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Fulltext Anti-inflammatory and antiplatelet activities of plasma are conserved across twelve mammalian species

Ahmed S, Gul S, Idris F, Hussain A, Zia-Ul-Haq M, Jaafar HZ, et al.

Molecules, 2014;19(8):11385-94.
PMID: 25090125 DOI: 10.3390/molecules190811385

Human plasma inhibits arachidonic acid metabolism and platelet aggregation. This helps human form a haemostatic control system that prevents the progress of certain aggregatory or inflammatory reactions. Whether this property of plasma is unique to human or extends to other species is not well known. It is speculated that this protective ability of plasma remains evolutionarily conserved in different mammals. In order to confirm this, the effect of plasma from 12 different mammalian species was investigated for its inhibitory potential against arachidonic acid metabolism and platelet aggregation. Metabolism of arachidonic acid by cyclooxygenase and lipoxygenase pathways was studies using radio-immuno assay and thin layer chromatography while platelet aggregation in the plasma of various mammals was monitored following turbedmetric method in a dual channel aggregometer. Results indicate that inhibition of AA metabolism and platelet aggregation is a common feature of plasma obtained from different mammalian species, although there exists large interspecies variation. This shows that besides human, other mammals also possess general protective mechanisms against various aggregatory and inflammatory conditions and this anti-inflammatory property of the plasma is evolutionarily conserved in mammalian species. The most likely candidates responsible for these properties of plasma include haptoglobin, albumin and lipoproteins.

Matched MeSH terms: Blood Platelets/drug effects; Blood Platelets/metabolism
Fulltext Glycoprotein IIb/IIIa and P2Y12 induction by oligochitosan accelerates platelet aggregation

Periayah MH, Halim AS, Yaacob NS, Saad AZ, Hussein AR, Rashid AH, et al.

Biomed Res Int, 2014;2014:653149.
PMID: 25247182 DOI: 10.1155/2014/653149

Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia) is a receptor detected on platelets. Adenosine diphosphate (ADP) activates gpiibiiia and P2Y12, causing platelet aggregation and thrombus stabilization during blood loss. Chitosan biomaterials were found to promote surface induced hemostasis and were capable of activating blood coagulation cascades by enhancing platelet aggregation. Our current findings show that the activation of the gpiibiiia complex and the major ADP receptor P2Y12 is required for platelet aggregation to reach hemostasis following the adherence of various concentrations of chitosan biomaterials [7% N,O-carboxymethylchitosan (NO-CMC) with 0.45 mL collagen, 8% NO-CMC, oligochitosan (O-C), and oligochitosan 53 (O-C 53)]. We studied gpiibiiia and P2Y12 through flow cytometric analysis and western blotting techniques. The highest expression of gpiibiiia was observed with Lyostypt (74.3 ± 7.82%), followed by O-C (65.5 ± 7.17%). Lyostypt and O-C resulted in gpiibiiia expression increases of 29.2% and 13.9%, respectively, compared with blood alone. Western blot analysis revealed that only O-C 53 upregulated the expression of P2Y12 (1.12 ± 0.03-fold) compared with blood alone. Our findings suggest that the regulation of gpiibiiia and P2Y12 levels could be clinically useful to activate platelets to reach hemostasis. Further, we show that the novel oligochitosan is able to induce the increased expression of gpiibiiia and P2Y12, thus accelerating platelet aggregation in vitro.

Matched MeSH terms: Blood Platelets/drug effects; Blood Platelets/physiology*
In vitro capacity of different grades of chitosan derivatives to induce platelet adhesion and aggregation

Periayah MH, Halim AS, Hussein AR, Saad AZ, Rashid AH, Noorsal K

Int J Biol Macromol, 2013 Jan;52:244-9.
PMID: 23063426 DOI: 10.1016/j.ijbiomac.2012.10.001

