The Well-of-the-Well system: an efficient approach to improve embryo development

Abstract

Transfer of human embryos at the blastocyst stage may offer considerable benefits including an increased implantation rate and a decreased risk of multiple pregnancies; however, blastocyst culture requires an efficient and reliable in-vitro embryo culture system. In this study, the effect of the Well-of-the-Well (WOW) system consisting of microwells formed on the bottom of the culture dish was tested in three mammalian species, including humans. The WOW system resulted in significant improvement when comparing the drops for culture of in-vitro-matured and parthenogenetically activated porcine oocytes, and in-vivo-derived mouse zygotes. In human embryos, using a sibling oocyte design, embryos cultured in WOW developed to the blastocyst stage in a significantly higher proportion than did embryos cultured traditionally (55% in WOW and 37% in conventional culture; P < 0.05). In a separate study, also in human, a total of 48 patients with a cumulative 214 unsuccessful previous IVF cycles were selected for the trials. In subsequent intracytoplasmic sperm injection cycles, oocytes/embryos were cultured individually in the WOW system or in microdrops. Transferable quality blastocyst development (48.9% of cultured zygotes) was observed in the WOW system. Ninety-four blastocysts transferred to 45 patients resulted in clinical pregnancy rates of 48.9%, including nine twin pregnancies, seven single pregnancies, five miscarriages and one ectopic pregnancy. The results indicate that the WOW system provides a promising alternative for microdrop culture of mammalian embryos, including human embryos.

Effect of the microenvironment and embryo density on developmental characteristics and gene expression profile of bovine preimplantative embryos cultured in vitro

“…WOWs (semi-isolated microenvironments with 0.15-0.04 ml) on the bottom of a conventional four well dish provide a constant and suitable microenvironment for embryos and the open condition of the WOW system seems to be a good compromise between the controversial needs of large (nutrition and dilution of metabolized toxic products) and small (accumulation of autocrine and paracrine factors) volumes. Most recently, the WOW system has been used to culture human preimplantative embryos up to the blastocyst stage (Vajta et al 2008). Comparative studies on the effects of various embryo densities have generally focused on the percentage of embryos that proceed to the blastocyst or hatched blastocyst stages (Ferry et al 1994, Fujita et al 2006.…”

“…Moreover, studies examining the pattern of expression of important genes as a function of embryo culture in WOWs are still lacking. Although some pregnancies have been achieved after the transfer of human embryos derived from WOW culture (Vajta et al 2008), it is still unresolved whether the gene expression pattern of embryos culture in WOWs is affected by microenvironment and/or embryo density.…”

Effect of number of oocytes and embryos on in vitro oocyte maturation, fertilization and embryo development in bovine

“…The in vitro production (IVP) of bovine embryos using single or low numbers of oocytes and embryos during culture is increasing among researchers linked to the production of embryos from oocytes collected by ovum pick-up (OPU) (see Carolan et al, 1996;Vajta et al, 2000Vajta et al, , 2008Ward et al, 2000;Goovaerts et al, 2009).…”

Use of Silicone Elastomer-Based Microfluidic Devices and Systems in Reproductive Technologies

“…Within the last decade, studies using PDMS microfluidic channels or funnels have suggested novel solutions for oocyte manipulation, sperm sorting, and embryo culture . Microfluidic systems that mimic oviductal structures and functions for use in RT are divided into those used for sperm motility control or monitoring [50][51][52][53][54][55][56][57][58][59][60], regulation of chemical gradients for in vitro fertilization and embryo culture [61][62][63][64][65][66][67][68][69], and applying mechanical stimuli to the developing embryo [70][71][72][73][74]. Although the unique characteristics of elastomers have been exploited for microstructure fabrication and/or micro-pumping, mechanical deformation of the elastomer membrane has not been used to produce new devices for RT.…”

“…The well-of-the-well system (WOW) has been used successfully with embryos from a variety of species including mouse, pig, cow, and human and entails using small impressions, or microwells, of varying sizes and arrangements created in the bottom of a vessel/dish [8,61] ( Figure 6A). An alternate approach that permits a commercial means of utilizing microwells in conjunction with existing dishware in the lab involves using microwell-inserts consisting of several rows of tiny culture wells composed of PDMS [38].…”