Pediatric and Teen Ovarian Tissue Removed for Cryopreservation Contains Follicles Irrespective of Age, Disease Diagnosis, Treatment History, and Specimen Processing Methods

Abstract

Purpose: Fertility preservation in a pediatric and teen female population is challenging because standard technologies of egg and embryo freezing may not be possible due to premenarcheal status. Ovarian tissue cryopreservation (OTC) with the intent of future ovarian tissue transplantation or in vitro follicle growth may be the only option to preserve fertility. The purpose of this study was to add to the general understanding of primordial follicle dynamics in young patients.

Methods: First, the unique infrastructure of the Oncofertility Consortium National Physicians Cooperative (OC-NPC) is described, which simultaneously drives clinical fertility preservation and basic research to explore and expand the reproductive options for those in need. Then, the OC-NPC research resource is used to perform a histological evaluation of ovarian tissue from 24 participants younger than 18 years of age.

Results: Primordial follicles, which comprise the ovarian reserve, were observed in all participant tissues, irrespective of variables, including age, diagnosis, previous treatment history, tissue size, and tissue processing methods. Primordial follicles were present in ovarian tissue, even in participants who had a previous history of exposure to chemotherapy and/or radiation treatment regimens, which placed them at risk for iatrogenic infertility or premature ovarian failure.

Conclusion: Primordial follicles were observed in ovarian tissue from all participants examined, despite population and tissue heterogeneity. These results increase the understanding of human follicle dynamics and support OTC as a promising fertility preservation modality in the young female population. Future studies to evaluate follicle quality within these tissues are warranted.

Keywords: fertility preservation; follicle; oncofertility; ovarian tissue cryopreservation; ovary.

Figures

FIG. 1.

There is a shift toward pediatric and teen usage of ovarian tissue cryopreservation (OTC). (A) Since its inception in 2007, the number of participants enrolled to undergo OTC has steadily increased (red line). In recent years, there has been a shift in the participant population electing to undergo this experimental procedure. There has been a decrease in females older than 18 years old (gray bars), and a corresponding increase in the number of females younger than 18 years old (black bars). (B) A histogram illustrating the age distribution of participants younger than 18 years old who have undergone investigational OTC protocols through the NPC. (C) The distribution of clinical diagnoses (malignant and non-malignant) of pediatric and teen populations that have elected to undergo OTC through the National Physicians Cooperative (NPC). (D) The treatment status of pediatric and teen populations prior to ovarian tissue removal and OTC (chemotherapy, radiation, disease modifying agent, or a combination of these).

FIG. 2.

Histological evaluation reveals primordial follicles in ovarian tissue from all participants with no prior exposure to gonadotoxic therapies. Representative standard hematoxylin and eosin (H&E) staining of ovarian tissue histological sections from pediatric and teen participants who had no previous treatment prior to undergoing OTC. The image labels correspond to the participant ID. More detailed information about each participant can be found in Table 1. Scale bar is 50 μm.

FIG. 3.

Histological evaluation reveals primordial follicles in ovarian tissue from participants who were exposed to low-risk gonadotoxic treatments prior to OTC. Representative standard H&E staining of ovarian tissue histological sections from pediatric and teen participants who had previous treatment prior to undergoing OTC that is considered to be low risk for infertility or premature ovarian failure. The image labels correspond to the participant ID. More detailed information about each participant can be found in Table 1 and Supplementary Table S2. Scale bar is 50 μm.

FIG. 4.

Histological evaluation reveals primordial follicles in ovarian tissue from participants who were exposed to high-risk gonadotoxic treatments prior to OTC. Representative standard H&E staining of ovarian tissue histological sections from pediatric and teen participants who had previous treatment prior to undergoing OTC that is considered to be high risk for infertility or premature ovarian failure. The image labels correspond to the participant ID. More detailed information about each participant can be found in Table 1 and Supplementary Table S2. Scale bar is 50 μm.

FIG. 5.

Histological evaluation reveals the presence of activated and growing follicles in a subset of participant ovarian tissue. In addition to primordial follicles, growing pre-antral follicles were observed in a total of three participants who had either not received prior treatment to gonadotoxic therapy (participants B and F) or had been exposed to treatment that would be considered low risk for infertility or premature ovarian failure (participant L). Multilayer secondary follicles are highlighted with asterisks, and the antral follicle is highlighted with an arrow. The image labels correspond to the participant ID. More detailed information about each participant can be found in Table 1 and Supplementary Table S2. Scale bar is 50 μm.