Objectives:

Primary: To demonstrate the safety of allogeneic UC-MSCs administered by injection for complex perianal fistulas in patients with Crohn's disease

Secondary: To determine the efficacy of a single/multiple allogeneic UC-MSCs injection in improving complex perianal fistula complications and (re-epithelialization of the external openings).

Design and Investigation:

Number of Patients: 5 (including a consideration of 20% [1 patient] dropout from the trial)

Dosage and mode of administration Dosage: A total of 60 million PF2020-CELL (UC-MSCs) will be injected locally around the fistula tract, with a separation of 1 cm between injections. All patients will receive a total of 60 million cells per visit for 5 visits, with a 6 - 12 weeks interval between the injections. If the patient is completely healed during any course of stem cell injections, subsequent stem cell treatments can be discontinued. However, patients will still be required to undergo regular follow-up examinations, including physical examinations and other medical tests, until the study is completed.

Mode of administration: The procedure involves localizing the fistulous tract, performing curettage and closing the internal opening, and the injection of PF2020-CELL (UC-MSCs). The indicated dose of PF2020-CELL (UC-MSCs) will be injected starting from the tissues around the internal orifice or orifices and then progressing towards the external opening.

Inclusion Criteria:

• Adult men and women age 18 years and above.
• Diagnosis of perianal fistulae associated with Crohn's disease refractory to medical therapy.
• Presence of perianal fistula(s) with a maximum of 2 internal openings and a maximum of 3 external openings based on clinical assessment.
• Fit for surgery.

Exclusion Criteria:

• Informed consent refusal.
• Pregnancy or breastfeeding women.
• Current diagnosis of active cancer or remission for less than 5 years.
• Evidence of active sepsis or significant localised infection.
• Patients with HIV, HBV, HCV or treponema infection, whether active or latent.
• Patients with documented allergies.
• Patients who have received infliximab or any other biologics in the 4 weeks before the cell treatment administration.
• Patients currently receiving, or having received within 1 month prior to enrollment into this clinical trial, any investigational drug.
• Patients with any other co-morbidity/ co-pathologies which is deemed as contraindication to stem cells infusion (infection, administration of steroids).