Phagocytosis of liposomes by human platelets.

Male, Roxanne; Vannier, Wilton E.; Baldeschwieler, John D.

doi:10.1073/pnas.89.19.9191

Cited by 40 publications

(27 citation statements)

References 15 publications

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“…Platelets have been reported to internalize nanoparticles through the open canalicular system (OCS), a surface-connected system of channels within the core of the platelet, and by cell engulfment and trafficking to storage vacuoles. [18] This is consistent with the results observed here, including the inability of any single inhibitor to completely abrogate uptake.…”

Section: Resultssupporting

confidence: 91%

Controlled Transcription of Exogenous mRNA in Platelets Using Protocells

et al. 2015

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Transcribing exogenous RNA in eukaryotic cells requires delivering DNA to their nuclei and changing their genome. Nuclear delivery is often inefficient, limiting the potential scope of gene therapy and synthetic biology. These challenges may be overcome by techniques that allow for extranucleate transcription within eukaryotic cells. Protocells have been developed that enable transcription inside of liposomes; however, it has not yet been demonstrated whether this technology can be extended for use within eukaryotic cells. Here we show RNA-synthesizing nanoliposomes allow transcription of exogenous RNA inside anucleate cells. To accomplish this, components of transcription were encapsulated into liposomes and delivered to platelets. These liposomes were capable of light-induced transcription in platelets, providing proof-of-concept that protocell technology can be adapted for use within mammalian cells.

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Section: Resultssupporting

confidence: 91%

Controlled Transcription of Exogenous mRNA in Platelets Using Protocells

et al. 2015

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“…Many studies have shown that platelets appear to internalize particles but that these particles are located in the open canalicular system (OCS), as opposed to undergoing internalization into a phagosome (26,28,38,43). These studies differ in their target choices, preparation techniques, and staining methods.…”

Section: Discussionmentioning

confidence: 99%

“…For example, human platelets have been observed to phagocytose liposomes, erythrocyte fragments, some bacteria, viruses, and even latex beads (26,28,36,43). Although the mechanism(s) for phagocytosis and the fate of internalized particles are disputed, nonetheless, platelets can sequester various targets (38,39).…”

mentioning

confidence: 99%

Internalization of IgG-Coated Targets Results in Activation and Secretion of Soluble CD40 Ligand and RANTES by Human Platelets

Antczak

Vieth

Singh

et al. 2011

Clin Vaccine Immunol

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Platelets are crucial elements for maintenance of hemostasis. Other functions attributable to platelets are now being appreciated, such as their role in inflammatory reactions and host defense. Platelets have been reported to bind immunological stimuli like IgG complexes, and for nearly 50 years it has been speculated that platelets may participate in immunological reactions. Platelets have been reported to bind and internalize various substances, similar to other leukocytes, such as macrophages and dendritic cells. In the present study, we tested the hypothesis that human platelets can bind and internalize IgG-coated particles, similar to leukocytes. To this end, we observed that interaction with IgG-coated beads resulted in platelet activation (as measured by CD62P expression), internalization of targets, and significant soluble CD40 ligand (sCD40L) and RANTES (regulated upon activation, normal T cell expresses and secreted) secretion. Blocking Fc␥RIIA with monoclonal antibody (MAb) IV.3 or inhibiting actin remodeling with cytochalasin D inhibited platelet activation, internalization, and cytokine production. These data suggest that platelets are capable of mediating internalization of IgG-coated particles, resulting in platelet activation and release of both sCD40L and RANTES.

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“…This mechanism alone would require that little membrane trafficking occur in the platelet because rapid membrane turnover would lead to membrane mixing and uniformity of SNARE protein distribution. However, constitutive endocytosis 1,3,55 and true phagocytosis 56,57 have been reported in platelets. In most cells, endocytosis is accompanied by exocytosis to maintain a relatively constant plasma membrane surface area.…”

Section: Discussionmentioning

confidence: 99%

Subcellular distribution of 3 functional platelet SNARE proteins: human cellubrevin, SNAP-23, and syntaxin 2

Feng

Crane

Rozenvayn

et al. 2002

Blood

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Morphologic studies have demonstrated a process by which ␣-granule contents are released from platelets. Studies aimed at defining the molecular mechanisms of this release have demonstrated that SNARE proteins are required for ␣-granule secretion. These observations raise the possibility that morphologic features of ␣-granule secretion may be influenced by the subcellular distribution of SNARE proteins in the platelet. To evaluate this possibility, we analyzed the subcellular distribution of 3 functional platelet SNARE proteins-human cellubrevin, SNAP-23, and syntaxin 2. Exposure of streptolysin O-permeabilized platelets to antihuman cellubrevin antibody inhibited Ca ؉؉ -induced ␣-granule secretion by approximately 50%. Inhibition of ␣-granule secretion by antihuman cellubrevin was reversed by a blocking peptide. Syntaxin 2 and SNAP-23 have previously been demonstrated to mediate platelet granule secretion. The subcellular localization of the 3 SNARE proteins was determined by ultrastructural studies, using a pre-embedding immunonanogold method, and by immunoblot analysis of subcellular fractions. Immunonanogold localization demonstrated that approximately 80% of human cellubrevin in resting platelets was localized to platelet granule membranes. In contrast, SNAP-23 localized predominantly to plasma membrane, whereas syntaxin 2 was more evenly distributed among membranes of ␣-granules, the open canalicular system, and plasma membrane. Thus, each of these SNARE proteins has a distinct subcellular distribution in platelets, and each of these membrane compartments demonstrates a unique SNARE protein composition. IntroductionPlatelets demonstrate a number of characteristics that render them an important model of membrane trafficking. They are anucleate, display rare strands of endoplasmic reticulum, do not have Golgi structures, and synthesize little new protein. They are thought to undergo just one round of granule secretion following activation because they do not have adequate synthetic capacity to generate new granules. Although receptor-mediated 1,2 and pinocytotic 3 endocytosis have been observed in platelets, constitutive coupled endocytosis-exocytosis cycles that occur in nucleated cells in general [4][5][6][7][8] and in hematopoietic cells in particular 9 have not been documented in platelets. Thus, the degree to which generalizations regarding the molecular mechanisms of membrane trafficking can be applied to the platelet is uncertain. A second distinctive characteristic of the platelet is that its limiting membrane is characterized by a system of tunneling invaginations of the plasma membrane, termed the open canalicular system (OCS). 10,11 Evidence that the OCS is open to the extracellular environment is derived from reports using various cell-impermeant tracers. 12 The fate of the OCS on platelet activation is the subject of debate. There is evidence that the OCS undergoes evagination during platelet activation that provides an extra membrane for the formation of pseudopodia. 13,14 Others have shown th...

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Phagocytosis of liposomes by human platelets.

Cited by 40 publications

References 15 publications

Controlled Transcription of Exogenous mRNA in Platelets Using Protocells

Controlled Transcription of Exogenous mRNA in Platelets Using Protocells

Internalization of IgG-Coated Targets Results in Activation and Secretion of Soluble CD40 Ligand and RANTES by Human Platelets

Subcellular distribution of 3 functional platelet SNARE proteins: human cellubrevin, SNAP-23, and syntaxin 2

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