A new study published by the journal STEM CELLS Translational Medicine has demonstrated the regenerative effects of mesenchymal stem cells (MSC) on the anal sphincter. This work could have implications for the 11 percent of the population who suffer from fecal incontinence as a result of injury or disease.
Massarat Zutshi, M.D., and Levilester Salcedo, M.D., led the research team made up of their colleagues at the Cleveland Clinic (Cleveland, Ohio) and Summa Cardiovascular Institute and Northeast Ohio Medical University (Akron, Ohio).
Unfortunately none of the present treatments for fecal incontinence “are efficacious in the long-term or without complications related to the surgery or the device,” explained Dr. Zutshi. Additionally, she noted that mesenchymal stem cells (MSCs) from adipose tissue and skeletal muscle have improved heart function and urinary sphincter in animal models, On the strength of these successes, Zutshi and her colleagues decided to use these cells to treat damaged anal sphincters.
In this study. Zutshi and Salcedo and their research teams used a single intramuscular (IM) injection of MSCs compared to a series of intravenous (IV) treatments. For these experiments, they employed rats that had undergone an excision of 25 percent of their anal sphincter complex. 24 hours after anal sphincter injury, one group received a single IM injection of stem cells directly into their anal sphincters. A second group began a series of six consecutive daily treatments delivered by IV through their tail veins, as did a group of non-injured animals. A third group of injured animals received no stem cells.
The scientists measured anal pressures in these animals. Accordingly, they measured anal pressures were recorded prior to injury, then again at 10 days and five weeks after treatment. Ten days after the IM treatment, resting and peak pressures were significantly increased in the injured groups compared to the control group that received no treatment. At five weeks, the anal pressures of the two groups of injured rats receiving treatments were almost on par with the non-injured group.
“Both IM and IV MSC treatment after injury cause increase in anal pressures sustained at five weeks even though fewer cells were injected IM,” Dr. Zutshi concluded. “The MSC-treated groups showed less scarring than PBS treatment, with the IV infusion group showing the least scarring.
“Since MSC delivered IM or IV both resulted in functional recovery, the IM route may be preferable as fewer cells seem to be needed.”
This research demonstrates the regenerative effects of mesenchymal stem cells on the injured anal sphincter. Since fewer cells were needed for intramuscular injections, this mode of administration might be used in future clinical trials, said Anthony Atala, M.D., editor of STEM CELLS Translational Medicine and director of the Wake Forest Institute for Regenerative Medicine.