At a glance
Stem cell therapy for anal fistula is one of the more promising developments in fistula treatment in recent years. The approach — injecting stem cells directly into the fistula tract to promote healing from within — offers the potential to close complex fistulas without surgery that risks sphincter damage.
The research is encouraging but still developing. This guide covers where things currently stand, who the treatment is for, and what the realistic expectations are.
The concept
Traditional fistula surgery works by removing or opening the tract, allowing it to heal from the outside in. This works well for simple fistulas but becomes increasingly challenging for complex ones, where the tract passes through significant sphincter muscle.
Stem cell therapy takes a different approach:
- Stem cells are harvested (usually from the patient’s own fat tissue or from donor cells)
- They are processed and prepared for injection
- The fistula tract is cleaned and the internal opening is closed
- The stem cells are injected into and around the tract
- The cells promote an anti-inflammatory, pro-healing response
- The goal is for the tract to close biologically without surgical division
The appeal is clear: healing the fistula without cutting any sphincter muscle, avoiding the continence risks that make complex fistula surgery so challenging.
The evidence
Darvadstrocel (Alofisel)
The most advanced stem cell product for fistula treatment is darvadstrocel, approved by the European Medicines Agency in 2018 for complex perianal fistulas in adult patients with non-active or mildly active Crohn’s disease.
The pivotal trial (ADMIRE-CD) showed:
- Clinical remission at 24 weeks in approximately 50 percent of treated patients versus 34 percent with placebo
- Sustained response at one year in a significant proportion of responders
- Favourable safety profile with no major safety concerns
These results are meaningful for a condition with limited treatment options, though they also show that the treatment does not achieve remission in all patients.
Other research
Beyond darvadstrocel, research is ongoing in several areas:
- Autologous stem cells — using the patient’s own fat-derived stem cells rather than donor cells. Several small studies have shown promising results
- Cryptoglandular fistulas — extending stem cell treatment to fistulas not associated with Crohn’s disease. Early evidence is encouraging but limited
- Combination approaches — using stem cells alongside other treatments such as fibrin glue or surgical techniques
- Different cell sources — exploring stem cells from bone marrow and other tissues
Who it is currently for
Based on current evidence and approvals, stem cell treatment is most applicable for:
- Complex perianal fistulas in Crohn’s disease — this is where the evidence is strongest and where regulatory approval exists
- Patients who have failed conventional treatment — when surgery has been unsuccessful or carries too high a continence risk
- Patients where sphincter preservation is critical — when the fistula anatomy makes conventional surgery too risky
It is generally not the first-line treatment for:
- Simple fistulas that can be treated with standard surgery
- Acute fistulas with active infection
- Patients who have not yet tried conventional approaches
Practical considerations
Availability
This is the main barrier for most people. Stem cell treatment for fistula is:
- Approved in Europe (EMA) but not everywhere globally
- Available mainly at specialist centres
- Sometimes accessible through clinical trials
- Generally expensive when available privately
- Variably covered by public healthcare systems — NHS access in the UK is limited
The procedure
The procedure itself is relatively straightforward:
- An examination under anaesthesia to prepare the tract
- Curettage (cleaning) of the tract
- Closure of the internal opening with sutures
- Injection of the stem cell preparation into the tract wall and surrounding tissue
- The procedure typically takes under an hour
Recovery
Recovery from the procedure itself is generally mild:
- Local discomfort for a few days
- Routine wound care
- Follow-up assessment at regular intervals (typically six months and one year)
The healing process — whether the tract actually closes — takes weeks to months and is assessed through clinical examination and sometimes MRI.
Realistic expectations
Stem cell treatment is a significant advance, but it is important to set realistic expectations:
- It works for roughly half of patients in clinical trials
- It does not work immediately — assessment of success is done months later
- Retreatment or additional procedures may be needed if the first attempt is not successful
- Long-term recurrence data is still being collected
- It is not a magic solution — it is one tool in a growing toolkit
The bigger picture
Stem cell treatment represents a shift in how complex fistulas might be treated in the future — moving from surgical approaches that carry continence risk toward biological approaches that promote healing from within. The research is active and the field is developing rapidly.
If you have a complex fistula and are interested in whether stem cell treatment might be appropriate, the conversation with your surgeon is the starting point. They can advise on eligibility, availability in your area, and whether clinical trials might be accessible.