Cytokines such as erythropoietin (EPO) and thrombopoitein (TPO) and so on, which stimulate hematopoiesis, can regulate self-renewal, proliferation, differentiation, maturation and programmed cell death of hematopoietic cells through specifically binding to surface receptors. Recently random phage display peptide libraries and other screening methods have been used to isolate mimetic including small peptides and non-peptides molecules, which can mimic the same effects as cytokines, such as EPO and TPO, and demonstrate the similar potency and activity as EPO and TPO in a panel of in vitro biological assays and in animal experiments. These approaches are critical to further research of interactive mechanisms between cytokine and receptor, receptor activation and rational design of other desired cytokine mimetic. This review concisely introduced recent advances in research on mimetic of EPO, TPO and other cytokines and future directions.
Animals ; Cytokines ; pharmacology ; Erythropoietin ; pharmacology ; Hematopoiesis ; drug effects ; physiology ; Humans ; Peptide Library ; Peptides ; pharmacology ; Thrombopoietin ; pharmacology

In order to find a new TPO-mimic peptide with similar activity to TPO while reducing the side effects, a TPO-mimic peptide (P1) screened from a random peptide library was restructured. The new structure of the TPO mimic peptide (P2) was synthesized. After coupling P2 with Dextran 10 and performing intermolecular oxidation, dextran-coupled and dimerized form of P2 were obtained, naming D-P2 and (P2)(2) respectively. The activities of the peptides in vitro were measured with MTT method. The results showed that the EC50 of P2 was 20 nmol/L, 700 times higher than P1. The EC50 of D-P2 and (P2)(2) were 0.35 nmol/L and 0.14 nmol/L, respectively. After administrating to the mouse, the peptides increased the number of platelets in the blood circulation obviously without influence on other blood cells. In conclusion, the TPO-mimic peptides have prospects in treating diseases related with thrombocytopenia.
Animals ; Female ; Male ; Mice ; Platelet Count ; Thrombopoietin ; analogs & derivatives ; chemical synthesis ; pharmacology

Animals ; Blood Coagulation ; drug effects ; Blood Platelets ; drug effects ; Female ; Haplorhini ; Humans ; Interleukin-11 ; pharmacology ; Male ; Platelet Count ; Thrombopoietin ; pharmacology

In order to investigate the influence of cytokine combinations on proliferation and differentiation of human umbilical cord blood CD34(+) cells into megakaryocytes/platelets in vitro, the CD34(+) cells from human umbilical cord blood were amplified in serum-free medium StemSpan(SFEM) supplemented with several cytokine combinations by three-phase culture system. The effects of the cytokine combinations were compared. The results showed that at day 14 of the first culture phase, the CD34(+) cells cultured with cytokine combinations SCF + TPO + FL + IL-3 were amplified (11 000 ± 1 000) times, which were significantly higher than that of cells cultured with SCF + TPO + FL, but were not significantly different from that of cells cultured with SCF + TPO + IL-3 or SCF + TPO + FL + IL-3+ hydroxyl-corticosteroids. At day 7 of the second culture phase, the CD34(+) cells cultured with cytokine combination SCF + TPO + FL + IL-11 were amplified by (204666.7 ± 11718.9) times, which were significantly higher than that of cells cultured with SCF + TPO + FL + IL-3, but were not significantly different from that of cells cultured with SCF + TPO + FL + IL-11 + BMP4 + VEGF. At day 3 and day 6, the CD34(+) platelet-like cells accounted for about (39.8 ± 1.9)%, (39.7 ± 2.6)% and (25.5 ± 1.4)%, (23.1 ± 3.5)% cultured with SCF + TPO + FL + IL-11 and SCF + TPO + FL + IL-11 + BMP4 + VEGF, and significantly higher than that of the cells cultured with SCF + TPO + FL + IL-3. It is concluded that the cytokine combination of SCF + TPO + FL + IL-3 is most suitable cytokines combination for the amplification of CD34(+) hematopoietic progenitor cells. The cytokine combination of SCF + TPO + FL + IL-11 is preferred for the proliferation and differentiation of megakaryocytes, this study lays an experimental basis for investigating the proliferation and differentiation of CD34(+) into megakaryocytes/platelets in vitro.
Antigens, CD34 ; immunology ; Blood Platelets ; cytology ; Cell Differentiation ; Fetal Blood ; cytology ; immunology ; Humans ; Interleukin-11 ; pharmacology ; Interleukin-3 ; pharmacology ; Megakaryocytes ; cytology ; Stem Cell Factor ; pharmacology ; Thrombopoietin ; pharmacology

