Bone marrow aplasia, also known as aplastic anemia (AA) is a potentially fatal bone marrow failure syndrome characterized by a paucity of hematopoietic stem cells (HSCs) and progenitor cells with varying degrees of cytopenia and fatty infiltration of the bone marrow space. Underlying mechanisms include immune-mediated attack, telomere defects, and inherent HSC compartment insufficiency. These events may occur individually or in concert, mostly involving effector T cells Historical treatment has included the use of high-dose chemotherapy and allogeneic stem cell transplantation as well as lymphotoxic immunosuppressive therapy (IST) Thrombopoietin (TPO) regulates platelet production, maturation, and release through binding of c-mpl on megakaryocytes.