Platelets have long been known to play critical roles in hemostasis by clumping and clotting blood vessel injuries. Recent experimental evidence strongly indicates that platelets can also interact with tumor cells by direct binding or secreting cytokines. For example, platelets have been shown to protect circulating cancer cells in blood circulation and to promote tumor metastasis. In-depth understanding of the role of platelets in cancer progression and metastasis provides promising approaches for platelet biomimetic drug delivery systems and functional platelet-targeting strategies for effective cancer treatment. This review highlights recent progresses in platelet membrane-based drug delivery and unique strategies that target tumor-associated platelets for cancer therapy. The paper also discusses future development opportunities and challenges encountered for clinical translation.
Animals ; Antineoplastic Agents ; chemistry ; pharmacology ; Biomimetic Materials ; chemistry ; Blood Platelets ; cytology ; Drug Carriers ; chemistry ; Humans ; Models, Animal ; Nanomedicine ; methods ; Nanostructures ; chemistry ; Neoplasms ; drug therapy

This study was designed to investigate inhibitory effects and possible mechanisms of snake venom tripeptide (pENW) on platelet adhesion in order to promote the development of a novel anti-platelet therapy. To study the inhibitory effects of pENW on platelet adhesion, washed platelets pre-incubated with pENW (116.5-466.2 μmol x L(-1)) were used to test the ability of platelet adhesion to fibrinogen. Effect of pENW on fibrin clot retraction was also tested. Effect of pENW on platelets viability was tested by MTT assay. Effect of pENW on reactive-oxygen species (ROS) levels of platelet was studied by flow cytometry assay. Calcium mobilization in Fura-2/AM-loaded platelets was monitored with a spectrofluorimeter. Cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP), thromboxane A2 (determined as its metabolite thromboxane B2) were measured using enzyme immunoassay kits. Akt, ERK and p38 phosphorylation were tested by Western blot. The results showed that pENW inhibited platelet adhesion and fibrin clot retraction in a concentration-dependent manner without cytotoxicity. Intracellular cGMP and cAMP in both resting and thrombin-activated platelets were increased by pENW. In addition, pENW attenuated intracellular Ca2+ mobilization and TXA2 production in platelets stimulated by thrombin. As shown by Western blot assay, Akt, ERK and p38 phosphorylation in thrombin-induced platelet were attenuated by pENW. However, inhibitory effects of pENW had nothing to do with ROS. Thus, pENW exhibited a significant inhibition on platelet adhesion to fibrinogen, which means pENW could block the first step of thrombosis as while as retard the more stable clot formation. The mechanisms of pENW on inhibition platelet adhesion might be related to instant regulations, such as protein kinases.
Blood Platelets ; drug effects ; Blotting, Western ; Calcium ; metabolism ; Cyclic AMP ; metabolism ; Cyclic GMP ; metabolism ; Flow Cytometry ; Phosphorylation ; Platelet Aggregation ; drug effects ; Reactive Oxygen Species ; metabolism ; Snake Venoms ; chemistry ; Thromboxane A2 ; metabolism ; Thromboxane B2 ; metabolism

OBJECTIVETo detect platelet anti-HPA-1a and -1b antibodies using recombinant GPIIIa fragments coupled to Luminex beads.

METHODSThe sensitivity of 2 techniques, monoclonal antibody specific immobilization of platelet antigen (MAIPA) and Luminex bead assay, was compared using 12 twofold-serial dilutions (from neat to 1 in 2048) of an anti-HPA-1a WHO international standard. The specificity of Luminex assay to identify anti-HPA-1a and -1b antibodies was assessed using 8 negative or positive controls and 36 blinded samples provided by WHO Platelet Workshop.

RESULTSThe sensitivity of MAIPA and Luminex bead assay to detect anti-HPA-1a was dilution 1/64 (i.e. 1.56 IU/ml) and far more than dilution 1/2048 (i.e. 0.049 IU/mL), respectively. The Luminex bead assay could specifically identify negative and positive controls of anti-HPA-1a and -1b. All results of 36 blinded samples by Luminex assay were accordant to reference results except one sample which contained high concentration antithetical antibody and resulted in false positive of anti-HPA-1b. Cross-reactivity was also not observed with the samples containing HLA, ABO or other platelet antibodies.

CONCLUSIONThe Luminex beads coupled with recombinant GPIIIa fragments can be used to detect HPA-1 system antibodies with sufficient sensitivity and specificity, that is suitable for the detection of platelet alloantibodies in clinical alloimmune thrombocytopenia.

