Preparation Of Platelet Concentrates Research Articles

Evaluation of platelets componentized with the Reveos Automated Blood Processing System and stored for 7 days at room temperature in a non-Di(2-ethylhexyl) phthalate (DEHP) platelet pooling set.

Platelet concentrates (PCs) used for transfusion can be produced by apheresis or derived from whole blood (WB). The Reveos device is the first US Food and Drug Administration-approved automated blood processing system that can produce PCs. In this work, we evaluated the quality and function of Reveos-collected PCs stored for 7 days at room temperature. WB was collected from healthy donors and componentized on the day of collection (Fresh) or after an overnight hold (Overnight). PCs were produced (n = 7 Fresh; n = 6 Overnight), stored at room temperature in plasma, and evaluated on days 1 and 7 for quality metrics, platelet activation, clot formation, and aggregation response. Platelet count was comparable between Fresh and Overnight PCs. A drop in pH was reported in Fresh day 7 PCs (p < .001, vs. day 1) but not in Overnight. Overnight units displayed the lowest levels of P-selectin expression (p = .0008, vs. day 7 Fresh). Reduced clot strength and increased lysis were observed in both Fresh and Overnight units on day 7 (vs. day 1). Overnight-hold PCs resulted in the highest clot strength on day 7 (p = .0084, vs. Fresh). No differences in aggregation were reported between groups. Reveos-processed PCs produced from overnight-hold WB performed better in hemostatic function assays and displayed reduced activation compared to fresh WB-derived PCs, although both PC groups maintained platelet quality throughout storage. Utilization of overnight WB for PC preparation with Reveos holds promise as an alternative method of producing platelets for transfusion purposes.

Evaluation of platelet concentrates prepared from whole blood donations with collection times between 12 and 15 min: The BEST Collaborative study.

In many countries, whole blood (WB) donations with collection times between 12 and 15 min are not allowed to be used for platelet concentrates (PC). Since the development of guidelines, many process-related changes have been introduced. We aimed to determine the effect of WB with long collection times on PC quality. Five participating centres tested buffy coat (BC)-derived PC in platelet additive solution type E prepared from only WB collections lasting <12 min (control) versus similar PC including one BC from a collection lasting >12 min (study group, n= 8). One centre produced platelet-rich plasma (PRP)-derived PC from single donations (<10 or >12 min). All PC were stored at 22 ± 2°C and sampled on Days 1, 6 and 8 post-collection for in vitro quality determination. Average collection time was significantly longer in the study group compared to controls (8.9 ± 2.6 vs. 7.3 ± 1.3min, p < 0.001). There were no differences in volume, platelet concentration, basal CD62P expression, soluble-CD62P and CCL5 levels, or nucleotide content between the groups. Stimulation with TRAP-6 resulted in comparable levels of cell surface CD62P. On Day 8, all PC fulfilled requirements for pH. The findings from single PRP-derived PC centre were similar. PC with one BC and single PRP derived from collections lasting >12 min had equivalent in vitro quality to controls during storage. This study provides evidence that 12-15 min donations should not be excluded for PC preparation and justifies to readdress the guidelines to <15 min instead of <12 min of collection in line with current practice in some countries.

The study of morphofunctional properties of platelets in the process of storing them in additive solution containing sodium fumarate

Background . Improving the quality of platelet concentrate by choosing an adequate medium for storing isolated platelets is a relevant problem of a blood function. Objective . The study of metabolic activity, platelet viability and their aggregation properties during storage of platelet concentrate in an additive solution containing sodium fumarate. Design and methods . The object of the study was donor platelet concentrates (PC). PC was obtained from donors who passed necessary examinations. Biochemical, hematological and coagulological research methods were utilized in carrying out the study. Results . During the research, reliable evidence was obtained on the best preservation of platelets by 9 days of their storage in a fumarate-containing additive solution (FCAS) as compared to storage in a commercial SSP+ solution (France). It was found that with practically the same glucose content in the compared solutions on the day of PC preparation, the glucose concentration by 9th day of observation was significantly higher in the FCAS than in the SSP+ solution. Furthermore, the FCAS was determined to have a consistently lower lactate content as compared to the SSP+ solution. In regard to their aggregation activity, the platelets prepared in the FCAS were not inferior to the platelets stored in the SSP+. Based on the results of the study, a methodology has been developed to obtain additive solution containing sodium fumarate. Conclusion . The developed composition of the additive solution allows to increase the shelf life of platelets up to 9 days, which is important for a more economical and effective use of this blood component in order to correct thrombocytopenia of various etiologies.

