Boston - November 2003, Harvard Medical School affiliate Children's Hospital - A preliminary animal study from Children's Hospital Boston suggests that people with urinary incontinence due to weak or inactive urinary sphincter muscles could someday regain bladder control through the use of their own muscle cells. The study, presented at the annual meeting of the American Academy of Pediatrics, was named a research finalist in the conference's urology section.
Some 10 million people in the U.S. alone suffer from urinary incontinence, and in one third of them, the cause is sphincter insufficiency. This includes children with congenital malformations such as spina bifida, other lower-spinal-cord defects, malformed bladders, and defective ureters, and many adults whose sphincter muscles have been weakened or damaged as a result of aging, cancer, or trauma.
Led by Rene Yiou, MD, in the tissue engineering laboratory of Anthony Atala, MD, study investigators successfully restored urinary continence in rats by injecting muscle precursor cells - stem cells taken from the animals' own limb muscles - into the sphincter. Follow-up studies showed that new muscle fibers had formed in the sphincter, that these fibers carried the appropriate chemical receptors to receive cues from the body, and that the fibers had attracted and interconnected with nearby nerve endings, creating functioning muscle tissue. Within one month, sphincter function had improved by 40%. Untreated rats showed no improvement in either sphincter-muscle anatomy or in bladder control.
Atala notes that current treatments for sphincter insufficiency in children are just mechanical fixes - injecting or implanting bulking agents or wrapping tissue around the sphincter to try to tighten it up and obstruct urine flow. In contrast, muscle precursor cells can build functioning sphincter muscle that grows with the patient, providing long-term benefit. Atala's lab plans follow-up studies to bring this tissue-engineering technology to human application.