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At least 19 recordsLinked to original sources
PubMed2026

Photothermal-Activated Platelet-Rich Plasma Versus Conventional Platelet-Rich Plasma for Melasma: A Split-Face, Double-Blind Randomized Controlled Trial.

BACKGROUND: Melasma is a common acquired pigmentary disorder that predominantly affects women with darker skin types and substantially impairs quality of life. Current treatments are limited by variable efficacy, adverse effects, and frequent recurrence. Platelet-rich plasma (PRP) has emerged as a potential regenerative treatment through growth-factor-mediated modulation of melanogenesis. Photothermal activation, which combines photobiomodulation with controlled hypothermic conditioning, has been hypothesized to promote a more sustained growth-factor release than conventional PRP. This study compared the efficacy and safety of photothermal-activated PRP (PT-PRP) and conventional PRP (C-PRP) for melasma treatment. METHODS: This split-face, double-blind, randomized controlled trial included 26 women with epidermal or mixed-type melasma. Each participant received three monthly sessions of intradermal PRP, with PT-PRP and C-PRP injected into opposite facial sides. Outcomes were assessed at weeks 0, 4, 8, and 12 using the modified Melasma Area and Severity Index (mMASI), Mexameter melanin and erythema indices, patient satisfaction, overall improvement, and adverse events. RESULTS: Both treatments significantly reduced mMASI by week 12, with no significant between-group differences at any time point. C-PRP showed significant mMASI improvement from week 4, whereas PT-PRP reached significance from week 8. For the melanin index, PT-PRP produced a significant within-group reduction at week 12, while C-PRP did not. At week 12, PT-PRP showed a significantly lower melanin index than C-PRP. Mild injection-site bruising was the only adverse event. CONCLUSION: PT-PRP and C-PRP produced comparable clinical improvement, but PT-PRP achieved greater objective melanin reduction at week 12. PT-PRP may represent a safe alternative treatment for melasma. TRIAL REGISTRATION: Thai Clinical Trials Registry: TCTR20260318004.

Humans↗
PubMed2026

Hysteroscopic platelet-rich plasma and medically assisted reproduction outcomes: a systematic review and SWOT analysis.

BACKGROUND: Platelet-rich plasma (PRP) has been proposed as an adjuvant treatment in reproductive medicine. While most evidence refers to blind intrauterine instillation, subendometrial administration under hysteroscopic guidance allows targeted delivery under direct visualisation. This systematic review aimed to synthesise the available evidence on hysteroscopic PRP administration and its impact on clinical medically assisted reproduction (MAR) outcomes. METHODS: A systematic search was conducted from inception to December 2025 across major databases. Studies were included if they evaluated hysteroscopic PRP administration in women undergoing MAR, comparing reproductive outcomes between treated and control groups. RESULTS: Out of 142 records, 3 studies met the inclusion criteria. Study populations were heterogeneous and included women with refractory thin endometrium and/or a history of implantation failure. Hysteroscopic PRP administration protocols varied in timing, technique, and dosage. In a prospective case-control study, hysteroscopic intraendometrial PRP injection at a depth of 2-3 mm in the four uterine walls, using an ovum aspiration needle, on days 11-13 of the cycle prior to euploid frozen embryo transfer (ET), was associated with higher implantation (IR), clinical pregnancy (CPR), and live birth rates (LBR) compared with standard therapy. Conversely, no significant differences in CPR, miscarriage rate, or LBR were observed in an observational study evaluating a single intraendometrial PRP injection (35-40 mL, 2-3 mm depth), administered via endoscopic needle on days 6-8 of the menstrual cycle preceding frozen ET, alone or after electrical impulse therapy. A randomised controlled trial in women undergoing intrauterine insemination reported a significant improvement in CPR following hysteroscopic subendometrial PRP instillation in the four uterine walls (1.0 mL each). CONCLUSIONS: Current literature on hysteroscopic PRP administration in reproductive medicine is limited, and robust conclusions cannot yet be drawn. Well-designed randomised controlled trials with standardised protocols are needed to clarify its clinical role.

