ABy Lee Billings University research team has discovered new properties of adult stem cells that could eventually treat neurological diseases such as multiple sclerosis, Huntington’s disease, Parkinson’s disease and Alzheimer’s disease.
Their findings are published in the April 25 edition of Cell Transplantation.
Dubbed multipotent adult progenitor cells, these rare stem cells are responsible for producing new cells that have a particular body function, such as generating red or white blood cells.
Though still shrouded in mystery, these cells appear perhaps more useful and less controversial than embryonic stem cells, the only other stem cell variety known to generate all types of brain cells.
“One of the problems with embryonic stem cells is, when you transplant them, they often have a tendency to form teratomas – uncontrolled growths of cells that develop into teeth, cartilage or hair, for example,” said Walter C. Low, a University neurosurgery professor and the study’s principal investigator. “This is something we would not want to see if we put stem cells into the brain.”
Scientists are uncertain of the full capabilities of multipotent adult progenitor cells. Discovered only last year in Dr. Catherine Verfaillie’s University lab, the cells’ role in the body is unknown. Extremely rare – on the order of one in every 1 million bone marrow cells – they require complicated in vitro growth techniques that are still being refined.
There is also an ethical concern with human embryonic stem cells.
Since they come from human embryos, human embryonic stem cell use is restricted in most countries. Multipotent adult progenitor cells have no similar restrictions.
Researchers are already planning tests of the multipotent adult progenitor cells in mice and rats with neurological disorders, with initial results less than a year away. But other questions about the cells’ experimental performance are not as close to being answered.
Typical research requires cell injections with approximately 200 to 400 cells, said Dirk Keene, a University Medical School doctoral student and the study’s lead author.
“You think about it, you put one cell into 200, and you’d think one out of every 200 would be stem cells, but in the neurons it was a much higher ratio. We’ve been asking, ‘Why could this be?’ “
Study co-author Dr. David Largaespada, a University professor of genetics, cell biology and development, agreed that much work lies ahead for researchers.
“A lot of basic biology remains to be performed on these cells,” he said.
Scientists at the University and around the country are rising to the challenge.
“The ultimate goal for all of us is twofold,” Keene said. “One is to develop a better understanding of biological systems; the other is, through this better understanding, to help people get better.”
In the University’s most recent experiment, researchers injected a single adult stem cell into early mouse embryos and allowed them to mature.
From days to weeks after birth, the mice were killed and examined. Based on earlier experiments, researchers expected to find new cells created by single stem cells throughout the mice. But most researchers were surprised when they examined the animals’ brains.
“It was expected to find the cells there – it was unexpected in the numbers that we found and how diverse they were,” Keene said. “They were throughout the entire brain and fully incorporated as far as we could tell.”
The transplanted stem cells produced not only neurons, the brain’s primary communication cells, but also brain tissue cells and myelin-forming cells.
Myelin insulates nerves, allowing the conduction of impulses from one part of the body to another.
“These adult stem cells have the capability of developing into essentially all of the cells one finds in the mammalian brain,” Low said. “We might be able to use them to form myelin-forming cells for patients with MS. We might be able to treat patients with Lou Gehrig’s or maybe even Parkinson’s patients.”
But, like all potential medical treatments, this revelation is only the first step in the long trek between discovery and application. In the past, many promising results have failed in later stages of testing.
“This was done with a very early embryo, before it is even planted in the uterus, so you can’t say it will work in the clinical environment,” said study co-author Xilma Ortiz-Gonzalez, a professional school fellow in the neurosurgery lab. “You’ll never get the chance to do it with a person at that point.”
“We can’t say anything about the efficacy of these cells in an actual treatment, and that’s the next step of experimentation,” Keene said. “All we’re showing is that they have this potential.”
Lee Billings covers faculty and staff affairs and welcomes comments at [email protected]