A team of scientists has identified a 'master gene' named NANOG, which is crucial for initiating the intricate process of human embryonic development. This landmark discovery, made by precisely altering the DNA of fertilised eggs using CRISPR base editing, sheds new light on the earliest stages of human life and holds significant implications for fertility treatments and regenerative medicine.
The research, conducted at the University of Cambridge, focused on understanding how a fertilised egg’s cells differentiate into the various components of an early embryo. While animal studies had previously suggested NANOG's role in embryonic development, this new work reveals a distinct and critical function in humans. In human eggs, disabling NANOG prevented cells from developing into the embryo itself, indicating its activation is the fundamental trigger for forming a human body. This contrasts with experiments in mice, where disabling NANOG affected the formation of the yolk sac, not the embryo.
Dr Kathy Niakan at the University of Cambridge highlighted the potential impact of this finding. She explained that a better understanding of these early developmental stages is profoundly important for stem cell biology. Improved knowledge could significantly advance stem cell research and regenerative medicine, potentially transforming treatments for a wide range of conditions. The precision of CRISPR base editing, which alters a single DNA letter at a time, was crucial for this discovery, reducing the likelihood of unintended chromosomal abnormalities that can occur with earlier CRISPR methods.
The discovery also has immediate relevance for In Vitro Fertilisation (IVF) treatments. Currently, the selection of embryos for implantation often relies heavily on their visible shape under a microscope. However, Dr Niakan noted that approximately half of embryos that appear to be developing well externally may still fail to implant. By identifying key markers or genes like NANOG, this new knowledge could help improve IVF success rates by providing more precise indicators of an embryo's developmental potential.
While this research marks a significant step forward, experts caution against immediate applications for gene-edited children. Dr Mary Herbert from Monash University, part of Dr Niakan’s team, emphasised that the technology is not yet ready for such uses, citing challenges like mosaicism, where only some cells in an embryo are successfully edited. However, the study reinforces the potential of CRISPR base editing as a safer tool for studying gene function in human embryos compared to older, less precise methods.