ΔCD19 sel. iC9-CAR.CD33 ATCs demonstrate limited toxicity against normal hematopoietic stem cells.

<p>(a) Human CD34⁺-selected hematopoietic stem cells (CD34⁺ HSC) from healthy volunteer donors were co-cultured overnight with or without non transduced (NT) or ΔCD19 sel. iC9-CAR.CD33 activated T-cells (ATCs), generated from healthy donors at an effector:target (E:T) ratio of 4:1. Afterwards, CD34⁺ HSC were isolated with hematopoietic lineage depletion kit, and enumerated by flow cytometry; (mean±SEM, N:4, from duplicate experiments using ATCs from 2 different healthy donors). (b) 500 CD34⁺lyneage^- HSC, from each respective condition outlined above, were plated on cytokine conditioned semisolid medium, <i>(MethoCult H4434)</i>. After 14 days, hematopoietic colony formation was scored using standard morphologic criteria; (mean±SEM, N:4, from duplicate experiments using ATCs from 2 different healthy donors). CFU: Colony-forming unit: BFU-E: burst-forming unit-erythroid: CFU-M/G/GM: CFU-macrophage/granulocyte/granulocyte, macrophage; CFU-GEMM: CFU-granulocyte, erythroid, macrophage, megakaryocyte; SEM: standard error of the mean; NS: not statistically significant.