The contribution of fish models in understanding of blood disorders

Abstract

Human and fish peripheral blood contains erythrocytes or red blood cells, leukocytes or white blood cells and platelets or thrombocytes. Although the fish present the same types of blood cells as humans, studies have highlighted some morphological, ultrastructural and cytochemical differences in blood cells of the two groups of vertebrates. In both human and fish hematological tests are indispensable tools which provide a considerable amount of useful information for evaluation of the general state of health. Although there are limited amount of studies on blood cells in fish, over the years especially Danio rerio, has become an powerful model organism for studying human hematological diseases, as anemia, leukemia, myeloproliferative diseases and others human hematological diseases. Thereby, fish are ideal model organisms for studying hematological diseases due to external fertilization, brief development time, large number of embryos and the results can be extrapolated to mammals, including human. Furthermore, ikaros, rag-1, rag-2 and lck genes that are found in human were observed in Danio rerio revealing the spatio-temporal proximity between these groups of vertebrates. Therefore, studies realized on fish can offer essential information about molecular mechanism which causes the appearance of numerous human hematological diseases and discovery of possible therapeutic methods. This review provides a comparative overview of blood cells in fish and humans and describes zebrafish mutants as models of human hematologic disorders.