Feasibility of applying the 2 day deferral for repeat plateletpheresis: Indian perspective

As the use of single donor apheresis platelets and plateletpheresis procedures done steadily increases in India, the plateletpheresis donors are at an increased risk of postpheresis anemia and thrombocytopenia. This study was planned in order to evaluate the effect of plateletpheresis on the hematological parameters in the local donor population and to evaluate the possibility of following the 2 day deferral for repeat plateletpheresis. A total of 60 plateletpheresis procedures performed over a period of 1 year with CS 3000 Plus Baxter Fenwal were evaluated. All the post-donation hematological parameters showed a significant decrease from the pre-donation values (p < 0.001). Post-donation hemoglobin <12 g, which is defined by WHO as anemia irrespective of the gender occurred in 25% (n = 15) of the donors. The post-donation platelet count was less than 100 × 10⁹/L in 16.6% (n = 10) of the procedure. The ability of these donors to serve as repeat plateletpheresis donor after 2 days as recommended by AABB needs to be evaluated by further studies done post donation. Keeping in view the hematological profile of our donor population we recommend that donors who already have a low or borderline pre-donation platelet count and hemoglobin should be assessed and monitored post-donation for decrements in these parameters. While serving as repeat donors, their pre donation hemoglobin and platelet counts should be tested again.     

Current topics on centrifugal plasmapheresis technologies.

In the field of plasmapheresis centrifugal technology has recently focused on the collection of peripheral blood stem cells (PBSCs) for both autologous and allogeneic transplantation in patients with malignancies or hematological diseases and on donor plasmapheresis. PBSC transplantation is rapidly replacing bone marrow transplantation in such patients. Various kinds of apheresis equipment were applied and described for PBSC collection. Comparison among machines is described. Allogeneic PBSCs were collected from healthy normal donors. Specific attention to the dose and administration duration of granulocyte colony-stimulating factor and a careful apheresis procedure should be made for donor safety. In platelet transfusion practice, a platelet concentrate product derived plateletpheresis from a single donor is preferable to minimize and to prevent adverse transfusion reactions. The status of platelet collection and its efficacy by various kinds of plateletpheresis equipment are discussed. The Amicus and CCS might be preferable plateletpheresis machines because of their collection efficiencies and wider indication for donors. With the limited number of donors, it is essential that plateletpheresis should be more effectively performed and managed by each regional blood center. The status of plasma and red cell collection by apheresis technologies is described also briefly.     

A randomized crossover trial comparing three plateletpheresis machines

BACKGROUND: The aim of the study was to compare three different apheresis machines with the same donors regarding the processing time required to obtain a 3.5 x 10(11) platelet (PLT) dose and acceptance by donors. STUDY DESIGN AND METHODS: A randomized crossover trial was performed to evaluate the differences between the Amicus Crescendo (Baxter Biotech Corp.), the MCS Plus (Haemonetics Corp.), and the Trima Accel (Gambro BCT). Donations from 51 donors were compared for time adjusted to obtain a standard 3.5 x 10(11) PLT dose (TSD3.5), efficiency, adverse reactions, yield, leukodepletion, machine accuracy, and donor preferences. Processing times were measured by chronometer. The same vein access was used during all three processes in each donor. In the statistical analysis, to take into account the nonindependence of several measurements from the same donor, generalized estimating equations were used with an autoregressive correlation matrix. RESULTS: The Accel produced a TSD3.5 (mean +/- SEM) of 47.9 +/- 1.0 min; the Amicus, 60.3 +/- 1.0 min; and the MCS Plus, 66.7 +/- 1.0 (p < 0.0001). The Amicus presented the greatest efficiency (87.5%; p < 0.0028). The MCS Plus demonstrated the highest capacity for leukodepletion (p < 0.0002) despite one process presenting more than 1 x 10(6) white blood cells per unit. The MCS Plus also measured the processing time with the greatest accuracy. No severe adverse effects were observed. The donors preferred the Accel (61%) followed by the Amicus (35%) and the MCS Plus (4%; p < 0.0001) and the processing speed was the most highly valued measure (55%). CONCLUSIONS: The Accel is the fastest and, because of this advantage, the machine preferred by donors. The Amicus was the most efficient and the MCS Plus was the only one not to underestimate the processing time.     

