| 1. |
- Alfredsson, Joakim, et al.
(författare)
-
Individual long-term variation of platelet reactivity in patients with dual antiplatelet therapy after myocardial infarction.
- 2019
-
Ingår i: Platelets. - : Informa UK Limited. - 0953-7104 .- 1369-1635. ; 30:5, s. 572-578
-
Tidskriftsartikel (refereegranskat)abstract
- There is a large inter-individual variation in response to clopidogrel treatment, and previous studies have indicated higher risk of thrombotic events in those with high residual platelet reactivity (HPR). Less is known about individual variation over time. The aim of this prospective cohort study was to investigate intra-individual variation in platelet reactivity. Platelet aggregation in whole blood was assessed in 77 patients, at 3 days, 8 days and 6 months after admission for acute myocardial infarction and loading dose of clopidogrel. All patients were treated with aspirin and clopidogrel through 6-month follow-up. We found a significant increase in median ADP-stimulated aggregation from third to eighth day (195 vs. 250 AU*min, p-value = 0.001) but not from day 8 to 6 months (250 vs. 223 AU*min, p-value = 0.666). There was no significant change in the overall rate of HPR (15.6% vs 20.8%, p-value 0.503) or low platelet reactivity (LPR) (37.7% vs 33.8%, p-value = 0.609) from day 8 to 6-month follow-up. In contrast, more than one in four changed HPR status, 15.6% from non-HPR to HPR and 10.4% HPR to non-HPR. A shift in LPR status appeared even more frequent, occurring in about one of three patients. In spite of similar median aggregation and rate of HPR during 6-month follow-up, about one in four of the patients changed HPR status and one in three changed LPR status. This may be important information for a concept of risk stratification based on a single aggregation value early after an acute coronary syndromes.
|
|
| 2. |
- Andersson Shams Hakimi, Caroline, et al.
(författare)
-
In vitro assessment of platelet concentrates with multiple electrode aggregometry.
- 2015
-
Ingår i: Platelets. - : Informa UK Limited. - 0953-7104 .- 1369-1635. ; 26:2, s. 132-137
-
Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT Storage impairs platelet function. It was hypothesized that multiple electrode aggregometry in vitro could be used to follow aggregability in platelet concentrates over time and that the results predict the efficacy of platelet transfusion in an ex vivo transfusion model. In vitro platelet aggregability was assessed in apheresis and pooled buffy coat platelet concentrates (BCs) (n = 13 each) using multiple electrode aggregometry with different agonists 1, 3, 5 and 7 days after preparation. In the ex vivo transfusion model, whole blood samples from nine healthy volunteers were collected every second day. The samples were supplemented with stored platelets (+146 × 10(9) × l(-1)) from the same unit 1, 3, 5 and 7 days after preparation. Platelet aggregability was assessed in the concentrate and in the whole blood samples before and after platelet supplementation. There was a continuous reduction in in vitro platelet aggregability over time in both apheresis and pooled BCs. The same pattern was observed after ex vivo addition of apheresis and pooled BCs to whole blood samples. The best correlation between in vitro aggregability and changes in aggregation after addition was achieved with collagen as agonist (r = 0.67, p
|
|
| 3. |
- Arinell, Karin, et al.
(författare)
-
Downregulation of platelet activation markers during long-term immobilization
- 2013
-
Ingår i: Platelets. - : Taylor & Francis. - 0953-7104 .- 1369-1635. ; 24:5, s. 369-374
-
Tidskriftsartikel (refereegranskat)abstract
- Immobilization and sedentary lifestyle are risk factors for venous thromboembolism and cardiovascular disease, yet little is known about platelet function during long-term physical inactivity. Our aim was to investigate platelet activation markers and their coupling to standardized immobilization: platelet-derived growth factor (PDGF-BB) and P-selectin. We studied 15 healthy females participating in the Women International Space simulation for Exploration study. Following a 20-day ambulatory control period, the subjects underwent 60 days of bed rest in head-down tilt position (-6 degrees) 24 hours a day, finalized by 20 days of recovery. The subjects were randomized into two groups during bed rest: a control group (n = 8) that remained physically inactive and an exercise group (n = 7) that participated in both supine resistance and aerobic exercise training. Blood samples for the analysis of platelet activation markers were collected at baseline (5 days before bed rest), after 44 days of bed rest and 8 days into the recovery period. Compared to baseline, the levels of P-selectin and PDGF-BB decreased after bed rest (by 55%, p = 0.01 and 73%, p < 0.03, respectively) and remained decreased in the recovery period (by 76%, p < 0.001 and 78%, p < 0.02, respectively, compared to baseline). Platelet count (baseline value for the exercise group 260 000/mu l +/- 34 000 and baseline value for the control group 210 000/mu l +/- 30 000) did not change during the bed rest study (two-way repeated measurements ANOVA, p = ns). There were no statistical differences between the physically inactive and the exercise group. During long-term immobilization, a known risk factor for thrombosis, the levels of P-selectin and PDGF-BB decreased. Our findings indicate downregulation of platelet activation during immobilization.
