THPO and idiopathic aplastic anemia: The stem cell effects of thrombopoietin can be demonstrated in vitro, with single cell culture experiments [16], in vivo in knock out mice (e.g. genetic elimination of c-Mpl or THPO reduce the number of transplantable hematopoietic stem cells by 10-fold [17]), and in people (missense or non-sense mutations of either gene cause congenital amegakaryocytic thrombocytopenia that can evolve into aplastic anemia if the mutation is severe [18]).