Platelet Concentrate Treatments for Temporomandibular Disorders: A Systematic Review and Meta-analysis.

This systematic review compared platelet concentrates (PCs) versus hyaluronic acid (HA) or saline/Ringer's solution injections as treatments of temporomandibular osteoarthritis and disc displacement in terms of pain and maximum mouth opening (MMO). PubMed, Cochrane, and Scopus were searched up to March 6, 2020. Inclusion criteria were randomized clinical trials (RCTs). Exclusion criteria were case series, observational studies, animal studies, and reviews. The Effective Public Health Practice Project (EPHPP) quality assessment tool was used to assess the risk of bias in the included studies. The weighted mean difference was used to compare the results. Nine RCTs were included with a total of 407 patients. The numbers of joints treated were 262, 112, and 112 in the PC, HA, and saline groups, respectively. The quality of studies was rated as strong in 4 studies, moderate in 4 studies, and weak in 1 study. The meta-analysis revealed that PCs decreased pain visual analogue scale (VAS) scores compared to HA by an average of -1.11 (CI, -1.62 to -0.60; P < 0.0001) and -0.57 (CI, -1.55 to 0.41; P = 0.26) at 3 and 12 mo follow-up respectively. Also, the average decrease in pain scores with PC compared to saline was -1.33 (CI, -2.61 to -0.06; P = 0.04), -2.07 (CI, -3.46 to -0.69; P = 0.003), and -2.71 (CI, -4.69 to -0.72; P = 0.008) at 3, 6, and 12 mo, respectively. Regarding MMO measurements, PC was comparable to HA, but it was significantly better than saline after 3 and 6 mo [2.9 mm (CI,1.47 to 4.3; P < 0.0001), and 1.69 mm (CI, 0.13 to 3.25; P = 0.03) respectively]. PC reduces pain VAS scores compared to HA during the first 3 m after treatment, and when compared to saline, it reduces pain and increases MMO for longer durations. However, due to differences between groups regarding PC preparation protocols and study heterogeneity, further standardized RCTs are required. This study provides researchers and clinicians with quantitative and qualitative analyses of the current evidence regarding the clinical outcomes of platelet concentrate injections in the treatment of temporomandibular joint osteoarthritis and disc displacement in terms of pain control and maximum mouth opening.

Comparing two blood culture systems for the detection of bacterial contamination in platelet concentrates.

The transfusion of platelet concentrates (PCs) contaminated with bacteria may cause serious, and even fatal, septic reactions in patients. The aim of this study was to compare the VersaTREK with the BACTEC FX automated culture systems for screening bacterial contamination, directly after the delay of 24 hours of preparation to obtain the final pooled buffy coat PCs, to prevent transfusion-transmitted bacterial infections. Seven bacterial strains were each inoculated into five replicate pooled buffy coat PCs at approximately 100 colony-forming units/unit, and 5- or 10-mL samples were inoculated into duplicate aerobic culture bottles. The time and detection rates were compared between BACTEC FX, as a reference method, and VersaTREK. Time to detection was significantly shorter using VersaTREK for most species detected by both systems for the volumes tested. Of 70 VersaTREK cultures, 69 (98.57% detection rate) were positive after 24 hours of incubation with the 5-mL sample. In contrast, the BACTEC FX system detected all positive samples in PCs for the volume of 10 mL, although seven samples were false negatives for the 5-mL volume. The VersaTREK system compared favorably to the BACTEC FX system for 5-mL volumes (p < 0.05) and could be considered a potential method for detecting bacterial contamination in PC samples directly after 24 hours of preparation of the final pooled buffy coat PCs.