Humans↗
PubMedDate not supplied

Aggregation response of human platelets stored at 22 C as platelet-rich plasma.

The aggregating response of human platelets stored at 22 C for 72 hours has been studied. Platelets were stored as platelet-rich plasma in order to maintain the plasma pH essentially constant. The response to ADP and collagen decreased with time, but the decrease was less with relatively high concentrations of the aggregating agents. The response to the ionophore A23187 was essentially unaltered during the storage period. Synergistic aggregation with combinations of ADP, collagen and ionophore A23187 was observed with platelets stored for 72 hours under conditions where singly each of the stimuli caused little or no effect. Stored platelets underwent reversible aggregation over a wide range of ADP concentrations but irreversible aggregation was observed in the presence of nonaggregating concentrations of collagen or ionophore A23187. The inhibition of aggregation by PGE1 or cyclic AMP was facilitated as a result of storage. It is suggested that the decreased response toward ADP and collagen reflects a reduced ability on the part of the platelets to mobilize calcium.

Adenosine Diphosphate↗
PubMed1976

The pH dependence of quantitative ristocetin-induced platelet aggregation: theoretical and practical implications-a new device for maintenance of platelet-rich plasma pH.

Quantitative ristocetin-induced platelet aggregation of normal platelet-rich plasma (PRP) decreased with time after PRP preparation. An increase in p H of the PRP with time proved to be responsible for this finding. Diffusion of CO2from the plasma is the prime determinant of the change in pH. Since a complex combination of factors influences CO2 diffusion (surface area-to-volume relationship, capping, mixing, etc.) The change in pH is variable with time. Thus, quantitative ristocetin aggregation should be pH controlled. A simple device for maintaining PRP pH constant by control of the ambient pCO2 was designed and found effective in keeping both pH and quantitative ristocetin aggregation constant over a prolonged period of time. It can be adapted for use in platelet aggregation studies employing other reagents. The pH dependence of ristocetin-induced platelet aggregation is consistent with other data supporting an elctrostatic interaction between the platelet, von Willebrand factor, and ristocetin. We favor a model wherein ristocetin neutralizes some of the platelet's negative change and permits the von Willebrand factor to bridge sites on separate platelets to induce agglutination.

Blood Coagulation Tests↗
PubMed1976

Contribution of granulocytopenia to endotoxin sensitivity of mice irradiated or undergoing graft-versus-host reaction.

Animals compromised by irradiation or graft-versus-host reaction (GVHR) are highly sensitive to endotoxin (ET). In order to determine the causes of the increased sensitivity of compromised mice, we studied alterations of hepatic (central) and bloodborne (peripheral) ET clearance processes. We observed that increased sensitivity to ET, as determined by mortality, occurred shortly after irradiation and correlated with granulocytopenia nd thrombocytopenia rather than with impairment of liver function. The involvement of granulocytes in ET clearance was indicated by injection of 51Cr-ET suspended in whole blood. By comparison with clearance of ET injected with saline or plasma, greater amounts of 51Cr-ET were sequestered in peripheral organs than in the liver. Similar results were obtained when Cr-ET in whole blood was perfused through a rat liver. ET clearance was enhanced 50% over that seen in M-199, plasma, or platelet-rich plasma. It was also found that intestinal ET contributes to mortality of granulocytopenic-thrombocytopenic mice. This was supported by the observation that bacteriologically decontaminated, irradiated animals were eight times more resistant to challenge with ET than were conventional animals. Thus, an important aspect of increased sensitivity to ET, in comprised mice, is defective peripheral clearance.

Agranulocytosis↗
PubMed2026

Effectiveness of Platelet Rich Plasma in Reducing Oronasal Fistula and Scar Width in Primary Cleft Lip and Palate Repair-A Systematic Review and Meta-Analysis.