|
|
| 4. |
- Arinell, Karin, 1982-, et al.
(författare)
-
Physical inactivity and platelet function in humans and brown bears : A comparative study
- 2018
-
Ingår i: Platelets. - : Taylor & Francis. - 0953-7104 .- 1369-1635. ; 29:1, s. 87-90
-
Tidskriftsartikel (refereegranskat)abstract
- Physical inactivity increases the risk of thromboembolism. However, good standardized human models on inactivity are in short supply and experimental models are few.Our objective was to investigate how standardized bed rest affects platelet aggregation in humans and to investigate if aggregation is altered in a translational model system - the hibernating brown bear (Ursus arctos). We collected blood from (1) healthy male volunteers participating in a 21-day bed rest study in head-down tilt position (-6°) 24 h a day; (2) free-ranging brown bears captured during winter hibernation and again during active state in summer. We analyzed platelet function using multiple electrode platelet aggregometry. In total, 9 healthy male volunteers (age 31.0 ± 6.4 years) and 13 brown bears (7 females and 6 males, age 2.8 ± 0.6 years) were included. In hibernating bears adenosine diphosphate, arachidonic acid, thrombin receptor activating peptide, and collagen impedance aggregometry tests were all halved compared to summer active state. In human volunteers no statistically significant changes were found between baseline and the end of bed rest. In human male volunteers 3 weeks of bed rest did not affect platelet function. In hibernating brown bears platelet aggregation was halved compared to summer and we hypothesize that this is a protective measure to avoid formation of thrombi under periods of low blood flow.
|
|
| 5. |
- Barro, Lassina, et al.
(författare)
-
Human platelet lysates for human cell propagation
- 2021
-
Ingår i: Platelets. - : Taylor & Francis. - 0953-7104 .- 1369-1635. ; 32:2, s. 152-162
-
Tidskriftsartikel (refereegranskat)abstract
- A pathogen-free and standardized xeno-free supplement of growth media is required for the ex vivo propagation of human cells used as advanced therapeutic medicinal products and for clinical translation in regenerative medicine and cell therapies. Human platelet lysate (HPL) made from therapeutic-grade platelet concentrate (PC) is increasingly regarded as being an efficient xeno-free alternative growth medium supplement to fetal bovine serum (FBS) for clinical-grade isolation and/or propagation of human cells. Most experimental studies establishing the superiority of HPL over FBS were conducted using mesenchymal stromal cells (MSCs) from bone marrow or adipose tissues. Data almost unanimously concur that MSCs expanded in a media supplemented with HPL have improved proliferation, shorter doubling times, and preserved clonogenicity, immunophenotype, in vitro trilineage differentiation capacity, and T-cell immunosuppressive activity. HPL can also be substituted for FBS when propagating MSCs from various other tissue sources, including Wharton jelly, the umbilical cord, amniotic fluid, dental pulp, periodontal ligaments, and apical papillae. Interestingly, HPL xeno-free supplementation is also proving successful for expanding human-differentiated cells, including chondrocytes, corneal endothelium and corneal epithelium cells, and tenocytes, for transplantation and tissue-engineering applications. In addition, the most recent developments suggest the possibility of successfully expanding immune cells such as macrophages, dendritic cells, and chimeric antigen receptor-T cells in HPL, further broadening its use as a growth medium supplement. Therefore, strong scientific rationale supports the use of HPL as a universal growth medium supplement for isolating and propagating therapeutic human cells for transplantation and tissue engineering. Efforts are underway to ensure optimal standardization and pathogen safety of HPL to secure its reliability for clinical-grade cell-therapy and regenerative medicine products and tissue engineering.
|
|
| 6. |
- Berlin, Gösta, et al.
