The nervous system directly regulates immunity through neurotransmitter receptors expressed on immune cells to participate in host defense and body reparation. Expression of neurotransmitter receptors on blood cells provides important evidence for a direct functional link between the nervous and hematopoietic systems. Our previous studies showed that 5-hydroxytryptamine, as a monoamine neurotransmitter, plays an important role in regulating megakaryocytopoiesis. This review summarizes recent findings of the effect of monoamine neurotransmitter on megakaryocytopoiesis and platelet function, focusing on the receptor expression on hematopoietic stem cells, megakaryocytes/platelets and their functions in order to explore the intrinsic relation of nervous system and hematopoietic system. Based on the existing research results, we find that the monoamine neurotransmitter participates in regulation of megakaryocytopoiesis, and affects on aggregation and functions activation of platelets. Moreover, it has a close link with the specific regulatory factor of megakaryocytopoiesis-TPO. Thus those results also support the "brain-bone marrow-blood-axis" viewpoint of some researchers. At present, the study of the nervous system regulating hematopoiesis is still in its infancy, the exact mechanism remains to be further studied.
Biogenic Monoamines ; physiology ; Blood Platelets ; physiology ; Humans ; Megakaryocytes ; cytology ; Neurotransmitter Agents ; physiology ; Platelet Function Tests

This study was aimed to investigate the aggregation of rehydrated-lyophilized platelets. The aggregation rate of fresh and rehydrated-lyophilized platelets were measured by using thrombin, ristocetin, ADP and collagen as inductors and APACT2 aggregameter; the effects of intra- and extra-cellular trehalose on maximum aggregation rate of rehydrated-lyophilized platelets were detected by using ADP as an inductor. The results showed that the aggregation rate of fresh platelets was all about 100%, while aggregation rate of rehydrated lyophilized platelets was (70.17 +/- 7.36)%, (15.3 +/- 2.81)%, (68.67 +/- 6.86)%, (64.67 +/- 11.6)% respectively, when the concentration of thrombin, ristocetin, ADP and collagen was 1 U/ml, 1.6 mg/ml, 20 micromol/L and 2 microg/ml. The maximum aggregation rates of rehydrated-lyophilized platelets in intra- and extra-cellular trehalose, extracellular trehalose and blank control groups were (66.0 +/- 4.69)%, (25.3 +/- 2.42)% and (11.5 +/- 1.87)% (P < 0.01), meanwhile there was significant difference of rehydrated-lyophilized platelet aggregation rate between intra- and extra-cellular trehalose and extracellular trehalose groups (P < 0.01). It is concluded that the concentrations of thrombin (1 U/ml), ristocetin (1.6 mg/ml), ADP (20 micromol/L) and collagen (2 microg/ml) are optimal for platelets aggregation tests, the internal and extracellular trehalose significantly enhance the aggregation of rehydrated-lyophilized platelets.
Blood Platelets ; cytology ; drug effects ; metabolism ; Blood Preservation ; methods ; Freeze Drying ; methods ; Humans ; Platelet Aggregation ; physiology

The dielectric spectroscopy of human platelets was measured within the frequency range of 100 KHz-100 MHz, and the dielectric numerical characters of human platelets in response to AC electric field were analyzed. We measured the AC impedance of normal human platelets with the impedance technique in the frequency domain for the first time. The experimental data were used to draw a relationship curve between the frequency of electric field and permittivity or conductivity, and then the dielectric spectrum and the Cole-Cole plots of human platelets were established and then, the characteristics of dielectric response of human platelets were decided, which demonstrated the dependence of permittivity and conductivity of human platelets upon frequency, and showed two characteristic frequencies of the dielectric spectroscopy of human platelets: the first characteristic frequency f(C1) = 6.66 MHz; the second characteristic frequency f(C2) = 9.81 MHz.
Blood Platelets ; cytology ; physiology ; Electric Conductivity ; Electric Impedance ; Electrochemistry ; methods ; Electrophysiology ; Humans ; Spectrum Analysis ; methods

OBJECTIVE: To induce hematopoietic progenitor/stem cells of umbilical cord blood to differentiate into mature megakaryocytes and platelets in vitro and to investigate the mechanism of production of platelets. METHODS: The CD34+ cells were sorted from umbilical cord blood by magnetic activated cell sorting (MACS) and then cultured in vitro with optimized medium to be differentiated into mature megakaryocytes and platelets. The cultured cells and the platelet-like particles were isolated from the culture and were checked by the fluorescence-activated cell sorter (FACS), immunohistochemistry assays, light microscope,electron microscope and platelet aggregation tests. RESULTS: The cultured megakaryocytes were detected with proplatelets and both the cultured cells and the platelet-sized particles were found to have the same structure with the normal megakaryocytes and platelets by light and electron microscope. The immunohistochemistry assays revealed the cultured cells expressed GP II b III a with a positivity of 95% which was a special antigen for platelets and megakaryocytes. Culture-derived platelet-sized particles aggregated in response to thrombin as the plasma derived-platelets did. The cultured platelets had the same positivity of CD41 as the platelets from platelet rich plasma. CONCLUSION The hematopoietic progenitor/stem cells can be induced to differentiate into purified and mature megakaryocytes and platelets. It provides a practical way to study the mechanism of platelets production.
Antigens, CD34 ; metabolism ; Blood Platelets ; cytology ; Cell Differentiation ; physiology ; Cells, Cultured ; Fetal Blood ; cytology ; metabolism ; Hematopoietic Stem Cells ; cytology ; metabolism ; Humans ; Megakaryocytes ; cytology

OBJECTIVETo observe the effect of the platelet-rich plasma (PRP) on osteogenesis during bone distraction.