A randomized comparison of plateletpheresis with the same donors using four blood separators at a single blood center

At one blood center, each of 20 donors underwent plateletpheresis on four blood cell separators in random order. We compared the CS3000+, Amicus V 2.41, MCS Plus, and Spectra LRS V 7 Turbo regarding platelet (PLT) yield, pre- and post-procedure PLT counts, percent fall in donor PLT count, process time, efficiency, PLT product and donor PLT volume (MPV). Using >or= 150 x 10(9) PLTs/L pre-donation counts, a goal was set of 4.5 x 10(11) PLTs unit in up to 100 minutes processing time. Results were (mean values) PLT yields of Amicus, Spectra, CS3000+, and MCS Plus: 4.3, 4.6, 4.3, 4.0 x 10(11) PLTS, respectively; percent donor PLT fall: 24, 32, 30, 29%, respectively; processing times: 50, 74, 87, 101 minutes, respectively; relative efficiency (RE): 2.2, 1.6, 1.2,1.0, respectively (based on the MCS Plus performance with RE of 1 = 4 x 10(9) PLTS/min); PLT product MPV: 6.7, 7.4, 6.8,7.1 fL, respectively; pre-procedure donor MPV: 7.7, 7.3, 7.6 and 7.6 fL, respectively; and percent donor MPV change: -5.2, 0, -6.6, and -10%, respectively. Significant changes in the donor MPV were noted (P < 0.05) but could not be related to product MPV. Spectra seemed to collect larger PLTs (higher MPV); the significance remains unknown for both donors and recipients. Importantly, all four separators gave acceptable and comparable PLT yields (P < 0.05) with Spectra trending higher. The short process time and high RE together indicate highly efficient collections particularly by Amicus and Spectra.     

单采血小板储存样品中某些细胞因子含量的变化

本研究探明不同血细胞分离机所采集的单个供者血小板（single donor platelets，SDP）在储存期间细胞因子含量的变化。使用MCS^＋、Trima和Amicus3种血细胞分离机采集18份SDP，于血库标准条件下储存，于第1、3、5、7天取样检测储存期内白介素8（IL-8）、RANTES、CD154和肿瘤生长因子β1（TGF-β1）、血管内皮细胞生长因子（VEGF）等细胞因子含量的变化情况。结果显示：MCS^＋、Trima和Amicus机器采集的SDP，在储存期间随着时间的延长细胞因子IL-8、RANTES、CD154、TGF-β1及VEGF的含量逐渐增高，但MCS^＋机器采集SDP的IL-8的含量在保存期的增高水平，与Trima和Amicus法采集的SDP水平相比有显著性差异（P〉0．05）；而其余的细胞因子含量虽有增高，但无显著性差异．结论：单采血小板储存期间IL-8、RANTES、CD154、TGF-β1和VEGF等细胞因子的含量随保存时间的延长有升高的趋势；少白细胞的单采血小板中的IL-8表达相对较少。     

Thrombelastographic evaluation of the influence of 2-RBC apheresis on donor’s coagulation system

Rotation thrombelastogram (ROTEM®/TEG®) assays allow rapid global assessment of hemostatic function using whole blood. Since published data about the effects of automated red cell collection on coagulation system are scarce, we aimed to investigate the effects of 2-RBC apheresis on donor’s coagulation system using ROTEM® assays.In INTEM assay, CFT was significantly shortened 24 h after apheresis compared with baseline value (p < 0.05) and MCF was significantly prolonged immediately after apheresis and 24 h after apheresis compared with baseline value (p < 0.05 and p < 0.01, respectively). In EXTEM assay, CFT was significantly prolonged immediately after apheresis and 24 h after apheresis compared with baseline value (p = 0.001 and p < 0.001, respectively) and MCF was significantly prolonged 24 h after apheresis compared with baseline value (p < 0,001).Our results demonstrate thromboelastographic signs of hypercoagulability in donors undergoing 2-RBC apheresis.     

Factors associated with peripheral blood stem cell yield in healthy pediatric donors

Background and Objectives

Although several studies have reported on the use of children as donors for peripheral blood stem cells (PBSC), data on the predictive factors of CD34+ stem cell yield in healthy pediatric donors are very limited.

Apheresis-induced platelet activation:comparison of three types of cell separators

BACKGROUND: Platelet-harvesting technology differs in various cell separators. Alteration in shear stress and biocompatibility of surfaces may give variable platelet activation and thereby affect the quality of the component. STUDY DESIGN AND METHODS: Four groups (n = 10) of single-needle apheresis procedures using three cell separators, were compared: 1) Spectra LRS, 90-minute harvesting time; 2) MCS+, 90-minute harvest; 3) Amicus, 90-minute; and 4) Amicus, 45-minute. Whole-blood samples were collected from the donors as were samples from the final components at intervals during the first 4 hours after cessation of the apheresis. Platelet activation status and platelet activation capacity after agonist stimulation were assessed by flow cytometry. RESULTS: No activated platelets were found in preapheresis and postapheresis samples from the donors. The platelets in the components from the Amicus (90-min) were significantly more activated than those in the other groups of components: that is, there was increased size of platelet aggregates, increased fraction of microparticles, increased degranulation, increased fibrinogen receptor activation, and decreased von Willebrand factor receptor expression. Moreover, the response of these platelets to agonist stimulation was reduced for all activation variables. CONCLUSIONS: After 90 minutes' processing time, platelets obtained with the Amicus cell separator were significantly more activated than platelets harvested with the Spectra and the MCS+.     

