Design of a new fistula plug using acellular small intestinal submucosa with platelet-rich fibrin for anal fistula in rabbit model

Abstract

Background: Anal fistula is an abnormal tract between the anal canal and the perianal skin. Anal fistula plug (AFP) as a sphincter-preventing method has drawn more interest because of its simple procedure and low risk of incontinence. Small intestine submucosa (SIS) as a biomaterial plug has been applied in managing anal fistulae. Platelet-rich fibrin (PRF) is a platelet-derived product containing several growth factors. PRF has been widely used for soft tissue regeneration because it promotes angiogenesis and mitogenesis and inhibits inflammation in the wound site. Because of the rigid consistency of SIS and the low mechanical resistance of PRF and their tissue-regenerative properties, we created a novel SIS-PRF plug for managing anal fistula. Methods: Anal fistulae were created in the rabbit model. 18 rabbits were used. Animals were divided into three groups, including SIS-PRF, SIS and control. Five weeks’ post-treatment, animals were sacrificed, and fistula specimens were obtained. Results: According to histological analysis, inflammation was significantly lower in the SIS-PRF group compared to other groups. Treatment with both biomaterials increased the number of closed fistula tracts, but it was markedly higher in the SIS-PRF group compared to the SIS group. No foreign body reaction was seen in the SIS-PRF group. Conclusions: In this study, SIS-PRF reduced inflammation and increased connective tissue in fistulae. Taken together, SIS-PRF can be used in further studies about anal fistula management in humans.