A novel animal model of long-term sustainable anal sphincter dysfunction

Cell Therapy for Anal Sphincter Incontinence: Where Do We Stand?

Anal sphincter incontinence is a chronic disease, which dramatically impairs quality of life and induces high costs for the society. Surgery, considered as the best curative option, shows a disappointing success rate. Stem/progenitor cell therapy is pledging, for anal sphincter incontinence, a substitute to surgery with higher efficacy. However, the published literature is disparate. Our aim was to perform a review on the development of cell therapy for anal sphincter incontinence with critical analyses of its pitfalls. Animal models for anal sphincter incontinence were varied and tried to reproduce distinct clinical situations (acute injury or healed injury with or without surgical reconstruction) but were limited by anatomical considerations. Cell preparations used for treatment, originated, in order of frequency, from skeletal muscle, bone marrow or fat tissue. The characterization of these preparations was often incomplete and stemness not always addressed. Despite a lack of understanding of sphincter healing processes and the exact mechanism of action of cell preparations, this treatment was evaluated in 83 incontinent patients, reporting encouraging results. However, further development is necessary to establish the correct indications, to determine the most-suited cell type, to standardize the cell preparation method and to validate the route and number of cell delivery.

Effects of bacterial cellulose gel on the anorectal resting pressures in rats submitted to anal sphincter injury

The aim of this study is to evaluate if a gel of bacterial cellulose gel can revert the loss of anal resting pressure after anorectum sphincter injury in rat model, elected as a model to simulate fecal incontinence. Thirty-nine animals were equally divided into three groups: Control (CG), Sphincter injury plus Saline injection (SG) and Sphincter injury plus Bacterial Cellulose Gel injection (BCG). Anal pressure at rest was assessed for all animal in the three groups using anorectum manometry. Saline and Gel groups were subject to anorectum sphincter injury to reduce the anal pressure at rest. Fifteen days later Saline or Gel was injected into the anorectum, according to their groups. Sixty days later first manometry, the anorectum of all animals were removed and processed histologically. The CG group showed maintenance of their mean anorectal resting pressure levels; SG presented a fall in their mean anorectal resting pressure. The BCG presented a significant elevation of the mean anorectal resting pressure levels, surpassing the pressure of CG. The gel of bacterial cellulose remained at the injection site and was neovascularized, colonized by fibroblasts and dense conjunctive tissue. Those data suggest that BC can be used as a future filling agent treatment for fecal incontinence in clinical trial protocols.

Systematic Review of Animal Models Used in Research of Origins and Treatments of Fecal Incontinence

BACKGROUND

Fecal incontinence is a common disorder, but its pathophysiology is not completely understood.

OBJECTIVE

The aim of this review is to present animal models that have a place in the study of fecal incontinence.

DATA SOURCES

A literature review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines performed in August 2016 revealed 50 articles of interest. Search terms included fecal/faecal incontinence and animal model or specific species.

STUDY SELECTION

Articles not describing an animal model, in vitro studies, veterinary literature, reviews, and non-English articles were excluded.

MAIN OUTCOME MEASURES

The articles described models in rats (n = 31), dogs (n = 8), rabbits (n = 7), and pigs (n = 4).

RESULTS

Different fecal incontinence etiologies were modeled, including anal sphincter lesions (33 articles) ranging from a single anal sphincter cut to destruction of 50% of the anal sphincter by sharp dissection, electrocautery, or diathermy. Neuropathic fecal incontinence (12 articles) was achieved by complete or incomplete pudendal, pelvic, or inferior rectal nerve damage. Mixed fecal incontinence (5 articles) was modeled either by the inflation of pelvic balloons or an array of several lesions including nervous and muscular damage. Anal fistulas (2 articles), anal sphincter resection (3 articles), and diabetic neuropathy (2 articles) were studied to a lesser extent.

LIMITATIONS

Bias may have arisen from the authors' own work on fecal incontinence and the absence of blinding to the origins of articles.

CONCLUSIONS

Validated animal models representing the main etiologies of fecal incontinence exist, but no animal model to date represents the whole pathophysiology of fecal incontinence. Therefore, the individual research questions still dictate the choice of model and species.