Figure 6 Injection of mesenchymal stem cells in perianal fistulas Figure 6 | Injection of mesenchymal stem cells in perianal fistulas. First the fistula internal opening is closed using polygalactin absorbable stitches. Subsequently, a suspension of 120 million mesenchymal stem cells are injected, distributing the cells into the tissue adjacent to all fistula tracts (60 million, blue spots) and internal openings (60 million, yellow spots). Panés, J. & Rimola, J. (2017) Perianal fistulizing Crohn’s disease: pathogenesis, diagnosis and therapy Nat. Rev. Gastroenterol. Hepatol. doi:10.1038/nrgastro.2017.104