This study aims to evaluate the clinical efficacy and safety of local injection of human umbilical cord mesenchymal stem cells (hUCMSCs) in the treatment of perianal fistulizing Crohn’s disease (pfCD).

Nineteen patients with non-active pfCD (aged 15~39 years) who received treatment at Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine between October 2022 and December 2024 were included. They underwent perianal local hUCMSCs transplantation surgery and were followed up for 6 to 12 months. The fistula closure was assessed through clinical signs and MRI imaging. The Crohn’s Disease Activity Index (CDAI), Perianal Disease Activity Index (PDAI), Visual Analog Scale (VAS) for pain, Inflammatory Bowel Disease Questionnaire (IBDQ), and Wexner score for anal incontinence were dynamically monitored. Adverse events and nutritional indicators were also recorded.

The cumulative fistula healing rates at 6 and 12 months postoperatively were 73.7% (14/19) and 90.9% (10/11), respectively, with complete fistula closure confirmed by pelvic MRI. The patients’ clinical activity index remained at an inactive level throughout the treatment period. Compared with baseline, the CDAI score showed a significant decrease by postoperative day 14, with the median score dropping to 27.5 (13.5, 40.4) (Z=−3.175, P=0.009). The PDAI index decreased to 2.0 (0.0, 2.0) by the second postoperative month (Z=−2.839, P=0.022). The median VAS score dropped to 0 from 1 to 6 months after surgery (P>0.05). The IBDQ score showed a slight, non-significant decrease on postoperative day 7 [201.0 (195.0, 212.5) (P>0.05)] and returned to baseline levels by postoperative day 14. The Wexner incontinence score demonstrated an improving trend compared with baseline, although the difference was not statistically significant (Z=−1.472, P>0.05), indicating no impairment of anal function. Furthermore, during the study period, mild and self-limiting pain was observed in 42.1% (8/19) of patients, and transient low-grade fever occurred in 10.5% (2/19), with no serious adverse events reported. Albumin levels were significantly increased at 6 months postoperatively compared with baseline (t=3.370, P=0.010).

Local injection of hUCMSCs for the treatment of pfCD offers advantages such as minimal trauma, fast recovery, light pain, and good anal function protection, demonstrating high clinical efficacy and safety.