Evaluation of Umbilical Cord-Derived Wharton's Jelly Stem Cells for the Treatment of Acute Graft Versus Host Disease

Inclusion Criteria: * Age: ≥ 18 years of age and ≤ 75 years of age. * Women of child-bearing potential and men with partners of child-bearing potential must agree to practice sexual abstinence, or to use two forms of adequate contraception (hormonal AND barrier method of birth control) prior to study entry, for the duration of study participation, and for 90 days following completion of therapy. If a woman becomes pregnant or suspects she is pregnant while participating in this study, she should inform her treating physician immediately. * A woman of child-bearing potential is any female (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria: * Has not undergone a hysterectomy or bilateral oophorectomy; OR * Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months) * Men of child-bearing potential must not donate sperm while on this study and for 90 days after their last study treatment. * NOTE: Acceptable forms of birth control are listed below: * One Barrier method (cervical cap with spermicide plus male condom; diaphragm with spermicide plus male condom) PLUS * Hormonal method (oral contraceptives, implants, or injections) or an intrauterine device (e.g., Copper-T). * Participant must have de novo HR or steroid refractory, Grade II-IV aGVHD as defined in Appendix 1. NOTE: Biopsy a…