A new class of lab-engineered stem cells that can transform into nearly all forms of tissue has been identified by researchers. These cells cluster together in “fuzzy-looking” colonies and have, therefore, been named F-class cells. Published in Nature and Nature Communications, the discovery has the potential of enabling more efficient methods of creating stem cells because it sheds new light on the process of cell reprogramming.
Pluripotent cells are of enormous value to medical researchers because of their extraordinary shape-shifting abilities. These cells make it possible for scientists to assess the effects of drugs and disease on human cells without experimenting on actual people, which is impossible. This has opened an all new flank in medical science called regenerative medicine, which seeks to restore lost or damaged organs and tissues.
Created using genetically engineered mouse cells, the F-class cells may not occur naturally outside the lab says senior author Andras Nagy, a stem cell researcher at Toronto’s Lunenfeld-Tanenbaum Research Institute of Mount Sinai Hospital. However, the discovery suggests that there may be other classes of pluripotent cells – or a spectrum of reprogrammed cells – yet to be discovered, authors say.
“We think that if we have time, and money and hands to do it, we might find additional novel cell lines,” Nagy said. Stem cells are currently obtained either from embryos or in labs through a painstaking process called induced pluripotency. The process uses a virus to alter an adult cell’s genetic information and returns it to a pliable, embryonic state. Pioneered by Dr Shinya Yamanaka this is an extremely inefficient process yielding embryonic-stem-cell-like cells just 1 per cent of the time.
Nagy and his colleagues began their work by examining the castoffs of that process, or the cells that did not look like embryonic stem cells. “Instead of ignoring or discarding these cells, we looked at them carefully on the hunch that we might find more than just one alternative cell type.” They were right. “Our effort yielded half a dozen cells very similar to each other, yet very different from the gold-standard embryonic-like cells. These F-cells were made differently than most induced pluripotent stem cells. The cell reprogramming process in these cells would occur only on exposure to the antibiotic doxycline. Otherwise they either turned into adult specialized cells or died, Nagy said. The newly discovered cells could reproduce quickly and were not “sticky”, Nagy said.
According to researchers it is highly possible that human cells too can be converted into F-class cells. “I think it’s inevitable that human F-class cells can be achieved in the near future through reprogramming,” said Juan Carlos Izpisua Belmonte, a developmental biologist at the Salk Institute for Biological Studies in La Jolla, California. “The next important step is to find culture condition(s) that can stabilise F-class state without transgene expression.”