(författare)
-
Effects of age, gender and menstrual cycle on platelet function assessed by impedance aggregometry
- 2019
-
Ingår i: Platelets. - : TAYLOR & FRANCIS INC. - 0953-7104 .- 1369-1635. ; 30:4, s. 473-479
-
Tidskriftsartikel (refereegranskat)abstract
- Platelets are needed to prevent or arrest bleeding and aggregate at the site of injury upon vascular damage. Platelets express receptors for estrogens which might affect the function of the platelets and their hemostatic ability. The aim was to identify possible differences in platelet function related to age, gender, and phases of the menstrual cycle by use of impedance aggregometry with Multiplate. In the first part of the study, platelet function was assessed in 60 healthy individuals (30 men and 30 women) in each of three age groups (20-25, 40-45, and 60-65 years). In the second part of the study, the platelet function was analyzed on four occasions during the menstrual cycle in women without oral contraceptives (OCs) (n = 17) and compared to 19 women on OCs and 18 men of similar age (20-40 years). For the women on OCs, aggregation was analyzed once during the tablet-free week and once late during the period with OCs. The men were sampled once. Women of younger age (amp;lt;45 years) had significantly higher agonist-induced aggregation response than both men and post-menopausal women (60-65 years). The agonist-induced aggregation response did not differ between phases of the menstrual cycle or OC use. The results suggest that estradiol and/or progesterone affect spontaneous aggregation since it was found to be lowest in the mid-luteal phase. Spontaneous aggregation was significantly lower in women on OCs than in both men and women without OCs. Our findings indicate that fertile age is associated with higher aggregation response capacity of the platelets, possibly to prevent excessive bleeding during menstruation, but this response capacity is not altered during the menstrual cycle or by use of OCs.
|
|
| 7. |
- Blomqvist, Fredrik Lennart Rune, 1947, et al.
(författare)
-
Platelet aggregation in healthy women during normal pregnancy - a longitudinal study.
- 2019
-
Ingår i: Platelets. - : Informa UK Limited. - 1369-1635 .- 0953-7104. ; 30:4, s. 438-444
-
Tidskriftsartikel (refereegranskat)abstract
- Increased platelet activation is involved in obstetric complications such as preeclampsia and intrauterine growth retardation. It is of interest to study platelet aggregation during pregnancy, since increased aggregation theoretically could be a mechanism associated with placenta-mediated complications, which possibly could be prevented by drugs inhibiting platelet aggregation. There are, however, few robust studies describing platelet aggregation during normal pregnancy. The present longitudinal study was performed in order to study platelet aggregation during normal pregnancy resulting in a healthy child, during the puerperium and in nonpregnant, fertile women. Healthy, nonsmoking, pregnant women (n=104), aged under 39years and with BMI <35, were followed during pregnancy and postpartum. Twenty-seven nonpregnant, non-puerperal, fertile women were studied for comparison. Platelet aggregation was determined with multiple electrode impedance aggregometry and analyzed at inclusion, 4 times during pregnancy and after at least 3 months postpartum. Platelet aggregation postpartum was compared with gestational weeks 8-15 and 37-40, respectively, and with nonpregnant, fertile women. Hemoglobin, leucocyte count, platelet count, prothrombin time, and activated partial thromboplastin time were determined at inclusion in order to verify normal hemostasis. Activation of platelets by arachidonic acid, adenosine diphosphate (ADP), and thrombin receptor activating peptide (trap-6) resulted in less aggregation during pregnancy, compared with postpartum (p<0.03-<0.001). Platelet aggregation following activation by collagen was unchanged. A minor increase in aggregation as pregnancy continued was found related to ADP (p<0.021). Positive correlations were found between platelet counts and platelet aggregation. Postpartum platelet aggregation after activation with arachidonic acid, collagen, and trap-6 was lower than in the non-puerperal fertile state. Other hemostatic analyses were normal. In conclusion, there is a minor decrease in platelet aggregation after activation with arachidonic acid, trap-6, and ADP, measured with multiple electrode impedance aggregometry during normal pregnancy resulting in healthy babies, compared with the postpartum period. The small changes in platelet aggregation may be a consequence of a minor decrease in platelet count and probably lack clinical significance under normal conditions. Interindividual variations at certain time-points are substantial, which limits the usefulness of the multiple electrode impedance aggregometry for determining minor changes in platelet function.
|
|
| 8. |
- Blomqvist, Lennart, 1947, et al.
