IGF-I Medium Supplementation Improves Singly Cultured Cat Oocyte Maturation and Embryo Development In Vitro

SIMPLE SUMMARY: Routine embryo production is the cornerstone for several research topics such as assisted reproduction techniques. For this, suitable culture media are needed to achieve satisfactory results, but the optimal culture medium is yet to be developed for felids. In this study, the supplementation of the medium with insulin-like growth factors (IGF-I, IGF-II) and granulocyte-macrophage colony-stimulating factor (GM-CSF) coordinated with other items related to in vitro procedures, such as type of fertilisation and type of culture, are analysed. Finally, the addition of IGF-I and GM-CSF to the culture medium improved embryo production in a single-culture system. The supplementation with IGF-I increased the maturation rate of feline oocytes, as well as the morula and blastocyst rates of embryos, independently of the fertilisation method used. As only a small number of oocytes can be retrieved from wild species, this conclusion may be of special relevance for protocols for endangered felids. ABSTRACT: Embryo production is a routine procedure in several species. However, in felids, the effectiveness of this approach is far behind that in the majority of laboratory species. The development of a suitable environment starts with the proper composition of culture media. Therefore, for the improvement of assisted reproduction techniques and their outcome in cats, this is an urgent task. As the addition of insulin-like growth factors (IGF-I, IGF-II) or granulocyte-macrophage colony-stimulating factor (GM-CSF) was beneficial in other mammalian species, this study aims to check whether these components, combined with other factors (such as type of fertilisation or type of culture) can provide a benefit in the felid culture system in current use. Thus, these supplements, in different concentrations and combinations, were merged with the use of two fertilisation techniques and randomly assigned to single or group culturing. The results showed that the addition of IGF-I and/or GM-CSF produced an increase in morula and blastocyst rate in a single culture system. In particular, the supplementation with 20 ng/mL of IGF-I incremented the maturation rate by 10% and significantly increased the morula and blastocyst rates in single culturing. This result is especially remarkable for wild felids, where only a few oocytes and/or embryos are available.