Chitosan-derived hemostatic agents with various formulations may have distinct potential in hemostasis. This study assessed the ability of different grades and forms of chitosan derivatives as hemostatic agents to enhance platelet adhesion and aggregation in vitro. The chitosan derivatives utilized were 2% NO-CMC, 7% NO-CMC (with 0.45 mL collagen), 8% NO-CMC, O-C 52, 5% O-CMC-47, NO-CMC-35, and O-C 53. Samples of chitosan derivatives weighing 5mg were incubated at 37°C with 50 μL of phosphate buffer saline (PBS) (pH 7.4) for 60 min. The morphological features of the platelets upon adherence to the chitosan were viewed using scanning electron microscope (SEM), and the platelet count was analyzed with an Automated Hematology Analyzer. For platelet aggregation, we added an adenosine diphosphate (ADP) agonist to induce the chitosan-adhered platelets. O-C 52 bound with platelets exhibited platelet aggregates and clumps on the surface of the membrane layer with approximately 70-80% coverage. A statistically significant correlation (p<0.01) for the platelet count was identified between the baseline value and the values at 10 min and 20 min. The results indicate that O-C 53 and O-C 52 were able to promote clotting have the potential to induce the release of platelets engaged in the process of hemostasis.

Matched MeSH terms: Blood Platelets/metabolism*; Blood Platelets/ultrastructure
Physicochemical evaluation and in vitro hemocompatibility study on nanoporous hydroxyapatite

Ooi CH, Ling YP, Abdullah WZ, Mustafa AZ, Pung SY, Yeoh FY

J Mater Sci Mater Med, 2019 Mar 30;30(4):44.
PMID: 30929088 DOI: 10.1007/s10856-019-6247-5

Hydroxyapatite is an ideal biomaterial for bone tissue engineering due to its biocompatibility and hemocompatibility which have been widely studied by many researchers. The incorporation of nanoporosity into hydroxyapatite could transform the biomaterial into an effective adsorbent for uremic toxins removal especially in artificial kidney system. However, the effect of nanoporosity incorporation on the hemocompatibility of hydroxyapatite has yet to be answered. In this study, nanoporous hydroxyapatite was synthesized using hydrothermal technique and its hemocompatibility was determined. Non-ionic surfactants were used as soft templates to create porosity in the hydroxyapatite. The presence of pure hydroxyapatite phase in the synthesized samples is validated by X-ray diffraction analysis and Fourier transform infrared spectroscopy. The TEM images show that the hydroxyapatite formed rod-like particles with the length of 21-90 nm and diameter of 11-70 nm. The hydroxyapatite samples exhibit BET surface area of 33-45 m2 g-1 and pore volume of 0.35-0.44 cm3 g-1. The hemocompatibility of the hydroxyapatite was determined via hemolysis test, platelet adhesion, platelet activation and blood clotting time measurement. The nanoporous hydroxyapatite shows less than 5% hemolysis, suggesting that the sample is highly hemocompatible. There is no activation and morphological change observed on the platelets adhered onto the hydroxyapatite. The blood clotting time demonstrates that the blood incubated with the hydroxyapatite did not coagulate. This study summarizes that the synthesized nanoporous hydroxyapatite is a highly hemocompatible biomaterial and could potentially be utilized in biomedical applications.

Matched MeSH terms: Blood Platelets/drug effects*; Blood Platelets/physiology
Fulltext Impact of specific functional groups in flavonoids on the modulation of platelet activation

Ravishankar D, Salamah M, Akimbaev A, Williams HF, Albadawi DAI, Vaiyapuri R, et al.

