In Vitro Fertilization on a Single-Oocyte Positioning System Integrated with Motile Sperm Selection and Early Embryo Development

TLDR

In vitro fertilization has been widely used to treat infertility, yet its physical tools have remained largely unchanged until recent microfluidic advances. The study introduces a microdevice that integrates oocyte positioning, sperm selection, fertilization, medium replacement, and embryo culture into a single platform. The device uses a 4 × 4 octacolumn array with symmetrical channels that position single oocytes, select motile sperm, enable rapid medium exchange, and allow microscopic tracking and fluorescent staining of fertilization and early development. Sperm motility rose from 60.8 % to 96.1 %, while embryo growth and blastocyst rates matched conventional Petri dishes, and healthy blastocysts could be retrieved by simple pipetting for transfer.

Abstract

In vitro fertilization (IVF) technology has been broadly applied to solve human infertility in recent years. However, the physical tools for IVF remain unchanged over several decades before microfluidic technology was introduced in this field. Here, we report a novel microdevice that integrates each step of IVF, including oocyte positioning, sperm screening, fertilization, medium replacement, and embryo culture. Oocytes can be singly positioned in a 4 × 4 array of octacolumn units. The four symmetrical straight channels, crossing at the oocyte positioning region, allowed efficient motile sperm selection and facilitated rapid medium replacement. The fertilization process and early embryonic development of the individual zygote was traced with microscopic recording and analyzed by in situ fluorescent staining. The murine sperm motility was increased from 60.8 ± 3.4% to 96.1 ± 1.9% through the screening channels. The embryo growth rate and blastocyst formation were similar between the routine Petri dish group and the microdevice group. The healthy blastocysts developed in the microdevice could be conveniently retrieved through a routine pipetting operation and used for further embryo transfer.