Assisted hatching in mouse embryos using a noncontact Ho:YSGG laser system

Area of Science:

• Reproductive biology
• Laser technology
• Embryology

Background:

• Assisted hatching (AH) is a technique used in assisted reproductive technology (ART) to improve implantation rates.
• Conventional AH methods can be invasive and may impact embryo viability.
• Novel noncontact laser systems offer potential for more precise and less damaging embryo manipulation.

Purpose of the Study:

• To evaluate the effectiveness of a noncontact holmium:yttrium scandium gallium garnet (Ho:YSGG) laser system for assisted hatching in mammalian embryos.
• To assess the impact of Ho:YSGG laser assisted hatching (LAH) on embryo viability and hatching rates.
• To determine the safety and precision of Ho:YSGG laser for zona pellucida (ZP) drilling.

Main Methods:

• A Ho:YSGG laser system was designed and utilized for micromanipulation of two- to four-cell FVB mouse embryos.
• The laser system employed 250-microsecond pulses at a 2.1-micron wavelength and 4 Hz frequency for ZP removal.
• Embryos were cultured under standard conditions and in a blastocyst anti-hatching model using serum-free HTF medium.

Main Results:

• Laser assisted hatching (LAH) showed no significant difference in blastocyst production or hatching rates compared to conventional AH or control groups in the initial experiment.
• In a serum-free medium, LAH treatment did not affect blastocyst formation.
• LAH significantly increased hatching rates from 4% to 60% in the anti-hatching culture model compared to controls (P < 0.01).

Conclusions:

• The Ho:YSGG laser system is effective for assisted hatching in mouse embryos.
• The laser system exhibits nontoxic properties and is suitable for precise zona pellucida drilling.
• Ho:YSGG laser assisted hatching presents a viable, noncontact alternative for improving embryo hatching rates.