Sci Rep, 2018 Jun 22;8(1):9528.
PMID: 29934595 DOI: 10.1038/s41598-018-27809-z

Flavonoids exert innumerable beneficial effects on cardiovascular health including the reduction of platelet activation, and thereby, thrombosis. Hence, flavonoids are deemed to be a molecular template for the design of novel therapeutic agents for various diseases including thrombotic conditions. However, the structure-activity relationships of flavonoids with platelets is not fully understood. Therefore, this study aims to advance the current knowledge on structure-activity relationships of flavonoids through a systematic analysis of structurally-related flavones. Here, we investigated a panel of 16 synthetic flavones containing hydroxy or methoxy groups at C-7,8 positions on the A-ring, with a phenyl group or its bioisosteres as the B-ring, along with their thio analogues possessing a sulfur molecule at the 4th carbon position of the C-ring. The antiplatelet efficacies of these compounds were analysed using human isolated platelets upon activation with cross-linked collagen-related peptide by optical aggregometry. The results demonstrate that the hydroxyl groups in flavonoids are important for optimum platelet inhibitory activities. In addition, the 4-C=O and B ring phenyl groups are less critical for the antiplatelet activity of these flavonoids. This structure-activity relationship of flavonoids with the modulation of platelet function may guide the design, optimisation and development of flavonoid scaffolds as antiplatelet agents.

Matched MeSH terms: Blood Platelets/drug effects; Blood Platelets/physiology
Fulltext Effects of chalcone derivatives on players of the immune system

Lee JS, Bukhari SN, Fauzi NM

Drug Des Devel Ther, 2015;9:4761-78.
PMID: 26316713 DOI: 10.2147/DDDT.S86242

The immune system is the defense mechanism in living organisms that protects against the invasion of foreign materials, microorganisms, and pathogens. It involves multiple organs and tissues in human body, such as lymph nodes, spleen, and mucosa-associated lymphoid tissues. However, the execution of immune activities depends on a number of specific cell types, such as B cells, T cells, macrophages, and granulocytes, which provide various immune responses against pathogens. In addition to normal physiological functions, abnormal proliferation, migration, and differentiation of these cells (in response to various chemical stimuli produced by invading pathogens) have been associated with several pathological disorders. The unwanted conditions related to these cells have made them prominent targets in the development of new therapeutic interventions against various pathological implications, such as atherosclerosis and autoimmune diseases. Chalcone derivatives exhibit a broad spectrum of pharmacological activities, such as immunomodulation, as well as anti-inflammatory, anticancer, antiviral, and antimicrobial properties. Many studies have been conducted to determine their inhibitory or stimulatory activities in immune cells, and the findings are of significance to provide a new direction for subsequent research. This review highlights the effects of chalcone derivatives in different types of immune cells.

Matched MeSH terms: Blood Platelets/drug effects; Blood Platelets/immunology; Blood Platelets/metabolism
Fulltext Enhanced Thermal and Dynamic Mechanical Properties of Synthetic/Natural Hybrid Composites with Graphene Nanoplateletes

Jesuarockiam N, Jawaid M, Zainudin ES, Thariq Hameed Sultan M, Yahaya R

Polymers (Basel), 2019 Jun 26;11(7).
PMID: 31247898 DOI: 10.3390/polym11071085

The aim of the present research work is to enhance the thermal and dynamic mechanical properties of Kevlar/Cocos nucifera sheath (CS)/epoxy composites with graphene nano platelets (GNP). Laminates were fabricated through the hand lay-up method followed by hot pressing. GNP at different wt.% (0.25, 0.5, and 0.75) were incorporated with epoxy resin through ultra-sonication. Kevlar/CS composites with different weight ratios (100/0, 75/25, 50/50, 25/75, 0/100) were fabricated while maintaining a fiber/matrix weight ratio at 45/55. Thermal degradation and viscoelastic properties were evaluated using thermogravimetric analysys (TGA), differential scanning calorimetric (DSC) analysis, and a dynamic mechanical analyser (DMA). The obtained results revealed that Kevlar/CS (25/75) hybrid composites at 0.75 wt.% of GNP exhibited similar thermal stability compared to Kevlar/epoxy (100/0) composites at 0 wt.% of GNP. It has been corroborated with DSC observation that GNP act as a thermal barrier. However, DMA results showed that the Kevlar/CS (50/50) hybrid composites at 0.75 wt.% of GNP exhibited almost equal viscoelastic properties compared to Kevlar/epoxy (100/0) composites at 0 wt.% GNP due to effective crosslinking, which improves the stress transfer rate. Hence, this research proved that Kevlar can be efficiently (50%) replaced with CS at an optimal GNP loading for structural applications.

