Numerous laboratory tests of the engineered sphincters, including stimulating the nerve cells, showed normal tissue function, such as the ability to relax and contract. The sphincters were then implanted just under the skin of mice to determine how they would respond in the body. Mice with suppressed immune systems were selected so that there would be no issues with rejection.
After 25 days of implantation, each sphincter was re-tested and also compared with the animals' native sphincters. The engineered sphincters had developed a blood vessel supply and continued to function like native tissue.
"The engineered sphincters were physiologically similar to native tissue," said Bitar. "This takes us one step closer to realizing the goal of using a patient's own cells to engineer a replacement sphincter in the lab."
Bitar's team had previously shown that circular pieces of tissue made from sphincter muscle cells displayed characteristics of native sphincters. However, the tissue lacked the nerve cells required for normal function in the body.
"Our latest advance, a sphincter engineered with muscle and nerve cells, will allow us to 'connect' the engineered tissue with nerve pathways in the intestine," said Bitar.
Bitar's group will continue the research in more advanced research models. The ultimate goal is to harvest both muscle and nerve cells from a patient, build a pre-wired sphincter in the lab, and implant it back in the same patient. Using the patient's own cells would eliminate the risk of rejection.
"While we have numerous challenges to meet, we have cross
|Contact: Karen Richardson|
Wake Forest Baptist Medical Center