Stem Cell Research Races Toward the Clinic
WebMD News Archive
There are, in fact, many different types of stem cells, representing various stages of cells taken from different parts of the body. Embryonic stem cells used in research are derived from embryos generated for the purpose of in vitro fertilization but never implanted. Although these embryos, more than 100,000 of which are currently in cold storage, are usually discarded, many anti-abortion rights activists are opposed to their use for scientific research, even when the ultimate goal is compassionate medical research.
In addition to embryonic stem cells, there are other types of stem cells that are derived from cells that have moved partway down the path to becoming a specific type of tissue, such as blood vessels, organs, or nerve cells.
As Black and colleagues show, they have been able to take stem cells from the bone marrow of adult rats and humans -- cells that are normally fated to grow into blood vessels and similar tissues -- and with a little manipulation in the laboratory convince them to turn into nerve cells instead. As if that trick weren't impressive enough, they've managed to do it in a matter of minutes or hours, rather than days or weeks as one might reasonably expect.
"There are a number of remarkable potential advantages," Black tells WebMD. "The cells grow remarkably quickly in culture, so that with a single bone marrow [collection] we can obtain a virtually limitless supply of cells. In addition, the accessibility certainly obviates the need to go into the brain ... [and] then obtain neural stem cells from deep within the cerebral hemisphere."
Not to be outdone, Fred H. Gage, PhD, and colleagues from the Salk Institute, Children's Hospital of Orange County and Stanford University, all in California, report that they were able to snatch adult rat and human nervous system stem cells from the jaws of death, get them to multiply, and turn into nerve cells -- even when the donor had been dead for more than 20 hours.
"We were able to induce some of the cells taken from the brains of cadavers to turn into neurons. The research shows that the tissue could be a new, noncontroversial source of human neural cells for transplantation and experimentation," says Gage in a written statement.
Researchers at the National Institute for Neurological Diseases and Stroke (NINDS) have also found it surprisingly easy to get nerve stem cells to do you what you want them to do. Ronald D. G. McKay, PhD, chief of the laboratory of molecular biology at NINDS and colleagues have been able to direct stem cells from mouse embryos to turn into one of two types of brain cells that are essential for normal function.
One type of cell they have been able to grow produces dopamine, a chemical that helps to control body movement and is largely absent in the brains of people with Parkinson's disease. The other type of cell produces serotonin, a hormone that helps to control mood; clinical depression can be caused by a defect in how the brain stores and uses serotonin.