Platelet Storage Lesions: What More Do We Know Now?

Platelet concentrate (PC) transfusions are a lifesaving adjunct to control and prevent bleeding in cancer, hematologic, surgical, and trauma patients. Platelet concentrate availability and safety are limited by the development of platelet storage lesions (PSLs) and risk of bacterial contamination. Platelet storage lesions are a series of biochemical, structural, and functional changes that occur from blood collection to transfusion. Understanding of PSLs is key for devising interventions that prolong PC shelf life to improve PC access and wastage. This article will review advancements in clinical and mechanistic PSL research. In brief, exposure to artificial surfaces and high centrifugation forces during PC preparation initiate PSLs by causing platelet activation, fragmentation, and biochemical release. During room temperature storage, enhanced glycolysis and reduced mitochondrial function lead to glucose depletion, lactate accumulation, and product acidification. Impaired adenosine triphosphate generation reduces platelet capacity to perform energetically demanding processes such as hypotonic stress responses and activation/aggregation. Storage-induced alterations in platelet surface proteins such as thrombin receptors and glycoproteins decrease platelet aggregation. During storage, there is an accumulation of immunoactive proteins such as leukocyte-derive cytokines (tumor necrosis factor α, interleukin (IL) 1α, IL-6, IL-8) and soluble CD40 ligand which can participate in transfusion-related acute lung injury and nonhemolytic transfusion reactions. Storage-induced microparticles have been linked to enhanced platelet aggregation and immune system modulation. Clinically, stored PCs have been correlated with reduced corrected count increment, posttransfusion platelet recovery, and survival across multiple meta-analyses. Fresh PC transfusions have been associated with superior platelet function in vivo; however, these differences were abrogated after a period of circulation. There is currently insufficient evidence to discern the effect of PSLs on transfusion safety. Various bag and storage media changes have been proposed to reduce glycolysis and platelet activation during room temperature storage. Moreover, cryopreservation and cold storage have been proposed as potential methods to prolong PC shelf life by reducing platelet metabolism and bacterial proliferation. However, further work is required to elucidate and manage the PSLs specific to these storage protocols before its implementation in blood banks.

Acoustophoretic purification of platelets: feasibility and impact on platelet activation and function

Purity, limited platelet activation, and preservation of platelet function are important stakes of preparation of platelet concentrates (PC) for clinical use. In fact, contaminating red blood cells and leukocytes, as well as activated and/or poorly functional platelets in PC, represents a risk of poor efficiency and adverse side effects during platelet transfusion. Therefore, optimization of preparation and storage of PC is still an active field of research. Shear-induced platelet activation is an unwanted side effect of the hard-spin (up to 5000g) step of centrifugation-based methods currently used in blood banks to prepare PC from whole blood samples. Here, we evaluated the effectiveness of an acoustic-based fractionation device for the isolation of human platelets from whole blood bags. The purity, activation status, and functionality of platelets isolated by acoustopheresis were compared with those of platelets isolated using a reference protocol known to produce limited platelet activation and consisting of two consecutive soft-spin centrifugations (120g and 1200g). Platelet concentration and purity were determined using an automated hematology analyzer. Platelet activation status and platelet reactivity to collagen and thrombin were assessed in flow cytometry by measurement of surface expression of P-selectin and activated integrin αIIbβ3. The ability of isolated platelets to incorporate into a thrombus when transfused to NOD/SCID mice was investigated by intravital microscopy using the ferric chloride-induced thrombosis model. Blood fractionation by acoustophoresis led to the elimination of more than 80% of red blood cells and leukocytes from the platelet fraction, whose mean purity was of 92.8 ± 12.8%. The activation status and reactivity to collagen and thrombin of acoustophoresis-isolated platelets were similar to those of platelets isolated by soft-spin centrifugation. Finally, acoustophoresis-isolated platelets were tethered, adhered to the vessel wall, and incorporated into a growing thrombus following ferric chloride-induced vascular injury. Together, our results indicate that acoustophoresis is a suitable method for the isolation of human platelets with minimal platelet activation and preservation of platelet function.

