Epoxyeicosatrienoic Acids Enhance Haematopoietic Stem and Progenitor Cell Specification and Engraftment

Haematopoietic stem and progenitor cell (HSPC) transplant is a widely used treatment for life-threatening conditions including leukemia; however, the molecular mechanisms regulating HSPC engraftment of the recipient niche remain incompletely understood. Here, we developed a competitive HSPC transplant method in adult zebrafish, using in vivo imaging as a non-invasive readout. We used this system to conduct a chemical screen and identified epoxyeicosatrienoic acids (EET) as a family of lipids that enhance HSPC engraftment. EETs’ pro-haematopoietic effects are conserved in the developing zebrafish, where this molecule promotes HSPC specification through activating a unique AP-1/runx1 transcription program autonomous to the haemogenic endothelium. This effect requires the activation of PI3K pathway, specifically PI3Kg. In adult HSPCs, EETs induce transcriptional programs including AP-1 activation, modulating multiple cellular processes, such as migration, to promote engraftment. Finally, we demonstrated that the EET effects on enhancing HSPC homing and engraftment are conserved in mammals. Our study established a novel method to explore the molecular mechanisms of HSPC engraftment, and discovered a previously unrecognized, evolutionarily conserved pathway regulating multiple haematopoietic generation and regeneration processes. EETs may have clinical application in marrow or cord blood transplantation. Overall design: To analyze the effect of 11,12-EET on gene expression of human blood cells, we treated human CD34+ cells (positively selected from cord blood) and the human leukemic cell line U937 with 5uM 11,12-EET for 2 hrs. Control treatment was done with DMSO.

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Li P, Lahvic JL, Binder V, Pugach EK, Riley EB, Tamplin OJ, Panigrahy D, Bowman TV, Barrett FG, Heffner GC, McKinney-Freeman S, Schlaeger TM, Daley GQ, Zeldin DC, Zon LI