Matched MeSH terms: Blood Platelets
Predictors and Clinical Outcomes of Poor Platelet Recovery in Adult Dengue With Thrombocytopenia: A Multicenter, Prospective Study

Archuleta S, Chia PY, Wei Y, Syed-Omar SF, Low JG, Oh HM, et al.

Clin Infect Dis, 2020 07 11;71(2):383-389.
PMID: 31626692 DOI: 10.1093/cid/ciz850

BACKGROUND: Platelet transfusion is common in dengue patients with thrombocytopenia. We previously showed in a randomized clinical trial that prophylactic platelet transfusion did not reduce clinical bleeding. In this study, we aimed to characterize the predictors and clinical outcomes of poor platelet recovery in transfused and nontransfused participants.
METHODS: We analyzed patients from the Adult Dengue Platelet Study with laboratory-confirmed dengue with ≤20 000 platelets/μL and without persistent mild bleeding or any severe bleeding in a post hoc analysis. Poor platelet recovery was defined as a platelet count of ≤20 000/μL on Day 2. We recruited 372 participants from 5 acute care hospitals located in Singapore and Malaysia between 29 April 2010 and 9 December 2014. Of these, 188 were randomly assigned to the transfusion group and 184 to the control group.
RESULTS: Of 360 patients, 158 had poor platelet recovery. Age, white cell count, and day of illness at study enrollment were significant predictors of poor platelet recovery after adjustment for baseline characteristics and platelet transfusion. Patients with poor platelet recovery had longer hospitalizations but no significant difference in other clinical outcomes, regardless of transfusion. We found a significant interaction between platelet recovery and transfusion; patients with poor platelet recovery were more likely to bleed if given a prophylactic platelet transfusion (odds ratio 2.34, 95% confidence interval 1.18-4.63).
CONCLUSIONS: Dengue patients with thrombocytopenia who were older or presented earlier and with lower white cell counts were more likely to have poor platelet recovery. In patients with poor platelet recovery, platelet transfusion does not improve outcomes and may actually increase the risk of bleeding. The mechanisms of poor platelet recovery need to be determined.
CLINICAL TRIALS REGISTRATION: NCT01030211.

Matched MeSH terms: Blood Platelets
Fulltext Determining the effectiveness of the different preparation protocols for platelet-rich plasma (PRP) in yielding higher concentrations of platelets

Kavitha, G., Sangeetha, V.N., Shani, S., Murali, M.R., Raja, E.A., Rukmanikanthan, S., et al.

JUMMEC, 2011;14(2):1-6.
MyJurnal

INTRODUCTION: Despite the various methods described in producing platelet-rich plasma (PRP), it is well established that this biological product in its many preparations have been proven to enhance wound healing. However, very little have been known about the efficacy of these methods hence there is a lack of evidence in the superiority of one method over another. Thus, a study was conducted to compare these different protocols to determine which produces the highest concentration of platelets.
METHODS: Peripheral blood was obtained from 24 healthy volunteers. Four different protocols using similar 2 step centrifugation methods of preparing PRP were applied to an equal number of samples in this study. Platelet counts were performed on whole blood (without processing), PRP preparations and platelet-poor plasma (PPP).
RESULTS: All protocols produced higher amounts of platelet concentrates in PRP preparations than plasma. However, centrifugation at 150g for 10 minutes followed by another at 450g at 10 minutes produces significantly higher amount of platelets concentration (p<0.05)
CONCLUSION: Optimizing the protocols to produce PRP appears to be important in obtaining a maximal yield of platelet concentrate. Here the protocol described has shown to provide significant concentration yield over all others.
Keywords: platelet-rich-plasma, growth factors, centrifugal forces

Matched MeSH terms: Blood Platelets
Fulltext Effect of higher centrifugation speed and shortened centrifugation time on prothrombin and activated thromboplastin time

Azlin, I., Hafiza, A., Azma, R.Z., Aidifitrina, R.K., Hamidah, N.H.

