Research Progress on the Mechanism of Tubulin in Megakaryopoiesis and Regulation of Platelet Count--Review / 中国实验血液学杂志

Tubulin affects platelets count through the control of mitosis and the formation of pro-platelets during the maturation of megakaryoblast to platelets. Tubulin is involved in maintaining the integrity of platelet skeleton, and also participates in the change of platelet morphology during platelet activation. Some new anti-tumor drugs targeting cell mitosis are trying to reduce the effect on tubulin in order to reduce the side effect of drugs on platelet formation. In some patients with thrombocytopenia, the variation and polymorphism of the tubulin gene affect the structure of microtubule multimers, which leads to the decrease of platelet formation. This review summarized the latest progresses of tubulin in the regulation of megakaryopoiesis and thrombopoiesis.

Regulation of the Megakaryocyte Development and the Platelet Production--Review / 中国实验血液学杂志

The main physiological function of megakaryocytes is the production of platelets, whose development, maturation and platelet production are a complex regulatory process, and are involved in many factors. In recent years it was found that the lung is also the main site of megakaryocyte-producing platelets in addition to bone marrow. Based on the findings of recent years, this review summarizes the process of megakaryocyte development, maturation and platelet production, with emphasis on the analyzing the regulatory effects of apoptotic factors, miRNA, thrombopoietin and its receptors, interleukins, transcription factors and their corresponding signal pathways on platelet production. To understand the regulatory mechanism of platelet production can help to understand the pathological mechanism of platelet-related diseases and provide new ideas for the diagnosis and treatment of platelet-related diseases.

Role of PDGF/PDGFR Pathway in Essential Thrombocythemia and Its Action Mechanism / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To study the role of PDGF/PDGFR in essential thrombocythemia (ET) by investigating the expression of PDGF-BB in bone marrow and the expression of PDGFR-β in bone marrow cells of patients with ET and explore the new target for treating ET patients through inhibiting the PDGFR of megakaryocytes.</p><p><b>METHODS</b>The expression level of PDGF-BB in bone marrow of ET patients and normal controls were assayed by using ELISA, the expression level of PDGFR-β (CD140) in bone marrow of ET patients and normal controls were detected by using flow cytometry, the effect of PDGF-BB in JAK2/STAT3 and PI3K/AKT pathway was detected by using flow cytometry or Werstern blot, and the effect of imatinib on the megakaryopoiesis of PDGF was observed.</p><p><b>RESULTS</b>The expression level of PDGF-BB in bone marrow of ET patients was significantly higher than that in normal controls; the expression level of PDGFR-β in bone marrow of ET patients was significantly higher than that in nornal controls; PDGF-BB could activate JAK2/STAT3 and PI3K/AKT pathway of megakaryocytes, while the imatinib could block the effect of PDGF-BB on megakaryocyte.</p><p><b>CONCLUSION</b>The elevated PDGF-BB and PDGFR-β may be involved in ET, and the physiopathologic mechanism is that the elevated PDGF-BB activates PDGFR with subsequent activation of the JAK2/STAT3 and PI3K/AKT pathways, stimulating megakaryopoiesis. Imatinib may have a therapeutical effect on ET via blocking of PDGFR.</p>

Research Progress on role of Abnormal Tryptophan Metabolism in Immune Thrombocytopenia / 中国实验血液学杂志

Immune thrombocytopenia (ITP) is a common acquired autoimmune hematological disorders. Platelet autoantibodies lead to the decrease of platelet production and (or) increase of its destruction. The latest researches showed that the abnormal tryptophan metabolism mediated by indoleamine-2, 3-dioxygenase(IDO) is related with the pathogenesis of ITP. The patients with ITP show less expression of IDO, reduction of Treg cells and increase of autoreactive T cells and autoantibodies. CTLA-4-Ig can improve the expression of IDO in the patients with ITP, which also can inhibit the proliferation and activation of self-reactive T cells. Thus, clarifying the abnormal tryptophan metabolism mediated by IDO may provide a new idea for improving the understand of the pathogenesis and treatment of ITP. This review focuses on reasearch progress of the tryptophan metabolism mediated by IDO and ITP.

