Early mammalian embryo development depends on cumulus removal technique

Area of Science:

• Reproductive Biology
• Developmental Biology
• Bioengineering

Background:

• Cumulus removal (CR) is a critical step in mammalian in vitro production (IVP) of embryos.
• Current CR methods, such as vortexing and pipetting, involve mechanical or enzymatic stress.
• These traditional methods may negatively impact zygote viability and subsequent embryonic development.

Purpose of the Study:

• To compare the efficacy of a novel microfluidic device for CR (microFCR) against traditional vortexing.
• To evaluate the impact of different vortexing durations on zygote development.
• To assess the biochemical activity of zygotes post-CR using an in situ transcription assay.

Main Methods:

• A newly developed microfluidic device was used for cumulus removal from zygotes.
• The microfluidic CR (microFCR) method was compared to traditional vortexing.
• An in situ transcription assay was employed to measure RNA transcription levels in zygotes.

Main Results:

• Microfluidic CR significantly increased development to Day 2 (35% vs. 20%) and blastocyst formation by Day 8 (57% vs. 33%) compared to vortexing (p < 0.01).
• Embryo development at Day 2 was inversely proportional to the duration of vortexing (15, 30, 120 s).
• Vortexed zygotes exhibited a transient spike in RNA transcription at 2 hours post-CR, which was not observed with microFCR.

Conclusions:

• Microfluidic CR is a more efficient method for cumulus removal in mammalian IVP, leading to improved embryo development.
• Traditional vortexing can negatively affect zygote development and biochemical activity, with effects increasing with exposure time.
• Microfluidic technology offers a promising alternative for enhancing IVP efficiencies and provides insights into early developmental mechanisms.