Isolation, expansion and functional characterization of hPL-expanded hBM-MSC for the treatment of systemic and severe acute Graft-versus-Host Disease

In this study, we first developed an expansion protocol for human bone marrow derived-MSC (hBM-MSC) using two different supplements for culture media, i.e. fetal bovine serum (FBS) or human platelet lysate (hPL). Interestingly, hPL supplement was more effective than FBS in expanding MSC. Afterwards, we characterized MSC and confirmed their genome stability through karyotype analysis and real time-PCR. MSC were then assessed in vitro for their ability to acquire the anti-inflammatory phenotype necessary for avoiding immune rejection and modulating host immune effector cells. MSC priming with TNF-α and IFN-γ led to increased ability in preventing NK cell-mediated lysis. Moreover, using standardized proliferation assays, MSC displayed strong immune suppressive activity towards T, B and NK cells. We then obtained a reproducible xenogeneic mouse model of aGvHD that was used to assess in vivo the efficacy of hPL-expanded MSC-based immunotherapy with different schedules of MSC administration