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Updated: Jun 12, 2026

Megakaryocyte Differentiation and Platelet Formation from Human Cord Blood-derived CD34+ Cells
Published on: December 27, 2017
Thrombopoietic agents
Roberto Stasi1, Jenny Bosworth, Elizabeth Rhodes
1Department of Haematology, St George's Hospital, London, United Kingdom. Roberto.Stasi@stgeorges.nhs.uk
Thrombopoietin (TPO) is the key cytokine involved in thrombopoiesis, and is the endogenous ligand for the thrombopoietin receptor that is expressed on the surface of platelets, megakaryocytes, and megakaryocytic precursors. First-generation thrombopoietic agents were recombinant forms of human TPO, and their development was discontinued after prolonged thrombocytopenia due to neutralizing auto-antibodies cross-reacting with endogenous TPO was observed. Second-generation thrombopoiesis-stimulating molecules are now available, which have unique pharmacological properties and no sequence homology to endogenous TPO. Two of these new agents, romiplostim and eltrombopag, have already completed phase III trials in primary immune thrombocytopenia and have been granted marketing authorization for use in this disease. Phase II and III trials with these novel drugs are ongoing in other conditions characterized by thrombocytopenia, such as chemotherapy, chronic liver disease, and the myelodysplastic syndromes. Most of the other second-generation thrombopoietic growth factors are in early phase clinical development.
Thrombopoietin (TPO) is the key cytokine involved in thrombopoiesis, and is the endogenous ligand for the thrombopoietin receptor that is expressed on the surface of platelets, megakaryocytes, and megakaryocytic precursors. First-generation thrombopoietic agents were recombinant forms of human TPO, and their development was discontinued after prolonged thrombocytopenia due to neutralizing auto-antibodies cross-reacting with endogenous TPO was observed. Second-generation thrombopoiesis-stimulating molecules are now available, which have unique pharmacological properties and no sequence homology to endogenous TPO. Two of these new agents, romiplostim and eltrombopag, have already completed phase III trials in primary immune thrombocytopenia and have been granted marketing authorization for use in this disease. Phase II and III trials with these novel drugs are ongoing in other conditions characterized by thrombocytopenia, such as chemotherapy, chronic liver disease, and the myelodysplastic syndromes. Most of the other second-generation thrombopoietic growth factors are in early phase clinical development.
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