Quality Assessment of Platelet Concentrate Preparations at the Nairobi Regional Blood Transfusion Centre in Kenya

Background: Evaluation of platelet concentrate was based on platelet volume, count, residual WBC and Hemoglobin. The study findings were compared with standards set by National Blood Transfusion Service (NRBTC). Objective: To evaluate platelet concentrates quality prepared at NRBTC. Study Design:This was a descriptive cross-sectional study was adopted. Setting: The present study was conducted at NRBTC. Subject: Nighty one (91) platelet concentrates were selected for the study. Results: Of the samples analyzed, 95.6% (87/91), 79.1% (72/91) met the criteria on platelet count and residual white blood cells respectively.Of note, all the 91 sampled platelet concentrate fell within the NRBTS volume criteria. Conclusion: The findings reveals that the quality parameters assessed in this study from the platelet concentrate were not met. Therefore, there is need to review the quality assurance protocol.Focus should be directed on the platelet concentrates preparation by plasma centrifugation to attain the desirable standards set by NBTS.

ASSESSMENT OF PLATELET CONCENTRATE PREPARED FROM FRESH AND OVERNIGHT HELD WHOLE BLOOD

Separation of platelet rich plasma (PRP) within 8 hours after holding whole blood at ambient temperature is the current practice in the preparation of platelet concentrate (PC). However, the ability to hold whole blood for up to 24 hours prior to PC preparation would allow every unit of whole blood to be used regardless of the distance from the collection site to the processing centre. Therefore the aim of this study is to assess and compare the platelet quality and activation of the platelet concentrate prepared from fresh whole blood (within 8 hours from collection) and overnight hold of whole blood at room temperature. In this study, 23 units of PC were prepared freshly from whole blood (i.e., within 8 hours of collection) and another 23 units were prepared after 24 hours of storage at 20–24 ºC. The following parameters of each unit of PC were assessed: pH, total white blood cell (TWBC) count, platelet count, presence of swirling, and platelet activation. When the parameters were compared between groups, no significant difference in platelet activation rate was found on sampling days 1, 3, and 5. pH and TWBC count for both groups were within the quality requirements of the National Blood Centre (&gt; 75% units tested fall within the standard), but not all of the samples complied with the standard requirement for platelet count. All units of PC prepared after 24 hours showed the presence of swirling, whereas one unit of PC in the fresh group did not show swirling activity after 3 days of storage. Delaying whole blood processing for up to 24 hours does not significantly affect certain in vitro quality or activation parameters as compared with freshly prepared PC.

Separation of centrifuged whole blood and pooled buffy coats using the new CompoMat G5: 3 years experience

Semi-automatic separation devices can be used for the separation of centrifuged whole blood into leucoreduced red cell concentrate (LR-RCC), plasma and buffy coat (BC) and to make platelet concentrates (PC) from pooled BCs. To improve and to obtain a more uniform and standardized process, the CompoMat G5 (Fresenius) was implemented, a new-generation semi-automated device. Uniform programs for WB separation and preparation of PCs were validated, using collection and pooling systems with CompoFlow (CF) closures, which can be automatically opened by the G5. Cell counts were performed and compared with historic data of blood components obtained with the formerly used Compomat G4 and Optipress II. After implementation, different adjustments were made to improve product quality. Leucoreduced red cell concentrates (280±15 ml, 53±5 g haemoglobin) and plasma (317±16 ml) met European guidelines. BCs (48±2 ml, 0·42±0·05l/l, 93±25×10(9) platelets) contained a similar platelet (PLT) content as BC prepared before with the Compomat G4. A relatively high percentage (4-6%) of PCs (330±17 ml, 330±50×10(9) PLT, 0·12±0·21×10(6) leucocytes) contained <250×10(9) PLT which was the subject of improvement studies. After implementation, RCC and BC discard decreased and workload was less. Operator complaints were also less frequent. The same high-quality blood components can be prepared by using the CompoMat G5 as previously with other semi-automated devices. Improvement was realized by automation of the opening process by the use of collection systems with CF closures, which led to a decrease in discarded units and workload.

