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.