Las trombopoyetinas en el tratamiento de la púrpura trombocitopénica inmunitaria y otras trombocitopenias / Thrombopoietines in the treatment of the thrombocytopenic purpura and other thrombocytopenics

La purpura trombocitopénica inmunitaria y las trombocitopenias secundarias representan condiciones patológicas graves cuyo tratamiento plantea diversos grados de dificultad. La aproximación terapéutica convencional ha sido la administración de esteroides, la esplenectomía y el uso de inmunoglobulina intravenosa u otros tipos de anticuerpos (e.g., anti-D). La mejor comprensión de la fisiología y fisiopatología de la trombopoyesis aunado a los avances en biología molecular ha permitido el desarrollo de una nueva aproximación terapéutica, la aplicación de las trombopoyetinas sintéticas o no inmunogénicas. Dentro de este grupo resaltan dos compuestos: el romiplostin (una proteína de fusión) y el eltrombopag (un compuesto sintético de bajo peso molecular). Ambas se encuentran disponibles comercialmente. Los estudios clínicos indican que estos medicamentos tienen un efecto satisfactorio en el tratamiento de las trombocitopenias, particularmente en los casos refractarios a los tratamientos convencionales.

Immune thrombocytopenic purpura and the secondary thrombocytopenias are conditions potentially severe with diverse degrees of treatment difficulties. Steroids administration, splenectomy and the use of intravenous immunoglobulin and other antibodies (e.g., anti-D) had been the conventional therapy. The better understanding of the thrombopoiesis physiology and physiopathology togetter with the biology advances have permitted the development of a new terapheutic approach: the use of synthetic or nonimmunogenic thrombopoietines. Among this group highlights composites: romiplostim (a fusion protein) and eltrombopag (a synthetic composite with low molecular wheigt). Both are already available and produce a satisfactory effect particularly in nonrespondent cases to the conventional treatment.

The role of PDGF/PDGFR in the regulation of platelet formation / 中国实验血液学杂志

Platelet-derived growth factor (PDGF), a potent chemotactic and mitogenic factor, is involved in the regulation of hematopoiesis and platelet production. Our studies demonstrate the presence of functional PDGF receptors (PDGFR) on human megakaryocytes/platelets and CD34(+) cells, and their ability to mediate a mitogenic response. PDGF promotes the ex vivo expansion of human hematopoietic stem (CD34(+)) and progenitor (CD41(+)) cells. More significantly, PDGF enhances the engraftment of human CD45(+) cells and their myeloid subsets (CD33(+), CD14(+) cells) in NOD/SCID mice. PDGF also stimulates in vitro megakaryocytopoiesis via PDGFR and/or the indirect effect on bone marrow microenvironment to produce TPO and other cytokines. It also shows a direct stimulatory effect of PDGF on c-Fos, GATA-1 and NF-E2 expressions in megakaryocytes. We speculate that these transcription factors may be involved in the signal transduction of PDGF on the regulation of megakaryocytopoiesis. PDGF also enhances platelet recovery in mouse model with radiation-induced thrombocytopenia. This radioprotective effect is likely to be mediated via PDGFR with subsequent activation of the PI3K/Akt pathway. It provides a possible explanation that blockage of PDGFR may reduce thrombopoiesis and play a role in imatinib mesylate-induced thrombocytopenia.

Molecular mechanism of imatinib-induced thrombocytopenia in treatment of patients with CML / 中国实验血液学杂志

Imatinib mesylate has been commonly used in the treatment of patients with chronic myeloid leukemia (CML). However, a significant number of CML patients treated with imatinib developed thrombocytopenia. Platelet-derived growth factor (PDGF)/platelet-derived growth factor receptor (PDGFR) plays a significant role in the regulation of thrombopoiesis. It is suggested that imatinib may block the PDGF/PDGFR and PI3-K/Akt pathway, then inducing the apoptosis of megakaryocytes and developing thrombocytopenia in these patients. In this review, the potential molecular mechanism of imatinib-induced thrombocytopenia in the treatment of CML patients is discussed, including imatinib and thrombocytopenia, PDGF/PDGFR and thrombopoiesis, potential mechanism of imatinib-induced thrombocytopenia in treatment of patients with CML and so on.

