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Expert Review of Hematology Jan 2021Platelet-rich plasma (PRP) is an autologous blood-derived product that contains platelet concentrations at least 2/3 times above the normal level and includes... (Review)
Review
Platelet-rich plasma (PRP) is an autologous blood-derived product that contains platelet concentrations at least 2/3 times above the normal level and includes platelet-related growth factors. The concept of PRP began in the 1970s in the field of hematology to treat patients with thrombocytopenia. In the 1980s and 1990s, PRP began to be used in surgical procedures such as maxillofacial surgery and plastic surgery. Since then, PRP had been used in orthopedic procedures, cardiac surgery, sports injuries, plastic surgery, gynecology, urology, and more recently in medical esthetics. This review analyzes the mechanisms of action, current indications, clinical evidence, safety and future directions of PRP in the management of various medical conditions. The literature search methodology included using medical subject headings terms to search in PubMed. Articles used were screened and critically appraised by the coauthors of this review. Platelet-rich plasma is a therapeutic option used to treat many medical conditions. PRP could be used alone or in combination with other procedures. The effectiveness and safety of PRP has been demonstrated in many medical scenarios, however there is limited availability of large randomized clinical trials.
Topics: Animals; Blood Platelets; Evidence-Based Medicine; Humans; Platelet-Rich Plasma; Regenerative Medicine; Stem Cell Transplantation
PubMed: 33275468
DOI: 10.1080/17474086.2021.1860002 -
Journal of Hematology & Oncology Oct 2018The interaction of tumor cells with platelets is a prerequisite for successful hematogenous metastatic dissemination. Upon tumor cell arrival in the blood, tumor cells... (Review)
Review
The interaction of tumor cells with platelets is a prerequisite for successful hematogenous metastatic dissemination. Upon tumor cell arrival in the blood, tumor cells immediately activate platelets to form a permissive microenvironment. Platelets protect tumor cells from shear forces and assault of NK cells, recruit myeloid cells by secretion of chemokines, and mediate an arrest of the tumor cell platelet embolus at the vascular wall. Subsequently, platelet-derived growth factors confer a mesenchymal-like phenotype to tumor cells and open the capillary endothelium to expedite extravasation in distant organs. Finally, platelet-secreted growth factors stimulate tumor cell proliferation to micrometastatic foci. This review provides a synopsis on the current literature on platelet-mediated effects in cancer metastasis and particularly focuses on platelet adhesion receptors and their role in metastasis. Immunoreceptor tyrosine-based activation motif (ITAM) and hemi ITAM (hemITAM) comprising receptors, especially, glycoprotein VI (GPVI), FcγRIIa, and C-type lectin-like-2 receptor (CLEC-2) are turned in the spotlight since several new mechanisms and contributions to metastasis have been attributed to this family of platelet receptors in the last years.
Topics: Animals; Blood Platelets; Humans; Neoplasm Metastasis; Neoplasms
PubMed: 30305116
DOI: 10.1186/s13045-018-0669-2 -
Cancer Metastasis Reviews Jun 2017Platelets play an important role in the vessel. Following their formation from megakaryocytes, platelets exist in circulation for 5-7 days and primarily function as... (Review)
Review
Platelets play an important role in the vessel. Following their formation from megakaryocytes, platelets exist in circulation for 5-7 days and primarily function as regulators of hemostasis and thrombosis. Following vascular insult or injury, platelets become activated in the blood resulting in adhesion to the exposed extracellular matrix underlying the endothelium, formation of a platelet plug, and finally formation and consolidation of a thrombus consisting of both a core and shell. In pathological conditions, platelets are essential for formation of occlusive thrombus formation and as a result are the primary target for prevention of arterial thrombus formation. In addition to regulation of hemostasis in the vessel, platelets have also been shown to play an important role in innate immunity as well as regulation of tumor growth and extravasations in the vessel. These primary functions of the platelet represent its normal function and versatility in circulation.
Topics: Animals; Blood Platelets; Hemostasis; Humans; Thrombosis
PubMed: 28667366
DOI: 10.1007/s10555-017-9677-x -
Seminars in Thrombosis and Hemostasis Apr 2016Platelets are the smallest blood cells, numbering 150 to 350 × 10(9)/L in healthy individuals. The ability of activated platelets to adhere to an injured vessel... (Review)
Review
Platelets are the smallest blood cells, numbering 150 to 350 × 10(9)/L in healthy individuals. The ability of activated platelets to adhere to an injured vessel wall and form aggregates was first described in the 19th century. Besides their long-established roles in thrombosis and hemostasis, platelets are increasingly recognized as pivotal players in numerous other pathophysiological processes including inflammation and atherogenesis, antimicrobial host defense, and tumor growth and metastasis. Consequently, profound knowledge of platelet structure and function is becoming more important in research and in many fields of modern medicine. This review provides an overview of platelet physiology focusing particularly on the structure, granules, surface glycoproteins, and activation pathways of platelets.
