Fistula is a representative devastating complication in Crohn's patients due to refractory to conventional therapy and high recurrence. In our phase I clinical trial, adipose tissue-derived stem cells (ASCs) demonstrated their safety and therapeutic potential for healing fistulae associated with Crohn's disease. This study was carried out to evaluate the efficacy and safety of ASCs in patients with Crohn's fistulae. In this phase II study, forty-three patients were treated with ASCs. The amount of ASCs was proportioned to fistula size and fistula tract was filled with ASCs in combination with fibrin glue after intralesional injection of ASCs. Patients without complete closure of fistula at 8 weeks received a second injection of ASCs containing 1.5 times more cells than the first injection. Fistula healing at week 8 after final dose injection and its sustainability for 1-year were evaluated. Healing was defined as a complete closure of external opening without any sign of drainage and inflammation. A modified per-protocol analysis showed that complete fistula healing was observed in 27/33 patients (82%) by 8 weeks after ASC injection. Of 27 patients with fistula healing, 26 patients completed additional observation study for 1-year and 23 patients (88%) sustained complete closure. There were no adverse events related to ASC administration. ASC treatment for patients with Crohn's fistulae was well tolerated, with a favorable therapeutic outcome. Furthermore, complete closure was well sustained. These results strongly suggest that autologous ASC could be a novel treatment option for the Crohn's fistula with high-risk of recurrence. STEM

Age, sex, and ultralow anterior resection were found to be risk factors for anastomotic leakage after rectal cancer surgery. In addition, leakage was associated with poor survival.

A previous phase II clinical trial of adipose-derived stem cell (ASC) therapy for fistulae associated with Crohn's disease, a devastating condition with a high recurrence rate, demonstrated safety and therapeutic potential with a 1-year sustained response. In the present study, 41 of the 43 phase II trial patients were followed for an additional year, regardless of response in the initial year. At 24 months, complete healing was observed in 21 of 26 patients (80.8%) in modified per protocol analysis and 27 of 36 patients (75.0%) in modified intention-to-treat analysis. No adverse events related to ASC administration were observed. Furthermore, complete closure after initial treatment was well-sustained. These results strongly suggest that autologous ASCs may be a novel treatment option for Crohn's fistulae.