Creating primordial germ cells using human embryonic stem cells. In collaboration with the Weizmann Institute in Rehovot, Israel, scientists from the University of Cambridge, UK have successfully created primordial germ cells (PGCs) using human embryonic stem cells. These cells have the potential to develop into eggs and sperm, marking a significant milestone in reproductive biology.
Unlike previous experiments using rodent stem cells. This study, published in the journal Cell, is the first to generate PGCs from human stem cells efficiently.
When a sperm fertilizes an egg, it begins dividing. It forms a cluster of cells known as blastocysts. This is the early stage of the embryo. Within this cell cluster, some cells form the inner cell mass. This will develop into the fetus. Others create the outer wall that becomes the placenta. The inner cell mass cells reset to become stem cells, which can differentiate into any cell type in the body.
Germ Cells and Genetic Information Transmission
A small subset of these cells transforms into PGCs. These can further develop into germ cells, like sperm and eggs. They pass genetic information to future generations.
“The creation of primordial germ cells is one of the earliest events during mammalian development,” says Dr. Naoko Irie, lead author of the study from the Wellcome Trust/Cancer Research UK Gurdon Institute at the University of Cambridge. “While we’ve replicated this process using mouse and rat stem cells, few studies have systematically achieved this with human stem cells, revealing critical differences between human and rodent embryonic development.”
Key Findings: The Role of SOX17 in Human PGC Specification
Professor Surani from the Gurdon Institute, UK, who led the research, and his team identified that a gene known as SOX17 is essential for guiding human stem cells to become PGCs, a process termed “specification.” Researchers did not expect this discovery, as the equivalent gene in mice does not play a role in this process, highlighting a crucial difference between mouse and human development.
Previously, researchers knew that SOX17 directs stem cells to become endodermal cells, which later differentiate into lung, intestine, and pancreas cells. This study is the first to observe SOX17’s involvement in PGC specification.
Understanding Epigenetic Inheritance
The team also demonstrated that reprogrammed adult cells, such as skin cells, could generate PGCs. This advancement could enhance research on patient-specific germline cells, including studies on infertility and germ-cell tumors.
The research has significant implications for understanding epigenetic inheritance. Scientists have long known that environmental factors, such as diet or smoking, can affect our genes through methylation, where molecules attach to DNA, regulating gene activity. Parents can pass these methylation patterns to their offspring.
Professor Surani and colleagues showed that during PGC specification, a process begins. It erases these methylation patterns, acting as a “reset” switch. However, some traces of these patterns may be inherited, the reasons for which remain unclear.
“Germ cells are ‘immortal’ in providing a continuous link across generations, carrying genetic information from one generation to the next. The complete erasure of epigenetic information ensures most epigenetic mutations are removed. This promotes the ‘rejuvenation’ of the lineage, allowing endless generations,” concludes Professor Surani. Understanding these mechanisms is crucial for studying age-related diseases, potentially linked to the accumulation of epigenetic mutations.
The NIH provides extensive resources on stem cell research and its applications in regenerative medicine.
National Institutes of Health (NIH)
Finally, to learn more about Stem Cells, read our article What Are Stem Cells?
