Small intestine submucosa and mesenchymal stem cells composite gel for scarless vocal fold regeneration

The purpose of this study is to demonstrate scarless vocal fold (VF) regeneration by using a composite gel composed of small intestine submucosa (SIS) and mesenchymal stem cells (MSCs). A scar was made with an electrocoagulator on both VFs in 24 rabbits, followed by injection of either MSCs, SIS, or MSCs-SIS composite gel in the right side VF, while the left side VF was left untreated. VF scars were evaluated with in vivo fluorescence live imaging system (IFLIS), endoscopy, histology, and videokymography (VKG) after eight weeks. IFLIS demonstrated that SIS enabled the MSCs to survive and be engrafted in the VF. The histological analysis showed increased hyaluronic acid accumulation and controlled collagen deposition by MSCs-SIS composite gel. VKG analysis showed more favorable vibrations of MSCs-SIS injected VF, compared to other treatment group. In conclusion, the injectable SIS supplied a niche for the MSCs to stably settle down in scarred VFs and helped to regulate ECM synthesis. The ECM remodeling underwent by the surviving MSCs eventually led to the functional improvement of the VF. The results of the present investigation suggest that SIS-MSCs composite gel is a plausible biomaterial for prolonged survival of MSCs in VFs and promotes scarless VF healing.