METHODSThe osteoblasts were cultured in vitro. The rabbits were used as the animal model of distraction osteogenesis. The proliferation of osteoblasts was analysed through MTT methods. The osteogenesis was observed by histochemical and histoimmunochemical methods.

RESULTSPRP stimulated the proliferation of osteoblasts and facilitated distraction osteogenesis.

CONCLUSIONSPRP could accelerate the osteogenesis during bone distraction. The application of PRP in clinical practice might shorten the period of distraction osteogenesis.

Animals ; Blood Platelets ; physiology ; Cells, Cultured ; Immunohistochemistry ; Male ; Osteoblasts ; cytology ; metabolism ; Osteogenesis ; physiology ; Osteogenesis, Distraction ; Platelet Count ; Rabbits

This study was aimed to compare the difference of quality between buffy-coat-collected platelet concentrates (BC-PC) and single-donor plateletpheresis (SDP). 15 packs of BC-PC and 15 units SDP were stored at 20 degrees C - 24 degrees C with agitation. Platelet concentration, platelet volume, residual leukocyte and residual erythrocyte in two groups were examined after preparation for 1 hour. Mean platelet volume, pH value, hypotonic shock response (HSR), CD62p expression and CD62p re-expression of platelet were detected on 0, 1, 2, 3, 4, 5 days of platelet preservation. The results showed that the platelet yields, residual leukocyte and residual erythrocyte in two groups accorded with the national quality standard respectively, but residual leukocyte and residual erythrocyte in BC-PC group were higher than those in SDP group when platelet yields in two groups were equal (p < 0.01). Lactate concentration, CD62p expression of platelet increased with prolongation of preseved time, while pH value decreased gradually. Compared with SDP group, there were significant differences in CD62p expression, CD62p re-expression of platelet preserved for 0 - 5 days (p < 0.01), and in pH value of platelet preserved 2 - 5 days (p < 0.01). There was no changes in HSR of SDP group for 0 - 5 days, while HSR in BC-PC group decreased gradually. There were significant differences in HSR of platelet preserved for 1 - 5 days (p < 0.01). It is concluded that the platelet concentrates prepared by BC-PC are not equal to SDP in quality, the preparation technology of BC-PC should be optimized further in order to reduce residual leukocyte, residual erythrocyte and activated platelet yields, as well as improve the quality of BC-PC.
Blood Platelets ; metabolism ; physiology ; Blood Preservation ; Cell Separation ; methods ; Erythrocytes ; cytology ; Humans ; Lactic Acid ; blood ; Leukocytes ; cytology ; P-Selectin ; blood ; Platelet Count ; Plateletpheresis ; instrumentation ; methods ; Quality Control

To investigate the effect of S-nitrosoglutathione (GSNO), a nitric oxide donor, on platelet production from megakaryocytes differentiated from cord blood CD34(+) cells in vitro, the CD34 (+) cells from eight fresh umbilical cord blood samples by a high-gradient magnetic cell sorting (MACS) system were cultured in serum-free medium for 14 d with thrombopoietin (TPO) 50 ng/ml, IL-3 10 ng/ml, stem cell factor (SCF) 50 ng/ml and rHuGM-CSF 20 ng/ml. Then, CD61 (+) cells were purified by MACS system from these CD34 (+) cells, and were cultured in serum-free medium supplemented with TPO 50 ng/ml, IL-3 10 ng/ml and SCF 50 ng/ml in the presence (treatment group) and absence (control group) of GSNO for 30 min or 2 h. Platelet-sized particles were counted by flow cytometry; megakaryocyte structure was detected by scanning electron microscope. Aggregation of the thrombin-induced platelet particle was observed under inversion microscope. cGMP was assessed by commercial ELISA kit. The results showed that, compared with the control group, the number of platelet-sized particles significantly increased (P<0.05) in the treatment group, in which megakaryocytes presented significant pseudopod formation and extensive membrane blebbing. The platelet particle aggregation could be observed under microscope after thrombin induction. cGMP activity was significantly increased after treatment with GSNO (P<0.05). These results propose that GSNO can facilitate platelet production from megakaryocyte, and it may be partly through cGMP pathway.
Antigens, CD34 ; analysis ; Blood Platelets ; cytology ; Cell Differentiation ; drug effects ; Cyclic GMP ; blood ; Female ; Fetal Blood ; cytology ; Hematopoiesis ; drug effects ; Hematopoietic Stem Cells ; cytology ; Humans ; Megakaryocytes ; cytology ; Nitric Oxide ; physiology ; Platelet Aggregation ; drug effects ; Pregnancy ; S-Nitrosoglutathione ; pharmacology