Vías de señalización implicadas en la megacariopoyesis / Signaling pathways involved in megakaryopoiesis

La hematotoxicología es un área poco estudiada en nuestro país y es limitado el conocimiento sobre el efecto que ciertos contaminantes atmosféricos inducen en la sangre y en la médula ósea. La contaminación por partículas suspendidas ha cobrado más interés, por los contaminantes que se adhieren a su superficie. Un ejemplo es el benceno, relacionado con aplasia medular y leucemia. Algunos metales que también están en las partículas inhaladas son hematotóxicos. Uno de ellos es el vanadio, que nuestro grupo ha identificado como un agente inductor de alteraciones en la megacariopoyesis, lo que motivó esta revisión. Las plaquetas desempeñan un papel muy importante en la hemostasia y derivan de la célula más grande de la médula ósea: el megacariocito. Hasta hace algunos años desconocíamos casi todo del megacariocito, pero con la clonación de la trombopoyetina, en 1994, la principal hormona reguladora de la producción plaquetaria, ha existido un desarrollo acelerado en el conocimiento de la megacariopoyesis. Este artículo hace una revisión de la megacariopoyesis y su regulación, con énfasis en las vías de señalización implicadas. Además, se mencionan algunas enfermedades relacionadas y se discuten las perspectivas de investigación de este proceso, con énfasis en la toxicología.

Hematotoxicology has been studied with less interest than other fields associated with atmospheric pollution. There is limited knowledge about on the effects that certain atmospheric pollutants may provoke in the blood and bone marrow. Suspended particle pollution has become an area of scientific inquiry due to the contaminants adhering to its surface. We have identified the association of inhaled vanadium and variations in megakaryopoyesis and thrombopoyesis. Platelets are the smallest elements in the blood, but they play a strategic role in hemostasis. They are derived from the largest cell of the bone marrow, the megakaryocite. This cell size is about 150 microm, with apolyploid nucleus and unknown origin until few years ago. When TPO was cloned in 1994 the knowledge about megakaryocyte began to growth exponentially, elucidating the mechanisms of proliferation, differentiation and release of platelets. More information is still needed in order to translate knowledge into clinical application for diseases such as thrombocytopenia or thrombocytosis. A review of the current concepts of megakaryopoiesis and its regulation, with emphasis on signaling pathways are presented in this paper; a classification in TPO-dependent and TPO-independent is also detailed. In addition, we review some diseases associated with changes in the signaling pathway of megakaryopoyesis, as well as possible perspectives in this field, including toxicology.

Comparison of the effect of Angelica polysaccharide, platelet-derived growth factor and thrombopoietin on megakaryocytopoiesis / 中华儿科杂志

<p><b>OBJECTIVE</b>To investigate the effect of Angelica polysaccharide (APS), platelet-derived growth factor (PDGF) and thrombopoietin (TPO) on the proliferation and apoptosis of human megakaryocytic cell line M-07e.</p><p><b>METHODS</b>Cell count and the viability testing of M-07e cells (trypan blue exclusion assay) were performed at 24 hours, 48 hours and 72 hours after treatment with APS, PDGF or TPO. Three apoptosis related flow cytometric assays including Annexin V, Caspase-3 and JC-1 were performed to determine apoptotic rate of each group at 72 hours after the treatment.</p><p><b>RESULTS</b>After the incubation, the number of M-07e cells in the APS, PDGF and TPO group increased and the viabilities of the three groups were significantly higher than the control group (P < 0.05). The dead cells in the APS, PDGF and TPO group were (19.41 +/- 7.59)%, (21.38 +/- 7.25)% and (18.77 +/- 8.00)%, respectively by flow cytometry using Annexin V method, which were significantly lower compared to the control group (34.33 +/- 5.46)%. The expression of the activated caspase-3 in the group of APS, PDGF and TPO were (12.27 +/- 5.18)%, (12.39 +/- 6.26)% and (13.75 +/- 8.25)%, the APS and PDGF group decreased significantly compared to the control group (18.92 +/- 6.09)%. The ratio of total cell deaths in the APS, PDGF and TPO group were (23.64 +/- 6.69)%, (28.00 +/- 10.05)% and (27.99 +/- 8.99)%, the ratio in APS group decreased significantly compared to the control group (39.48 +/- 11.86)% by JC-1 method. Differences between APS and PDGF groups and between APS and TPO groups were not statistically significant.</p><p><b>CONCLUSION</b>APS, PDGF and TPO have similar effect in stimulating proliferation and inhibiting serum-free-culture induced apoptosis of M-07e cells.</p>

Correlation between CD34+CD61+ megakaryocyte precursors and platelet engraftment in allogeneic hematopoietic stem cell transplantation / 中国实验血液学杂志

