After many years of failed attempts, scientists finally moved a step closer to generating stem cells that perfectly match to a patient’s DNA to treat diseases, as a team of researches announced on Thursday, they have created patient-specific cell lines out of the skin cells of two adult men.
The scientific work, first published online in the journal Cell Stem Cell, is the first time researchers have achieved “therapeutic cloning” of adults. Using the cloning technique that produced Dolly the sheep in 1996, researchers were able to turn human skin cells, taken from two men, one aged 35, the other the 75-year-old, into stem cells, which can grow into any type of tissue in the body.
The current work is based on a research conducted 11 months ago by researchers from the Research Institute for Stem Cell Research at CHA Health Systems in Los Angeles and the University of Seoul, who claimed they had produced the world’s first human embryo clones and used them to make stem cells.
“Our finding offers new ways of generating stem cells for patients with dysfunctional or damaged tissues and organs,” said Shoukhrat Mitalipov at Oregon Health and Science University. “Such stem cells can regenerate and replace those damaged cells and tissues and alleviate diseases that affect millions of people.”
The process used to create cloned embryos is called somatic cell nuclear transfer, or SCNT. It involves removing the nucleus from an egg cell and replacing it with a nucleus from a cell of the person to be cloned.
“The proportion of diseases you can treat with [lab-made tissue] increases with age. So if you can’t do this with adult cells, it is of limited value,” said Robert Lanza, co-author of the study and chief scientific officer at Advanced Cell Technology Inc. of Marlborough, Mass.
Lanza’s colleagues, including Young Gie Chung at the CHA Stem Cell Institute in Seoul, Korea, injected skin cells into 77 human egg cells, and from all those attempts, managed to create two viable cells that contained DNA from one or the other man. Each of those two cells is able to divide indefinitely, “so from a small vial of those cells we could grow up as many cells as we would ever want,” Lanza says.
“I’m happy to hear that our experiment was verified and shown to be genuine,” said Shoukhrat Mitalipov, a development biologist at Oregon Health and Science University, in Portland, Ore., who led the 2013 study that Dr. Lanza and his colleagues have now replicated.
However, some consider such practices to be controversial because when cells are extracted from an early-stage human embryo, it destroys the embryo, which some people believe is equivalent to taking a life. In 2005, the United Nations called on countries to ban it, and the United States prohibits the use of federal funds for either reproductive or therapeutic cloning.
Paul Knoepfler, an associate professor at the University of California at Davis who studies stem cells, called the new research “exciting, important, and technically convincing.”
“In theory you could use those stem cells to produce almost any kind of cell and give it back to a person as a therapy,” he said.
Nuclear transfer, however, could treat such disorders like diabetes, Alzheimer’s or Parkinson’s disease since it involves an egg that provides its own, healthy mitochondria. If each stem-cell line has to be created from scratch for each patient, the low success and expected high costs means that “only a few wealthy old men could do it,” said Lanza. At the same time the process requires a good supply of eggs, which have to be donated by healthy volunteers and very few women want to donate eggs, as sometimes it is a rather painful process.