Expression profiles of 7-day cultured HSPCs in the presence or absence of valproic acid and/or lithium. Mus musculus

Two small molecules, valproic acid (VPA) and lithium (Li), were tested to inhibit differentiation of hematopoietic stem/progenitor (HSPC) cells in culture. HSPCs exposed to VPA and Li during differentiation-inducing culture preserved an immature cell phenotype, provided radioprotection to lethally irradiated recipients and enhanced in vivo repopulating potential. Furthermore, VPA and Li synergistically preserved expression of stem cell-related genes and repressed genes involved in differentiation. Target genes were collectively co-regulated during normal hematopoietic differentiation. Additionally, transcription factor networks were identified as possible primary regulators. Our results demonstrate that the combination of VPA and Li potently prevents differentiation at the biological and the molecular level, and provide evidence to suggest that combinatorial screening of chemical compounds may uncover possible additive/synergistic effects to modulate stem cell fate decisions. Overall design: These data consist of total mRNA obtained from hematopoietic cells cultured for 7 days in the presence or absence of valproic acid and/or lithium. All samples were analyzed in independent biological triplicates.