This study was aimed to investigate the correlation of thrombosis with increased platelet turnover in essential thrombocythemia. According to presence or absence of thrombosis, 26 patients with ET were divided into two groups. Reticulated platelets (RP) were measured by flow cytometry and 26 healthy volunteers were selected as healthy controls. The ET patients with thrombosis were treated with hydroxyurea and interferon-alpha. The results demonstrated that the ET patients with thrombotic events had a significantly higher RP percentage (14.8% +/- 7.2%) than that in both asymptomatic ET patients (4.5% +/- 2.3%) and normal control (3.3% +/- 1.5%), (P < 0.05); the RP percentage in asymptomatic ET patients did not differ significantly from controls. ET patients with thrombosis also had a significantly higher absolute RP (ARP) count than those in ET patients without thrombosis [(176 +/- 37) x 10(9)/L vs (46 +/- 12) x 10(9)/L]. The ET patients with thrombosis were successfully treated with hydroxyurea plus INF-alpha, the RP percentage and ARP counts obviously reduced. In conclusion, when the ET patients had thrombotic events, those patients had a significantly higher RP percentage and ARP compared with patients without thrombosis and healthy controls. The ET patients with thrombosis were successfully treated with hydroxyurea plus INF-alpha.
Adult ; Aged ; Aged, 80 and over ; Blood Platelets ; cytology ; physiology ; Female ; Humans ; Male ; Middle Aged ; Platelet Count ; Thrombocythemia, Essential ; blood ; complications ; Thrombosis ; blood ; complications

This study was purposed to investigate the effects of platelet-derived membrane microparticles (PMP) on the proliferation and apoptosis of human umbilical vein endothelial cells (HUVEC). Different concentrations of thrombin were adopted to activate the platelets so as to release PMPs. Flow cytometry (FCM) was adopted to evaluate the efficiencies of different concentrations of thrombin to release PMPs. By using the HUVEC cultivated in vitro as vector, the effects of PMPs on the proliferation and apoptosis of HUVEC were investigated by MTT and FCM. The results showed that the efficiencies releasing PMPs from platelets activated by 2.0, 1.5, 1.0, 0.5 U/ml thrombin were 28.7, 47.7, 50.1 and 43.9% respectively; PMPs induced proliferation of HUVEC in a dose dependent manner. At the concentration of 40 microg/ml PMPs, the proliferation rate of HUVEC was 1.8 +/- 0.3 times as much as blank control, the proliferation rate in group of vascular endothelial growth factor was 1.9 +/- 0.5 times of as much as blank control, there was no statistic difference (p > 0.05). The PMPs inhibited HUVEC apoptosis. Compared with the apoptosis rate of control (9.4 +/- 0.5)%, apoptosis rate in PMP group (40 microg/ml) was (3.9 +/- 0.4)% (p < 0.05). The addition of VEGF (10 microl/ml) did not successfully prevented apoptosis of HUVEC with apoptosis rate of (8.0 +/- 0.8)%. It is concluded that platelets activated by 1 U/ml thrombin gets the best efficiency of PMP release, which stimulates proliferation of HUVEC and inhibits its apoptosis.
Apoptosis ; drug effects ; Blood Platelets ; physiology ; Cell Proliferation ; drug effects ; Cell-Derived Microparticles ; physiology ; Cells, Cultured ; Endothelial Cells ; cytology ; Humans ; Particle Size ; Platelet Membrane Glycoproteins ; physiology ; Thrombin ; pharmacology ; Umbilical Veins ; cytology

The study was aimed to investigate the potential immunotherapeutical values of umbilical cord tissue-derived mesenchymal stem cells (UC-MSC) on patients with chronic idiopathic thrombocytopenic purpura (ITP). UC-MSC was cocultured in vitro with splenocytes isolated from ITP patients who experienced splenectomy. The level of IgG antiplatelet antibody (PAIgG) was determined by a competitive micro-enzyme-linked immunosorbent assay (ELISA) method. The proliferation of platelet-reactive CD4+ T lymphocytes was also measured in the presence of UC-MSCs. The results showed that UC-MSCs could stimulate the spontaneous secretion of PAIgG in supernatants; In the platelet-inducing condition, UC-MSC inhibited the production of PAIgG at a low ratio of 1 UC-MSC to 100 splenocytes, but promoted at a high proportion of 1 UC-MSC to 10 splenocytes. Moreover, UC-MSC exerted a suppressive effect on proliferation of platelet-reactive T helper cells in a dose-dependent manner. It is concluded that the UC-MSCs can regulate secretion of antiplatelet antibodies in vitro. Its concrete regulation mechanism and potential immunotherapeutical value are need to further study.
Antibodies ; metabolism ; Blood Platelets ; immunology ; CD4-Positive T-Lymphocytes ; cytology ; Cell Proliferation ; Humans ; Infant, Newborn ; Lymphocyte Activation ; Mesenchymal Stromal Cells ; physiology ; Purpura, Thrombocytopenic, Idiopathic ; metabolism ; Spleen ; cytology ; Umbilical Cord ; physiology