Topics: Blood Platelets; Hemostasis; Humans; Models, Biological; Platelet Activation; Platelet Adhesiveness; Platelet Aggregation; Platelet Membrane Glycoproteins; Signal Transduction; Thrombosis
PubMed: 26926581
DOI: 10.1055/s-0035-1564835 -
Platelets 2019The utility of a methods section of a research paper is often tempered by the brevity demanded by manuscript word limitations. Whilst word limits help streamline a...
The utility of a methods section of a research paper is often tempered by the brevity demanded by manuscript word limitations. Whilst word limits help streamline a paper, a Methods section often bears the brunt of the editorial scalpel, resulting in only brief sketches of experimental protocols and consignment of methodology to online supplementary information files. To retain a place for important detailed methodology, and to encapsulate and highlight new and existing important techniques for platelet and megakaryocyte biology, the Platelets Journal Editorial board now accept Methods manuscripts.
Topics: Blood Platelets; Humans; Platelet Function Tests
PubMed: 30346864
DOI: 10.1080/09537104.2018.1529865 -
Blood Jun 2021Platelets have long been known to play important roles beyond hemostasis and thrombosis. Now recognized as a bona fide mediator of malignant disease, platelets influence... (Review)
Review
Platelets have long been known to play important roles beyond hemostasis and thrombosis. Now recognized as a bona fide mediator of malignant disease, platelets influence various aspects of cancer progression, most notably tumor cell metastasis. Interestingly, platelets isolated from cancer patients often display distinct RNA and protein profiles, with no clear alterations in hemostatic activity. This phenotypically distinct population, termed tumor-educated platelets, now receive significant attention for their potential use as a readily available liquid biopsy for early cancer detection. Although the mechanisms underpinning platelet education are still being defined, direct uptake and storage of tumor-derived factors, signal-dependent changes in platelet RNA processing, and differential platelet production by tumor-educated megakaryocytes are the most prominent scenarios. This article aims to cover the various modalities of platelet education by tumors, in addition to assessing their diagnostic potential.
Topics: Animals; Blood Platelets; Humans; Liquid Biopsy; Megakaryocytes; Neoplasm Metastasis; Neoplasm Proteins; Neoplasms; RNA, Neoplasm
PubMed: 33940594
DOI: 10.1182/blood.2019003976 -
Physiology (Bethesda, Md.) Mar 2017Upon blood vessel injury, platelets are exposed to adhesive proteins in the vascular wall and soluble agonists, which initiate platelet activation, leading to formation... (Review)
Review
Upon blood vessel injury, platelets are exposed to adhesive proteins in the vascular wall and soluble agonists, which initiate platelet activation, leading to formation of hemostatic thrombi. Pathological activation of platelets can induce occlusive thrombosis, resulting in ischemic events such as heart attack and stroke, which are leading causes of death globally. Platelet activation requires intracellular signal transduction initiated by platelet receptors for adhesion proteins and soluble agonists. Whereas many platelet activation signaling pathways have been established for many years, significant recent progress reveals much more complex and sophisticated signaling and amplification networks. With the discovery of new receptor signaling pathways and regulatory networks, some of the long-standing concepts of platelet signaling have been challenged. This review provides an overview of the new developments and concepts in platelet activation signaling.
Topics: Animals; Blood Platelets; Cyclic GMP; Humans; Inflammation; Integrins; Mice; Platelet Activation; Platelet Adhesiveness; Signal Transduction; Thrombosis
PubMed: 28228483
DOI: 10.1152/physiol.00020.2016 -
Circulation Research Jan 2018Platelets, non-nucleated blood components first described over 130 years ago, are recognized as the primary cell regulating hemostasis and thrombosis. The vascular... (Review)
Review
Platelets, non-nucleated blood components first described over 130 years ago, are recognized as the primary cell regulating hemostasis and thrombosis. The vascular importance of platelets has been attributed to their essential role in thrombosis, mediating myocardial infarction, stroke, and venous thromboembolism. Increasing knowledge on the platelets' role in the vasculature has led to many advances in understanding not only how platelets interact with the vessel wall but also how they convey changes in the environment to other circulating cells. In addition to their well-described hemostatic function, platelets are active participants in the immune response to microbial organisms and foreign substances. Although incompletely understood, the immune role of platelets is a delicate balance between its pathogenic response and its regulation of thrombotic and hemostatic functions. Platelets mediate complex vascular homeostasis via specific receptors and granule release, RNA transfer, and mitochondrial secretion that subsequently regulates hemostasis and thrombosis, infection, and innate and adaptive immunity.