This study was purposed to investigate the correlation between the dose infused megakaryocytic precursors (CD34+, CD34+CD61+) and recovery time of platelet count following an allogeneic PBSCT and/or BMT through quantitative detection of CD34+ and its subpopulation in peripheral blood and BM mobilized by G-CSF. 24 patients with various hematologic malignancies received PBSCT/BMT from their HLA matched or unrelated donors and haploidentical siblings in April-December 2007. 20 evaluated patients were divided into 2 groups according to different transplant schemes. HLA matched group received PBSCT regime and haploidentical group received PBSCT combined with BMT. CD34+CD61+ subpopulations in sample from patients receiving PBSCT/BMT were measured by flow cytometry immediately or storage over night. The results showed that the median number of infused CD34+, CD34+CD61+ and CD34-CD61+ cells in haploidentical group were 6.24x10(6)/kg (1.53-20.48), 66.19x10(4)/kg (8.16-493.83), and 34.38x10(6)/kg (14.71-109.16) respectively, in HLA matched group those were 4.88x10(6)/kg (1.00-8.24), 14.16x10(4)/kg (11.63-96.87), and 13.50x10(6)/kg (1.74-35.61), respectively. Median days of ANCs>0.5x10(9)/L and platelets>20x10(9)/L were 18.5 (11.0-29.0) days and 16.5 (9.0-35.0) days in haploidentical group respectively; in HLA matched group those were 14.5 (9.0-24.0) and 10.5 (6.0-37.0) respectively. A significance difference of median days for ANC engraftment presented between two groups (p=0.048). There was no significant difference of time for platelet engraftment between 2 groups. For patients with CD34+ cell dose>2x10(6)/kg there was significant difference of time of platelet engraftment between HLA matched and haploidentical groups (p=0.006). The number of CD34+CD61+ cells infused in 12 haploidentical patients or in 8 HLA matched patients were much better correlated with the time of platelet recovery up to 20x10(9)/L than that of number of CD34+ cells infused in total 20 patients (r=-0.768 and p=0.004 for haploidentical CD34+CD61+ cells, r=-0.747 and p=0.033 for HLA matched CD34+ CD61+ cells, r=-0.449 and p=0.047 for CD34+ cells). There was an inverse correlation between the number of infused CD34+ CD61+ cells and time of platelet engraftment. Therefore, as the number of CD34+ CD61+ cells increased, duration of platelet engraftment (time to reach platelet count of 20x10(9)/L) shortened significantly. It is concluded that the determining the number of megakaryocytic precursor by flow cytometry may predict the platelet reconstitutive capacity of the allogeneic hematopoietic stem cell transplantation, which is in haploidentical PBSCT and in BMT.

Evaluation of Immature Platelet Fraction as a Marker of Platelet Recovery in Prophylactic Platelet Transfusion / 대한수혈학회지

BACKGROUND: It has been known that the increase of reticulated platelets indicates the increase of thrombopoiesis in platelet consumptive diseases or the impending platelet recovery in patients with thrombocytopenic conditions. A new rapid automated method to assess reticulated platelets, the immature platelet fraction (IPF), was recently introduced. We evaluated the usefulness of the IPF for the prediction of platelet recovery in patients after hematopoietic stem cell transplantation (HSCT) and cytotoxic chemotherapy. METHODS: Thirty one healthy volunteers and 59 patients formed 3 groups: the allogenic HSCT group (n=23, an ABO major-mismatch 6 of 23), the autologous HSCT group (n=8) and the cytotoxic chemotherapy group (n=28). The platelet count, % of IPF and the % of reticulocytes were checked every day by using a Sysmex XE-2100. RESULTS: The IPF in the healthy volunteers was a mean of 2.2+/-1.6% (range: 0.3~6.7%), and the maximum level of the IPF in the patient group was 6.1+/-1.7% (range: 3.3~13.5%). The ideal cut-off value of the IPF increase to discriminate the platelet recovery group was 5.1%. When this cut-off value is used, the positive predictive value is 90.9% in the HSCT groups and 87.5% for the total patients. The 4 patients who showed an IPF higher than 5.1% without platelet recovery were in platelet consumptive conditions. It took 8.0+/-8.3 days to show platelet recovery after elevation of the IPF over 5.1% and an ABO major mismatch HSCT doesnt affect platelet recovery. CONCLUSION: The IPF is thought to be a useful parameter for the prediction of platelet recovery after HSCT and cytotoxic chemotherapy, but the problem of the patient' conditions affects the accuracy of the IPF, and the variable intervals between the increase of the IPF and platelet recovery is thought to be improved.

Effect of 5-hydroxtryptamine on megakaryocytopoiesis--review / 中国实验血液学杂志

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.