This review aimed to investigate platelet-rich plasma (PRP) and platelet-rich fibrin (PRF) efficiency in reducing oronasal fistula during primary cleft lip and palate repair. An extensive search of PubMed, Google Scholar, Global Index Medics (WHO), PubMed Scopus, Cochrane Central, Proquest was performed up to march 2025. Eligible studies included prospective RCTs and non-randomized controlled trials in human subjects. Patients aged 6-24 months undergoing primary cleft lip and palate repair were involved. Interventions involved intraoperative use of PRP/PRF compared with controls without PRP/PRF. The primary outcome was occurrence of oronasal fistula; secondary outcomes were scar width, wound infection and postoperative bleeding with wound dehiscence. Study selection followed PRISMA guidelines, and the risk of bias was determined with the ROB-2 and ROBINS-I method of assessment. Seven studies met the required criterion and were qualitatively synthesized. Evidence suggested that PRP/PRF application was associated with a lower incidence of oronasal fistula and reduced scar width compared with controls. Additional benefits included accelerated wound healing and faster recovery. The use of autologous PRP was also reported to decrease the need for further surgical interventions. However, the certainty of evidence was limited due to small sample sizes and methodological heterogeneity. PRP and PRF show promising benefits in cleft lip and palate repair, particularly decreased fistula formation and reduced scar width. Nevertheless, current evidence is of low to very low certainty. Larger, well-designed randomized trials are required to validate the results obtained. Trial Registration: PROSPERO registration no. CRD420251032421.

Humans↗
PubMed1979

Stimulation of human platelets by carrageenans.

The rank order of four carrageenans tested as inducers of human platelet aggregation was the same (iota greater than lambda greater than gelcarin greater than kappa) as their relative inflammatory potencies in vivo. All four carrageenans caused some precipitation of plasma proteins, and induced aggregation in platelet-rich plasma or washed platelet suspensions. The second phase of aggregation was citrate-dependent and associated with secretion of 5-hydroxytryptamine and lysosomal enzymes. Platelets could provide a useful model for investigating the actions of carrageenans on cell membranes.

Blood Platelets↗
PubMed2026

Comparative proteomic analysis reveals the pathological mechanisms of overuse achilles tendinopathy and the therapeutic mechanisms of ESWT and PRP.

BACKGROUND: Achilles tendinopathy is a common musculoskeletal disorder with limited self-repair capacity. Although extracorporeal shock wave therapy (ESWT) and platelet-rich plasma (PRP) are widely used, their therapeutic mechanisms remain unclear. METHODS: A rat model of overuse Achilles tendinopathy was established by uphill treadmill running. Tendon morphology and structure were assessed by ultrasound and histology, and proteomic profiling was performed to identify differentially expressed proteins (DEPs) and enriched pathways. RESULTS: Ultrasound revealed subcutaneous edematous infiltration after overuse, and histology showed disorganized collagen fibers and altered cellular density. Compared with the normal group, the injury group showed 429 DEPs, which were enriched in pathways related to actin cytoskeleton and complement and coagulation cascades. Both ESWT and PRP treatments ameliorated these overuse-induced pathological changes. Compared with the rest group, the ESWT group showed 30 DEPs, while the PRP group showed 244, with 17 DEPs overlapping between the two comparisons. In the ESWT group, enriched pathways included actin cytoskeleton organization, protein stabilization, and sulfur metabolism. In the PRP group, enriched pathways included FcγR-mediated phagocytosis, lysosome, and endoplasmic reticulum protein processing. Compared with the normal group, the ESWT group showed 32 DEPs, whereas the PRP group showed only one (Serpina6), which was the only protein shared between the two comparisons. CONCLUSION: ESWT and PRP improve tendon healing in overuse Achilles tendinopathy through different molecular mechanisms. The PRP group showed a proteomic profile more similar to the normal group than the ESWT group. These findings provide a molecular basis for optimizing clinical treatment strategies.

Animals↗
PubMed1976

Plasma membrane phosphorylation by endogenous phosphate donors in human blood platelets. Selectivity of the action of dibutyryl cyclic AMP.