Autologous Platelet Concentrate as a Treatment for Horses with Refractory Fetlock Osteoarthritis

Osteoarthritis (OA) is one of the most common musculoskeletal pathologies in horses and is a disease capable of halting their athletic career. Clinically, OA can be a difficult problem to deal with, particularly when there is no longer a positive response to corticosteroids or rest. In order to avoid further articular tissue degeneration, which could lead to the loss of the joint function, novel therapies are focusing not only on controlling inflammation and pain but also on tissue healing and repair. Autologous platelet concentrate (PC) growth factors are known to have anabolic and angiogenic properties and a positive effect on synovial epithelium, cartilage, and pain. The aim of this study was to analyze the clinical outcome of horses with OA treated with PC. Selected cases were treated only with PC, and they all belong to the same sport activity. We show here the method for PC preparation, follow-up evaluation, and outcome of 20 cases with refractory OA treated exclusively with autologous PC. After a 1-year follow-up, 80% of patients were able to resume work. According to our results and observations, PC can be used as a safe and low-cost intra-articular therapy for refractory OA in the horse.

In reply

In reply: We read with interest the article by Feys and colleagues1 comparing nitrite/nitrate (NO2−/NO3−) levels during storage and preparation of platelet concentrate (PC) from pooled buffy coats. Although they did not measure nitrite separately, their results suggest no substantial production of nitric oxide (NO) in stored PCs since NO produced in large quantities would likely affect the nitrite/nitrate levels. It is also consistent with our report2 that apheresis PCs did not produce NO by endogenous nitric oxide synthase (NOS) during storage. However, based on our electron paramagnetic resonance results, NO level in PCs was higher than that in plasma. Furthermore, we also showed that there was a slight decrease in nitrite levels during storage. We believe that our results suggest a possibility of a nitrite reduction system in PCs or nitrite reaction with residual hemoglobin, cell free or in red blood cells (RBCs), possibly indicative of some NO metabolic processes. Interestingly, Feys and colleagues observed an increase in nitrite/nitrate levels immediately after the procedures of PC preparation from buffy coats in which centrifugations and dilution with additive solution are used. As they suggested, it is possible that RBCs and white blood cells in buffy coats contribute to this increase in nitrite/nitrate levels as a native mechanism to prevent overt platelet (PLT) activation during preparation. Some authors have suggested the presence of active NOS in RBCs, although the definitive proof of functional NOS in RBCs is still under debate.3 In addition, it is still not clear if PLTs themselves express NOS.4 Considering the fact that buffy coat PCs show the lowest level of PLT activation by in vitro assays compared with apheresis PCs or PLT-rich plasma (PRP)-derived PCs,5 it would be interesting to see if the procedures of apheresis or PRP PC preparations also increase nitrite and nitrate levels. As Feys and colleagues note, production of NO in these preparations may be important for the maintenance of PLT function during in vitro storage, allowing clinical utility of PLT transfusions. ANS is a co-inventor of a patent issued to NIH for the use of sodium nitrite in the treatment of cardiovascular diseases. The authors declare that they have no conflicts of interest relevant to the manuscript submitted to TRANSFUSION.

