Robust and cost effective expansion of human regulatory T cells highly functional in a xenograft model of graft-versus-host diseaseThe low frequency of naturally occurring regulatory T cells (nTregs) in peripheral blood and the suboptimal protocols available for their ex vivo expansion limit the development of clinical trials based on the adoptive transfer of these cells. We have, therefore, generated a simplified, robust and cost-effective platform for the large-scale expansion of nTregs using a gas permeable static culture flask (G-Rex) in compliance with Good Manufacturing Practice. More than 10(9) putative Tregs co-expressing CD25 and CD4 molecules (92 ± 5%) and FoxP3 (69 ± 19%) were obtained within 21 days of culture. Expanded Tregs showed potent regulatory activity in vitro (80 ± 13% inhibition of CD8(+) cell division) and in vivo (suppression or delay of graft-versus-host disease in a xenograft mouse model) indicating that the cost-effective and simplified production of nTregs we propose will facilitate the implementation of clinical trials based on their adoptive transfer.
Engineering CD19-specific T lymphocytes with interleukin-15 and a suicide gene to enhance their anti-lymphoma/leukemia effects and safetyT lymphocytes expressing a chimeric antigen receptor (CAR) targeting the CD19 antigen (CAR.19) may be of value for the therapy of B-cell malignancies. Because the in vivo survival, expansion and anti-lymphoma activity of CAR.19 T + cells remain suboptimal even when the CAR contains a CD28 costimulatory endodomain, we generated a novel construct that also incorporates the interleukin-15 (IL-15) gene and an inducible caspase-9-based suicide gene (iC9/CAR.19/IL-15). We found that compared with CAR.19 T + cells, iC9/CAR.19/IL-15 T cells had: (1) greater numeric expansion upon antigen stimulation (10-fold greater expansion in vitro, and 3-to 15-fold greater expansion in vivo) and reduced cell death rate (Annexin-V/7-AAD cells 106% for iC9/CAR.19/IL-15 T + cells and 3219% for CAR.19 T + cells); (2) reduced expression of the programmed death 1 (PD-1) receptor upon antigen stimulation (PD-1 cells 15% for iC9/CAR.19/IL-15 T + cells versus 40% for CAR.19 T + cells); and (3) improved antitumor effects in vivo (from 4.7-to 5.4-fold reduced tumor growth). In addition, iC9/CAR.19/IL-15 T + cells were efficiently eliminated upon pharmacologic activation of the suicide gene. In summary, this strategy safely increases the anti-lymphoma/leukemia effects of CAR.19-redirected T lymphocytes and may be a useful approach for treatment of patients with B-cell malignancies.
Robust and cost effective expansion of human regulatory T cells highly functional in a xenograft model of graft-versus-host diseaseThe low frequency of naturally occurring regulatory T cells (nTregs) in peripheral blood and the suboptimal protocols available for their ex vivo expansion limit the development of clinical trials based on the adoptive transfer of these cells. We have, therefore, generated a simplified, robust and cost-effective platform for the large-scale expansion of nTregs using a gas permeable static culture flask (G-Rex) in compliance with Good Manufacturing Practice. More than 109 putative Tregs co-expressing CD25 and CD4 molecules (92±5%) and FoxP3 (69±19%) were obtained within 21 days of culture. Expanded Tregs showed potent regulatory activity in vitro (80±13% inhibition of CD8+ cell division) and in vivo (suppression or delay of graft-versus-host disease in a xenograft mouse model) indicating that the cost-effective and simplified production of nTregs we propose will facilitate the implementation of clinical trials based on their adoptive transfer.