Medicines available to the patients with severe blood diseases like aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH) are very limited. The idea of improvement the quality of blood cells with small molecules may give a new opportunity to cure AA and hope to reverse PNH. Our proposal is based on discovery of drugs (TCC1 and TCC2) which improve performance of blood stem cells by increasing their life span. We hypothesize that the unique biological activity of these agents can already be used in clinic to treat AA and PNH by restoration the function of damaged/exhausted blood stem cells. Such effects may help to alleviate diseases and accelerate recovery of normal blood in patients with AA or PNH. The objective of this study is preclinical testing of the identified drugs to enhance the biologic effects on blood stem cells in laboratory settings. In sum, this project represents early preclinical study investigations in a clinically important field of AA and PNH with a prospect of direct translation toward development of new therapies.