Bioengineered sphincters and intestinal fragments
Researchers at the Wake Forest Institute of Regenerative Medicine, working under the leadership of Professor Khalil N Bitar, have made significant progress in the development of bioengineered intestinal fragments and anal sphincters suitable for transplantation.
When creating prototypes of intestinal tube implants, the researchers used layers of innervated muscle tissue grown from smooth muscle and nerve stem cells of the human intestine. These layers were wrapped around tubular frames made of chitosan, a natural biological material obtained from shrimp shells. Chitosan has already been approved by the U.S. Food and Drug Administration for a number of applications in medical practice.
At the first stage of assessing the functionality of the resulting tubular structures, they were implanted under the skin of rats for 14 days. Subsequent analysis demonstrated the safety of the implant lumen and the presence of its own blood supply system. In addition, signs of muscle tissue remodeling were revealed, that is, the process of cells releasing structural materials that gradually replace the framework.
The next stage of the authors' work will be the creation of the inner lining of the intestine, which performs the functions of absorption and secretion. In experiments on animal models, they also plan to evaluate the functionality of the implants by surgically connecting them to the recipient's intestines.
In the future, such implants may be a salvation for children born with short bowel syndrome, and adults who have lost large fragments of the intestine as a result of cancer treatment or other diseases.
The second direction of the researchers' work – the creation of artificial sphincters – has also brought significant success. Sphincters are ring-shaped muscles that regulate the release of urine and feces. In fact, there are two sphincters in the anus: external and internal. Most cases of fecal incontinence are caused by a weakening of the internal sphincter.
To create bioengineered sphincters, the researchers used smooth muscle cells isolated from small samples of biopsy material of rabbit sphincter tissue. These cells were multiplied in laboratory conditions, after which they were placed in a ring-shaped form, alternating them in layers with layers of nerve cells isolated from the tissue of the small intestine. After that, the mold was placed in an incubator to form a full-fledged tissue. The whole process took about 4-6 weeks.
The tissue structure of the resulting bioengineered sphincters was similar to the structure of the original tissue. When transplanted to rabbits, such sphincters effectively performed their function, eliminating the symptoms of fecal incontinence for the entire follow-up period of 6 months. At the same time, there were no signs of inflammation or infection at the transplant site.
The authors note that the rapid and effective integration of bioengineered sphincters developed by them into the recipient's digestive tract is due to the presence in their structure of not only muscle, but also nerve cells. They hope that over time their proposed technology will find application in clinical practice.
The results of the work were presented at the Digestive System Diseases Week held on May 16-19 in Washington.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the Wake Forest Institute for Regenerative Medicine: Researchers Make Progress Engineering Digestive System Tissues.
20.05.2015