Infusions of Mesenchymal Stromal Cells in Children With Multisystem Inflammatory Syndrome

The purpose of this multi-site, pilot study is to test whether infusions of human cord tissue mesenchymal stromal cells (hCT-MSC) are safe in children with multi system inflammatory syndrome (MIS-C). We will also describe the symptom course and duration of this hyper-inflammatory syndrome in these patients. Six patients less than 21 years old with MIS-C that is refractory to intravenous immune globulin (IVIG) and/or steroids will be given intravenous infusions of hCT-MSCs. Doses of 2x10\^6 cells/kg (up to a maximum dose of 100x10\^6 cells) will be given on days 1, 2, 3, +/-7 (day 7 is optional). Participants will be followed up to 90 days after administration for severe adverse events and survival. Safety will be evaluated through adverse event monitoring, clinical evaluations (i.e., vital signs, physical examinations), laboratory tests (i.e., hematology, serum chemistries, and urinalysis), and cardiac function (i.e., echocardiogram, ECG) from the signing of informed consent and throughout the patient's participation in this treatment protocol.