Surgical implantation of a bioengineered internal anal sphincter

Abstract

PURPOSE: Fecal incontinence is a common disorder that can have devastating social and psychologic consequences. However, there are no long-term ideal solutions for such patients. Although loss of continence is multifactorial, the integrity of the internal anal sphincter (IAS) has particular significance. We previously described the development of 3-dimensional bioengineered constructs using isolated smooth muscle tissue from donor C57BL/6 IAS. We hypothesized that the bioengineered ring constructs would retain cellular viability and promote neovascularization upon implantation into a recipient mouse.

METHODS: Internal anal sphincter ring constructs were surgically implanted into the subcutaneous tissue of syngeneic C57BL/6 mice and treated with either fibroblastic growth factor 2 (0.26 microg daily) or saline controls using a microosmotic pump. Internal anal sphincter constructs were harvested after 25 days (range, 23-26 days) and assessed morphologically and for tissue viability.

RESULT: Gross morphology showed that there was no rejection. Rings showed muscle attachment to the back of the mouse with no sign of inflammation. Fibroblastic growth factor 2 infusion resulted in a significantly improved histologic score and muscle viability compared with the control group.

CONCLUSIONS: Three-dimensional bioengineered IAS rings can be successfully implanted into the subcutaneous tissue of recipient mice. The addition of fibroblastic growth factor 2 led to improved muscle viability, vascularity, and survival. This approach may become a feasible option for patients with fecal incontinence.