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Supplier: STEMCELL Technologies

Flt3/Flk-2 (Fms-like tyrosine kinase 3/fetal liver kinase-2) ligand is a hematopoietic cytokine that plays an important role as a co-stimulatory factor in the proliferation, differentiation, and survival of hematopoietic stem and progenitor cells and the development of the immune system (Lyman et al.; Rosnet et al.). Flt3/Flk-2 ligand, together with stem cell factor and thrombopoietin, is commonly used to promote expansion of primitive hematopoietic cells in culture. In combination with myeloid cytokines such as GM-CSF, G-CSF, or M-CSF, Flt3/Flk-2 ligand enhances the growth and numbers of clonogenic myeloid progenitor cells. In synergy with IL-3, IL-4, IL-7, IL-11, IL-12, IL-15, GM-CSF, and TNF-α, Flt3/Flk-2 ligand regulates the development of various lymphoid progenitor cells, including dendritic cell, B cell, T cell, and NK cell progenitors. In contrast, Flt3/Flk-2 ligand has no significant effect on erythropoiesis or megakaryopoiesis (Drexler and Quentmeier; Wodnar-Filipowicz). Flt3/Flk-2 ligand exists as membrane-bound and soluble isoforms. Both isoforms are biologically active and signal through the class III tyrosine kinase receptor (Flt3/Flk-2, CD135; Rosnet et al.). Flt3/Flk-2 ligand is produced by a variety of cell types, including uncommitted and committed hematopoietic cells and stromal fibroblasts, whereas expression of the Flt3/Flk-2 receptor is restricted to CD34+ hematopoietic stem and progenitor cells. Flt3/Flk-2 receptor is also expressed outside the hematopoietic system in the brain, placenta, and testis (Drexler and Quentmeier; Hannum et al.).

Supplier: STEMCELL Technologies

The platelet-derived growth factor (PDGF) family has five heparin-binding members that assemble into four homodimers (PDGF-AA, PDGF-BB, PDGF-CC, and PDGF-DD) and one heterodimer (PDGF-AB; Li and Eriksson). PDGF signals through the receptor tyrosine kinases PDGFRα and PDGFRβ. It has been shown that PDGF-induced migration involves signaling pathways involving MEK/ERK, EGFR, Src and PI3K/AKT (Kim et al.). PDGF is a potent mitogen for cells of mesenchymal origin such as fibroblasts and vascular smooth muscle cells. PDGF has been implicated in pathogenesis of atherosclerosis, glomerulonephritis, cancer, and in the contraction of vascular smooth muscle cells of rat aortic tissues (Fretto et al.; Sachinidis et al.). PDGF-CC is secreted as a latent growth factor and requires activation by proteolytic processing (Li and Eriksson). PDGF-CC binds to PDGFRα homodimers and PDGFRαβ heterodimers, but not to PDGFRβ homodimers (Li and Eriksson). PDGF-CC is an angiogenic factor that stimulates coronary artery smooth muscle cell proliferation and plays a role in cardiovascular development (Gilbertson et al.). PDGF-CC is also expressed in many tumors and plays a role in tumorigenesis (Zwerner and May).

Supplier: STEMCELL Technologies

Ciliary neurotrophic factor (CNTF) is a neurotrophic factor that belongs to the four-helix bundle cytokine family and is structurally related to interleukin 6 (IL-6), interleukin 11 (IL-11), leukemia inhibitory factor (LIF), and oncostatin M (OSM). CNTF binds to its receptor CNFTRα and induces formation of a heterodimer of the signal-transducing IL-6 receptor gp130 and LIF receptor (LIFR)-β, which triggers JAK/STAT, ERK, and the PI3K signaling cascades (Schuster et al.). CNTF plays an important role in neurogenesis and the differentiation of neural stem cells and has been suggested to possess a therapeutic role in treating neurological disorders (Ding et al.; Oppenheim et al.). CNTF has also been shown to protect rod photoreceptors from light-induced damage and to have therapeutic effects on retinal degenerative diseases caused by genetic defect or damage induced by toxins, autoantibodies, or strong light (Pernet et al.; Rhee et al.). Another therapeutic role of CNTF has been reported in protecting oligodendrocytes from death induced by apoptosis (Louis et al.). Additionally, CNTF is commonly used to differentiate human pluripotent stem cell (hPSC)-derived neural progenitor cells into astrocytes (Krencik and Zhang).

Supplier: STEMCELL Technologies

Granulocyte-macrophage colony-stimulating factor (GM-CSF) promotes the proliferation and differentiation of hematopoietic progenitor cells and the generation of neutrophils, eosinophils, and macrophages. In synergy with other cytokines such as stem cell factor, IL-3, erythropoietin, and thrombopoietin, it also stimulates erythroid and megakaryocyte progenitor cells (Barreda et al.). GM-CSF is produced by multiple cell types, including stromal cells, Paneth cells, macrophages, dendritic cells (DCs), endothelial cells, smooth muscle cells, fibroblasts, chondrocytes, and Th1 and Th17 T cells (Francisco-Cruz et al.). The receptor for GM-CSF (GM-CSFR) is composed of two subunits: the cytokine-specific α subunit (GMRα; CD116) and the common subunit βc (CD131) shared with IL-3 and IL-5 receptors (Broughton et al.). GM-CSFR is expressed on hematopoietic cells, including progenitor cells and immune cells, as well as non-hematopoietic cells. Recombinant human GM-CSF (rhGM-CSF) promotes the production of myeloid cells of the granulocytic (neutrophils, eosinophils, and basophils) and monocytic lineages in vivo. It has been tested for mobilisation of hematopoietic progenitor cells and used to treat chemotherapy-induced neutropenia in patients. GM-CSF is able to stimulate the development of DCs that ingest, process, and present antigens to the immune system (Francisco-Cruz et al.).

Supplier: STEMCELL Technologies

Interleukin 11 (IL-11) is a pleiotropic cytokine with effects on various tissues including the bone marrow, brain, and intestinal mucosa (Du and amp; Williams). It belongs to the IL-6 family of cytokines that share a common signal transducer, gp130. Culture of mouse bone marrow cells with IL-11 in combination with IL-3, IL-6, and stem cell factor induces significant expansion and proliferation of colony-forming cells in vitro (Peters et al.). In addition, in combination with IL-3, IL-11 significantly enhances the growth of megakaryocytic colonies in vitro, suggesting its role in augmenting mouse megakaryopoiesis (Yonemura et al.). IL-11 is expressed in a wide range of normal adult mouse tissues, including the central nervous system, thymus, lung, and bone. The mouse IL-11 cDNA was cloned using an expression library generated from the lipopolysaccharide-induced mouse fetal thymic cell line, T2 (Morris et al.). The binding of IL-11 to its receptor induces heterodimerization with the gp130 subunit and activation of JAK tyrosine kinases. IL-11 also plays a role in cancer progression by inducing the proliferation of epithelial cancer cells and the survival of metastatic cells at distant organs. Recently, IL-11 has gained interest for its role in the pathogenesis of diseases in dysregulated mucosal homeostasis associated with STAT3 upregulation, including gastrointestinal cancers (Putoczki et al.).