Relevance of clonogenic assays in hematotoxicology.

Clonogenic assays have been established in hematology for 30 years. They have been widely used in fundamental studies on hematopoiesis and they are also routinely used in clinical hematology to confirm diagnosis or to predict time to recovery in cases of bone marrow failure. Their use in toxicological studies is more recent. Adverse effects of xenobiotics can induce hematological problems and pathologies such as neutropenia, thrombocytopenia, anemia, and aplastic anemia. Three clonogenic assays are proposed for granulopoiesis, megakaryopoieisis and erythropoieisis. Hematopoietic progenitors from murine or human origin can be cultured in the presence of xenobiotics using validated protocols to complete standard animal toxicological studies. These clonogenic assays can help to predict adverse effects of drugs or toxicants. Clonogenic assays using white blood cell progenitors (CFU-GM culture) have recently been validated by ECVAM and can be used routinely. Megakaryocyte progenitor (CFU-MK) culture is under development and prevalidation in toxicological studies supported by ECVAM. Red blood cells progenitor culture (BFU-E) has been proposed but needs international validation to be recognized.