Medicine & Health, 2011;6(1):68-72.
MyJurnal

Centrifugation of blood samples to produce platelet-poor plasma is one of the important steps for coagulation testing. Reduction of the time required for specimen processing without affecting quality of results should be ideal for tests which require immediate results. Centrifugation of platelet-poor plasma (3580 rpm) for 15 minutes performed for routine coagulation tests would prolong the turn-around time for an urgent test (30 minutes). This study was done to determine the effect of reducing centrifugation time for routine coagulation tests in order to meet the turn-around time (TAT) for urgent tests. Seventy-nine blood samples sent for routine coagulation tests, were assayed for prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen level and platelet counts, using two different centrifugation speed for plasma preparation: centrifugation at 3580 rpm for 15 minutes and rapid centrifugation at 4000 rpm for five minutes. Paired sample t-test showed that there was a significant
difference in the platelet count between the two groups (p=0.001). However, there was no significant difference in the normal APTT (p=0.16), abnormal APTT (p=0.80), abnormal PT (p=0.43) and the results of fibrinogen levels (p=0.36). In conclusion, rapid centrifugation at 4000 rpm for five minutes does not modify results of routine coagulation tests (PT, APTT and fibrinogen). It would be beneficial in providing rapid results for urgent coagulation tests.

Matched MeSH terms: Blood Platelets
Fulltext Platelet Transcriptome-based approaches in the fight against dengue and other diseases

Suppiah, J., Sakinah, S., Chan, S.Y., Wong, Y.P., Subbiah, S.K., Chee, H.Y., et al.

Pertanika Journal of Science & Technology, 2018;26(3):933-946.
MyJurnal

Human platelets are anucleate cells that lack in deoxyribonucleic acid (DNA), thus hampering genomic study on them. However, the presence of their own messenger ribonucleic acid (mRNA) transcript allows functional study via the transcriptome approach. Transcriptome not only allows profiling of platelet but also aids in studying gene regulation in virus infections and other diseases that have an impact on platelets. Some viruses are known to affect the platelet either by causing a reduction or destruction. Dengue virus is one of the most postulated virus having such effect and frequently linked to platelet reduction. The transcriptome approach has a pivotal role in providing a deeper insight to link certain diseases and their effect on platelets. This review critically discusses role of platelet in dengue and other viral diseases of public health relevance, with a specific focus on the methods currently used in platelet transcriptome profiling.

Matched MeSH terms: Blood Platelets
Fulltext Influence of alkylphosphonium modified montmorillonite to the tensile properties of PMMA composites

Abdullah, M.A.A., Mamat, M., Rusli, S.A., Kassim, A.A.

ASM Science Journal, 2018;11(101):96-104.
MyJurnal

Considering its excellent thermal stability, alkyl phosphonium surfactant: triisobutyl(methyl)phosphonium
(TIBMP) was used in this research as an intercalant for surface
modification of Na+-MMT via ion exchange process forming organomontmorillonite
(OMMT). The OMMT was then used as filler in poly(methyl methacrylate) (PMMA) via
melt intercalation technique. OMMT decomposed at a higher temperature than commercial
alkyammonium modified MMT. Exfoliated and intercalated types of nanocomposites
are obtained from PMMA/OMMTs at low and high content of OMMT loading, depending
on the space of those clay platelets had to disperse in PMMA. The ability of OMMT to
carry a certain load applied in PMMA matrix enhances the tensile strength in all composites.
TIBMP are compatible with PMMA matrix, and significantly improves the tensile
properties of PMMA composites.

Matched MeSH terms: Blood Platelets
Fulltext Phenytoin-induced severe thrombocytopaenia post dexamethasone co-administration in a patient with intracerebral haemorrhage

Lau, E.F., Mazlan, M., Shanmugam, H.

