Quality of Platelets in Stored Whole Blood

Transfusion of whole blood rather than blood components is gaining popularity. It is easy to use, with one transfusion product to administer rather than 3, and is held at one storage temperature. It only contains anticoagulant-preservative solution, while components contain various storage solutions, which in theory may induce dilution coagulopathy.In this review, the quality of platelets in stored whole blood is summarized. In cold-stored whole blood, the platelet count declines by 1% to 2% per day. The responsiveness to various agonists declines during the storage time, but this appears to have a limited impact on clotting time or on clot strength as measured with thromboelastography. Animal studies have confirmed that platelets from stored whole blood participate equally well in clot formation. The recovery of platelets in stored whole blood is acceptable during at least 15 days of storage. The survival of platelets after transfusion is only 1 day, but this is likely to be sufficient for the intended patient group requiring massive transfusions, as the platelets are rapidly consumed in the wound area.In addition to the logistic benefits, there are drawbacks, most importantly having a sufficiently large inventory with an acceptable outdating rate, particularly since massive transfusions are rare, while requiring a lot of whole blood. The positive experience of the United States military with whole blood transfusion is often brought forward for introduction in the civilian blood bank, but patients with trauma are only a small fraction of the civilian population requiring massive transfusions. It needs to be determined whether in the resourceful environment of the hospital, these patients benefit from whole blood transfusions. Optimization of whole blood storage, with focus on platelet quality, needs to be performed to allow extension of the storage time beyond 15 days to a point where the number of units in inventory and outdating can be balanced.     

Insignificance of Gluconeogenesis in Human Blood Platelets

Abstract. Human blood platelets contain no detectable activity of the enzymes fructose diphosphatase (EC 3. 1. 3. 11), phospho-enolpyruvate carboxykinase (EC 4. 1. 1. 32) and pyruvate carboxylase (EC 6. 4. 1. 1.). Glucose-6-phosphatase (EC 3. 1. 3. 9) activity is very low.
Phosphofructokinase present in human blood platelets, catalyzes a reaction which can be stimulated by AMP in a platelet homogenate, due to the presence of endogenous ADP and myokinase. These enzymes are responsible for the formation of fructose-6-phosphate from fructose-1, 6-diphosphate.
Pyruvate kinase (EC 2. 7. 1. 40) in human blood platelets belongs to the M-type, which is not inhibited by ATP, at least not under the conditions applied.
The results obtained indicate that gluconeogenesis in human blood platelets is not present in the way which has been established for liver and kidney.     

献血者血小板数量及血容量对机采血小板采集量的影响

目的：分析献血员血小板数量及处理血量对机采血小板采集量的影响。方法应用Trima血细胞分离机采集100名献血者的双份血小板。结果通过多元回归分析发现,献血者采前的血小板计数（Plt）和血容量（BV）与血小板采集量之间存在回归关系,其标准偏回归系数β值分别为-0.370和-0.201,P＜0.01。结论对采前的Plt和BV水平较低的献血者,可采用Trima血细胞分离机进行采集。     

糖基化修饰后人血小板形态、超微结构及功能的研究

经糖基化修饰可使4℃保存的血小板在输入体内后延长其存活。本研究探讨尿苷二磷酸半乳糖（UDP—Gal）糖基化修饰对血小板形态、结构、功能以及其膜糖蛋白的影响。实验分为室温对照组、冷藏对照组和修饰组。用荧光标记的特异凝集素（FITC—RCA I）检测膜糖蛋白糖残基变化，用扫描、透射电镜观察修饰后血小板形态和超微结构的变化，用比浊法测定血小板聚集率，用流式细胞术检测血小板膜蛋白CD42b、膜表面标志CD62P以及血小板凋亡标志annexinV结合率。结果表明，UDP—Gal修饰组RCAI结合率显著高于室温对照组和冷藏对照组（P〈0．01）；与新鲜血小板相比，UDP—Gal处理后的血小板超微结构无明显变化，而冷藏对照组则有伪足延伸等形态学改变；修饰后最大聚集率可达新鲜血小板的50％以上；血小板膜蛋白CD42b、膜表面标志C1362P及annexinV结合率与室温对照组相比均无明显差异。结论：UDP—Gal可使β-半乳糖有效地结合于链聚糖末端，糖基化血小板仍然具有较强的聚集活性和相对完整的超微结构，功能基本正常。     

Formation of Prostaglandins during the Aggregation of Human Blood Platelets

Prostaglandins E(2) and F(2alpha) were formed in response to ADP, L-epinephrine, or collagen by human platelets suspended in plasma containing citrate anticoagulant and stirred at 37 degrees C. The prostaglandins formed by platelets in response to collagen were rapidly released and the amounts formed were proportional to the amount of collagen added. The formation of the prostaglandins was associated with the single wave of aggregation induced by collagen or the second wave of aggregation induced by epinephrine. The above findings are discussed with reference to published studies on the biochemical changes occurring during platelet aggregation. It is suggested that the formation and release of prostaglandins is associated with the secretion of endogenous ADP and 5-hydroxytryptamine.     

