The use of mesenchymal stem cells is considered a novel and promising therapeutic option for patients with perianal fistulizing Crohn's disease. However, due to limited clinical data, this multicentre, nationwide study aimed to assess its clinical efficacy in closing complex anal fistula.

Fifteen applications in 14 patients (3 male, 11 female) with complex anal fistulas treated in three tertiary hospitals in Austria were included between October 2018 and April 2021. Injection of 120 million allogeneic expanded adipose-derived mesenchymal stem cells (Cx601 - Darvadstrocel, Alofisel®) was performed in each patient. Closure of the external fistula opening without secretion by finger compression was defined as success.

Inclusion Criteria:

• patients aged 18 and older who had a non-active or mildly active luminal CD with complex fistula with a maximum of two internal and three external fistulas

Exclusion Criteria:

• rectovaginal fistulas
• rectal and/or anal stenosis
• active proctitis
• diverting stomas
• an abscess (<2cm) that was not drained at the fistula preperation visit

14 patients with Crohn's disease and complex fistula got enrolled in this study.

IPD can be shared just in anonymised form in case of an ethical agreement with other researches.