Valproic acid and all trans retinoic acid differentially induce megakaryopoiesis and platelet-like particle formation from the megakaryoblastic cell line MEG-01.

Both, the activity of transcription factors as well as epigenetic alterations in defined DNA regions regulate cellular differentiation processes. Hence, neuronal differentiation from neural progenitor cells is promoted by the transcription factor all trans retinoic acid (ATRA) and the histone deacetylase inhibitor valproic acid (VPA). VPA has also been shown to be involved in differentiation of tumor cells and to greatly improve the reprogramming of human somatic cells to induced pluripotent stem cells. Here we have investigated the impact of ATRA and VPA on the differentiation of megakaryoctes and platelets from the megakaryocyte progenitor cell line MEG-01. Our results show that treatment with ATRA (10⁻¹¹ M) and VPA (2 × 10⁻³ M) induces megakaryopoiesis of MEG-01 cells as estimated by polyploidy, formation of characteristic proplatelets and elevated expression of the megakaryocytic markers CD41 and CD61. The resulting megakaryocytes stayed viable for more than 3 weeks and shed platelet-like particles positive for CD41, CD61 and CD42b into the supernatant. Platelet-like particles responded to thrombin receptor activating peptide (TRAP-6) with increased externalization of P-selectin. Thus, ATRA and VPA proved to be efficient agents for the gentle induction of megakaryopoiesis and thrombopoiesis of MEG-01 cells providing the possibility to study molecular events underlying megakaryopoiesis and human platelet production over longer time periods.