Incubation of platelet-rich plasma with 32Pi leads to cellular uptake of the isotope and covalent incorporation into several cell constituents. Plasma membranes isolated from intact labelled platelets, delipidated and solubilized in sodium dodecyl sulfate, show, upon gel electorphoretic analysis, three main peaks of radioactivity: two in the molecular weight range 100 000-30 000 and an additional very slow migrating component strong positive by the peirodic acid-Schiff reaction. Treatment of the cells with dibutyryl cyclic AMP under conditions just sufficient to completely inhibit platelet aggregation leads to an increased isotope incorporation. Electrophoretic analysis of membranes isolated from dibutyryl cyclic AMP-treated cell reveals: (a) no change in the general pattern of distribution of the isotope, (b) no difference in the isotope incorporation to the two components of lower mol. wt. and (c) a marked increase (greater than 100%) in isotope incorporation in the slow migrating material as compared to membranes isolated from control cells. This material can be extracted from platelet plasma membranes after treatment of the membranes for 5 h with Triton X-100, at a detergent-to-protein ratio of 7.5. When the membrane material extracted with Triton X-100 is subjected to gel chromatography in Agarose (Biogel A-15m), the phosphorylated material that corresponds to the slow migrating band in polyacrylanide gel electrophoresis is eluted with or very close to the void volume of the column. Isoelectric focussing of this fraction, shows a single radioactive peak corresponding to an isolectric point of 3.78. The isolated component is pronase-sensitive, contains 52% of carbohydrate and 15% sialic acid. Analysis of the stability of the bound phosphate suggests that about 43% of it is bound as acyl-phosphate. The results reported, obtained through an approach that closely resembles physiological conditions are compatible with the participation of this membrane phosphoglycoprotein in the phenomena of platelet aggregation.

Blood Platelets↗
PubMed1975

The isolation and characterisation of a platelet-specific beta-globulin (beta-thromboglobulin) and the detection of antiurokinase and antiplasmin released from thrombin-aggregated washed human platelets.

A protein fraction was isolated from the supernatant of thrombin-aggregated washed human platelets and was shown, by immunodiffusion techniques, to contain a platelet-specific beta-globulin (beta-thromboglobulin) as the major component. A molecular weight of 35 800 was determined for beta-thromboglobin from the measured sedimentation coefficient of3.0 S and Stokes radius of 2.85 nm. Beta-Thromboglobin was detected in the serum from whole blood and the supernatant of 48-h-old platelet-rich plasma and 28-day-old citrated whole blood, but not in platelet-poor plasma. The fraction containing beta-thromboglobulin was shown to possess an antiurokinase activity but was devoid of antiplasmin activity. A further fraction of approximate molecular weight 70 000 was also isolated which contained an antiplasmin but was devoid of antiurokinase activity.

Animals↗
PubMed1979

Is a slow reacting substance-like compound involved in rat platelet agglutination.

Endoperoxide analogs at doses 100-fold higher than those required to aggregate human platelet-rich plasma (PRP), were ineffective on rat PRP. Indomethacin (20 microM) and imidazole did not affect arachidonate-induced aggregation of rat PRP. On the other hand, prostaglandin (PG) E1 inhibited aggregation at doses similar to those effective on human PRP, while high doses of PGI2 failed to inhibit arachidonate aggregation in the rat. Eicosatetraynoic acid (10 microgram) blocked the second phase of aggregation; the Ca2+-ionophore A 23187 potentiated the arachidonate effect. Thus, it appears that endoperoxides or thromboxane A2 may not be involved in rat platelet aggregation and that the formation of aggregants from arachidonate shares many properties with the biosynthesis of slow reacting substance, a metabolite of arachidonic acid containing a sulphate group. To test this, rat PRP was incubated with labeled sulphate and aggregated with arachidonate. After column and thin layer chromatography a labeled lipid was identified having a mobility higher than phospholipids but lower than PGF2 alpha. Treatment with arylsulphatase decreased radioactivity by at least 70%.

