The investigators propose to study the safety of autologous mesenchymal stromal cell transfer using a biomatrix (the Gore® Bio-A®; Fistula Plug) in a Phase I study using a single dose of 20 million cells. Twenty adult patients (age 18 years or older) with refractory, complicated perianal fistulizing Crohn's disease will be enrolled. Subjects will undergo standard adjuvant therapy including drainage of infection and placement of a draining seton with continuation of pre-existing anti-Crohn's therapy. Six weeks post placement of the draining seton, the seton will be replaced with the MSC loaded Gore® Bio-A® fistula plug as per current clinical practice. The subjects will be subsequently followed for fistula response and closure for 24 months. This is an autologous product derived from the patient and used only for the same patient.