**6.1 Clinical potential and market of MSC in hematopoietic disorders**

MSCs have been implicated in immunomodulatory therapy, in particular, in GVHD treatment and as an adjunct to hematopoietic stem cell transplantation (HSCT) to help enhance engraftment [87, 88]. The first major clinical trial of MSCs (Prochymal) was for the treatment of steroid-refractory of GVHD (NCT00366145) [89, 90]. The primary endpoint of the study was complete remission at day 28 after allogeneic BM-MSCs infusion but was not significantly increased compared to placebo [89, 91]. In 2012, MSCs have bens conditional approval to treat children GVHD in Canada, based on subset analysis that suggested children with GVHD were responsive to MSCs [89, 92, 93]. Many new studies have been developed in recent years; however, a few of them have attempted to look at biological correlates of response to therapy. Isolated studies reported serum biomarkers of GVHD severity including IL-2, *tumor necrosis factor receptor 1 (*TNFR1), regenerating islet-derived protein 3 alpha (Reg3a), and levels of inflammatory cytokines, which not clearly correlate with the response in humans. More studies are needed to obtain correlative research data [94, 95]. This outcome results in the first Food and Drug Administration (FDA) approved MSCs product in the United States [96, 97].