Antibodies, Monoclonal ; Antigens, Human Platelet ; immunology ; Blood Platelets ; Humans ; Integrin beta3 ; chemistry ; Isoantibodies ; blood ; Purpura, Thrombocytopenic, Idiopathic ; diagnosis ; Recombinant Proteins ; chemistry ; Sensitivity and Specificity

OBJECTIVETo study the effect of aqueous extract of several kinds of herbs on human platelet aggregation and expression of P-selectin in vitro.

METHODSBlood was collected from volunteers. Effects of the prepared water extracts of herbs on platelet aggregation were monitored on a Packs-4 aggregometer. The fluorescence intensity of water extracts of Caulis Spatholobi, Flos Carthami and Rhizoma Curcumae on the expression of P-selectin in human platelets of healthy persons was measured with flow cytometry.

RESULTSOut of several herbs investigated, Flos Carthami and Rhizoma Curcumae potently inhibited platelet aggregation after incubation with platelet-rich plasma (PRP) for 15 min. Caulis Spatholobi Flos Carthami and Rhizoma Curcumae inhibited adenosine-5'-diphosphate (ADP) or platelet activating factor (PAF)-induced platelet aggregation in PRP in a dose-dependent manner. In contrast to Flos Carthami and Rhizoma Curcumae, Caulis Spatholobi could not inhibit thrombin-induced platelet aggregation. Despite its inability to inhibit thrombin-induced platelet aggregation in PRP, Caulis Spatholobi had a greater anti-aggregating activity in PRP induced by ADP or PAF. Caulis Spatholobi and Flos Carthami showed significant inhibitory effects on the expression of P-selectin.

CONCLUSIONSCaulis Spatholobi, Flos Carthami and Rhizoma Curcumae have potent anti-platelet properties, and their inhibitory actions are mediated via different mechanisms. Caulis Spatholobi inhibited ADP-induced platelet aggregation but not by thrombin, indicating that its mechanism of action might be independent of the thromboxane pathway. The effect of Caulis Spatholobi and Flos Carthami were associated with suppressing the expression of P-selectin.

Adult ; Blood Platelets ; drug effects ; metabolism ; Curcuma ; chemistry ; Fabaceae ; chemistry ; Humans ; P-Selectin ; metabolism ; Plant Extracts ; chemistry ; pharmacology ; Plants, Medicinal ; chemistry ; Platelet Aggregation ; drug effects ; Platelet Function Tests ; Water ; chemistry ; Young Adult

The changes of bioactive constituents were analyzed for Puhuang-Wulingzhi before and after compatibility and the antiplatelet and antithrombin activitives were evaluated in order to elucidate the scientific and reasonable of Puhuang-Wulingzhi compatibility. UPLC-QTOF-MA-Markerlynx, principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis were used for data analysis and tracking changes of chemical composition during the decocting process. In vitro platelet aggregation induced by ADP, thrombin time(TT) and prothrombin time (PT) were investigated for Puhuang-Wulingzhi before and after compatibility. The results showed that significant differences were found between the mixed decoction and codecoction of Wulingzhi and Puhuang. Five compounds changed obviously were identified as typhaneoside, naringenin, isorhamnetin-3-O-ruinoside, quercetin-3-O-neohesperidoside, kaempferol-3-O-neohesperidoside. The codecoction, comparing with the single decoction, was more significant in antiplatelet aggregation and could prolong thrombin time. In the same crude drug dose, the thrombin time (TT) elongation were greater. These data could provide references for elucidation of bioactive components for this herb pair.
Animals ; Antithrombins ; chemistry ; pharmacology ; Blood Platelets ; drug effects ; physiology ; Drugs, Chinese Herbal ; chemistry ; pharmacology ; Female ; Humans ; Molecular Structure ; Platelet Aggregation ; drug effects ; Rabbits ; Thrombin Time

Chemical constituents of Leonurus japonicus were isolated and purified by a combination of various chromatographic techniques including column chromatography over silica gel, Sephadex LH-20, MCI, and Rp C18. Structures of the isolates were determined by spectroscopic analysis as 10 coumarins: bergapten (1), xanthotoxin (2), isopimpinellin (3), isogosferal (4), imperatorin (5), meransin hydrate(6), isomeranzin(7), murrayone(8) , auraptenol(9), and osthol(10). In addition to compound 9, the others were isolated from the genus Leonurus for the first time. In the in vitro assay, compounds 4 and 8 significantly inhibited the abnormal increase of platelet aggregation induced by ADP.
Blood Platelets ; drug effects ; Coumarins ; chemistry ; pharmacology ; Leonurus ; chemistry ; Platelet Aggregation ; drug effects ; Platelet Aggregation Inhibitors ; chemistry ; pharmacology

