Ricolinostat promotes the generation of megakaryocyte progenitors from human hematopoietic stem and progenitor cells

Ex vivo production of induced megakaryocytes (MKs) and platelets from stem cells is an alternative approach for supplying transfusible platelets. However, it is still difficult to generate large numbers of MKs and platelets from cord blood hematopoietic stem cells. To optimize the differentiation efficiency of megakaryocytic cells from hematopoietic stem and progenitor cells (HSPCs), we first employed a platelet factor 4 (PF4)-promoter reporter and high-throughput screening strategy to screen for small molecules. We found that a small molecule, Ricolinostat, efficiently promoted the generation of CD34+CD41+ megakaryocyte progenitor cells (MkPs) and CD41+CD61+ MKs from cord blood HSPCs. Ricolinostat showed the capacity to enhance the cell fate commitment of MkPs from HSPCs and promoted the proliferation of CD34+CD41+ MkPs. Ricolinostat significantly increased the gene expression levels of key MK transcriptional factors, including HOXC6 and PCGF2. Notably, these megakaryocytic cells generated from Ricolinostat-induced HSPCs could differentiate into mature MKs and platelets. Additionally, RNA sequencing data suggested that Ricolinostat might enhance MkP fate mainly by inhibiting the secretion of IL-8 and decreasing the expression of IL-8 receptor CXCR2. Our study will help in the development of manufacturing protocols for large-scale generation of induced MKs and platelets for clinical application. Overall design: CD34+CD41+ cells were sorted by flow cytometry on day 7. After 7 days of Ricolinostat treatment, the cells were collected and centrifuged at 2000 rpm.