To identify the expression of thrombopoietin (TPO) receptors (c-mpl) on central nervous system (CNS) and to evaluate the role of TPO on neural cell proliferation and protection, immunohistochemical staining, RT-PCR, MTT, and annexin-V methods were used in this study. The results showed the expression of TPO receptor on human CNS and murine neural cells. C-mpl mRNA was identified in human cerebral hemispheres and cerebellum, and mouse neural cell line C17.2 by RT-PCR. C-mpl was also confirmed in human cerebral hemispheres by immunohistostaining with con-focal microscopy. Furthermore, TPO had a stimulating effect on the growth of in vitro neural cell C17.2 by MTT assay. The anti-apoptotic effect of TPO on C17.2 cells was also demonstrated by staining with annexin-V and PI. In conclusion, the first evidence showed the expression of TPO receptor c-mpl in central nervous system. Moreover, the effect of TPO on neural cell proliferation and anti-apoptosis was also demonstrated on in vitro neural cells.
Animals ; Apoptosis ; drug effects ; Brain Chemistry ; Cell Line ; Cell Proliferation ; drug effects ; Erythropoietin ; pharmacology ; Humans ; Mice ; Neoplasm Proteins ; analysis ; Neurons ; drug effects ; Oncogene Proteins ; analysis ; Proto-Oncogene Proteins ; analysis ; Receptors, Cytokine ; analysis ; Receptors, Thrombopoietin ; Thrombopoietin ; pharmacology

Animals ; Bone Marrow Cells ; cytology ; Cells, Cultured ; Culture Media, Conditioned ; Megakaryocytes ; cytology ; Mice ; Mice, Inbred Strains ; Thrombopoietin ; pharmacology

5-hydroxtryptamine (5-HT, serotonin) has been recognized not only as a neurotransmitter and vasoactive agent, but also as a growth factor. 5-HT mainly binds to 5-HT(2) receptors or 5-HT(1) receptors on cell surface to stimulate cell proliferation through Ras or MAPK pathway in many cell types. It has been reported that 5-HT stimulates megakaryocytopoiesis via 5-HT receptors. The possible mechanism of 5-HT on the proliferation and differentiation of megakaryocytes (MK) has been discussed in this review article. In early stage of megakaryocytopoiesis, 5-HT may bind to 5-HT(2B) receptor on megakaryocytes, and promotes their proliferation and differentiation. In the late stage, 5-HT may involve in the platelet release procedure by inducing nitric oxide (NO) synthesis via 5-HT(2A) receptors. 5-HT can also antagonize the apoptotic effect induced by thrombospondin-1 (TSP-1) which is a platelet alpha granule protein and has synergic effect with platelet-derived growth factor (PDGF) to enhance megakaryocytes proliferation. Therefore, 5-HT is likely to be an important substance in the feedback regulation of thrombopoiesis. In this review the 5-HT and its receptors, 5-HT as cell growth factor, pathway of 5-HT stimulating cell proliferation and influance of 5-HT on MK-progenitor cells were summarized.
Humans ; Megakaryocytes ; physiology ; Receptors, Serotonin ; metabolism ; Receptors, Serotonin, 5-HT2 ; metabolism ; Serotonin ; metabolism ; pharmacology ; Thrombopoiesis ; physiology ; Thrombopoietin ; physiology

This study was aimed to investigate whether the thrombopoietin (rhTPO) may facilitate myelofibrosis or not. The modified Dexter culture system with various concentrations of rhTPO was used to culture the stromal cells in vitro; the proliferative activity of cells was detected by MTT method; the morphologic changes were observed by light and scanning electron microscopy; the staining changes of ALP, PAS, AS-D NCE and IV type collagen were observed by cytochemistry method; the changes of fibronectin, laminin and IV type collagen were assayed by immunohistochemistry method; the cell surface antigens were assayed by flow cytometry. The results indicated that rhTPO could promote the proliferation of stromal cells which was related to the concentrations of rhTPO. Proliferative activity of stromal cells increased with increasing of rhTPO concentration, and was not related to the exposure time. On day 3 stromal cells adhered to the wall, and became oval. On day 7 stromal cells turned to fusiform and scattered dispersively. On day 12 to 14 these cells ranged cyclically and became long fusiform. Cells covered 70%-80% area of bottle bottom at that time. By day 16 to 18 these cells covered more than 90% area of bottom and ranged cyclically. They displayed the same shape as fibroblasts. By light microscopy with Wrights-Giemsa staining, fibroblasts predominated morphologically, few macrophages, endothelial cells and adipose cells were found. There were no significant differences between experimental group and control group. On day 14 to 42 the adherent cells were positive with PAS staining, poorly positive with ALP and naphthol AS-D chloroacetate esterase (AS-D NCE) staining, and the difference in cytochemistry was not significant between two groups. When these cells were dyed with Masson's trichrome and Gomori's staining, neither collagen fibers nor reticular fibers were positive, but fibronectin, laminin, and collagen type IV appeared positive stronger in experimental group than those in control. The expressions of these molecules were not dependent on culture time. By scanning electron microscopy microvilli and fibers on cell surface appeared more and more, monolayer cells evolved into multilayer cells, and newly-formed fibroblasts appeared gradually as culture time prolonged. These alterations were not different among various groups. The expressions of CD34, CD45, CD105, CD106, and CD166 were not affected obviously by rhTPO. It is concluded that rhTPO had no effects on histochemical properties of stromal cells. Fiber staining and scanning electron microscopic examinations revealed that rhTPO can not facilitate fiber formation of stromal cells. But rhTPO may be able to augment the expressions of fibronectin, laminin and collagen type IV of stromal cells. Therefore it is still necessary to follow up the patients for a long time, who have received rhTPO therapy clinically.
Bone Marrow Cells ; cytology ; drug effects ; Cell Proliferation ; drug effects ; Fibroblasts ; Humans ; Stromal Cells ; cytology ; drug effects ; Thrombopoietin ; pharmacology

