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

Abstract

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.

Figure 1

Comparison of IVM for COCs cultured in the same media: DMEM-F12 (a), G1-PLUS (b), G2-PLUS (c), and TYH (d). The data were analyzed by the chi-squared test. A value of P < 0.05 was considered statistically significant.

Figure 2

qPCR analysis of OCT4 in hWJ-MSCs cultured under the 4 coculture conditions. In G1-PLUS, TYH, and G2-PLUS, OCT4 expression was downregulated to 25.9, 24.7, and 6.6%, respectively, compared to the OCT4 level in hWJ-MSCs cultured in DMEM-F12. The expression of OCT4 from hWJ-MSCs was not affected by the presence of COCs when cultured in DMEM-F12 (control group). The data was analyzed with the two-tailed paired Student's t-test. A P value < 0.05 was considered to indicate statistical significance. ^∗∗(P < 0.01) is the statistical significance compared with coculture-DMEM-F12.