Abstract
BACKGROUND: There is an urgent need for gut lengthening secondary to massive resections of the gastrointestinal tract. In this study, we propose to evaluate the remodeling, vascularization, and functionality of a chitosan-based, tubular neuromuscular tissue on subcutaneous implantation in the back of athymic rats. METHODS: Aligned innervated smooth muscle sheets were bioengineered with the use of human smooth muscle and neural progenitor cells. The innervated sheets were wrapped around tubular chitosan scaffolds. The engineered tubular neuromuscular tissue was implanted subcutaneously in the back of athymic rats. The implant was harvested after 14 days and assessed for morphology, vascularization, and functionality. RESULTS: Gross examination of the implants showed healthy color with no signs of inflammation. The implanted tissue became vascularized as demonstrated by gross and histologic analysis. Chitosan supported the luminal patency of the tissue. The innervated muscle remodeled around the tubular chitosan scaffold. Smooth muscle maintained its circumferential alignment and contractile phenotype. The functionality of the implant was characterized further by the use of real-time force generation. A cholinergic response was demonstrated by robust contraction in response to acetylcholine. Vasoactive intestinal peptide-, and electrical field stimulation-caused relaxation. In the presence of neurotoxin tetrodotoxin, the magnitude of acetylcholine-induced contraction and vasoactive intestinal peptide-induced relaxation was attenuated whereas electrical field stimulation-induced relaxation was completely abolished, indicating neuronal contribution to the response. CONCLUSION: Our results indicated the successful subcutaneous implantation of engineered tubular neuromuscular tissues. The tissues became vascularized and maintained their myogenic and neurogenic phenotype and function, which provides potential therapeutic prospects for providing implantable replacement GI segments for treating GI motility disorders.