JUMMEC, 2018;21(2):31-34.
MyJurnal

Phenytoin is commonly prescribed for the prophylaxis of seizures in neurosurgical patients. A phenytoininduced
serious adverse effect of thrombocytopenia has been reported in the literature. The concurrent
use of dexamethasone, another commonly prescribed drug in neurosurgical patients, has been reported to
aggravate this adverse haematological effect. We present a report of phenytoin-induced thrombocytopenia
in a patient concurrently prescribed with dexamethasone, after an intracerebral haemorrhage secondary to
a rupture of an arteriovenous malformation. The thrombocytopenia was noted after two weeks of phenytoin
medication. Phenytoin was immediately withheld, and seven units of random donor platelets were transfused.
A gradual resolution of thrombocytopenia was observed within a week.

Matched MeSH terms: Blood Platelets
Estimation of a cut-off value for immature platelet fraction (IPF) in predicting platelet recovery in dengue patients with thrombocytopenia

Ahmad J, Md Noor S, Mustapha SZ, Idris F

Malays J Pathol, 2022 Dec;44(3):499-508.
PMID: 36591717

INTRODUCTION: Thrombocytopenia is a common complication in dengue that sometimes necessitates platelet transfusion. Immature platelet fraction (IPF) measures immature platelets that indirectly reflect thrombopoiesis and is helpful in predicting platelet recovery.
OBJECTIVES: This study aimed to evaluate the role of IPF% and identify its cut-off value in predicting platelet recovery in dengue patients with thrombocytopenia.
MATERIALS AND METHODS: Serial platelet count and IPF results were obtained from fifty-four confirmed dengue patients with platelet count <50x109 /L. Median peak IPF% and number of patients with platelet recovery were determined. Receiver operating characteristic (ROC) curve is generated to identify the IPF% cut-off value to predict platelet recovery.
RESULTS: Median peak IPF% among dengue patients was 12.15% with 83.3% of them achieving platelet recovery after reaching the peak IPF%. There was a significant difference between median IPF% on day one of admission with peak IPF% among dengue patients. ROC curve analysis showed IFP% of 10.55% can be used to predict platelet recovery with a sensitivity of 69% and a specificity of 67%.
CONCLUSION: IPF% is a reliable and useful parameter in predicting platelet recovery in dengue patients. This would assist the clinician in managing dengue patients especially those with severe thrombocytopenia without giving unnecessary platelet transfusion.

Matched MeSH terms: Blood Platelets
Fulltext Platelets kill circulating parasites of all major Plasmodium species in human malaria

Kho S, Barber BE, Johar E, Andries B, Poespoprodjo JR, Kenangalem E, et al.

Blood, 2018 Sep 20;132(12):1332-1344.
PMID: 30026183 DOI: 10.1182/blood-2018-05-849307

Platelets are understood to assist host innate immune responses against infection, although direct evidence of this function in any human disease, including malaria, is unknown. Here we characterized platelet-erythrocyte interactions by microscopy and flow cytometry in patients with malaria naturally infected with Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, or Plasmodium knowlesi Blood samples from 376 participants were collected from malaria-endemic areas of Papua, Indonesia, and Sabah, Malaysia. Platelets were observed binding directly with and killing intraerythrocytic parasites of each of the Plasmodium species studied, particularly mature stages, and was greatest in P vivax patients. Platelets preferentially bound to the infected more than to the uninfected erythrocytes in the bloodstream. Analysis of intraerythrocytic parasites indicated the frequent occurrence of platelet-associated parasite killing, characterized by the intraerythrocytic accumulation of platelet factor-4 and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling of parasite nuclei (PF4+TUNEL+ parasites). These PF4+TUNEL+ parasites were not associated with measures of systemic platelet activation. Importantly, patient platelet counts, infected erythrocyte-platelet complexes, and platelet-associated parasite killing correlated inversely with patient parasite loads. These relationships, taken together with the frequency of platelet-associated parasite killing observed among the different patients and Plasmodium species, suggest that platelets may control the growth of between 5% and 60% of circulating parasites. Platelet-erythrocyte complexes made up a major proportion of the total platelet pool in patients with malaria and may therefore contribute considerably to malarial thrombocytopenia. Parasite killing was demonstrated to be platelet factor-4-mediated in P knowlesi culture. Collectively, our results indicate that platelets directly contribute to innate control of Plasmodium infection in human malaria.

