rHu TPO Protein

Product Summary

• High purity human protein (Uniprot: P40225)
• 16 kDa (monomer)
• >98%, by SDS-PAGE quantitative densitometry
• Expressed in E. coli
• Animal origin-free (AOF) and carrier protein-free
• Manufactured in Cambridge, UK at Qkine laboratories
• Lyophilized from acetonitrile, TFA

Alternative Names

• Thyroid Peroxidase, TPX, Thyroid Microsomal Antigen, Thyroperoxidase, TDH2A, Thrombopoietin, THPO, MPL ligand, megakaryocyte colony-stimulating factor, MGDF, Qk98

Reconstitution

Resuspend in 10 mM HCl (Reconstitution solution A) at >50 µg/ml, add carrier protein if desired, prepare single-use aliquots and store frozen at -20 °C (short-term) or -80 °C (long-term)

For Use Statement

For research use only. This product is not for human use or for direct clinical use as a drug, therapeutic, biologic or medical device.

Certificate of Analysis (CoA)
Certificate of Origin (CoO)
Safety Data Sheet (SDS)
Product Page

TPO is a class I hematopoietic cytokine encoded by a gene located on chromosome 3q26-27. The TPO protein consists of 355 amino acids with the first 155 being homologous to erythropoietin (EPO) [1]. TPO binds to its receptor, Mpl and regulates proliferation and maturation of megakaryocytes as well as platelet production [1, 2].

TPO is primarily synthesized in the liver but can also be produced by the kidney, spleen, and bone marrow. In the liver, its production is constitutive and not linked to anemia like its homolog EPO [2]. Reduced platelet production leads to thrombocytopenia, a common hematological disorder which can lead to spontaneous bleeding, frequently as a side effect of cancer treatment [4, 5]. Severe cases may require a platelet transfusion [4]. However, the use of recombinant TPO as a treatment for thrombocytopenia has been investigated and has shown to increase platelet count [5].

TPO can also be used in the culture and differentiation of hematopoietic stem cells (HSCs) for research and therapeutic applications. TPO can support ex vivo expansion of HSC in combination with Flt3L and SCF [2]. In addition, it also increases the number of erythroid and myeloid progenitors, in synergy with stem cell factor (SCF) and interleukin-3 (IL-3) [3].

The TPO receptor Mpl is expressed primarily on megakaryocytes and platelets. TPO binding to Mpl causes receptor dimerization and phosphorylation by JAK2. This activates multiple downstream signaling pathways including STATs, the MAPK pathway, and the PI3K pathway [2].

[1] Foster DC, Sprecher CA et al. Human thrombopoietin: gene structure, cDNA sequence, expression, and chromosomal localization. Proc Natl Acad Sci U S A. 1994. doi: 10.1073/pnas.91.26.13023.

[2] de Graaf CA, Metcalf D. Thrombopoietin and hematopoietic stem cells. Cell Cycle. 2011. doi: 10.4161/cc.10.10.15619.

[3] Kobayashi M, Laver JH et al. Thrombopoietin Supports Proliferation of Human Primitive Hematopoietic Cells in Synergy with Steel Factor and/or Interleukin-3. Blood 1996. https://doi.org/10.1182/blood.V88.2.429.bloodjournal882429.

[4] Wörmann B. Clinical indications for thrombopoietin and thrombopoietin-receptor agonists. Transfus Med Hemother. 2013. doi: 10.1159/000355006.

[5] Vadhan-Raj S, Murray LJ et al. Stimulation of Megakaryocyte and Platelet Production by a Single Dose of Recombinant Human Thrombopoietin in Patients with Cancer. Ann Intern Med.1997. doi:10.7326/0003-4819-126-9-199705010-00001