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bioRxiv · 10.1101/2022.11.09.514870

Effects of lactate, super-GDF9 and low oxygen tension during biphasic in vitro maturation on the bioenergetic profiles of mouse cumulus-oocyte-complex

Akin, N.·Ates, G.·von Mengden, L.·Herta, A.-C.·Meriggioli, C.·Billooye, K.·Stocker, W. A.·Ghesquiere, B.·Harrison, C. A.·Klamt, F.·Massie, A.·Smitz, J.·Anckaert, E.
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Abstract

In vitro maturation (IVM) is an alternative assisted reproductive technology (ART) with reduced hormone related side-effects and treatment burden compared to conventional IVF. Capacitation (CAPA)-IVM is a biphasic IVM system with improved clinical outcomes compared to standard monophasic IVM. Yet, CAPA-IVM efficiency compared to conventional IVF is still suboptimal in terms of producing utilizable blastocysts. Previously we have shown that CAPA-IVM leads to a precocious increase in cumulus cell (CC) glycolytic activity during cytoplasmic maturation. In the current study, considering the fundamental importance of CCs for oocyte maturation and cumulus-oocyte complex (COC) microenvironment, we further analyzed the bioenergetic profiles of maturing CAPA-IVM COCs. Through a multi-step approach, we (i) explored mitochondrial function of the in vivo and CAPA-IVM matured COCs through real-time metabolic analysis with Seahorse analyzer; and to improve COC metabolism (ii) supplemented the culture media with lactate and/or super-GDF9 (an engineered form of growth differentiation factor 9) and (iii) reduced culture oxygen tension. Our results indicated that the pre-IVM step is delicate and prone to culture related disruptions. Lactate and/or super-GDF9 supplementations failed to eliminate pre-IVM induced stress on COC glucose metabolism and mitochondrial respiration. However, when performing pre-IVM culture under 5% oxygen tension, CAPA-IVM COCs showed a similar bioenergetic profiles compared to in vivo matured counterparts. This is the first study providing real-time metabolic analysis of the COCs from a biphasic IVM system. The currently used analytical approach provides the quantitative measures and the rational basis to further improve IVM culture requirements.

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Akin, N., Ates, G., von Mengden, L., Herta, A.-C., Meriggioli, C., Billooye, K., Stocker, W. A., Ghesquiere, B., Harrison, C. A., Klamt, F., Massie, A., Smitz, J., Anckaert, E.. 2022-11-10. Effects of lactate, super-GDF9 and low oxygen tension during biphasic in vitro maturation on the bioenergetic profiles of mouse cumulus-oocyte-complex. https://doi.org/10.1101/2022.11.09.514870

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