Augmented expansion of Treg cells from healthy and autoimmune subjects via adult progenitor cell co-culture

Abstract Recent clinical experience has demonstrated that adoptive regulatory T cell therapy is a safe and feasible strategy to suppress immunopathology via induction of host tolerance to allo- and autoantigens. However, clinical trials continue to be compromised due to an inability to manufacture a sufficient Treg cell dose. Multipotent adult progenitor cells (MAPC Ⓡ ) promote regulatory T cell differentiation in vitro , suggesting they may be repurposed to enhance ex vivo expansion of Tregs for adoptive cellular therapy. Here, we use a GMP compatible Treg expansion platform to demonstrate that MAPC cell-co-cultured Tregs (MulTreg) exhibit a log-fold increase in yield across two independent cohorts, reducing time to target dose by an average of 30%. Enhanced expansion is linked with a distinct Treg cell-intrinsic transcriptional program, characterized by diminished levels of core exhaustion ( BATF, ID2, PRDM1, LAYN, DUSP1 ), and quiescence ( TOB1, TSC22D3 ) related genes, coupled to elevated expression of cell-cycle and proliferation loci ( MKI67, CDK1, AURKA, AURKB ). In addition, MulTreg display a unique gut homing (CCR7lo β 7 hi) phenotype and importantly, are more readily expanded from patients with autoimmune disease compared to matched Treg lines, suggesting clinical utility in gut and/or Th1-driven pathology associated with autoimmunity or transplantation. Relative to expanded Tregs, MulTreg retain equivalent and robust purity, FoxP3 TSDR demethylation, nominal effector cytokine production and potent suppression of Th1-driven antigen specific and polyclonal responses in vitro and xeno graft vs host disease (xGvHD) in vivo . These data support the use of MAPC cell co-culture in adoptive Treg therapy platforms as a means to rescue expansion failure and reduce the time required to manufacture a stable, potently suppressive product.