Topics: Adaptive Immunity; Animals; Blood Platelets; Hemostasis; Humans; Immunity, Cellular; Immunity, Innate; Inflammation; Platelet Aggregation Inhibitors; Thrombosis
PubMed: 29348254
DOI: 10.1161/CIRCRESAHA.117.310795 -
Platelets Jul 2020Mass cytometry is a next generation flow cytometry technology which analyzes cells one at a time (up to 1000/sec) using mass spectrometry to detect probes labeled with... (Review)
Review
Mass cytometry is a next generation flow cytometry technology which analyzes cells one at a time (up to 1000/sec) using mass spectrometry to detect probes labeled with rare-earth metals. Rare-earth metals detected by mass spectrometry have extremely low backgrounds and can be identified with high resolution enabling the routine simultaneous detection of more than 45 probes on each cell without the need for complex compensation matrices. Here we describe a panel of 14 platelet-specific metal-conjugated antibodies (targeting cluster of differentiation [CD] 9, CD29, CD31, CD36, CD41, CD42a, CD42b, CD61, CD62P, CD63, CD107a, CD154, glycoprotein [GP] VI and activated integrin αIIbβ3) and methods for staining and analysis of platelets by mass cytometry. High dimensional clustering algorithms, which take into account the levels of all 14 markers detected by mass cytometry on each cell, allow identification of platelet subpopulations not previously appreciated. We previously reported that platelet heterogeneity identified by mass cytometry appears similar across healthy donors and consistent over time. High dimensional analysis revealed the presence of a platelet subpopulation with significantly higher levels of surface expression of activated GPIIb-IIIa and -selectin suggesting this subpopulation may play a greater role in thrombus formation than other platelet subpopulations. Thus, analysis by mass cytometry of platelet heterogeneity and subpopulations may suggest distinct biological roles for different platelet subpopulations and may be useful in evaluating inherited or acquired platelet disorders and platelet function in health and disease.
Topics: Blood Platelets; Flow Cytometry; Humans
PubMed: 31544564
DOI: 10.1080/09537104.2019.1668549 -
Blood Jun 2021Platelets play significant and varied roles in cancer progression, as detailed throughout this review series, via direct interactions with cancer cells and by long-range... (Review)
Review
Platelets play significant and varied roles in cancer progression, as detailed throughout this review series, via direct interactions with cancer cells and by long-range indirect interactions mediated by platelet releasates. Microvesicles (MVs; also referred to as microparticles) released from activated platelets have emerged as major contributors to the platelet-cancer nexus. Interactions of platelet-derived MVs (PMVs) with cancer cells can promote disease progression through multiple mechanisms, but PMVs also harbor antitumor functions. This complex relationship derives from PMVs' binding to both cancer cells and nontransformed cells in the tumor microenvironment and transferring platelet-derived contents to the target cell, each of which can have stimulatory or modulatory effects. MVs are extracellular vesicles of heterogeneous size, ranging from 100 nm to 1 µm in diameter, shed by living cells during the outward budding of the plasma membrane, entrapping local cytosolic contents in an apparently stochastic manner. Hence, PMVs are encapsulated by a lipid bilayer harboring surface proteins and lipids mirroring the platelet exterior, with internal components including platelet-derived mature messenger RNAs, pre-mRNAs, microRNAs, and other noncoding RNAs, proteins, second messengers, and mitochondria. Each of these elements engages in established and putative PMV functions in cancer. In addition, PMVs contribute to cancer comorbidities because of their roles in coagulation and thrombosis and via interactions with inflammatory cells. However, separating the effects of PMVs from those of platelets in cancer contexts continues to be a major hurdle. This review summarizes our emerging understanding of the complex roles of PMVs in the development and progression of cancer and cancer comorbidities.
Topics: Animals; Blood Platelets; Cell Communication; Extracellular Vesicles; Humans; Neoplasms; RNA, Neoplasm; Tumor Microenvironment
PubMed: 33940593
DOI: 10.1182/blood.2019004119