Matched MeSH terms: Blood Platelets/metabolism; Blood Platelets/parasitology*; Blood Platelets/pathology
Fulltext Preliminary comparative analysis of antibacterial effects of activated and non-activated of expired platelet concentrate by disc diffusion method

Zabidi MA, Yusoff NM, Kader ZS

Indian J Pathol Microbiol, 2012 Jan-Mar;55(1):47-51.
PMID: 22499300 DOI: 10.4103/0377-4929.94855

Platelets release more than 30 cytokines to provide primary hemostatic function. In addition, platelets are also known to release antimicrobial peptides upon activation by thrombin.

Matched MeSH terms: Blood Platelets/chemistry*
Blood compatibility of human amniotic membrane compared with heparin-coated ePTFE for vascular tissue engineering

Kakavand M, Yazdanpanah G, Ahmadiani A, Niknejad H

J Tissue Eng Regen Med, 2017 06;11(6):1701-1709.
PMID: 26190586 DOI: 10.1002/term.2064

Amniotic membrane (AM), a placenta-derived natural biomaterial, has several characteristics which make it a potential substitute for blood vessels. However, there are no reports on the effects of the AM on blood components. The aim of this study was to evaluate the blood compatibility of the epithelial and mesenchymal surfaces of the amnion for potential use in vascular tissue engineering. The activation of intrinsic and extrinsic pathways of the clotting system, haemolysis and platelet adhesion were studied and the results were compared with heparin-coated expanded polytetrafluoroethylene (ePTFE) as a standard synthetic vascular graft. Prothrombin time (PT), activated partial thromboplastin time (aPTT), clotting time (CT) and haemolysis (%) tests showed that both the epithelial and mesenchymal sides of the AM are haemocompatible. Platelet aggregation and P-selectin production from the platelets showed that the epithelial surface of the AM has less induction of platelet activation than ePTFE. The results of scanning electron microscopy (SEM) demonstrated that platelets in contact with ePTFE had a higher rate of adhesion than with the epithelial and mesenchymal surfaces of the AM. Moreover, the morphological distribution of the platelets showed that the majority of platelets were round, while a large number of cells on ePTFE were dendritic. These results suggest that the AM which contains epithelial and mesenchymal stem cells has appropriate haemocompatibility to be employed in vascular tissue engineering, especially as a vein substitute. Copyright © 2015 John Wiley & Sons, Ltd.

Matched MeSH terms: Blood Platelets/metabolism
Fulltext Circular RNA enrichment in platelets is a signature of transcriptome degradation

Alhasan AA, Izuogu OG, Al-Balool HH, Steyn JS, Evans A, Colzani M, et al.

Blood, 2016 Mar 03;127(9):e1-e11.
PMID: 26660425 DOI: 10.1182/blood-2015-06-649434

In platelets, splicing and translation occur in the absence of a nucleus. However, the integrity and stability of mRNAs derived from megakaryocyte progenitor cells remain poorly quantified on a transcriptome-wide level. As circular RNAs (circRNAs) are resistant to degradation by exonucleases, their abundance relative to linear RNAs can be used as a surrogate marker for mRNA stability in the absence of transcription. Here we show that circRNAs are enriched in human platelets 17- to 188-fold relative to nucleated tissues and 14- to 26-fold relative to samples digested with RNAse R to selectively remove linear RNA. We compare RNAseq read depths inside and outside circRNAs to provide in silico evidence of transcript circularity, show that exons within circRNAs are enriched on average 12.7 times in platelets relative to nucleated tissues and identify 3162 genes significantly enriched for circRNAs, including some where all RNAseq reads appear to be derived from circular molecules. We also confirm that this is a feature of other anucleate cells through transcriptome sequencing of mature erythrocytes, demonstrate that circRNAs are not enriched in cultured megakaryocytes, and demonstrate that linear RNAs decay more rapidly than circRNAs in platelet preparations. Collectively, these results suggest that circulating platelets have lost >90% of their progenitor mRNAs and that translation in platelets occurs against the backdrop of a highly degraded transcriptome. Finally, we find that transcripts previously classified as products of reverse transcriptase template switching are both enriched in platelets and resistant to decay, countering the recent suggestion that up to 50% of rearranged RNAs are artifacts.

