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Adult stem cells can produce brain cells, study shows
ED EDELSON
Asbury Park Press - 03/29/05 - Experiments involving chicken eggs may have hatched a major advance in stem cell research, as investigators watched adult human stem cells develop into functioning brain cells.
Experts hope that, someday, adult stem cells from a patient's own bone marrow might be used to regrow and replace brain or spinal cord cells lost to injury or disease. That goal had been elusive, however, because adult stem cells have failed to produce significant amounts of neurons.
Until now, that is.
"We found that bone marrow stem cells did make neurons in the environment of the regenerating embryonic (chick) spinal cord," said senior researcher Joel C. Glover, of the Institute of Basic Medical Science at the University of Oslo, in Norway.
"This happened at a much higher rate than had been observed in any other experimental system," he added.
The key to the success of this model lies in as-yet-unidentified compounds within the quickly developing "microenvironment" of the embryonic spinal cord, said Paul Sanberg, a professor of neurosurgery and director of the University of South Florida's Center for Aging and Brain Repair.
Sanberg says that if scientists can identify those compounds, they might then be able to use them as a kind of cellular fertilizer — encouraging adult stem cells to generate into human neurons.
"This study really shows that the microenvironment a stem cell is placed in is really very critical for defining how that stem cell will work," he said.
According to Glover, his team knew that "the spinal cord of the chicken embryo could regenerate rapidly after an injury, to make many new neurons." So he wondered if, "perhaps the same environment might stimulate (human) bone marrow stem cells to make neurons?"
The Norwegian group tested that theory using fertilized chicken eggs. They first caused injury to the embryo's developing spinal cord. Then they introduced adult stem cells from human bone marrow into the affected area.
Not only did these stem cells quickly develop into neurons to repair the site of injury, "we were able to show for the first time that these neurons were really functional," Glover said.
"They had the right shape, they could generate nerve impulses, and they received contacts from other neurons," he said.
The next step, according to Glover, will be experiments aimed at identifying exactly which compounds within this microenvironment are pushing adult stem cells to turn into neurons.
Hysterectomy, heart disease link
A woman who has a hysterectomy is more vulnerable to heart disease, stroke and other cardiovascular problems, a new study finds — but the hysterectomy is not to blame.
Instead, say researchers reporting in the March 22 issue of Circulation, women who have hysterectomies are also more likely to have the classic risk factors for cardiovascular trouble such as obesity, high blood pressure, high cholesterol, diabetes and smoking.
"We found that they had higher levels of most risk factors than women who did not have hysterectomies, (but) if you adjust for those risk factors, there is no increased risk associated with a hysterectomy," said lead researcher Barbara V. Howard, president of the MedStar Research Institute, in Baltimore.
"We started this study because of our knowledge about hormone levels influencing cardiovascular risk," Howard explained, so "it was conceivable that having a hysterectomy put a woman at higher risk."
According to the study, more than 41 percent of the women had undergone hysterectomies. The overall risk for cardiovascular disease in women with a history of this type of surgery was 26 percent higher than for women who had never had their uterus removed.
There's a strong socioeconomic influence on the prevalence of all of those cardiovascular disease risk factors, Howard added. Women who had hysterectomies tended to be in lower-income groups, and black women, Native Americans and Hispanic women were more likely to have had the surgery than whites.
Confusion persists about painkillers
Following months of public wrangling over the safety of cox-2 inhibitors and even with a federal advisory panel's endorsement to keep them on the market, consumers are still as confused as ever about these powerful painkillers.
Recent surveys show many have cut back or stopped taking the medications because they're uncertain whether the heart risks seen with these drugs are outweighed by the benefits.
Separately, Boston's Rippe Lifestyle Institute released survey results showing that close to half the arthritis patients they questioned have stopped or cut back the use of pain relievers because they are confused about which treatment options are safe.
"My sense would be that the public understands that this continues to be an important class of drugs," said Dr. John H. Klippel, president and CEO of the Arthritis Foundation. People simply want to be informed about the potential risks so they can make choices, he added.
Merck's move to pull Vioxx off the market in September initially boosted the market share of rival products, as doctors switched Vioxx patients to Celebrex or Bextra and started new patients on those competing cox-2 therapies, according to IMS Health, a pharmaceutical information company.
But by year-end, the entire market began to shrink. Cox-2 prescriptions slid nearly 6 percent to 50,742 in 2004, from 53,890 the prior year, the company reported.
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