Activated human platelets release connective tissue growth factor (original) (raw)
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Platelets: Physiology and Biochemistry
Seminars in Thrombosis and Hemostasis, 2005
Platelets are specialized blood cells that play central roles in physiologic and pathologic processes of hemostasis, inflammation, tumor metastasis, wound healing, and host defense. Activation of platelets is crucial for platelet function that includes a complex interplay of adhesion and signaling molecules. This article gives an overview of the activation processes involved in primary and secondary hemostasis, for example, platelet adhesion, platelet secretion, platelet aggregation, microvesicle formation, and clot retraction/stabilization. In addition, activated platelets are predominantly involved in cross talk to other blood and vascular cells. Stimulated ''sticky'' platelets enable recruitment of leukocytes at sites of vascular injury under high shear conditions. Platelet-derived microparticles as well as soluble adhesion molecules, sP-selectin and sCD40L, shed from the surface of activated platelets, are capable of activating, in turn, leukocytes and endothelial cells. This article focuses further on the new view of receptor-mediated thrombin generation of human platelets, necessary for the formation of a stable platelet-fibrin clot during secondary hemostasis. Finally, special emphasis is placed on important stimulatory and inhibitory signaling pathways that modulate platelet function.
Influence of antiplatelet substances on platelet-rich plasma
Journal of Oral and Maxillofacial Surgery, 2004
Purpose: Platelets containing a number of growth factors (platelet-derived growth factor [PDGF], transforming growth factor- [TGF-], etc) can be obtained in high concentrations through centrifugal separation and are used in clinical applications as platelet-rich plasma (PRP). However, only a few studies have been conducted on the growth factors present in PRP. In this study, we focused on the concentrations of growth factors in PRP and clarified the influence of using antiplatelet substances in the process of platelet concentration to improve the concentration rate of growth factors in PRP. Materials and Methods: We made platelet pellets from whole blood obtained from humans with or without some antiplatelet substances (prostaglandin E 1 , aspirin, apyrase). Platelet pellets were resuspended in phosphate-buffered saline as platelet resuspensions. We measured PDGF and TGF-1 concentrations in the samples. In measurements, we had the samples treated to release growth factors from platelets to measure accurate concentrations. Results: PDGF and TGF-1 were concentrated to a mean of over 400% in the samples with antiplatelet substances as compared with the samples without antiplatelet substances. Conclusions: The antiplatelet substances were effective for efficiently concentrating growth factors in platelets.
Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontology, 2006
Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. In this second article, we investigate the platelet-associated features of this biomaterial. During PRF processing by centrifugation, platelets are activated and their massive degranulation implies a very significant cytokine release. Concentrated platelet-rich plasma platelet cytokines have already been quantified in many technologic configurations. To carry out a comparative study, we therefore undertook to quantify PDGF-BB, TGFb-1, and IGF-I within PPP (platelet-poor plasma) supernatant and PRF clot exudate serum. These initial analyses revealed that slow fibrin polymerization during PRF processing leads to the intrinsic incorporation of platelet cytokines and glycanic chains in the fibrin meshes. This result would imply that PRF, unlike the other platelet concentrates, would be able to progressively release cytokines during fibrin matrix remodeling; such a mechanism might explain the clinically observed healing properties of PRF.
Platelets (thrombocytes): The other recognized functions
Hospital Pharmacology - International Multidisciplinary Journal, 2016
Introduction: Platelets are smallest blood cells of discoid or round shape and are cytoplasmic fragments of megakaryocytes.Platelets consist of 3 types of granules: alpha granules, dense granules and lysosomes. Granule secretion releases coagulation factors, growth factors, cytokines, and a number of proteolytic enzymes.Platelets contain a number of receptors known as platelet agonists. Basic and most studied role of platelets is in hemostasis process. The aim of this paper is to point on platelet function unrelated to hemostasis. Matherials and methoods: Papers on other recognized functions of platelets were searched for in biomedical journals idexed in MEDLINE form 2004 to 2016. Topic: This paper studies less known platelet functions becoming subject of interest with the development of applied science. Platelets participate in infl ammation by releasing proinfl ammatory mediators (CD154, CD40L). Complement activation via Pselectin, platelet-generates immunomodulatory eff ect. CD40L accelerates releasing RANTES protein leading to intensifi ed activation of T-lymphocytes. During embryonic development, platelets allow blood and lymph vessels separation by activating CLE-2 receptor and ligand PDPN. Platelets alleviate migration and invasiveness of tumor cells, contribute to disease progression and development of metastases. Platelets affect maturation of follicles and oocytes and have important role in embryo implantation process and placentation. Conclusion: Based on these fi ndings, conclusion imposes platelets as not only active participants in the hemostasis process but as having signifi cant role in infl ammation, unspecifi ed and specifi ed body defending, tumor biology, embryonic development and in female reproductive system regulation. Numerous roles of platelets open wide range for the new drugs' operation. Their specifi c characteristic is the basis for the personalized Clinical pharmacology development and possibility of applying specifi c drug as polyindicative therapeutic agent.
Basic studies on the clinical applications of platelet-rich plasma
Cell transplantation, 2003
Platelets, which contain many growth factors such as platelet-derived growth factor (PDGF) and transforming growth factor-beta (TGF-beta), are being used in clinical applications as platelet-rich plasma (PRP). Only a few studies, however, have been conducted on the growth factors present in PRP and on the clinical applications using the drug delivery system (DDS). For the purpose of clinical application, we first modified the PRP preparation method and assessed the amounts of growth factors contained in the human platelet concentrates. Furthermore, we assessed fibrin glue as a DDS of platelet concentrates. Platelet precipitations were made by twice centrifuging human whole blood. The precipitated platelet was resuspended to yield the platelet concentrates. The growth factor concentrations were measured. Fibrin glue sheets containing this platelet concentrate were implanted in rabbit pinna and samples were obtained for immunostaining (anti-PDGF antibody) to assess the use of PRP over...
Vox Sanguinis, 1995
Pooled platelet concentrates (PC) prepared by the platelet-rich plasma (PRP) method were filtered with three different filters and stored for 8 days at room temperature. The effect of filtration on leukocyte contamination, platelet concentration, and the in vitro function, morphology, metabolism and activation of platelets were studied. Eight pools of 20 PRP-PC were used, each pool was split into 4 equal volumes; 3 were filtered over a PLSOHF, a PL-IOA and a Bio P10 filter, the 4 served as a control. After filtration, leukocyte counts exceeded 3 x lo5 in none of the pooled PC. Platelet loss induced by filtration was about 17%. During storage, no differences in pH, PC02, and lactate and glucose concentration were found between the filtered and the unfiltered units, nor were any differences observed between filtered and unfiltered pooled PC in aggregation upon stimulation with collagen andor ADP, adhesion capacity to collagen in flowing blood, nucleotide content of the platelets and nucleobase concentration in the plasma, expression of activation-dependent antigens, or platelet morphology as observed by light microscopy and by the swirling effect. Selective removal of B-thromboglobulin (22%) by the PLSOHF filter was observed. Pooled PC prepared by the PRP-method can be filtered and stored for 8 days without detrimental effect on platelet function, metabolism or activation.