Adenosine Diphosphate↗
PubMed1977

HLA-antibody-induced 14C-serotonin release from platelets. A methodological analysis.

The prerequisites and kinetics of HLA-antibody-induced 14C-serotonin release from platelets were investigated with five HLA-specific antisera. By studying the influence of incubation time, temperature, pH, platelet count, stirring and extent of platelet labeling, optimal results were obtained after 30 (to 60) min of incubation at 37 degrees C, pH 7.5-8.0, under constant stirring (400 rpm). Optimal platelet counts varied between 160,000 and 400,000/microliter depending on the antiserum applied. A comparison of the amount of 14C-serotonin released by different antisera from washed platelets and from platelets in platelet-rich plasma suggests that plasma components--most likely complement--may additionally influence the results. Based on these experiments, a standardized microtechnique of HLA-antibody-induced 14C-serotonin release is recommended.

Antibody Specificity↗
PubMed1975

Effect of pneumococci on blood clotting, platelets, and polymorphonuclear leukocytes.

Infections due to Streptococcus pneumoniae and products from the organism have been associated with alterations in blood clotting and function of platelets. Pneumococci and pneumococcal polysaccharide shortened the clotting times of whole blood, platelet-rich plasma (PRP), and platelet-poor plasma (PPP) in vitro. Clotting times of PPP and PRP from C6-deficient animals were likewise decreased. The bacteria had no effect on the one-stage prothrombin time or the partial thromboplastin time when the organisms were used as activating agents. Platelets aggregated in the presence of pneumococci, but aggregation was prevented by the addition of cyclic adenosine 3', 5'-monophosphate (cAMP). Furthermore, cAMP corrected the shortened clotting time of PRP in the presence of pneumococci. The clumping and release of polymorphonuclear coagulant that was induced by pneumococci was not prevented by cAMP. Thus, pneumococci exert several dose-dependent thromboplastic effects: (i) release of platelet thromboplastic substances; (ii) a direct thromboplastic effect; and (iii) release of polymorphonuclear coagulant.

Animals↗
PubMed2025

Proteomic insights into platelet dysregulation and pathogenic mechanisms of chronic thromboembolic pulmonary hypertension.

BACKGROUND: Undissolved thrombus blocks the pulmonary arteries in chronic thromboembolic pulmonary hypertension (CTEPH), a potentially fatal illness that raises pulmonary resistance, causes right heart failure, and even results in death. Although platelets are linked to vascular dysfunction and thrombus formation, it is yet unknown what precise proteome alterations and mechanistic roles they play in CTEPH. METHODS: We extracted platelet-rich plasma from peripheral blood and separated the plasma to obtain enriched platelet pellet (EPP). Quantitative proteomics was used to examine EPP from CTEPH patients and healthy controls using mass spectrometry. The relationship between protein levels and clinical markers of right heart function was examined. Platelet activity, morphology, and interactions with other blood components were evaluated using transmission electron microscopy, immunofluorescence, and flow cytometry. RESULTS: The proteomic investigation found that 179 proteins were differentially expressed in CTEPH patients. The analysis revealed that these proteins were involved in crucial processes such as complement and coagulation cascades, phagosome, and neutrophil extracellular trap (NET) formation. Elevated proteins, specifically NOX2, PAD4, ITGB2, and HMGB1, have been associated to platelet-neutrophil aggregates and NET formation. In addition, enhanced P-selectin expression in platelets and plasma confirmed greater platelet activation in CTEPH patients. Notably, PAD4 and NOX2 levels showed a substantial correlation with hemodynamic parameters and right heart dysfunction. MPO-DNA, a NET marker associated with P-selectin and ITGB2 expression, was discovered in higher concentrations in CTEPH patients' plasmas. CONCLUSION: Platelet aggregation and activation in CTEPH encourage the formation of NETs, which advances the disease and prolongs thrombus. Right heart insufficiency and hemodynamic markers had a strong correlation with PAD4 and NOX2 levels, indicating that these biomarkers may be employed to assess the severity and prognosis of CTEPH disease and offer a fresh approach to targeted treatment. The results highlight the need for additional study to elucidate platelet-mediated pathways and create therapies for CTEPH that target platelets.

