RecruitingEarly Phase 1Clinical trialAddition of Cord Blood Tissue-Derived Mesenchymal Stromal Cells to Ruxolitinib for the Treatment of Steroid-Refractory Acute Graft Versus Host DiseaseThis early phase I trial is to find out the effect of adding cord blood tissue-derived mesenchymal stromal cells (cb-MSCs) to ruxolitinib in treating patients with acute graft versus host disease that does not respond to steroid therapy (steroid-refractory). Ruxolitinib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. cb-MSCs are a type of tissue helper cell that can be removed from donated umbilical cord blood tissue and grown into many different cell types that can be used to treat cancer and other disease, such as graft versus host disease. This trial aims to learn if adding cb-MSCs to ruxolitinib may help control steroid-refractory acute graft versus host disease.