Differentiation Potential of Human Wharton's Jelly-Derived Mesenchymal Stem Cells and Paracrine Signaling Interaction Contribute to Improve the In Vitro Maturation of Mouse Cumulus Oocyte Complexes

In vitro maturation (IVM) in cumulus oocyte complexes (COCs) can be improved by the presence of human Wharton's jelly-derived MSCs (hWJ-MSCs), under specific culture conditions. COCs were cultured in twelve different culture systems, composed of four stock media, stock media conditioned with hWJ-MSCs, and stock media in which the oocytes were indirectly cocultured with the hWJ-MSCs. The rates of maturation to meiosis II were compared among the groups. G2-PLUS and coculture with DMEM-F12 were the most efficient systems for the maturation of COCs. The fertilization rate and rate of development to the blastocyst stage were compared between these two groups. Moreover, hWJ-MSC-conditioned media showed no benefits for the COC-IVM. The analysis of OCT4 expression of hWJ-MSCs in G1-PLUS, TYH, and G2-PLUS showed a downregulation of OCT4 by 25.9, 24.7, and 6.6%, respectively, compared to that in hWJ-MSCs cultured in DMEM-F12. Finally, we have demonstrated that two prerequisites appeared to be necessary for the hWJ-MSCs to improve the IVM of COCs: hWJ-MSCs' differentiation potential and the presence of coordinated paracrine interaction between the stem cells and COCs. Under the appropriate conditions, the paracrine factors produced in the coculture system with DMEM-F12 may help to develop synthetic media for successful in vitro culture of COCs.