Before assessing the hematopoietic support of PV and ET MSCs towards their respective CD34+ HSPCs in primary patient samples, we initially evaluated the hematopoietic support provided by MPN stroma to a JAK2V617F CRISPR model, as JAK2V617F mutation is the most common mutation found in MPN patients.1 This evidence concerns the gene CD34 and myeloproliferative disorder.