EuroStemCell researchers at the Pasteur Institute in Paris used sophisticated techniques, including video imaging, to record how stem cells could avoid mutations during cell division. This is the best visual evidence for a hypothesis that ‘immortal' DNA would remain unchanged while all around mutate.
Cell division is the biological basis for life, the process through which organisms grow and reproduce, and renew and repair themselves. When cells divide in two, their DNA is duplicated and each daughter cell gets a copy – this is how genetic information is carried through the generations – and errors in duplication can lead to mutations and cause cancers.
|Muscle stem cells in culture: 'immortal' DNA (green) is seen in only one daughter cell.|
Stem cells are a vital part of an organism's repair system with immense therapeutic potential. They can undergo ‘asymmetric division' to produce another stem cell and a specialised cell that contributes to tissue regeneration in the parent organism. The ‘immortal DNA hypothesis' proposes that when stem cells divide the daughter stem cell retains the original DNA strands, and the daughter specialised-cells get the DNA copy. In this situation, only the specialised cells are open to mutation, while the stem cells avoid it and always remain the same – immortal thus.
“The immortal DNA theory has captured the imagination of many scientists for decades, but it has been particularly difficult to prove,” said Shahragim Tajbakhsh, leader of the Pasteur Institute research team and a partner in the EU-funded EuroStemCell project.
The EuroStemCell project is building the scientific foundations to take stem cell research into clinical applications. As part of this research, the team at the Pasteur Institute tracked muscle stem cells from mice with sophisticated techniques, including video imaging, to show that stem cells do in fact retain their original DNA strands.
“This is an exciting finding,” says Tajbakhsh, “it seems to defy one of the basic rules of cell biology and genetics: that genetic material is distributed randomly. It appears that the cellular machinery distinguishes old from new when it comes to DNA and it may thus use this distinction to protect the body from mutations and cancer.” This finding has important implications for cell biology and cancer research.
This is another success for the ‘camera happy' EuroStemCell team whose short film ‘A Stem Cell Story' took top honours at a recent science media festival held in Norway, beating off strong competition from European broadcasters in the process.
Nature Cell Biology