Mesenchymal stem cell therapy for therapy refractory complex Crohn's perianal fistulas: a case series

Mesenchymal stem cell treatment (MST) has emerged as a new therapeutic strategy for Crohn's perianal fistulas. It has been demonstrated that a fibrotic tract on MRI with a MAGNIFI-CD score ≤ 6 is the best predictor for long-term clinical closure. Therefore, the aim of the current study was to analyse the effectiveness of MST for complex Crohn's perianal fistulas based on MRI.

Consecutive patients with complex Crohn's perianal fistulas, previously failing both anti-TNF treatment and surgical closure, who had surgical closure of the internal opening with MST were included. The primary endpoint was radiological remission of the fistula(s) defined as a MAGNIFI-CD ≤ 6 on MRI, read by an experienced radiologist.

Between December 2019 and March 2023, 30 patients (15 males) with 48 fistula tracts were included with a median follow-up of 16.5 months. Radiological remission was achieved in thirteen patients (43.3%) after a median follow-up of 5.0 months (IQR 3.0-6.0). The median MAGNIFI-CD at baseline was 15.0 (IQR 7.0-20.0) which significantly decreased to 8.0 (IQR 3.0-15.0) after treatment (p = 0.001). Clinical closure was achieved in 21 patients (70.0%). Three patients (14.3%) developed a recurrence during long-term FU, all with clinically closed fistula(s), but no radiological remission. The median PDAI decreased significantly from 10.5 (IQR 7.0-14.0) to 4.0 (IQR 0.0-7.3) (p = 0.001).

MST is a promising treatment strategy for therapy refractory Crohn's perianal fistulas, resulting in > 40% radiological remission, clinical closure in 70% and a significant improvement in quality of life. No recurrences were seen in patients with radiological remission.