>Last year, we read, and blogged about experiments by Drs. Kazutoshi Takahashi and Shinya Yamanaka of Kyoto University in Japan demonstrating that (adult) mouse fibroblasts could be reprogrammed to become embryonic stem cells in hopes of being able to one day develop truly “patient specific” stem cells made from the person’s own adult stem cells.
This summer four labs, including Yamanaka’s Kyoto University, a collaboration between Harvard and the University of California at Los Angeles, and a group at MIT, confirmed the technique as well as reporting on refined methods.
Now, Cell Stem Cell has published a free report from stem cell researchers Robert Blelloch, Monica Venere, Jonathan Yen, and Miguel Ramalho-Santos at the University of California at San Francisco, describing a simplified and improved technique to turn mouse fibroblasts into mouse embryonic stem cells.
Here’s an explanation of the significance of the new process, from ScienceDaily:
The UCSF team said their new finding should accelerate research aimed at improving the original strategy, as well as increasing its potential use for studying disease development and creating patient-specific stem-cell based therapies.
“The new technique removes a major technical hurdle that has likely discouraged many labs around the world from carrying out studies on the strategy,” said the study’s senior author Ramalho-Santos.
There are hurdles to overcome before human adult cells are reprogrammed and useful in the treatment of the donor’s diseases. From a news report in Nature, June 2007:
If it works, researchers could produce iPS [“induced pluripotent stem” LifeEthics] cells from patients with conditions such as Parkinson’s disease or diabetes and observe the molecular changes in the cells as they develop. This ‘disease in a dish’ would offer the chance to see how different environmental factors contribute to the condition, and to test the ability of drugs to check disease progression.
But the iPS cells aren’t perfect, and could not be used safely to make genetically matched cells for transplant in, for example, spinal-cord injuries. Yamanaka found that one of the factors seems to contribute to cancer in 20% of his chimaeric mice. He thinks this can be fixed, but the retroviruses used may themselves also cause mutations and cancer. “This is really dangerous. We would never transplant these into a patient,” says Jaenisch. In his view, research into embryonic stem cells made by cloning remains “absolutely essential”.
If the past year is anything to judge by, change will come quickly. “I’m not sure if it will be us, or Jaenisch, or someone else, but I expect some big success with humans in the next year,” says Yamanaka.
However, the very same hurdles face researchers who utilize human embryonic stem cells harvested from human embryos. The worries about tumors are inherent in research with embryonic stem cells. The reports from Texas researchers last March on lung cells derived from human embryonic stem cells described a method that was also dependent on infection with viruses in order to induce the desired cell type.
The difference is that reprogrammed adult cells from patients who ar to be treated would truly be “patient specific,” without the further hurdle of as-yet-unachieved human cloning. More importantly, they would not depend on the unethical creation and destruction of human embryos.