Endoscopy and FACS analysis in classic and humanized murine models of GVHD (HUM1P.316)

Abstract It is perplexing that standard murine GVHD model endpoints of weight loss (WL) and composite clinical changes (CCC) often fail to respond to standard forms of therapy (tacrolimus and anti-p40 monoclonal antibody). To improve on the translatability of GVHD models we evaluated serial endoscopy as a means to directly assess injury and serial blood counts to predict onset of severe disease. Two models were used. CD3+ cells were magnetically depleted from bone marrow harvested from male Balb/c mice. Varying numbers of (depleted) bone marrow and splenocytes were then injected IV into lethally irradiated (8Gy) C57Bl/6 hosts. Serial endoscopy performed after GVHD onset (~2 weeks post transfer) demonstrated changes which strongly correlated with WL and CCC (R2=-0.84 and 0.79). Next we induced GVHD in a humanized model by the adoptive transfer of human PBMCs into severely immunocompromised mice (NSG). Serial blood draws demonstrated a strong correlation between peripheral blood human T cell (PBTC) numbers and WL and CCC (R2=-0.85 and 0.67 on day 42) suggesting that assessment of PBTC numbers may be applicable to the evaluation of therapies directly targeting these cell types. Day 7 human PBTC counts predicted final WL and CCC scores with high correlation (R2=-0.86 and 0.90) indicating that this metric can be used to stratify animals into groups prior to the onset of observable disease and treatment.