Multimodal Interventions to Prevent Anal Sphincter Dysfunction After Childbirth-Related Neuromuscular Injury - ABSTRACT Fecal incontinence (accidental leakage of stools; FI) is a major medical illness, occurs in a significant population of women (>7%) and is under reported. Most common cause of FI is childbirth related injury to the external anal sphincter (EAS), pelvic floor muscles and pudendal nerve (PN) that innervates sphincter muscle by a variety of mechanisms. Many FI patients show anatomical disruptions and impairment of EAS muscle function. Our animal (rabbit) studies confirm these findings and further demonstrate abnormal healing with increased fibrosis in the regenerating muscle after experimental injury. Our mechanistic studies show upregulation of fibrosis network involving Wnt-β/ STAT-3 proteins and a novel central hub for multi-receptor driven profibrogenic signaling, Gα-interacting vesicle-associated protein (GIV; also known as Girdin) in the injured animals. We hypothesize that PN stretch/crush during childbirth impairs sphincter function and sustained neurotrophic (using brain derived neurotrophic factor; BDNF) therapy would accelerate PN re- growth. Innovative, multimodular therapies that target nerve and muscle regrowth would prevent EAS muscle dysfunction. Our specific aims are to: i. evaluate efficacy of a novel BDNF sustained release formulation in a dual injury (PN crush and EAS injury) model alone and 2. In combination with GIV- siRNA delivered as sustained release lipid nanoparticle formulation (LNP). We will use a female rabbit model and several novel approaches, 1; longitudinal assessment of in-vivo length tension function of the EAS muscle, 2; use of BDNF for sustained neurotrophin delivery, 3; gene silencing (GIV siRNA) with LNP to modulate fibrogenic signaling with a goal of improving sphincter function in our studies. Thus, our proposal is both conceptually novel, and innovative (paving the way for new treatment strategies). Rabbits will be monitored for 180 days and subjected to EMG, anal canal pressure and sphincter muscle thickness (using endoluminal ultrasound) measurements at pre-determined time points to determine anatomical and functional recovery. All the animals will be sacrificed at the end of the study and EAS tissues will be harvested to perform tissue analysis to determine nerve and muscle regeneration. Use of sustained BDNF therapy to promote EAS function remains unexplored, as does the beneficial role of this multimodal approach. We have enlisted international leaders in these fields for this novel research and our team has all the expertise to conduct this innovative study. Our proposal aligns with R21 goals intended to support high risk, high payoff research. We envision a strong potential for translation where patients could benefit from a simple, one-time office procedure during which the PN/EAS is injected with the proposed neurotrophin /siRNA (LNP) formulations using a transperineal approach to prevent post-partum FI.
