells (CCTL) is known to be a biomarker of oocyte and embryo quality, but its assessment is not practical. Hence, we previously proposed leukocyte telomere length (LTL) as an alternative to directly measuring telomere length in follicular cells, but so far it has only been assessed in samples of moderate size and homogeneous populations without consistent results.

Study design, size, duration
This prospective, non-interventional cohort study involved 300 women aged 18 to 46 years undergoing controlled ovarian stimulation over a 24-month period. The cohort included 169 egg donors and 131 IVF patients. Oocyte retrieval was performed 36 hours after maturation induction, with cumulus cells collected during oocyte stripping and blood samples taken via peripheral venous access.

Participants/materials, setting, methods
Genomic DNA was isolated from leukocytes and cumulus cells of all subjects for TL measurements. Relative TL was determined using a SYBR-Green quantitative real-time PCR protocol. A Taqman assay for the multicopy gene Alu was used to normalize the measurements. A Pearson’s correlation test was used to analyze the correlation between CCTL and LTL, as well as between TL and age, antral follicle count, Anti-Müllerian hormone, and number of mature oocytes retrieved.

Main results and the role of chance
Mean age of the subjects was 30.70±7.61 years. Anti-Müllerian hormone (AMH) mean level was 2.60±1.87 ng/ml, antral follicle count (AFC) was 17.8±7.4 and the number of mature oocytes was 14.3±9.3.
A significant correlation was observed between CCTL and LTL (R = 0.6, p-value=2.2E-16). Notably, the relationship between leukocyte and cumulus cell telomere lengths was stronger in the 97 participants over 35 years (R = 0.67, p-value=1.55E-13), especially those between 39 to 46 years (R = 0.70, p-value=1.19E-12).
Telomere length was inversely correlated with age in both leukocytes and cumulus cells (R=-0.23, p-value=6.98E-05; R=-0.4, p-value=2.38E-05), meaning the older the subject, the shorter the telomeres in both cells.
Furthermore, longer telomeres in leukocytes and cumulus cells were significantly correlated with higher AFC (R = 0.20, p-value=0.0006; R = 0.25, p-value=1.83E-05), and more mature oocytes retrieved (R = 0.16, p-value=0.0043; R = 0.27, p-value=2.83E-06). However, we did not find any association between AMH levels and LTL or CCTL (R = 0.07, p-value=0.2666; R = 0.07, p-value=0.2747).

Limitations, reasons for caution
The method used to measure the average telomere length from pooled leukocyte samples may not reflect individual cell variability. Additionally, it allows for relative but not absolute telomere length comparisons.

Wider implications of the findings
This study is the first to demonstrate in a large and heterogeneous population that LTL could be a viable marker for ovarian aging by reflecting follicular cell telomere length. This finding may provide a valuable tool for assessing and monitoring the reproductive health of IVF patients.

Trial registration number
Not applicable