Matched MeSH terms: Blood Platelets/metabolism*
Hemocompatibility evaluation of poly(1,8-octanediol citrate) blend polyethersulfone membranes

Zailani MZ, Ismail AF, Sheikh Abdul Kadir SH, Othman MH, Goh PS, Hasbullah H, et al.

J Biomed Mater Res A, 2017 05;105(5):1510-1520.
PMID: 28000366 DOI: 10.1002/jbm.a.35986

In this study, poly (1,8-octanediol citrate) (POC) was used to modify polyethersulfone (PES)-based membrane to enhance its hemocompatibility. Different compositions of POC (0-3%) were added into the polyethersulfone (PES) dope solutions and polyvinylpyrrolidone (PVP) was used as pore forming agent. The hemocompatible POC modified PES membranes were fabricated through phase-inversion technique. The prepared membranes were characterized using attenuated total reflectance-Fourier transform infrared (ATR-FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Atomic-force microscopy (AFM), contact angle, Zeta-potential, membrane porosity and pore size and pure water flux (PWF) and BSA rejection. The hemocompatibility of the modified PES membranes was evaluated by human serum fibrinogen (FBG) protein adsorption, platelet adhesion, activated partial thromboplastin time (APTT) and prothrombin time (PT), and thrombin-antithrombin III (TAT), complement (C3a and C5a) activation and Ca2+ absorption on membrane. Results showed that by increasing POC concentration, FBG adsorption was reduced, less platelets adhesion, prolonged APTT and PT, lower TAT, C5a and C3a activation and absorb more Ca2+ ion. These results indicated that modification of PES with POC has rendered improved hemocompatibility properties for potential application in the field of blood purification, especially in hemodialysis. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1510-1520, 2017.

Matched MeSH terms: Blood Platelets/metabolism*
Human platelet lysate permits scale-up of dental pulp stromal cells for clinical applications

Govindasamy V, Ronald VS, Abdullah AN, Ganesan Nathan KR, Aziz ZA, Abdullah M, et al.

Cytotherapy, 2011 Nov;13(10):1221-33.
PMID: 21929379 DOI: 10.3109/14653249.2011.602337

BACKGROUND AIMS. Dental pulp stromal cells (DPSC) are considered to be a promising source of stem cells in the field of regenerative therapy. However, the usage of DPSC in transplantation requires large-scale expansion to cater for the need for clinical quantity without compromising current good manufacturing practice (cGMP). Existing protocols for cell culturing make use of fetal bovine serum (FBS) as a nutritional supplement. Unfortunately, FBS is an undesirable additive to cells because it carries the risk of transmitting viral and prion diseases. Therefore, the present study was undertaken to examine the efficacy of human platelet lysate (HPL) as a substitute for FBS in a large-scale set-up. METHODS. We expanded the DPSC in Dulbecco's modified Eagle's medium-knock-out (DMEM-KO) with either 10% FBS or 10% HPL, and studied the characteristics of DPSC at pre- (T25 culture flask) and post- (5-STACK chamber) large-scale expansion in terms of their identity, quality, functionality, molecular signatures and cytogenetic stability. RESULTS. In both pre- and post-large-scale expansion, DPSC expanded in HPL showed extensive proliferation of cells (c. 2-fold) compared with FBS; the purity, immune phenotype, colony-forming unit potential and differentiation were comparable. Furthermore, to understand the gene expression profiling, the transcriptomes and cytogenetics of DPSC expanded under HPL and FBS were compared, revealing similar expression profiles. CONCLUSIONS. We present a highly economized expansion of DPSC in HPL, yielding double the amount of cells while retaining their basic characteristics during a shorter time period under cGMP conditions, making it suitable for therapeutic applications.

Matched MeSH terms: Blood Platelets/cytology; Blood Platelets/metabolism*

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