(författare)
-
Arachidonic acid-induced platelet aggregation and acetylsalicylic acid treatment during pregnancy in women with recurrent miscarriage, a post hoc study
- 2022
-
Ingår i: Platelets. - : Informa UK Limited. - 0953-7104 .- 1369-1635. ; 33:2, s. 278-284
-
Tidskriftsartikel (refereegranskat)abstract
- In this post hoc study, arachidonic acid (AA)-induced platelet aggregation during pregnancy with and without acetylsalicylic acid (ASA) treatment was studied in 323 women with unexplained recurrent first-trimester miscarriage and in 59 healthy women with normal pregnancies. All women had normal AA-induced platelet aggregation in the non-pregnant state. Women with recurrent miscarriage were treated with 75 mg ASA or placebo daily. AA-induced platelet aggregation was measured with multiple electrode impedance aggregometry and presented in units (U), where 1 U = 10 aggregation units x minutes. There were no significant differences in platelet aggregation between placebo-treated women with recurrent miscarriage and healthy women. The mean differences were -0.7 (95%CI; -7.0; 5.6) U in the non-pregnant state, 3.8 (95%CI; -4.6; 12.2) U during the late first trimester and 1.7 (95%CI; -6.7; 10.3) U and 4.1 (95%CI; -3.9; 12.0) U during the early and late third trimester, respectively. ASA reduced platelet aggregation by median -84.0% (Q1; Q3; -89.8; -76.3), -79.9% (-84.7; -69.2) and -75.7% (-83.5; -49.5), respectively, during pregnancy. The degree of inhibition by ASA decreased during the third trimester (p < .0001). There were two (1.9%) complete non-responders to ASA and 32.1% with a partial response. The rate of subsequent miscarriage was not affected by ASA, which did not seem to influence the rate of early miscarriage if treatment was initiated when a viable pregnancy was detectable by ultrasound.
|
|
| 9. |
- Boknäs, Niklas, et al.
(författare)
-
Flow cytometry-based platelet function testing is predictive of symptom burden in a cohort of bleeders
- 2018
-
Ingår i: Platelets. - : Taylor & Francis. - 0953-7104 .- 1369-1635. ; 29:5, s. 512-519
-
Tidskriftsartikel (refereegranskat)abstract
- Platelet function disorders (PFDs) are common in patients with mild bleeding disorders (MBDs), yet the significance of laboratory findings suggestive of a PFD remain unclear due to the lack of evidence for a clinical correlation between the test results and the patient phenotype. Herein, we present the results from a study evaluating the potential utility of platelet function testing using whole-blood flow cytometry in a cohort of 105 patients undergoing investigation for MBD. Subjects were evaluated with a test panel comprising two different activation markers (fibrinogen binding and P-selectin exposure) and four physiologically relevant platelet agonists (ADP, PAR1-AP, PAR4-AP, and CRP-XL). Abnormal test results were identified by comparison with reference ranges constructed from 24 healthy controls or with the fifth percentile of the entire patient cohort. We found that the abnormal test results are predictive of bleeding symptom severity, and that the greatest predictive strength was achieved using a subset of the panel, comparing measurements of fibrinogen binding after activation with all four agonists with the fifth percentile of the patient cohort (p = 0.00008, hazard ratio 8.7; 95% CI 2.5-40). Our results suggest that whole-blood flow cytometry-based platelet function testing could become a feasible alternative for the investigation of MBDs. We also show that platelet function testing using whole-blood flow cytometry could provide a clinically relevant quantitative assessment of platelet-related hemostasis.
|
|
| 10. |
|
|