BACKGROUNDHematopoietic growth factor (HGF) is indispensable to hematopoiesis in the body. The proliferation and differentiation of hematopoietic cells must rely on the existence and stimulation of HGF. This study investigated the effect of catechin, an active component extracted from Spatholobus suberectus Dunn (SSD), on bioactivity of granulocyte-macrophage colony-stimulating activity (GM-CSA), burst-promoting activity (BPA) and megakaryocyte colony-stimulating activity (MK-CSA) in spleen condition medium (SPCM) of mice to clarify the hematopoietic mechanism of catechin and SSD.

METHODSSpleen cells of mice were separated and spleen condition medium (SPCM) was prepared from spleen cell culture. Bone marrow cells of mice were separated and cultured in a culture system including 10% (v/v) SPCM (induced by catechin in vivo or ex vivo) for 6 days. Granulocyte-macrophage colony forming units (CFU-GM), erythrocyte burst-colony-forming units (BFU-E) and megakaryocyte colony-forming units (CFU-Meg) formation were employed to assay the effects of different treatment on the bioactivity of GM-CSA, BPA and MK-CSA in SPCM.

RESULTSSPCM induced by 100 mg/L catechin ex vivo could promote the growth of CFU-GM, BFU-E and CFU-Meg, which indicated that catechin could stimulate the production of GM-CSA, BPA and MK-CSA in SPCM. SPCM prepared at the fourth day of spleen cell culture showed the best stimulating activity. The bioactivity of GM-CSA, BPA and MK-CSA in the SPCM prepared after intraperitoneally injecting catechin into mice was also increased. The number of CFU-GM, BFU-E and CFU-Meg gradually increased as the dose of catechin increased and the time of administration prolonged. CFU-GM, BFU-E and CFU-Meg of the high-dose catechin group were significantly higher than those of the control group (P < 0.01) and reached the maximum at the seventh day after administration.

CONCLUSIONSThis study suggests that catechin extracted from the active acetic ether part of Spatholobus suberectus Dunn can regulate hematopoiesis by inducing bioactivity of GM-CSA, BPA and MK-CSA in SPCM of mice. This may be one of the mechanisms for the hematopoietic-supportive effect of catechin and Spatholobus suberectus Dunn.

Animals ; Catechin ; pharmacology ; Granulocyte-Macrophage Colony-Stimulating Factor ; physiology ; Hematopoiesis ; drug effects ; Interleukin-3 ; physiology ; Mice ; Thrombopoietin ; physiology

This study was aimed to investigate the effect of angiotensin II on differentiation of cord blood CD34+ cells into megakaryocytes in vitro. The CD34+ cells from eight fresh umbilical cord blood samples sorted by a high-gradient magnetic cell sorting system (MACS) were cultured in serum-free culture medium containing thrombopoietin (TPO) 50 ng/ml, IL-3 10 ng/ml, stem cell factor (SCF) 50 ng/ml and different concentrations of angiotensin II (0, 50, 100, 1000 microg/ml) for 14 days. Mononuclear cells (MNC) were counted by automatic cell analyzer. Cultured CD41+ cell and platelet counts in cultured system, and cell cycle were analyzed by flow cytometry. CD41 specific monoclonal antibody staining was observed by immunofluorescence microscopy. The results showed that as compared with the control group, the number of MNC not increased significantly (P > 0.05), but the number of CD41+ cells and platelets increased significantly in treatment group (P < 0.05). Cell cycle analysis revealed that the amounts of 4N cells increased and apoptosis cells obviously existed in treatment group (P < 0.05). After fluorescence staining, more CD41+ cells of different sizes were observed by means of fluorescence microscopy in both groups. It is concluded that angiotensin II can induce the cord blood CD34+ cells to differentiate towards megakaryocyte, and enhance the function of megakaryocyte to produce platelet.
Angiotensin II ; pharmacology ; Antigens, CD34 ; analysis ; Cell Differentiation ; drug effects ; Cells, Cultured ; Culture Media, Serum-Free ; Fetal Blood ; cytology ; Humans ; Megakaryocytes ; cytology ; Stem Cell Factor ; pharmacology ; Thrombopoietin ; pharmacology