TGF-BETA AND MEGAKARYOCYTES IN THE PATHOGENESIS OF MYELOFIBROSIS IN MYELOPROLIFERATIVE DISORDERS

Myeloproliferative disorders are clonal disorders of the hematopoietic stem cell and comprise a spectrum of more or less well-defined clinic al entities: polycythaemia vera, chronic myeloid leukemia, essential t hrombocythaemia, and agnogenic myeloid metaplasia. Myelofibrosis, whic h contributes substantially to the impaired hematopoiesis, is commonly observed in myeloproliferative disorders but it represents the criter ion of agnogenic myeloid metaplasia also termed idiopathic myelofibros is. Although progress has been made in the elucidation of the pathogen esis of myelofibrosis, it still remains unclear. The aim of this revie w is to adress the new insights that outline the potential role of TGF -beta in the promotion of myelofibrosis, through its release from mega karyocytes/platelets, particularly in agnogenic myeloid metaplasia.