Tissue Factor Expression on Platelet Surface during Preparation and Storage of Platelet Concentrates

Background: Tissue factor (TF), the main activator of blood coagulation, is expressed on platelet surface and, together with procoagulant phospholipids, contributes to the global coagulation potential of these blood components. The present study evaluated, for the first time, the expression of TF on platelet surface during preparation and storage of platelet concentrates (PC) for transfusional use. Methods: Platelet TF was measured by flow cytometry in healthy donor whole blood (WB) and in pooled buffy-coat-derived PC on the day of preparation and up to 4 days of storage in parallel with classical markers of platelet activation, i.e., fibrinogen, P-selectin, and glycoprotein GPIIb. Data were analyzed according to donor age and blood ABO group. Results: TF was detected on whole blood platelets and was found highest in O donors. Compared to whole blood, platelet surface TF was higher upon PC preparation and further increased during storage. The rise in TF levels positively correlated with the elevations of the other platelet markers. Conclusions: Our findings show that platelet surface TF is maintained in PC obtained by the pooled buffy coat method. Further studies are warranted to investigate a possible correlation between TF levels and the hemostatic response of the platelet transfusion recipient.

Effects of Prostaglandin E1 on the Preparation of Platelet Concentrates in Dogs

Platelet concentrates (PC) are prepared by centrifugation of platelet-rich plasma (PRP) that is prepared by centrifugation of whole blood. The resuspension of the platelet pellet during PC preparation from dogs is difficult because of platelet activation induced by centrifugation. To investigate the efficacy of adding prostaglandin E(1) (PGE(1) ) to prevent platelet activation during PC preparation from dogs. Fifteen healthy Beagle dogs. Prospective, experimental trial: PGE(1) was added to PRP before the high-speed centrifugation during PC preparation. To estimate the effect of this addition, we assessed the platelet aggregability before transfusion, the survival of the platelets after transfusion, and the platelet reactivity after transfusion, which is estimated by the P-selectin expression of the platelets when stimulated by thrombin. The difficulty associated with platelet resuspension was resolved by PGE(1.) PGE(1) strongly inhibited platelet aggregation induced by collagen and ADP; however, it recovered after the platelets were resuspended in plasma without PGE(1) (mean aggregation ratio; collagen: 10.00-80.80%, ADP: 8.20-53.60%). Survival of the platelets after transfusion was not affected by PGE(1) (mean 8.04 and 7.56 days, without and with PGE(1) ), and thrombin-induced P-selectin expression after transfusion in PGE(1) -treated PC was also well maintained (mean positive ratio 53.7 and 47.9%, before and 24 hours after transfusion). The addition of PGE(1) in PRP before the centrifugation of PRP can improve the preparation efficiency of PC from dogs, while maintaining the therapeutic efficacy of the platelets.

Evaluation of the effect of calcium gluconate and bovine thrombin on the temporal release of transforming growth factor beta 1 and platelet-derived growth factor isoform BB from feline platelet concentrates.

BackgroundThere are not reported regarding the protocols for obtaining platelet concentrates (PC) in cats for medical purposes. The objectives of this study were: 1) to describe a manual method for producing two kinds of PC in cats (PC-A and PC-B), 2) to describe the cellular population of the PC, 3) to measure and compare the effect of calcium gluconate (CG) and bovine thrombin (BT) on the temporal release of transforming growth factor beta 1 (TGF-β1) and platelet-derived growth factor type BB (PDGF-BB) at 3 and 12 hours post-activation and 4) to establish correlations between the cellular population of both PCs and the concentration of growth factors (GF). Blood samples were taken from 16 cats for complete blood count, plasma collection and PC preparation. The PC were arbitrarily divided into two fractions, specifically, PC-A (lower fraction) and PC-B (upper fraction).ResultsThe platelet counts were significantly different (P<0.05) between the PC and whole blood but not between the PC fractions. The TGF-β1 concentration efficiencies for PC-A and PC-B activated with CG were 42.86% and 46.54%, and activated with BT were 42.88% and 54.64%, respectively. The PDGF-BB concentration efficiencies for PC-A and PC-B activated with CG were 61.36% and 60.61%, and activated with BT were 65.64% and 72.12%, respectively. The temporal release of GFs showed no statistically significant difference (P>0.05) between the activating substances at the time or for any PC fraction.ConclusionsWhatever the activation means, these preparations of cat PC provide significant concentrations of platelets and GFs for possible clinical or experimental use.

