Protocol 620 provides PROCHYMAL(R) adult human mesenchymal cells to specifically chosen Crohn's disease patients at participating centers who typically have already demonstrated good response in another PROCHYMAL study, are not eligible for other PROCHYMAL studies, and in the view of the investigator, would not benefit significantly from other Crohn's therapies but would benefit from use of PROCHYMAL.

The study is not placebo-controlled or randomized.

Inclusion Criteria:

• currently active moderate-to-severe Crohn's disease
• exhausted standard-of-care options
• age 18 to 70 inclusive
• body weight between 30 and 150 kg
• adequate renal function
• not at risk for tuberculosis (TB) activation or re-activation

Exclusion Criteria:

• biologic therapy for Crohn's within last 8 weeks
• confirmed adverse reactions during prior PROCHYMAL study participation
• alcohol or substance abuse, current or within past 6 months
• active HIV or hepatitis B or C infection
• surgery or trauma with 6 weeks
• allergy to bovine or porcine products
• elevated serum liver enzymes
• elevated serum bilirubin
• active malignancy within 5 years (other than some resected skin cancers)
• bacteremia or other serious bacterial or fungal infection within 3 months
• colonic dysplasia
• unstable arrhythmia or serious heart condition