The effective management of fistulas in patients with Crohn's disease presents an extremely challenging problem. Mesenchymal adult stem cells extracted from certain tissues, such as adipose tissue, can differentiate into various cell types. Therefore, we have tried to use such cells to stimulate healing of Crohn's fistulas. We designed a prospective Phase I clinical trial, involving five patients with Crohn's disease, to test the feasibility and safety of autologous stem cells transplantation in the treatment of fistulas. We also studied the expression of various cell markers and the growth rates of the lipoaspirate-derived cells that were used for transplantation. One patient was excluded because of bacterial contamination of cultured cells. We inoculated nine fistulas in four patients with autologous adipose tissue-derived stem cells at Passage 3 or earlier. Eight inoculated fistulas were followed weekly for at least eight weeks. In six fistulas, the external opening was covered with epithelium at the end of Week 8, and, thus, these fistulas were considered healed (75 percent). In the other two fistulas, there was only incomplete closure of the external opening, with a decrease in output flow (not healed; 25 percent). No adverse effects were observed in any patient at the end of the follow-up period (minimum follow-up,12 months; maximum follow-up, 30 months; follow-up average, 22 months). To our knowledge, this is the first report of a clinical trial of cell therapy using autologous stem cells obtained from a lipoaspirate. Our results indicate that our protocol is feasible and safe for the treatment of fistulas in Crohn's disease. The number of patients included and the uncontrolled nature of Phase I clinical trials do not allow demonstration of the effectiveness of the treatment. However, the results of the present study encourage to perform further studies in Phase II.

The feasibility and safety of stem cell-based therapy with expanded adipose-derived stem cells (ASCs) has been investigated in a phase I clinical trial. The present study was designed as a phase II multicenter, randomized controlled trial to further investigate the effectiveness and safety of ASCs in the treatment of complex perianal fistulas. Patients with complex perianal fistulas (cryptoglandular origin, n = 35; associated with Crohn's disease, n = 14) were randomly assigned to intralesional treatment with fibrin glue or fibrin glue plus 20 million ASCs. Fistula healing and quality of life (SF-12 questionnaire) were evaluated at eight weeks and one year. If healing was not seen at eight weeks, a second dose of fibrin glue or fibrin glue plus 40 million ASCs was administered. Fistula healing was observed in 17 (71 percent) of 24 patients who received ASCs in addition to fibrin glue compared with 4 (16 percent) of 25 patients who received fibrin glue alone (relative risk for healing, 4.43; confidence interval, 1.74-11.27); P < 0.001). The proportion of patients with healing was similar in Crohn's and non-Crohn's subgroups. ASCs were also more effective than fibrin glue alone in patients with a suprasphincteric fistulous tract (P = 0.001). Quality of life scores were higher in patients who received ASCs than in those who received fibrin glue alone. At one year follow-up, the recurrence rate in patients treated with ASCs was 17.6 percent. Both treatments were well tolerated. Administration of expanded ASCs (20 to 60 million cells) in combination with fibrin glue is an effective and safe treatment for complex perianal fistula and appears to achieve higher rates of healing than fibrin glue alone.