The Actin and Myosin Filaments of Human and Bovine Blood Platelets

The contractility of platelets has been attributed to an actomyosin-like protein which has been well defined on a physicochemical basis. Moreover, platelets contain +/-80 A filaments which resemble actin filaments in smooth muscle. Studies were undertaken on human and bovine platelets to better define the morphologic structures which may subserve this contractile function. In order to identify actin, the ability of the filaments to react with heavy meromyosin (HMM) was tested. Accordingly, platelets were glycerinated and treated with HMM. In addition, platelet actin was extracted, reacted with HMM, and examined by negative staining. In both instances typical arrowhead structures with clearly defined polarity and a periodicity of +/-360 A formed. As is the case with purified muscle actin, the complexes were dissociable with Mg-ATP. The formation of myosin-like filaments was observed when osmotically shocked platelets were incubated with MgCl(2) and excess ATP. These "thick" filaments measured 250-300 A in width, tapered at both ends and often occurred in clumps. They resembled aggregates of thick filaments described in contracted smooth muscle. Extraction of platelets by methods suitable for the demonstration of myosin showed filaments with an average length of 0.3 mu, a smooth shaft, and frayed or bulbous ends. These appeared identical to those seen in synthetically prepared myosin of striated muscle. It is suggested that the filaments described here represent the actin and myosin of platelets.     

机采血小板在妇科大型手术中的应用

目的分析妇科大型复杂手术中采用预防性输注机采血小板的效果。方法选择妇科大型复杂手术病例共46例,随机分为观察组和对照组各23例,观察组除在术中常规输注晶胶体液外,手术开始0．5h预防性输注机采血小板1个治疗剂量单位,对照组则按常规作术前准备。结果两组的手术时间、术中出血、术中输血量和住院天数的差异均有显著性（P〈0．01）,观察组手术时间明显缩短,出血量显著减少,异体输血量明显降低,住院时间低于对照组6～8d。结论妇科大型复杂手术中预防性输注机采血小板能减少术中出血量,缩短手术时间,减少术中输血,提高了手术质量。     

Evaluation of White Blood Cell- and Platelet-Derived Cytokine Accumulation in MIRASOL-PRT-Treated Platelets

Zusammenfassung

Hintergrund

Aus Leukozyten oder Thrombozyten stammende Mediatoren in Plättchenkonzentraten können allergische und nicht hämolytische febrile Transfusionsreaktionen im Empfänger hervorrufen. Da Pathogenreduktionstechniken (PRT) die Replikation und Proliferation von Pathogenen und Leukozyten unterbinden, könnten die mit der Zytokinanrei-cherung verbundenen unerwünschten Transfusionsereignisse verhindert werden. Andererseits ist es denkbar, dass PRT die leukozytäre und thrombozytäre Zytokinproduktion durch photodynamische oder photochemische Stimulation dieser Zellen erhöht.

Material und Methoden

12 leukozy-tendepletierte Dreifachplättchenkonzentrate wurden durch Apherese mit dem Trima-Accel-Zellseparator gewonnen. Gleich nach Auftrennung wurde eine Einheit der Mirasol-PRT-Behandlung unterzogen (M), die beiden anderen blieben entweder unbehandelt (C) oder wurden mit 30 Gy gammabestrahlt (X). Während 7 Tagen Lagerung wurden Plättchenaktivierung, leukozytäre Th-1/2 bzw. inflammatorische Zytokine sowie plättcheneigene Zytokine untersucht.

Ergebnisse

Ungeachtet der Behandlung wiesen alle Einheiten nur sehr geringe Konzentrationen leukozytärer Zytokine auf. Hö here Konzentrationen wurden für Plättchenzytokine gemessen. Diese stiegen in allen Einheiten mit wachsender Lagerungsdauer an. Wahrscheinlich aufgrund höherer Plättchenaktivierung lag die Konzentration der M-Einheiten ab Tag 5 der Lagerung signifikant höher als die der unbehandelten und bestrahlten Einheiten.

Schlussfolgerung

In allen Einheiten stammten die Zytokine hauptsächlich aus den Plättchen selbst. Die Mirasol-PRT-Behandlung führte zu einem signifikanten Anstieg der Plättchenaktivierung und dadurch zu vermehrter Freisetzung von Plättchenzytokinen. Leukozytäre Zytokine blieben im Vergleich zu unbehandelten und bestrahlten Kontrollen unbeeinflusst.     