Contaminación bacteriana en concentrados de plaquetas de caballos

SUMMARY The aims of the study were to: 1) assess the risk of bacterial contamination in equine platelet concentrates (PCs) obtained by the tube method under three technical conditions (laminar flow cabinet or in a clean laboratory environment both with burner and without burner) 2) identify the critical points of the process of PCs preparation with risk of bacterial contamination; and 3) identify the potential bacterial contaminants in the process. Bacteriological samples were taken from the skin (shaved or unshaved) of the venipuncture site in 15 horses, both before and after being disinfected; hands and throat of the operator; caps of the tubes where the blood was processed; environment where the equine blood samples were collected; laboratory environment; laminar flow cabinet; bacteriological stove; and PCs obtained under 3 technical conditions. Bacteria were isolated from non-aseptically prepared equine skin, hands and throat of the operator, and the place where the blood samples were taken. Bacteria were not isolated from tube caps, laboratory environment, laminar flow cabinet, or PCs. The isolated bacteria were normal biota from equine skin, human skin and throat, and environmental contaminants. Uncontaminated PCs can be obtained by the tube method in a clean laboratory environment.

Pooled platelet concentrates: An alternative to single donor apheresis platelets?

Three types of platelet concentrates (PC) are compared: PC either processed with the platelet-rich plasma (PRP) or the Buffy coat (BC) method from whole blood units and PC obtained by apheresis. Leuko-reduction (LR) pre-storage is advocated to improve quality of the PC during storage and reduce adverse reactions in recipients. Standardization of methods allow preparation of PC with comparable yields of ∼400 × 10 9 platelets in pooled non-LR-PRP, ∼370 × 10 9 in pooled LR–BC–PC and in LR apheresis PC the number of platelets can be targeted on 350 × 10 9 or more with devices of various manufacturers. While viral transmission can be prevented by outstanding laboratory tests, the risk of bacterial contamination should be reduced by improved arm disinfection, deviation of the first 20–30 ml of blood and culture or rapid detection assays of the PC pre-issue. In a large prospective multicenter trial no significant difference was observed between cultures of apheresis PC ( n = 15,198): 0.09% confirmed positive units versus 0.06% in pooled BC–PC ( n = 37,045), respectively. Though platelet activation as measured by CD62 expression may differ in vitro in PC obtained with various apheresis equipment, and also between PC processed with the two whole blood methods there is scarce literature about the clinical impact of these findings. In conclusion the final products of LR–PC derived from whole blood or obtained by apheresis can be comparable, provided the critical steps of the processing method are identified and covered and the process is in control.

Clinical Evaluation of Platelet Concentrates Either in Plasma or in Additive Solution

Background and Objectives. Platelet concentrates (PC) obtained from Buffy-Coat (BC) may be diluted in a platelet additive solution (PAS). These PCs may reduce plasma-related adverse reactions. We have tried to assess the rela- tionship between PAS PCs and adverse reactions. Materials and Methods. During 6 months, patients treated with inten- sive chemotherapy, participated in a prospective study and were randomly assigned to receive, on a prophylactic basis, PCs in either plasma or PAS-2. Five iso-group BCs were pooled diluted in either plasma or PAS-2. One hour after each transfusion, corrected count increments (CCIs) were calculated, presence of hemorrhage and adverse reactions were re- corded. Results. Platelet increment, 1-hour platelet count, and corrected count increments (CCI) after transfusion in both groups were similar. There were more transfusion- dependent adverse reactions in plasma group. Conclusion. Use of PAS-2 resulted in less transfusion related reactions; therefore, we recommend synthetic additive solutions to dilute PCs. BACKGROUND AND OBJECTIVES Bleeding in a number of acute and chronic conditions that require medical and surgical treatment may be prevented and treated with platelet transfusions (1). Prophylactic plate- let concentrate (PC) transfusions in patients with severe thrombocytopenia have increased over the last years due to more frequent and more intensive radiations and chemother- apy treatments. PC may be obtained from whole blood col- lected into a multiple plastic bag set. The procedures for the preparation of PC from whole blood donations are the buffy- coat (BC) and the platelet-rich plasma (PRP) methods. The former one is performed in Europe and the latter in North America and in several European countries. PCs obtained from BC may be diluted in autologous plasma or in a platelet additive solution (PAS). The use of a synthetic medium re- duces the plasma content in every PC and therefore may re- duce plasma-related adverse reactions. We have performed a prospective clinical trial trying to assess the relationship be- tween PAS PCs, adverse reactions and their clinical effec- tiveness.

