Innovative non-pump gravity driving microfluid culture chip enhance mouse blastocyst formation

Objectives: Various microfluidic technologies are currently used in ART. Herein we designed an innovative non-pump microfluidic culture platform to enhance the embryo culture in-vitro. We try to elucidate its feasibility and differences compared to traditional micro-drip culture systems. Materials and methods: We innovated a microfluidic chips with series procedures, including fabrication of an SU-8 master mould; casting of polydimethylsiloxane (PDMS) on mould; and integrating microfluidic device. All mouse embryos were divided: (1) traditional static drops; (2) microfluid static controls; (3) dynamic microfluid chip. We used the gravity plateform with tilt angle 15 degree to drive the culture medium through the whole microchannels. The cytotoxicity surveys of chip materials were performed with MTT assay. The embryo developments in each groups was compared. Results: The MTT surveys appeared the non-toxicity of PDMS chip materials. The percentages of 2 cell embryos reaching the stage of 4-8 cells, morula, and early blastocyst were comparable between both groups. In contrast, higher percentages of expanding blastocys and hatching blastocyst were observed in microfluid chip group. The percentages of 4-8 cells/morula/early/expanding/hatching blastocyst in each groups were 92.4/85.4/71.2/52.5/45.7%; 93.5/84.5/69.2/52.2/45.7%; and 93.8/86.5/74.5/67.2/60.4%, respectively. Conclusions: Combined microfluid and non-pump tilting culture system results in the dynamic stimulation of the embryos and automatic waste swept, which could not provided by traditional culture system. The tilting gravity instead of the motor driving system improves the convenience and feasibility for improving the embryo qualities of embryo culture in-vitro.