Two small-molecule compounds can help researchers maintain leukemic stem cells (LSCs) in culture, according to a paper published in Nature Methods.
Investigators said they created improved culture conditions for primary human acute myeloid leukemia (AML) cells, based on serum-free medium supplemented with the small molecules SR1 and UM729.
These conditions increased the yield of phenotypically undifferentiated CD34+ AML cells and supported the ex vivo maintenance of LSCs that are typically lost in culture.
Caroline Pabst, MD, of the Institute for Research in Immunology and Cancer at the University of Montreal in Quebec, Canada, and her colleagues conducted this research using AML patient samples.
The team screened about 6000 compounds in an attempt to identify small molecules that promote the ex vivo expansion of undifferentiated AML cells.
And they found that suppressors of the aryl-hydrocarbon receptor (AhR) pathway were enriched among the hit compounds.
So the researchers decided to study 2 chemically distinct AhR suppressors: N-methyl-β-carboline-3-carboxamide (C05), which yielded the highest CD34+CD15- cell counts in secondary screens, and the known AhR antagonist SR1. They also studied the pyrimidoindole UM729, which had shown no effects on AhR target genes.
Experiments showed that the AhR pathway was “rapidly and robustly” activated in the AML samples upon culture. However, suppressing the pathway with SR1 and C05 enabled the expansion of CD34+ AML cells and supported the maintenance of LSCs.
In addition, UM729 had an additive effect with SR1 on the maintenance of AML stem and progenitor cells in vitro.
The investigators said these results should help establish defined conditions to overcome spontaneous differentiation and cell death in ex vivo cultures of primary human AML specimens.
The team believes at least 3 molecular targets could be involved in this process, and 2 of them are targeted by SR1 and UM729.
So these compounds could serve as a standardized supplement to culture media. They might aid studies of self-renewal mechanisms and help researchers identify new antileukemic drugs.