The possibility of polyoxymethylene (POM) as heart valve leaflet material was investigated by comparing the hemocompatibility with that of 316L stainless steel and low-temperature isotropic pyrolytic carbon (LTIC). Surface hydrophobicity was characterized by water contact angle measurement. Platelet adhesion, APTT/PT/TT and hemolysis rate tests were applied for evaluating hemocompatibility. The results showed that POM was hydrophobic and had a low hemolytic rate, adhesion amount and activation degree of platelets on POM surface were less than 316L stainless steel, and was similar to LTIC. This research pointed out potential application of POM as heart valve leaflets.
Biocompatible Materials ; chemistry ; Blood Platelets ; Carbon ; chemistry ; Heart Valve Prosthesis ; Heart Valves ; Humans ; Platelet Adhesiveness ; Resins, Synthetic ; chemistry ; Stainless Steel ; chemistry

BACKGROUND: Standard protocols are lacking for the preparation of platelet lysates (PL) as an alternative to using fetal bovine serum as a cell culture supplement. This study aimed to establish optimum conditions for preparing PL for use in cell cultures. METHODS: Cell density in three pooled platelet concentrates (PC) were adjusted to 1x10(12)/L and 2x10(12)/L. PL was prepared from PC by 1 to 3 freeze-thaw (FT) cycles. HaCaT cells were cultured in media supplemented with 5% or 10% PL. Cell numbers were estimated using a Cell Counting Kit-8 (CCK-8; Dojindo Laboratories, Japan). Growth factors were quantified by using the Luminex 200 system (Luminex Corporation, USA). RESULTS: Cell proliferation rates in the presence of PLs were similar when prepared from PCs of both cell densities. The rates were higher in media containing 5% PL than 10% PL when prepared by two FT cycles. Concentrations of vascular endothelial growth factor (VEGF), platelet-derived growth factor-AB/BB (PDGF-AB/BB), PDGF-AA, and epidermal growth factor (EGF) were significantly higher in PL prepared from PC with a cell density of 2x10(12)/L than 1x10(12)/L PC. However, only VEGF and PDGF-AA concentrations in PLs were correlated with HaCaT cell counts. CONCLUSIONS: The 5% PL from PC with a cell density of 1x10(12)/L prepared by two FT cycles treatment was the most effective condition that supported steady HaCaT cell proliferation. Our finding may be useful for preparing PL-supplemented cell culture media.
Blood Platelets/chemistry/*metabolism ; Cell Line ; Cell Proliferation/drug effects ; Culture Media/pharmacology ; Epidermal Growth Factor/chemistry/pharmacology ; Humans ; Platelet-Derived Growth Factor/chemistry/pharmacology ; Vascular Endothelial Growth Factor A/chemistry/pharmacology

The chemical constituents of Safflower injection were isolated and purified by polyamide, silica gel, Sephadex LH-20, ODS column chromatographies and preparative HPLC. As a result, sixteen compounds have been isolated. Based on the spectral data analysis, their structures were elucidated as scutellarin (1), kaempferol-3-O-β-rutinoside(2), hydroxysafflor yellow A(3), rutin (4), coumalic acid(5), adenosine(6), syringoside(7), (3E)-4-(4'-hydroxyphenyl)-3-buten-2-one(8), (8Z)-decaene-4, 6-diyne-1-Oβ-D-glucopyranoside(9), 4-hydroxybenzaldehyde (10), (2E, 8E) -tetradecadiene-4, 6-diyne-1, 12, 14-triol-1-O-β-D-glucopyranoside (11), kaem-pferol-3-O-β-sophorose (12), uridine (13), roseoside (14), cinnamic acid (15), and kaempferol (16). Compounds 1,2,7,9,11 and 12 were isolated from the Safflower injection for the first time. The anti-platelet aggregation activities of the isolated compounds were assayed. The results indicated all tested compounds exhibited potent activity except for 5, while 2, 3, 9 and 12 showed strong activity against platelet aggregation.
Animals ; Blood Platelets ; drug effects ; physiology ; Carthamus tinctorius ; chemistry ; Drugs, Chinese Herbal ; chemistry ; isolation & purification ; pharmacology ; Fibrinolytic Agents ; chemistry ; isolation & purification ; pharmacology ; Molecular Structure ; Platelet Aggregation ; drug effects ; Rabbits ; Spectrometry, Mass, Electrospray Ionization

Animals ; Blood Platelets ; Cell Proliferation ; drug effects ; Dental Implants ; Fibrin ; chemistry ; history ; pharmacology ; therapeutic use ; Gingival Recession ; therapy ; History, 20th Century ; Humans ; Mesenchymal Stromal Cells ; cytology ; drug effects ; Osteoblasts ; cytology ; drug effects ; Sinus Floor Augmentation ; methods