Study of 161 chronic idiopathic myelofibrosis patients for clinicopathological staging / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the significance of clinicopathological stage of chronic idiopathic myelofibrosis (CIMF) in WHO classification of 2001.</p><p><b>METHODS</b>Histopathological analysis of bone marrow biopsy plastic-embedded sections stained with H-G-E and Gomori's stains and clinical features of 113 cases previously diagnosed as primary myelofibrosis (PMF) and 48 cases MPD-U (total of 161 cases which including male 79 and female 82) were studied retrospectively.</p><p><b>RESULTS</b>There was no significant differences on the clinical features among the cellular phase, collagen fiber phase, sclerotic phase and osteomyelosclerosis of 113 previously diagnosed patients. According to WHO classification 2001 of CIMF, previously diagnosis in 48 cases with MPD-U was WHO pre-CIMF, and in 113 cases with PMF was WHO CIMF-Fs. There were significant differences between of WHO pre-CIMF and WHO CIMF-Fs about clinicopathological features except age. The percentage of immature granulocytes, normoblasts, lymphocytes in peripheral blood, the size of hepatosplenomegaly, and the percent age of tear drop-like red blood cells in pre-CIMF were significantly lower than those in CIMF-Fs (P < 0.05). However, the number of hemoglobin and platelets in patients with pre-CIMF were significantly higher than that with CIMF-Fs (P < 0.01).</p><p><b>CONCLUSION</b>pre-CIMF and CIMF-Fs in clinical and histopathological features were different development stage of CIMF, while osteomyelosclerosis is a variant of CIMF, but not an independent disease.</p>

Influence of repeated platelet donation on megakaryopoiesis in donors / 中国实验血液学杂志

To explore influence of platelet donation on donor's megakaryocytopoiesis, platelet counts and plasma concentrations of thrombopoietin (TPO), interleukin-3 (IL-3), IL-6 and nitric oxide (NO) were determined in 42 frequent platelet donors (undergoing plateletpheresis more than once a month for 24 months and their mean platelet yield of collection was 2.5 x 10(11)), in 62 limited platelet donors (undergoing plateletpheresis less than once a month for 24 months) after a donation-free period of > 5 weeks and in 40 whole blood donors who never undergoing plateletpheresis after a donation-free period of > 6 months. The results showed that the TPO levels was significantly lower in frequent platelet donors than in limited platelet donors (P < 0.01) and whole blood donors (P < 0.01). There were no significant differences between three groups in platelet counts, IL-3, IL-6 and NO. These findings suggest that the number of megakarocytes significantly increased in frequent platelet donors.

Gene Expression Analysis of Megakaryocytes Derived from Human Umbilical Cord CD34(+) Cells by Thrombopoietin

Although much is known about the molecular biology of platelets, the megakaryocytes' (MKs) molecular biology was not understood so well because of their rareness. By the cloning and characterization of thrombopoietin (TPO), which is the principal regulator of the growth and development of the MKs, researches on the MKs have been growing rapidly. To understand megakaryocytopoiesis, we investigated the gene expression profile of the MKs using oligonucleotide microarray where 10, 108 unique genes were spotted. Comparing the fluorescence intensities of which ratio is > or = |2|, 372 genes were up-regulated and 541 genes were down-regulated in MKs. For confirmatory expression, RNase protection assay (RPA) establishing abundant apoptotic gene expression was carried out. In MKs, many of the known genes, including several platelet related genes, GATA binding protein were highly expressed. Particularly, TGF beta, clusterin (complement lysis inhibitor), and thymosin beta 4 (actin-sequestering molecules) were expressed highly in MKs. As MKs specific expressed genes may regulate normal and pathologic platelet (and/or MK) functions, the transcript profiling using microarray was useful on molecular understanding of MKs.

Estimate of Thrombopoiesis by Flow Cytometric Analysis of Reticulated Platelets in Patients with Severe Thrombocytopenia / 대한진단검사의학회지

