| Despite advances in in vitro manipulation of pre-implantation embryos, there is still a lag in the quality of embryos produced in vitro leading to lower pregnancy rates compared to embryos produced in vivo. Reducing the incidence of high-order multiple pregnancies while maintaining the overall in vitro fertilization (IVF) success rate is a holy grail of human IVF and would be greatly assisted by the ability to produce and identify the highest quality embryos. A promising new technology, microfluidics, does exist and is becoming increasingly studied. A challenge of studying embryo on microfluidic device is that preimplantation mouse embryos are highly sensitive cells and their development is affected greatly by osmolality shifts as will occur in devices with thin poly(dimethylsiloxane) (PDMS) membranes even in typical humidified cell culture incubators. Here we characterized and resolved evaporation mediated osmolality shifts that constrained microfluidic cell culture in Poly(dimethylsiloxane) devices. Next, we developed a dynamic microfunnel embryo culture system would enhance outcomes by better mimicking the fluid mechanical stimulation and chemical agitation embryos experience in vivo from ciliary currents and oviductal contractions. Using a mouse embryo model, average cell counts for blastocysts after 96 hours of culture in dynamic microfunnel conditions increased 70% over that of conventional static cultures. Importantly, the dynamic microfunnel cultures significantly improved embryo implantation and ongoing pregnancy rates over static culture to a level that approached that of in utero -derived preimplantation embryos. Lastly, we reported a new computerized microfluidic real time embryo culture and assay device that can perform automated periodic analyses of embryo metabolism over 24 hrs. Biochemical methods for embryo analysis based on measurement of metabolic rates do exist, but are not practical for clinical use because of difficulties in manipulating precise amounts of sample and reagents at the sub-microliter scale. The convenient, non-vasive, reliable, and automated nature of these assays open the way for development of practical single embryo biochemical analysis systems. Collectively, these results confirm that microfluidic technology can be used to properly mimic a broad range of the embryo environments seen in physiology and to assess embryo viability for in vitro fertilization clinics. |
