Effect of mesenchymal stem cells and mouse embryonic fibroblasts on the development of preimplantation mouse embryos.

Despite advances in assisted reproduction techniques, the poor quality and failures in embryo in vitro development remain as drawbacks resulting in low pregnancy rate. Mouse embryonic fibroblasts (MEFs) have been widely used to support embryonic stem cells. Mesenchymal cells (MSCs) have also been shown to release bioactive factors. In the present study, we have evaluated the ability of MSCs and MEFs to support early development of mouse embryos. The embryos were cultivated alone or in coculture with inactivated MSC or MEF for 4 d. After 4 d in culture, the percentage of blastocyst formation in coculture with MSC (91.7 ± 4.3%) or MEF (95.1 ± 3.3%) was higher than in the control group (72.2 ± 9.0%). We did not observe any difference in proliferation or apoptosis. However, the blastocysts cocultured with MSC or MEF presented a significantly higher number of cells within the inner cell mass per embryo when compared to the controls. The MSC and MEF groups presented also a higher cell number and diameter when compared to the control (CTRL). In summary, our data indicate that coculture with MSC or MEF improves early embryonic development and quality in vitro.