Scientists at Wake Forest Baptist Medical Center’s Institute for Regenerative Medicine have developed the world’s first fully functional replacement sphincters built from human tissue.

“In essence, we have built a replacement sphincter that we hope can one day benefit human patients. This is the first bioengineered sphincter made with both muscle and nerve cells, making it ‘pre-wired’ for placement in the body,” said senior author Khalil N. Bitar, Ph.D., a professor of regenerative medicine at Wake Forest Baptist Medical Center’s Institute for Regenerative Medicine. Bitar performed the work when he was on the University of Michigan faculty and it included a colleague from Emory University.

Sphincters are ring-like muscles that maintain constriction of a body passage. There are numerous sphincters in the human body, including those that control the release of urine and feces. There are actually two sphincters at the anus – one internal and one external. Fecal incontinence is the result of a weakened internal sphincter.

These replacement buttholes will go a long way toward helping the elderly, women who face severely weakened sphincter control after childbirth and men and women who lack bladder and urinary tract control. Until now, sufferers of no-good deadbeat sphincters had to put up with options made from silicon, skeletal muscle, and mechanical constructs that converted recipients to butthole cyborgs of some sort. Or so we gather.

To engineer an internal anal sphincter in the laboratory, the researchers used a small biopsy from a human sphincter and isolated smooth muscle cells that were then multiplied in the lab. In a ring-shaped mold, these cells were layered with nerve cells isolated from mice to build the sphincter. The mold was placed in an incubator for nine days, allowing for tissue formation. The entire process took about six weeks.

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.