Viable offspring derived from single unfertilized mammalian oocytes.

Area of Science:

• Developmental Biology
• Epigenetics
• Mammalian Reproduction

Background:

• Mammalian reproduction typically requires the fusion of sperm and egg.
• Parthenogenesis, or development from an unfertilized egg, is limited in mammals due to genomic imprinting challenges.
• Genomic imprinting involves parent-specific epigenetic modifications crucial for normal development.

Purpose of the Study:

• To investigate the feasibility of generating live mammalian offspring from unfertilized oocytes.
• To overcome developmental barriers associated with parthenogenesis by targeting genomic imprinting.
• To demonstrate the efficacy of targeted epigenetic rewriting in enabling full-term development.

Main Methods:

• Utilized CRISPR-Cas9 technology with catalytically inactive Cas9 (dCas9) fused to DNA methyltransferase (Dnmt3a) or Cpf1 fused to Tet1.
• Co-injected messenger RNA (mRNA) and single-guide RNAs (sgRNAs) into unfertilized oocytes to target specific imprinting control regions.
• Induced targeted de novo methylation or demethylation at seven critical imprinting control regions.

Main Results:

• Successfully achieved targeted epigenetic rewriting of multiple imprinting control regions in parthenogenetic embryos.
• Edited regions maintained appropriate methylation patterns during early embryonic development.
• Modified parthenogenetic embryos showed significantly extended development and resulted in viable, full-term offspring upon transfer to foster mothers.

Conclusions:

• Targeted epigenetic rewriting of imprinting control regions can overcome developmental limitations in mammalian parthenogenesis.
• This study demonstrates the generation of live mammalian offspring from single, unfertilized oocytes.
• The findings highlight the potential of precise epigenetic editing to enable novel reproductive strategies.