Scientists to regrow muscle by using stem cells
CAROLYN ABRAHAM, MEDICAL REPORTER
Wednesday, June 6, 2001
From a thimbleful of cells, scientists say they have regenerated a lowly but valuable body part: the sphincter muscle that regulates the ability to urinate.
Urologists at the University of Pittsburgh are touting the feat as a harbinger of 21st-century medicine, in which scientists hope to replace patients' damaged or diseased tissue and organs with spare body parts grown from the molecular magic of stem cells.
The Pittsburgh team relied on stem cells to grow the urethral sphincter muscles in experiments with rats, but say they intend to move a lab-generated valve into the bladder of a test patient next year.
Hope is bound to spring from their prediction. Millions of North Americans, most of them elderly women, lose bladder control with age, an embarrassing condition doctors refer to as "urinary incontinence."
"We think we can move this quickly from bench to bedside," said urologist Michael Chancellor, whose Pittsburgh team is presenting their work to an American Urological Association meeting this week.
"We're looking at clinical trials for, say, a 70-year-old patient in 2002."
Stem cells, the primitive cells that sprout shortly after conception, have the ability to blossom into the various cells that make up a human body. Like seeds that all look the same in the beginning, stem cells grow and eventually change into everything from bone to brain, freckle to foot.
Since researchers captured them in the lab in 1998, stem cells have become the the hottest frontier in science. As Dr. Chancellor put it, scientists hope they'll be able to produce new parts "like a starfish regenerates a limb."
Research has concentrated on growing nerves damaged in spinal cord injuries and dopamine-producing brain cells as a potential new treatment for Parkinson's disease. In the United States and France, trials are investigating whether stem cells can repair the damaged heart muscles of cardiac patients.
But the field has also been dogged with controversy. To capture the most versatile stem cells, scientists must destroy an embryo or tap an aborted fetus. Increasingly, they've been investigating stem cells from the placenta, umbilical cord blood and even from fat removed in liposuction.
In Pittsburgh, the urologists sidestepped prickly moral issues by using stem cells they derived from the muscles of adult mice. In a lab dish, they exposed the stem cells to particular growth chemicals and proteins, coaxing them to the brink of becoming smooth sphincter muscle cells. "It looks like soup at this point," Dr. Chancellor said. "It's gooey. Under the microscope, you can see the cells, no bigger than corpuscles."
The research team had already disabled the muscles and nerves of the urethral sphincters in two groups of normal rats. One group then had their bladder-valve areas injected with the stem-cell broth. After two weeks, researchers compared the progress of the rats who received the stem cells to that of the rodents that had been disabled.
Using electrical stimulation on the urethral sphincter, which contracts to hold urine and relaxes to release it, the research team found they had restored function in the "denervated sphincters" by 88 per cent. What's more, postmortem exams showed new skeletal muscle fibre had begun to grow over the regenerated sphincters.
"If you can't control your urine . . . you can go in to your doctor and have a muscle biopsy and they can get a few stem cells, and they double about once a day . . . and then in a month or so, you can be injected with your own stem cells to fix it," Dr. Chancellor said.