Transcription Factor Levels after Forward Programming of Human Pluripotent Stem Cells with GATA1, FLI1, and TAL1 Determine Megakaryocyte versus Erythroid Cell Fate Decision.

Abstract

The production of blood cells and their precursors from human pluripotent stem cells (hPSCs) in vitro has the potential to make a significant impact upon healthcare provision. In this manuscript we demonstrate that the forward programming of hPSCs through overexpression of GATA1, FLI1 and TAL1 leads to the production of a population of progenitors that can differentiate into megakaryocyte or erythroblasts. Using “rainbow” lentiviral vectors to quantify individual transgene expression in single cells, we demonstrate that cell fate decision towards an erythroblast or megakaryocyte is dictated by the level of FLI1 expression and independent of culture conditions. Early FLI1 expression is critical to confer proliferative potential to programmed cells whilst its subsequent silencing or maintenance dictates an erythroid or megakaryocytic fate, respectively. These committed progenitors subsequently expand and mature into megakaryocytes or erythroblasts in response to thrombopoietin or erythropoietin. Our results reveal molecular mechanisms underlying hPSC forward programming and novel opportunities for application to transfusion medicine