Improvement of Human Early Embryo Development in Vitro by Coculture on Monolayers of Vero Cells1

Abstract

Human "spare" embryos, judged unsuitable for freezing because of their poor quality, were cocultured for 5 days on a "Vero" cell layer. These epithelial cells were selected because kidney and genital tract have a common embryologic origin and "Vero" cells are a safe and highly controlled cellular support used for vaccine production. In the control group, the embryos were cultured in culture medium alone (B2 + 15% serum). At the end of the culture, the number of blastocysts was significantly higher in the coculture group: 61% vs. 3%. Moreover, at least half of the blastocysts were expanding and hatching (13/25), with a chronologically normal development. These observations suggest that (1) the coculture system improves human embryonic development; (2) it can rescue early degenerating embryos; (3) beneficial effects of coculture are not strictly genital-tract specific, but rather epithelium dependent. This coculture system could be used for in vitro fertilization to prolong in vitro culture and thus make it possible to transfer embryos at a more appropriate time, to eliminate early-blocked eggs, and to freeze embryos at the blastocyst stage, when freezing procedures are most successful.

Beneficial effects of Vero cells for developing IVF bovine eggs in two different coculture systems

“…However, the mechanism of this action is still unclear. It seems that the embryotrophic or embryo-regulating factors are neither oviduct specific, hormonedependent (Papaioannou and Ebert, 1986) nor species specific (Boland, 1984 (Ouhibi et al, 1990;Menezo et al, 1990;Voelkel and Hu, 1992;Myers et al, 1994;Reed et al, 1996) In our experiments the overall blastocyst yield in presence of Vero cells was higher than that obtained by Myers et al (1994). These authors reported a 30% blastocyst rate, but their rate is expressed as a ratio to cleaved eggs (2-4 cell) and not to inseminated oocytes as in our study.…”

Fertilization and early embryology: Differential effect of epithelial cell-conditioned medium fractions on preimplantation mouse embryo development

“…For example, Gandolfi and Moor (1987) showed that coculture with oviduct cells enhanced cleavage-stage sheep embryo development compared to culture medium without cells. A positive effect from coculture has also been shown by Menezo et al (1990) in human embryo development and by Ouhibi et al (1990) and Lai et al (1992) in mouse. At the same time, similar experiments using IVF bovine embryos in coculture with oviduct cells using TCM199 without FCS (Pinyopummintr and Bavister, 1991) failed to show any benefit from coculture.…”

“…In coculture with Vero cells, Menezo et al (1990) and Ouhibi et al (1990) observed beneficial effects of Vero cells on coculture of human embryos but not with 1 -cell mouse embryos. In contrast, Lai et al (1992) reported mouse embryo development from the 2-cell stage until the blastocyst stage using Vero cells.…”

Can we grow sperm? A translational perspective on the current animal and human spermatogenesis models

“…Vero cells are an immortalized cell line derived from kidney epithelial cells of the green monkey that are used in coculture because they are easy to grow, are embryologically similar to genital epithelial cells and remove toxic compounds from culture medium and act as 'feeder' cells by contributing trophic growth factors. 48 Cremades and colleagues 49 cocultured testicular biopsy samples from azoospermic men with Vero cells and reported in vitro maturation of round spermatids to elongated spermatids and mature sperm. However, modern experience with microsurgical testicular sperm extraction has shown that sperm is present in more than 50% of men with non-obstructive azoospermia.…”