Various case reports and phase II trials have demonstrated potential efficacy with a good safety profile of MSCs for GVHD. This study can be com-mended simply for completing a randomized study in a large group of patients with SR-GVHD. Response rates in the MSC-treated patients were reasonable, and higher than placebo-treated patients. Nevertheless, despite including such a large number of patients, many questions remain unanswered. Would MSCs be most effective combined with a specific consistent second-line therapy? Numerous trials of SR-GVHD show high response rates but ultimately limited survival due to recurrent GVHD, infections, and even relapse; long-term outcomes beyond day 100 from this trial will be important to report for the transplant community. Finally, given the suggestion of important activity, further studying the role of MSCs for GVHD therapy earlier in the course of the disease will be important.