红细胞污染机采血小板的献血者因素分析

目的找出红细胞污染机采血小板的献血者因素,从而在挑选献血员中考虑这些因素,以提高血小板质量和外观,减少输血反应,减免交叉配血过程。方法对2003年至2005年三年间出现的红细胞污染机采血小板进行分析,排除机器故障、操作失误及脂血等原因,就献血员自身因素进行回顾性研究。结果发生红细胞污染的献血者在血小板体积分布宽度方面与正常献血者有显著性差异。结论红细胞污染机采血小板与献血员的血小板体积分布宽度偏大有关。     

Bacterial Pre-Release Testing of Platelets - the Australian Red Cross Blood Service Clinical Experience

SUMMARY: The risk of bacterial transmission by platelet transfusion has been recognised internationally as the leading residual infections transfusion risk in the last decade. We describe the clinical and logistical aspects of bacterial contamination screening of platelets introduced in Australia in early 2008. Sampling occurs at 24 h, and platelets are released to hospitals 'negative to date'. Bacterial screening detection of initial machine-positive (IMP) and all follow-up results are notified to transfusing laboratories. Results of screening between 2008 and 2010 found a significant rate of IMP samples (1.06%) with a true-positive/indeterminate rate of 0.18%. Components were already transfused in 32.5% of cases at time of initial notification. Confirmed cases of septic transfusion reactions have declined significantly since the introduction of pre-release platelet screening, reflecting an important additional improvement in transfusion safety in Australia.     

定量检测残留白细胞方法的建立及在辐照血小板中的应用

目的建立定量检测单采血小板中残留白细胞的流式细胞术方法,探讨经血液辐照仪辐照前后血小板中白细胞的含量变化。方法应用绝对计数管内的定量微球(Beads)调整流式细胞仪参数,确定流式细胞仪检测条件。血小板样品经过RNA酶、固定剂、渗透剂作用后,再经碘化丙啶标记,通过流式细胞仪计数经标记的白细胞,建立检测残留白细胞含量的方法。采用血细胞分离机采集单采血小板16人份,通过血液辐照仪25Gy照射310s,应用建立的流式细胞术方法跟踪检测单采血小板辐照前及辐照后0、1、3、5d的白细胞含量,比较白细胞含量的变化。结果单采血小板中残留白细胞含量范围为1.85×106～1.3×108/袋。单采血小板中残留白细胞计数于辐照前与辐照后0d相比没有变化,与辐照后1d相比残留白细胞数量的减少有显著性(P<0.05);辐照后1d白细胞计数与辐照后3d和5d相比没有改变。结论流式细胞术方法具有较好的准确性、客观性和重复性,可以成为评估血小板质量的监控手段。辐照不立即改变血小板中残留白细胞的计数,辐照后1d残留白细胞的数量减少。     

Effect of Aspirin on Thrombin-Induced Adherence of Platelets to Cultured Cells from the Blood Vessel Wall

An in vitro method was used to detect adherence of ⁵¹Cr-labeled platelets to monolayers of cultured human endothelial, fibroblast, and smooth muscle cells. Washed platelets did not adhere to untreated or aspirin-treated endothelial monolayers in the absence of thrombin. In contrast, thrombin-induced platelet aggregates adhered to all of the monolayers but adherence to endothelium was significantly less than to the other cells. Additional evidence for adherence of platelets to the endothelium was provided by scanning and transmission electron microscopy. Thrombin-induced platelet adherence to endothelium was inhibited by hirudin. Platelet adherence induced by thrombin was enhanced significantly by treatment of the endothelial monolayer with 1—2 mM aspirin. This increase in adherence was seen even when aspirin-treated platelets were used; adherence values approached those seen with fibroblasts and smooth muscle cells. An aspirin concentration of 0.1 mM was sufficient to block thrombin-induced malonaldehyde production in platelets but it did not interfere with the inhibitory effect of the endothelium against platelet adherence. The effect of aspirin on the endothelium was temporary and inhibitory activity of the endothelium was restored 1 h after aspirin had been removed from the incubation system. The ability of thrombin to cause adherence of platelets to undamaged endothelium, and the potential for aspirin to enhance this adherence have implications for mechanisms which operate in platelet interaction with the blood vessel wall.     

Platelets and autoimmunity

Vascular injury is the initial manifestation of inflammation resulting in the recruitment and activation of various cell types. The integrity of the vascular wall is monitored by platelets that become activated in the presence of exposed subendothelium. Besides their well‐established role in haemostasis, ample data are now emerging on the many immunoregulatory functions of platelets. Platelets store and release a large plethora of cytokines, chemokines and growth factors. They also represent the largest circulating pool of many inflammatory mediators like P‐selectin, CD40L and non‐neuronal serotonin. Furthermore, complement activation occurs on the platelet surface and deposition of complement results in platelet activation. Overall, platelets have multiple functions in both innate and adaptive immunity. Further insight into the multifaceted role of platelets could therefore provide important clues into how we could implement current platelet therapy to reduce both platelet‐induced thrombosis and inflammation. In this review, we discuss the current perceptions of platelet involvement in various autoimmune diseases like rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis and multiple sclerosis.