A Landmark Study Reveals Critical Role of NANOG Gene in Human Embryo Development
A groundbreaking study led by developmental biologist Kathy Niakan from the University of Cambridge has confirmed the role of the NANOG gene in early human embryo development, revealing that its function differs from that observed in mice. The research, published in Nature, utilized base editing—a precise genome-editing technique—to disrupt the NANOG gene in normal human embryos and human embryonic stem cells. This marks the first use of base editing to study gene function in human embryos.
Key Findings
- With NANOG disabled, pluripotent epiblast cells could not transform into stem cells. These cells were redirected to form yolk sac or placental cells.
- The embryos prioritized the development of supporting structures (placenta and yolk sac) over the formation of the fetal body.
- Unlike in mice, NANOG was not essential for yolk sac development in humans.
"The result highlights the importance of studying human embryos directly, as animal models may not fully reflect human development." — Janet Rossant, Developmental Biologist, Hospital for Sick Children
Methodology
- Base editing was used instead of CRISPR/Cas9 knockout to replace a single DNA base. This method is considered less damaging to the genome and less likely to cause off-target effects.
- Embryos were donated from assisted conception or generated from donor gametes.
- The embryos were not allowed to develop beyond 14 days, in accordance with regulatory oversight from the UK Human Fertilisation and Embryology Authority (HFEA).
Expert Perspectives
- Dusko Ilic (Stem Cell Scientist, King's College London) noted that the study's immediate value is mechanistic, not clinical, and does not demonstrate safe embryo editing for clinical use.
- Robin Lovell-Badge (Developmental Biologist, Francis Crick Institute) stated that understanding early embryo development could help reduce distress related to infertility and pregnancy loss.
- Joy Zhang (Sociologist, University of Kent) noted that there has been little progress on deciding when gene editing of embryos would be acceptable.
- Alta Charo (Biotechnology Ethics Consultant) stated that base editing may be safer than CRISPR–Cas9 for disease prevention, but many safety hurdles remain, including the risk of mosaicism in embryos.