Survival of fresh human platelets in a rabbit model as traced by flow cytometry

Rothwell, Stephen W.; Maglasang, P.; Krishnamurti, Chitra

doi:10.1046/j.1537-2995.1998.38698326334.x

Cited by 31 publications

(37 citation statements)

References 28 publications

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“…With the use of fluorescent markers such as CD42a and CD62a, 32 we were able to show that the platelets adhering to the endothelial cells were activated. During inflammation, adhesion molecules such as E-selectin, P-selectin, vascular cell adhesion molecule-1, and intercellular adhesion molecules are induced and/or upregulated on endothelial cells.…”

Section: Discussionmentioning

confidence: 99%

Platelet adhesion to dengue-2 virus-infected endothelial cells.

Krishnamurti¹,

Peat²,

Cutting³

et al. 2002

The American Journal of Tropical Medicine and Hygiene

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Abstract. Platelets in circulation normally do not adhere to resting endothelial cells. However, in response to vascular injury they adhere to stimulated endothelium and thereby play an essential role in hemostasis and thrombosis. Infection with dengue-2 virus can cause illness accompanied by thrombocytopenia and hemorrhage. Increased adherence of platelets to stimulated endothelial cells could contribute to the thrombocytopenia. In this study, adherence of radioisotopically labeled platelets to 1) unstimulated, 2) lipopolysaccharide (LPS)-stimulated, and 3) dengue-2 virusinfected human umbilical vein endothelial cells (HUVEC) was measured in an in vitro assay. Primary HUVEC were cultured in 96-well tissue culture plates in the presence or absence of LPS or dengue-2 virus. These cells were coincubated with 3 H-adenine-labeled fresh platelets for 30 min after which the cells were assayed for adherent platelets. Within 30 min there was maximum adherence of platelets to confluent LPS-stimulated HUVEC (36 ± 4% over controls; P ‫ס‬ 0.005). In comparison, there was a significant increase in adherence to dengue-2 infected HUVEC (78 ± 7%; P Յ 0.001). Additionally, platelet adherence was visualized using fluorescent microscopy. Dengue-2 infection stimulated the HUVEC as monitored by expression of E-selectin. Platelets that adhered to dengue-2 or LPS-stimulated HUVEC were activated as visualized by dual fluorescent probes. These data demonstrate that human platelets adhere to dengue-2 virus-stimulated HUVEC and this interaction could contribute to the thrombocytopenia observed during infection.

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Section: Discussionmentioning

confidence: 99%

Platelet adhesion to dengue-2 virus-infected endothelial cells.

Krishnamurti¹,

Peat²,

Cutting³

et al. 2002

The American Journal of Tropical Medicine and Hygiene

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“…To exclude a role for PACAP signaling in platelet turnover, we studied the survival of human platelets in a rabbit model. 23,24 Patient and control platelets were intravenously injected in a thrombocytopenic rabbit that had been pretreated with busulfan and ethyl palmitate, and human platelets were counted after certain time points to determine the platelet survival. We observed no differences in platelet survival between wild-type and patient platelets (data not shown).…”

Section: Phenotypic Characterization Of Platelets and Megakaryocytes mentioning

confidence: 99%

PACAP and its receptor VPAC1 regulate megakaryocyte maturation: therapeutic implications

Freson

Peeters

Vos³

et al. 2008

Blood

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Megakaryocytes and platelets express the Gs-coupled VPAC1 receptor, for which the pituitary adenylyl cyclase-activating peptide (PACAP) and the vasointestinal peptide (VIP) are agonists. We here demonstrate a regulatory role for VPAC1 signaling during megakaryopoiesis. A total of 2 patients with trisomy 18p with PACAP overexpression and transgenic mice overexpressing PACAP in megakaryocytes have thrombopathy, a mild thrombocytopenia, and a reduced number of mature megakaryocytes in their bone marrow. In vitro differentiation of hematopoietic stem cells from the patient and transgenic mice shows a reduced number of megakaryocyte colonies compared with controls. The addition of PACAP, VIP, or the adenylyl cyclase activator forskolin to CD34 ؉ cells inhibits megakaryocyte differentiation. In contrast, neutralizing monoclonal anti-PACAP (PP1A4) or anti-VPAC1 (23A11) antibodies inhibit cAMP formation and stimulate megakaryopoiesis in a thrombopoietin-independent manner. Moreover, wild-type mice obtain an increased platelet count after subcutaneous injection of PP1A4 or 23A11. These antibodies also elevate platelet numbers in animal models of myelosuppressive therapy and in GATA1-deficient mice with congenital thrombocytopenia. Furthermore, 23A11 stimulates the in vitro megakaryocyte differentiation of both normal and GATA1-deficient human CD34 ؉ cells. Together, our data strongly suggest that VPAC1 signaling tempers normal megakaryopoiesis, and that inhibition of this pathway stimulates megakaryocyte differentiation, enhancing platelet recovery after myelosuppressive therapy and in GATA1 deficiency. IntroductionVasointestinal peptide (VIP) and pituitary adenylyl cyclaseactivating peptide (PACAP) belong to the glucagon hormone superfamily, which in humans includes secretin, growth hormonereleasing hormone (GHRH), glucagon, glucagon-like peptides 1 and 2 (GLP-1 and GLP-2), peptide histidine methionine (PHM), and glucose-dependent insulinotropic polypeptide (GIP). 1 These peptides have been grouped into a superfamily because the precursor molecules share a strikingly similar structural organization and similar amino acid sequences; in general, the hormones are related in terms of distribution and function. PACAP and VIP effects have been described in the digestive tract, cardiovascular system, airways, reproductive system, immune system, endocrine glands, and brain. 1,2 These pleiotropic neuropeptides share 2 common G protein-coupled receptors, VPAC1 (VIPR1) and VPAC2 (VIPR2), while PACAP has an additional specific receptor, PAC1 (ADCYAP1R1). 1,3 The human PACAP gene (ADCYAP1) is located on chromosome 18p32, 4 and is mainly expressed in testis and brain, but this peptide crosses the blood-brain barrier. 5 We previously found an important role for PACAP and its receptor VPAC1 in platelet function. 6 Studies in 2 related patients with a partial trisomy 18p and monosomy 20p revealed 3 copies of the PACAP gene and elevated PACAP concentrations in plasma. The patients suffer from mental retardation, have a bleeding tendency...

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“…However, there are inherent risks associated with the transfusion of platelet concentrates, in particular, the risk of transmission of bacterial and/or viral infections. Additionally, the number and functionality of platelets in platelet concentrates decreases in dependency of storage time [28][29][30].…”

Section: Plateletsmentioning

confidence: 99%