MRI Evolution And Efficacy Of Bone Marrow-Derived Mesenchymal Stem Cells In Perianal Fistulae In Crohn’s Disease: Results From A Prospective Monocentric Study

Background and aims: Local injection of adipose tissue-derived mesenchymal stem cells (MSC) is effective in fistulizing perianal Crohn’s disease (CD). Less is known about bone marrow-derived MSC and little is known about predictive factors of response and MRI evolution of the fistulae after MSC injection. Our aims were to evaluate the safety and clinical outcome of bone marrow-derived MSC injection (BMMSC) for perianal fistulizing CD, to evaluate the MRI evolution of the fistulae and to identify factors associated with
fistula closure.
Patients and methods: All CD patients with perianal fistula and appropriate drainage with a seton without abscess at MRI were eligible. Clinical examination, biomarkers and pelvic MRI were performed at weeks 0, 12 and 48. The MAGNIFI-CD index13 and the Van Assche index12 were evaluated The degree of fibrosis of the fistula tract was evaluated by 2 radiologists The clinical outcome was assessed by closure of the treated external openings at clinical examination and MRI exploration. Fistula closure was defined by the
closure of all external openings at clinical examination without discharge at digital pressure and no collection >2 cm at the pelvic MRI. “Super closure” was defined as fistula closure and absence of discharge reported by the patient the week before the clinical visit.
Results: Sixteen patients with a median age of 49 years old and a median duration of perianal CD of 8 months were included. No unexpected safety event occurred. At week 12 and 48, 9/16 and 8/16 patients had complete fistula(e) closure, respectively, whereas 11/16 patients had at least partial closure. At MRI, the degree of fibrosis significantly increased after MSC injection. Eighty-six % of patients with >80% of fibrosis of the fistula tract at week 48 had fistula closure. Fistula closure at week 12 was predictive of fistula
closure at week 48. The MAGNIFI-CD did not change significantly overtime.
Conclusion: Open-label injection of bone marrow-derived mesenchymal stem cells was safe and was effective in half of the patients in fistulizing perianal CD and induced significant MRI changes associated with favorable clinical outcome.