Humans↗
PubMed1976

Competitive inhibition by lithium and hydrogen ions of the effect of calcium on the aggregation of rabbit platelets.

ADP-induced platelet aggregation and shape change were monitored optically in citrated rabbit platelet-rich plasma (PRP) diluted with isotonic salt solutions. Lithium (Li) produced a concentration-dependent reduction in the rate of platelet aggregation but had no discernible effect on the shape change which precedes aggregation. When PRP was pre-incubated with Li, the inhibitory effect of the ion was independent of the duration and temperature of the treatment. The inhibitory effect of Li also was observed in heparinized PRP or when 5-HT was used as the aggregation-inducing agent. When Li was combined with aggregation inhibitors which enhance platelet cyclic AMP content either by activating adenylate cyclase or by inhibiting phosphodiesterase, only additive effects were observed. The inhibitory effect of Li was opposed by added calcium. Kinetic evaluation of the interaction between Li and Ca indicated that their antagonism was competitive. Added calcium also displayed competitive antagonism toward the aggregation inhibiting effect of increased hydrogen ion concentration in the pH range between 6 and 8.

Adenosine Diphosphate↗
PubMed1977

Plasma constituent (s) inhibiting platelet adhesiveness.

Adhesiveness in citrated whole blood is critically pH dependent at hydrogenion concentrations close to the physiological range. While platelets in platelet-rich plasma (PRP) adhere poorly in glass-bead columns, washed platelets and particularly gel-filtered platelets (GFP), prepared from PRP, are adhesive, Separation of PRP on a Sepharose 2B column revealed the presence of an inhibitor of adhesiveness of GFP. The inhibitory compound is thermostable and nondialyzable. It is inactivated completely by pronase digestion and partally by trypsin digestion. It is distinct from any one of the known platelet factors. Washed erythrocytes and erythrocyte membranes attenuate the potency of the inhibitor. Following separation by isoelectric focusing, the inhibitory activity is limited primarily to a single fraction with an isoelectric point of 5.1 containing equal amounts of proteins and lipids. Two protein bands are revealed by sodium dodecyl sulfate-gel electrophoresis of the purified fraction. It is concluded that PRP contains a compound, apparently a lipoprotein, which inhibits platelet adhesiveness.

Adult↗
PubMed1979

Spontaneous platelet aggregation in cerebrovascular disease II. Further characterisation of the platelet defect.

A group of 186 patients with Transient Ischaemic Attacks (TIA) or cerebral infarction (CI) was found to demonstrate in vitro Spontaneous Platelet Aggregation (SPA) in 39% of those studied. Of the 176 normal subjects studied the incidence on in vitro SPA was found to be 5%. Further investigation of the phenomenon of SPA revealed that: 1. it is associated with ADP-hyperaggregability, i. e. the threshold concentration to induce second wave aggregation is decreased; 2. it is dependant on the increase in pH which occurs in platelet-rich plasma stirring in an aggregometer while concurrent ADP-hyperaggregability is independant of this change in pH; 3. it is associated with malondialdehyde production and the release of endogenous 5-hydroxytryptamine; and that 4. in addition Km and Vmax values for [14c]-5HT incorporation are normal; and that 5. no gross abnormalities of the platelet membrane glycoproteins were apparent although occasionally glycoprotein III was found to be increased. This study demonstrates abnormal platelet behaviour in patients with TIA and CI where the enzyme system involved in thromboxane production is sufficiently stimulated, by stirring alone, to induce aggregation of platelets and the release reaction. Acetylsalicylic acid abolishes SPA and prolongs the bleeding time with similar characteristics as has been described for normal individuals. Plasma beta-thromboglobulin levels are significantly increased in the patients studied. However, no correlation was established with the incidence of in vitro SPA.

Adenosine Diphosphate↗