Intracytoplasmic sperm injection affects embryo developmental potential and gene expression in cattle

Area of Science:

• Reproductive biology
• Embryology
• Genetics

Background:

• Intracytoplasmic sperm injection (ICSI) has been associated with potential risks in embryo development, including chromosomal abnormalities and altered gene expression.
• Conflicting reports exist regarding the long-term effects and developmental potential of ICSI-generated embryos.
• Bovine embryos serve as a valuable model for studying assisted reproductive technologies.

Purpose of the Study:

• To compare embryo development, quality, and gene expression between bovine embryos produced via ICSI and conventional in vitro fertilization (IVF).
• To identify specific gene expression differences that may explain variations in developmental potential.

Main Methods:

• Bovine embryos were generated using ICSI and IVF techniques.
• Morphological assessment included cleavage rates, blastocyst formation rates, inner cell mass (ICM) proportion, total cell number, and apoptosis.
• Quantitative gene expression analysis was performed on selected genes involved in embryonic development and stress response.

Main Results:

• IVF embryos exhibited significantly higher cleavage (88.5% vs 64.1%) and blastocyst formation rates (36.1% vs 22.3%) compared to ICSI embryos.
• ICSI embryos had a higher proportion of ICM cells (39.2% vs 29.5%) but similar total cell numbers and apoptosis rates.
• Gene expression analysis revealed down-regulation of IGF2 and overexpression of BAX, OCT4, IFNt, SOD2, and CAT in ICSI embryos.

Conclusions:

• Significant differences exist in morphological development and gene expression patterns between bovine ICSI and IVF embryos.
• The observed alterations in gene expression and reduced developmental rates suggest a potentially lower developmental potential for ICSI-derived bovine embryos.
• Further research is warranted to elucidate the long-term implications of these findings for assisted reproductive technologies.