83 Carotenoids presence in zona pellucida of human oocytes: potential role of chemical compounds evaluation by life-cell imaging for oocyte selection
S. Bisogno A , A. Pieczara B , J. Depciuch C , Z. Holubcova D E , M. Baranska B F and G. Ptak AA Malopolska Center of Biotechnology, Jagiellonian University, Kraków, Poland
B Jagiellonian Centre for Experimental Therapeutics, Kraków, Poland
C Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland
D Faculty of Medicine, Masaryk University, Brno, Czech Republic
E Reprofit International, Brno, Czech Republic
F Faculty of Chemistry, Jagiellonian University, Kraków, Poland
Reproduction, Fertility and Development 35(2) 167-168 https://doi.org/10.1071/RDv35n2Ab83
Published: 5 December 2022
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
Morphological assessment of oocytes is, so far, the only method utilised for selection of oocytes in IVF programs. This methodology is based on light microscopy evaluation of oocyte dysmorphisms, including perivitelline space, polar body, cell shape, vacuoles presence, refractile bodies, granularity, colour, etc. Available live-cell methodologies based on chemical structures and their relative abundance to assess oocyte quality have not been sufficiently explored, especially in relation to human oocytes. We investigated whether the chemical composition of human oocytes can be a potential method for selection of oocytes. To do this, we collected human oocytes from young, healthy donors of IVF programs in various ages (19–33 years old) and evaluated their composition by live-cell imaging using Confocal Raman Microscopy, then compared the results with Fourier-transform infrared (FTIR) spectroscopy. The presence of carotenoids in the zona pellucida (ZP) of part of the oocytes was identified using Raman spectroscopy by the characteristic band: 1,157 and 1,517 cm−1. From 41 analysed oocytes, 58.97% (23/41) showed the presence of carotenoids. Grouping the oocytes in two ranges of age (19–28 years old, and 29–33 years), we found that, in the oocytes from more advanced-age donors, carotenoids were present at a higher rate in their zonae (7/7, 100%) than in the oocytes from younger donors, in which only 16/34 (47.06%) showed carotenoids in the ZP (Fisher-test, P = 0.0123). The same oocytes were then evaluated by FTIR spectroscopy to analyse the three infrared regions corresponding to the vibrations of lipids, proteins, and polysaccharides. FTIR analysis of oocytes with and without carotenoids was not able to differentiate the two classes of oocytes based on the presence or absence of carotenoids. Moreover, these results indicate that live-cell imaging by Raman is a more sensible method for carotenoid detection than cell-destructive FTIR spectroscopy. Primarily, our results show, for the first time, the presence of carotenoids in the ZP of human oocytes. Their presence, previously reported in granulosa cells, follicular fluid, and plasma, was correlated with a higher success of oocyte maturation and fertilisation in animals and humans, and with high-quality embryo production in IVF programs. Our results indicate that oocytes from older donors (29–33 years) show a higher rate of carotenoid presence in comparison with younger donors. Altogether, the presence of carotenoids, known for their antioxidant activity, likely compensate oxidative stress characteristic for oocytes from aged donors. Our study shows that live-cell evaluation of chemical composition of oocytes is feasible, but more studies and more replicates are required to confirm our results and identify other chemical compounds distinctive of good-quality gametes helping to increase success rates in IVF programs.
This work was supported by the National Science Centre, Poland (GA no. 2019/35/B/NZ4/03547 and 2021/41/B/NZ3/03507).
