Targeting the aryl hydrocarbon receptor nuclear translocator complex with DMOG and Stemregenin 1 improves primitive hematopoietic stem cell expansion

•G-CSF provided a 3.2 fold increase in cell proliferation and actual number of cells with the side population characteristics.•DMOG provided similar, but not the same observations compared to hypoxia.•The use of Stemregenin 1 provided significant increase in the side population as well as secondary engraftment.•Stemregenin 1 with DMOG significantly inhibited cell proliferation and provided the highest proportion of side population.•The use of Stemregenin 1 with hypoxia provided less sells but similar engraftment levels compared to the use of Stemregenin 1.

Culture conditions used for the expansion of hematopoietic stem and progenitor cells (HSCs and HPCs, collectively HSPCs) should ideally favor the self renewal of long-term HSCs. At 20% O2, the synthesis of HIF-1α is balanced by its hydroxylation and proteasomal degradation. This favors HSPC differentiation, but can be prevented by culturing CD34 + cord blood cells in the presence of dimethyloxaloylglycine (DMOG). This differentiation may also be reduced by culturing the cells in the presence of Stemregenin 1, an antagonist of the aryl hydrocarbon receptor (AhR). The objective of this study was to investigate how hypoxia, DMOG and Stemregenin 1 might affect the expansion of HSPCs with the aim of identifying optimal conditions for expansion in culture. It was found that DMOG decreased proliferation but was effective in preserving the number of cells in the primitive hematopoietic sub-populations in vitro. The effect of DMOG was similar to hypoxia, although differences were observed with regard to the side population and CD34 + sub-populations. Stemregenin 1 on the other hand increased the size of the primitive as well as the other HSC sub-populations. The use of Stemregenin 1 with DMOG increased the proportion of primitive HSCs to 3.54% compared to 2.61% for Stemregenin 1 alone. In vivo engraftment studies confirmed these findings and showed that fewer cells (3710) are required for long-term engraftment when HSCs are grown in Stemregenin 1 together with hypoxia than in Stemregenin 1 under conditions of normoxia (13430).