Preparation of Platelet Membrane Microparticles with High Pressure Homogenization Method.

Objective To investigate the preparation technique of infusible platelet membrane microparticles (IPMs), and evaluate hemostatic function and effect of IPMs on pathological thrombogenicity after transfused into model of rabbit thrombocytopenia.Methods Whole bloods collected in the street were used to prepare platelet concentrates(PCs),white cells were removed by white cell filter, and red cells by centrifugation at 1000rpm in for 10min. After that, platelets were washed twice with 0.9% NaCl solution by repeated resuspension and centrifugation, and adjusted concentration to 2×109/ml with 0.9% NaCl. The washed platelets were disrupted by repeated freezing (at −80°) and thawing (at 25°) three times, and were heated at 60° for twenty hours to inactivate any viral contaminants. Finally, the heat 2 treated platelets were crushed by high pressure homogenizer to form IPMs. In this study, particle analyser was applied to mean diameter and the particle size distribution of IPMs, APCT to test the procoagulation activity of IPMs in vitro. Hemostatic function and effect of IPMs onpathological thrombogenicity were observed after IPMs were transfused into thrombocytopenia rabbitmodels.Results mean diameter of IPMs was from 200 to 300 nm. The procoagulation activity of 50Lg/ml of IPMs was equal to 250×109/L of fresh platelets. Rabbit ear bleeding time and APCT significantly shortened from two hours to twelve hours after transfusion of 2mg IPMs per Kg into thrombocytopenia rabbit models, but other indexes such as PT, APTT, Fg, and TT changed less.Conclusions IPMs possess good hemostatic function and less effect on pathological thrombogenicity. It is a kind of promising biologic hemostatic reagent.

Detection of bacteria in platelet concentrates prepared from spiked single donations using cultural and molecular genetic methods

Bacteria show differences in their growth kinetics depending on the type of blood component. On to storage at 22 degrees C, platelet concentrates (PCs) seem to be more prone to bacterial multiplication than red cell concentrates. Knowledge of the potential for bacterial proliferation in blood components, which are stored at a range of temperatures, is essential before considering implementation of a detection strategy. The efficacy of bacterial detection was determined, using real-time reverse transcriptase-polymerase chain reaction (RT-PCR), following bacterial growth in blood components obtained from a deliberately contaminated whole-blood (WB) unit. Cultivation was used as the reference method. WB was spiked with 2 colony-forming units mL(-1)Staphylococcus epidermidis or Klebsiella pneumoniae, kept for 15 h at room temperature and component preparation was processed. Samples were drawn, at intervals throughout the whole separation process, from each blood component. Nucleic acids were extracted using an automated high-volume extraction method. The 15-h storage revealed an insignificant increase in bacterial titre. No bacterial growth was detected in red blood cell or plasma units. K. pneumoniae showed rapid growth in the pooled PC and could be detected immediately after preparation using RT-PCR. S. epidermidis grew slowly and was detected 24 h after separation. These experiments show that sampling is indicative at 24 h after preparation of PCs at the earliest to minimize the sampling error.