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Simple Separation of Good Quality Bovine Oocytes Using a Microfluidic Device

Penelitian - Researchers of the National Institute of Advanced Industrial Science and Technology in Japan performed IVF after the microfluidic separation of oocytes, the developmental rate to blastocysts of oocytes collected from the lower outlet was significantly higher than those collected from the upper outlet.

Success of in vitro fertilization (IVF) depends highly on quality of oocytes. The oocyte quality has been evaluated based on morphological observations and the degree of adhesion of the cumulus cells. However, it is difficult to distinguish between good and fair quality oocytes and assigned based on the personal judgments.

Penelitian Simple Separation of Good Quality Bovine Oocytes Using a Microfluidic Device

Therefore, it is necessary to develop a new sorting technique that can efficiently separate good and poor quality oocytes. Brilliant cresyl blue (BCB) staining is one oocyte selection method. Oocytes stained by BCB show better quality in manipulation than unstained oocytes.

In addition, some recent studies do not recommend use of BCB stain for oocyte selection because of DNA damage, chromosomal abnormality, cleavage, and apoptosis of oocytes caused by BCB staining. In contrast, the speed of sedimentation of cumulus-oocyte complexes (COCs) and denuded oocytes in hypertonic solution correlated with the morphological quality of COCs.

The sedimentation method could be a useful method to objectively select good quality oocytes. With this method, non-toxic solutions should be used to separate oocytes. Sucrose solution is one of the ideal separation solution candidates because of its attributes, such as non-damaging to oocytes and ease in controlling the solution density.

Previous researchers demonstrated that one hour exposure to 0.3 M sucrose in PBS containing 20% bovine fetal serum was harmless to the parthenogenetic development of bovine oocytes. Therefore, Masaya Miyazaki of the National Institute of Advanced Industrial Science and Technology and tema used a sucrose solution as a hypertonic solution.

Several newly developed high-throughput cell and particle sorting techniques have used microfluidic devices in the past few decades. The microfluidic devices have various advantages, including easy fabrication and low cost. Fabricated a robot-integrated microfluidic chip that can introduce and transport oocytes, measure their mechanical characteristics, and collect them automatically.

This method simplified evaluation of the mechanical characteristics of oocytes using an automated system, however, it lost the advantages of simple and low-cost fabrication of a microfluidic device because it requires a microelectromechanical system device and a control unit.

“We applied this previous technique to separate good quality oocytes based on differences in the sedimentation rate. Further, we validated the separation quality by estimating the developmental competence of separated oocytes after IVF,” Miyazaki said.

Miyazaki have previously developed a density-based separation technique using a microfluidic device. This method is based on sink-float separation of particles. Relative to the buffered solution, particles with a lower density floated while particles with a higher density sank. The density of the buffer was controlled by the sucrose concentration.

Journal : Wataru Iwasaki et al. Simple separation of good quality bovine oocytes using a microfluidic device, Scientific Reports, 24 September 2018, DOI:10.1038/s41598-018-32687-6



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