Efficacy and safety of allogeneic umbilical cord-derived mesenchymal stem cells for the treatment of complex perianal fistula in Crohn's disease: a pilot study

The aim of the study was to evaluate the efficacy and safety of allogeneic umbilical cord-derived mesenchymal stem cells (TH-SC01) for complex perianal fistula in patients with Crohn's disease (CD). This was an open-label, single-arm clinical trial conducted at Jinling Hospital. Adult patients with complex treatment-refractory CD perianal fistulas (pfCD) were enrolled and received a single intralesional injection of 120 million TH-SC01 cells. Combined remission was defined as an absence of suppuration through an external orifice, complete re-epithelization, and absence of collections larger than 2 cm measured by magnetic resonance imaging (MRI) at 24 weeks after cell administration. A total of 10 patients were enrolled. Six patients (60.0%) achieved combined remission at 24 weeks. The number of draining fistulas decreased in 9 (90.0%) and 7 (70.0%) patients at weeks 12 and 24, respectively. Significant improvement in Perianal Crohn Disease Activity Index, Pelvic MRI-Based Score, Crohn Disease Activity Index, and quality of life score were observed at 24 weeks. No serious adverse events occurred. The probability of remaining recurrence-free was 70% at week 52. The study demonstrated that local injection of TH-SC01 cells might be an effective and safe treatment for complex treatment-refractory pfCD after conventional and/or biological treatments fail (ClinicalTrials.gov ID, NCT04939337). The study was retrospectively registered on www. gov (NCT04939337) on June 25, 2021.