Ding, of the Gladstone Institutes, said his work builds on the cell-reprogramming work of another Gladstone scientist, Senior Investigator Shinya Yamanaka, MD, PhD. Yamanaka's 2006 discovery of a way to turn adult skin cells into cells that act like embryonic stem cells has advanced the fields of cell biology and stem-cell research.
Embryonic stem cells are "pluripotent" cells that can develop into any type of cell in the human body and have been touted for their potential in regenerative medicine but their use has been controversial and limited since Pres. Bill Clinton signed a law placing funding restrictions on their use in federal research in 1996. Some of the restrictions, allowing leftover embryos from in vitro fertilization to be used in research, were recently overturned in courts.
Yamanaka's discovery of an alternate way to obtain human stem cells, without the use of embryos, was important because it bypassed cultural issues and kept research moving. The Gladstone Institutes exist in similar fashion, being outside academia or the corporate world and were instead a creation of J. David Gladstone, a Los Angeles real estate entrepreneur who left his estate almost entirely for medical education and research.
"This work could have important ramifications for patients and families who suffer at the hands of neurodegenerative diseases such Alzheimer's, Parkinson's and Huntington's disease," said Lennart Mucke, MD, who directs neurological research at Gladstone. "Dr. Ding's latest research offers new hope for the process of developing medications for these diseases, as well as for the possibility of cell-replacement therapy to reduce the trauma of millions of people affected by these devastating and irreversible conditions."
Ding's work extends Yamanaka's by offering still another method for avoiding the use of embryonic stem cells and creating an entirely new platform for fundamental studies of human disease.
Rather than using models made in yeast, flies or mice for disease research, all cell-reprogramming technology allows human brain, heart and other cells to be created from the skin cells of patients with a specific disease. The new cells created from the skin cells contain a complete set of the genes that resulted in that disease—representing the potential of a far-superior human model for studying illnesses, drugs and other treatments. In the future, such reprogrammed skin cells could be used to test both drug safety and efficacy for an individual patient with, for example, Alzheimer's disease.
In the experiments reported today in Cell Stem Cell, Ding used two genes and a microRNA to convert a skin sample from a 55-year-old woman directly into brain cells. MicroRNAs are tiny strands of genetic material that regulate almost every process in every cell of the body. The cells created by Ding's experiments exchanged the electrical impulses necessary for brain cells to communicate things such as thoughts and emotions. Using microRNA to reprogram cells is a safer and more efficient way than using the more common gene-modification approach. In ensuing experiments, Ding hopes to rely only on microRNAs and pharmaceutical compounds to convert skin cells to brain cells, which should lead to more efficient generation of cells for testing and regenerative purposes.
The work was done in collaboration with Stuart Lipton, M.D., Ph.D., who directs the Del E. Webb Neuroscience, Aging and Stem Cell Research Center at Sanford-Burnham Medical Research Institute. "This technology should allow us to very rapidly model neurodegenerative diseases in a dish by making nerve cells from individual patients in just a matter of days—rather than the months required previously," said Lipton.
"This will help us avoid any genome modifications," said Ding. "These cells are not ready yet for transplantation. But this work removes some of the major technical hurdles to using reprogrammed cells to create transplant-ready cells for a host of diseases."
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