P-629 In vivo follicular activation (IVFA) through repeated ovarian punction: results of an experimental study in a premature ovarian insufficiency rodent model
Authors: Galán Rico R , Soriano M  J , Del Castillo L  M , Fadon P , Buigues A , Díaz-García C 
Published: July 2024

Abstract

Study question
Can the new IVFA therapy effectively promote ovarian follicle development and increase oocyte number in a premature ovarian insufficiency (POI) animal model.

Summary answer
The IVFA technique reveals favourable reproductive outcomes in the animal model, demonstrating increased oocyte retrieval without compromising quality, making a promising advancement in fertility restoration.

What is known already
POI is characterized by the loss of the primordial follicular pool before the age of 40. Ovarian fragmentation for in vitro follicular activation (IVA) is a technique based on the disruption of the ovarian extracellular matrix, subsequently promoting actin polymerization and interfering with the evolutionarily conserved tumour suppressor Salvador-Hippo-Warts (SHW) signalling pathway. This has been proven to increase expression of downstream growth factors, thus promoting the primordial follicle growth and the generation of mature oocytes. Yet, this procedure is invasive and expensive. Consequently, a demand exists for less invasive in vivo therapies.

Study design, size, duration
Experimental animal study. Sixty 6-week-old C57BL/6 female mice were divided into control (CT) and POI groups. Each group, was further divided into three subsets (n = 10/group): without ovarian punctures (CT-0 and POI-0), 15 punctures (CT-15 and POI-15), and 22 punctures (CT-22 and POI-22). Twenty-one days after POI induction, the new IVFA technique was performed on the anaesthetized animals. Subsequently, controlled ovarian stimulation (COS) was initiated, followed by euthanasia for the oocyte retrieval and histological ovarian evaluation.

Participants/materials, setting, methods
POI condition was induced with intraperitoneally injections of 120 mg/kg of cyclophosphamide and 12 mg/kg of busulfan. The IVFA technique involved ovarian punctures using a 30-gauge needle. COS was induced with 10 IU of PMSG and 10 IU of hCG 48 hours later, leading to euthanasia for oocytes and ovaries collection. Ovaries (n = 6/group) were fixed for follicular counts and immunohistochemistry. Oocyte quality assessment included reactive oxygen species (ROS) levels, mitochondrial fluorescence (Mitotracker), and spindle analysis.

Main results and the role of chance
The control groups subjected to the IVFA technique (CT-15 and CT-22) demonstrated significantly higher mean total oocyte counts compared to the non-intervention group (CT-0) (30.0±9.8 and 27.7±7.9 vs 18.1±11.7, respectively; p-value&lt;0.05 in both comparisons). Similarly, within the POI model, interventions (POI-15 and POI-22) showed significantly elevated mean total oocyte counts than the non-intervention group (POI-0) (8.1±4.4 and 7.2±2.8 vs 3.8±3.6, respectively; p-value&lt;0.05). The intensity of ROS fluorescence, Mitotracker fluorescence, and spindle analysis in retrieved oocytes were not affected by the IVFA therapy, thereby preserving oocyte quality. Notably, the percentage of growing follicles was significantly increased in the intervention groups compared to the non-intervention groups in the control (60±5.7% and 58.1±4.7% vs 41.5±4.5%; p-value&lt;0.001). In the POI model, statistically significant differences were observed for POI-15 vs POI-0 (57.8±9% vs 41.6±13.3%; p-value&lt;0.05), but not for POI-22 vs POI-0 (51.5±14.2% vs 41.6±13.3%, p=n.s.) Moreover, the global Ki67 proliferation marker demonstrated a significant increase in the percentage of proliferative cells in the CT-15 intervention group compared to the CT-0 group (53±11.2% vs 46.1±15.1; p &lt; 0.01). Finally, in the POI model, the percentage of Ki-67 positive cells was also significantly higher in both IVFA groups (39.4±18.5% and 38.1±17.3% vs 32±17.5%, respectively; p &lt; 0.05).

Limitations, reasons for caution
Since this is an animal model of POI, further validation of the new therapy with human ovarian samples would be required. The magnitude of the effect could vary due to inter-species variability.

Wider implications of the findings
The positive results of the new therapy in promoting follicle development and increasing oocyte retrieval, without compromising quality, have significant implications for developing new fertility treatments. If validated in humans, this approach could offer a promising solution for women with POI.

Trial registration number
not applicable