P–234 Doubling oocytes using the 1st polar body: how it works according to patient’s age
Authors: Ilyin I , Gontar J , Nataliia B , Lavrynenko S , Kazachkova N , Parnitskaya O , Gerevich Y , Kapustin E , Lakhno Y 
Published: August 2021

Abstract

Study question
Does the 1st polar body (PB) transfer technique for oocytes and embryo doubling works at any patients’ age?

Summary answer
The transfer of the patient’s 1stPB to a donor oocyte shows an increase in the number of blastocysts in all studied age groups of patients.

What is known already
The problem of low ovarian reserve is one of the most difficult to solve by ART. Particular difficulties arise when patients are not ready to use donor oocytes. But transfer of the patient’s 1st polar body (PB) to donor oocyte cytoplasm has proven to be an effective method to help patients with low ovarian reserve and poor response. In confirmation of this, three healthy babies have been born to this date thanks to this technique. But the question remains open as until what age the application of this method is effective. It was evaluated in this study.

Study design, size, duration
The study was performed in the Medical Center IGR from March 2017 to January 2021 and involved 695 cells: 361 oocytes (group A) obtained from 85 patients (mean age 38.4±6.4 years) and 334 oocytes (group B) that were obtained received from 47 donors (mean age 27.0±3.6). We evaluated the number of high quality blastocysts (HQB) from maternal and modified oocytes by the 1st PB transfer and blastocysts euploidy in the different age groups.

Participants/materials, setting, methods
We used patients’ oocytes obtained from 85 women with low ovarian reserve and poor response. Donor oocytes have been previously enucleated and modified by the transfer of patients’ 1stPB with further fertilization. The procedure was carried out using Nikon Ti Eclipse(Japan) inverted microscope, Saturn 3 laser console(UK). Preimplantation genetic testing for aneuploidy was performed using trophectoderm biopsy. Samples were diagnosed using Ion S5(USA). Statistical analysis was carried out using Chi-square test and Fisher’s exact test.

Main results and the role of chance
In the group A there were 93 HQB (25.8%) that formed from 361 original patients’ oocytes and 70 HQB (20.9%) developed from 334 modified oocytes (group B) on the post-fertilization day 5 or 6. The statistically significant difference (SSD) was not found between the groups on this parameter (p &gt; 0.05).
Also, the data were grouped according to the age of the patients, namely group I (23–30 years) that included 13 patients, group II (31–39 years) – 28 patients, group III (40–48 years) – 44 patients. In group I there were 12 HQB (25.0%) that formed from 48 original patients’ oocytes and 14 HQB (29.9%) developed from 47 modified oocytes, in group II - 50 HQB (38.5%) that formed from 130 original patients’ oocytes and 31 HQB (27.2%) developed from 114 modified oocytes, in group III - 31 HQB (16.9%) that formed from 183 original patients’ oocytes and 25 HQB (14.5%) developed from 173 modified oocytes. The analysis showed SSD between the number of patients’ blastocysts in groups II and III (p &lt; 0.001), as well as between the number of blastocysts from modified oocytes in groups II and III (p &lt; 0.005), I and III (p &lt; 0.05). There was not SSD among the number of euploid embryos.

Limitations, reasons for caution
With increasing age of patients, the morphological quality of their oocytes deteriorates, which is reflected in the structure of the polar bodies. In turn, the quality of the patient’s polar body plays a major role in the successful modification of the donor’s oocyte.
Wider implications of the findings: : Results of analysis shows that even in the group of advanced maternal age it is possible to increase the yield of high qualitative blastocysts at least by 14,5% using the1st PB transfer technique. At the same time, the biological relatedness of patient with the future child is maintaining.

Trial registration number
Not applicable