BACKGROUND: Analysis of reticulated platelets (RPs) is useful for discriminating the causes of thrombocytopenia and monitoring the thrombopoiesis. In the patients with severe thrombocytopenia, we evaluated the thrombopoiesis-discriminating ability of several indices applying forward scatter (FSC) and thiazole orange (TO) fluorescence in addition to the percentage of reticulated platelets (RPs%). METHODS: Forty cases with decreased thrombopoiesis, twenty cases with increased thrombopoiesis and twenty cases with liver cirrhosis were selected. By flow cytometry with two analytic methods, dependent on or independent of the staining of CD41-PE as a platelet marker, the primary parameters including RPs% were measured and the applied parameters were calculated from them. And we compared the diagnostic efficiency of each parameter and analyzed the purity of platelet light scatter gate. RESULTS: The purity of platelet light scatter gate was significantly lower in patients with severe thrombocytopenia than in healthy persons with normal platelet counts (P<10(-6)), so the use of CD41-PE for platelet gating improved the diagnostic efficiency of RPs%. Compared to the primary parameters, the applied parameters originated from RPs%, FSC and TO fluorescence improved diagnostic efficiency significantly (RPs%: 55%, RPs%xs delta MFI: 80%) between decreased and increased thrombopoiesis groups. CONCLUSIONS: In the patients with severe thrombocytopenia, the estimate of the thrombopoiesis by a flow cytometric analysis can be more predictable by using platelet markers and by considering the fluorescence intensity of TO together with the RPs%.

Factors Related to the Thrombocytosis in Children with Iron Deficiency Anemia / 대한소아혈액종양학회지

PURPOSE: We investigated to identify factors related to thrombocytosis and clinical data for thrombopoiesis in children with iron deficiency anemia (IDA). METHODS: We retrospectively analyzed clinical and laboratory data for 85 children admitted for acute infection or inflammation. Seventy patients of 85 children were diagnosed as IDA. The others were clinically suspected as IDA but they were not diagnosed. We divided three groups: group 1 included severe anemia below hemoglobin (Hb) 8.0 g/dL, group 2 mild to moderate anemia (Hb: 8.0~10.0 g/dL), and group 3 (control) were clinically suspected but without IDA. RESULTS: There are no differences among groups except age at diagnosis. The age at diagnosis in group 1 are higher than other groups. In control group, there are not any factors correlated with thrombocytosis. In group 1, the white blood cell and lymphocyte counts are significantly related to the platelet counts. However, serum iron level is only correlated with platelets in group 2. In multiple regression analysis, we found significantly correlation between white blood cell counts and serum iron level and thrombocytosis in IDA including group 1 and 2. CONCLUSION: We suggest that white blood cell counts and serum iron level in IDA may be related with increased platelet counts, as a reactive thrombocytosis. We need further study for correlation between acute phase reactants and thrombocytosis in IDA.

Clinical Significance of Thrombopoietin Levels in Maintenance Hemodialysis Patients with Thrombocytopenia / 대한신장학회잡지

BACKGROUND: Thrombopoietin (TPO) is a major cytokine which plays a critical role in the regulation of thrombopoiesis and megakaryopoiesis. Since the kidney is one of the TPO-producing organs, it is hypothesized that TPO deficiency in end stage renal disease can give rise to thrombocytopenia. However, serum TPO levels and their clinical significance in maintenance hemodialysis patients with thrombocytopenia are not completely evaluated. The aim of the present study was to compare the percentage of reticulated platelets and serum TPO levels between non-thrombocytopenic group (platelet count > or =150x109/L, non-T group) and thrombocytopenic group (platelet count <150x109/L, T group) and to investigate the local and/or systemic effect of the TPO on the platelet count in hemodialysis patients. METHODS: We measured the percentage of reticulated platelets and serum TPO levels in samples obtained from venous returns of arteriovenous fistula (AVF) and contralateral peripheral veins in 44 hemodialysis patients. Serum reticulated platelets were measured by flow cytometry and serum TPO levels were determined with a commercially available ELISA kit. Patients with a history of HBV/HCV infection and hepatobiliary disease were excluded. RESULTS: Reticulated platelets of T group (4.57+/-2.32%) were significantly lower than non-T group (7.79+/-3.62%) (p<0.05). Serum TPO levels obtained from venous return of AVF in T group (78.37+/-15.48 pg/mL) were lower than non-T group (98.15+/-35.05 pg/mL) (p<0.05). Serum TPO levels obtained from contralateral peripheral veins in T group (77.20+/-17.28 pg/mL) were lower than non-T group (104.73+/-38.45 pg/mL) (p<0.01). There were no statistically significant difference of serum TPO levels between venous return of AVF and contralateral peripheral veins in T group. CONCLUSION: Decreased circulating reticulated platelets and serum TPO levels despite low platelet counts in comparison with normal platelet counts in hemodialysis patients, suggesting that the feedback mechanism, the TPO producing organ and bone marrow is not working with effect in the regulation of thrombopoiesis. An alteration in the production and regulation of TPO level is not influenced by local factor like an AVF endothelium.