‘Off the shelf’ stem cells show promise for perianal fistula

Expanded allogenic adipose-derived stem cells (eASCs) are effective for the treatment of perianal fistula in patients with Crohn's disease, suggest the results of a phase I/II trial.

"These clinical results of eASCs show that eASCs are a safe treatment for fistulas that could overcome most of the problems associated with surgery and systemic anti-TNFs currently used for the management of perianal fistulas," say Fernando de la Portilla (Virgen del Rocio University Hospital, Seville, Spain) and colleagues.

The cells, which are obtained from the adipose tissue of healthy donors, were injected into the sphincter wall of 24 Crohn's disease patients with perianal fistula. Patients received a second injection at 12 weeks if their fistula had not closed and were followed up for 24 weeks.

During the study period, there were 32 treatment-emergent adverse events, of which five were deemed to be treatment-related. This included anal abscess in three patients, pyrexia in one patient, and uterine leiomyoma in another.

Two serious adverse events - pyrexia and perianal abscess - were thought to be related to the treatment procedure and not the treatment itself.

The authors also reported efficacy results as secondary outcomes. In patients who completed the treatment regime, over two-thirds (69.3%) experienced a reduction in at least one of their draining fistulas at 24 weeks.

In addition, 53.3% had closure of at least one opening and 27.8% had complete fistula closure at this time point.

Autogeneic stem cells have already shown efficacy in multiple studies but allogenic cells are considered immune-privileged and therefore can be administered without human leukocyte antigen matching or immunosuppression.

eASC treatment could have many benefits say de la Portilla and colleagues, including a more convenient procedure. They believe it could reduce the need for infliximab when disease is restricted to the perianal region, minimize the incontinence associated with surgery, and potentially reduce the tumor incidence associated with recurrent fistula.

"Additional studies are necessary to confirm in a controlled design the efficacy profile of the eASCs and to establish the best strategy for their administration," they conclude in the International Journal of Colorectal Disease.

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