Paired crossover study of two plateletpheresis systems concerning platelet product quality and donor comfort

BACKGROUND: Two plateletpheresis cell separator systems were compared in a paired crossover study with respect to the product quality, the number of platelet (PLT) units per donation, and the donor comfort. STUDY DESIGN AND METHODS: Forty‐four female and 47 male donors were distributed to three body weight groups. Double PLT units with 6 × 10¹¹ PLTs were collected from three Fenwal Amicus Crescendo (AC) and three CaridianBCT Trima Accel (TA) machines. Each donor made one donation on each randomly assigned system and answered a questionnaire on the subjective donor comfort. The answers were scored from 5 (best) to 1 (worst). RESULTS: Based on 182 donations, with 91 donations on AC and TA separators each, 179 runs resulted in double PLT units and three (2×AC, 1×TA) in single units. The white blood cell counts were below 1 × 10⁶ in all but eight therapeutic units (8×TA; mean, 1.98 × 10⁶). The mean PLT yield (AC 6.00 × 10¹¹, TA 5.98 × 10¹¹), the collection rate, and the PLT extraction coefficient did not significantly differ between the two devices. Differences of the donor comfort over all groups were only observed for the loudness of the instrument (4.63 AC vs. 4.24 TA, p < 0.001) and the subjective impression of the run time (4.24 AC vs. 4.48 TA, p < 0.05). Male donors greater than 88 kg preferred the TA instruments concerning the impact of the needle, run time, overall experience (p < 0.01 each), and willingness to donate on the same instrument again (p < 0.05). CONCLUSIONS: Only minor differences were observed despite the fact that the AC separators are run with two needles and the TA with one needle.     

Response to vWF-coated beads and soluble p-selectin to characterize apheresis platelets: a comparison of three cell separators

BACKGROUND: Plateletpheresis technologies differ among various cell separators. Differences in centrifugation force, centrifugation time, and platelet concentration in the platelet concentrate may affect platelet activation and function. STUDY DESIGN AND METHODS: In a three-way crossover design, 12 donors were randomly assigned to three types of cell separators, two continuous flow systems (Amicus DN, Fenwall Division, Baxter and Spectra LRS, Gambro BCT) and one intermittent flow system (MCS+, Haemonetics). The response to vWF-coated beads was determined in the peripheral blood and fresh platelet concentrates to obtain information about the initiating step of platelet aggregation, that is, platelet adhesion. Levels of soluble p-selectin were measured as a marker of platelet activation. RESULTS: Platelet yield and concentration of platelets were higher in platelet concentrates obtained with the Amicus DN than with the Spectra LRS or the MCS+. Maximal aggregation was significantly higher in platelets from the Amicus DN than in platelets from the Spectra LRS or the MCS+. Higher concentrations of soluble p-selectin were seen in platelet concentrates obtained with the Amicus DN than in concentrates from the Spectra LRS or the MCS+, but they did not differ after correction for the number of platelets per component. CONCLUSIONS: Different plateletpheresis procedures induced distinct changes of platelet function. Platelets collected using the Amicus DN retained the strongest adhesion capacity irrespective of their activation.     

Comparison of double dose plateletpheresis on the Fenwal Amicus,Fresenius COM.TEC and Trima Accel cell separators

BackgroundA variety of apheresis instruments are now available on the market for double dose plateletpheresis. We compared three apheresis devices (Fenwal Amicus, Fresenius COM.TEC and Trima Accel) with regard to processing time, platelet (PLT) yield, collection efficiency (CE) and collection rate (CR).Study Design and MethodsThe single-needle or double-needle double plateletpheresis procedures of the three instruments were compared in a retrospective, randomized study in 135 donors.ResultsIn the pre-apheresis setting, 45 double plateletpheresis procedures performed with each instrument revealed no significant differences in donor's age, sex, weight, hemoglobin, white blood cell and PLT count between three groups. The blood volume processed to reach a target PLT yield of ≥ 6 × 10¹¹ was higher in the COM.TEC compared with the Amicus and Trima (4394 vs. 3780 and 3340 ml, respectively; p < 0.001). Also there was a significantly higher median volume of ACD used in collections on the COM.TEC compared with the Amicus and Trima (426 vs. 387 and 329 ml, respectively; p < 0.001). There was a significantly higher median time needed for the procedures on the COM.TEC compared with the Amicus and Trima (66 vs. 62 and 63 min, respectively; p = 0.024). The CE was significantly higher with the Trima compared with the Amicus and COM.TEC (83.57 ± 17.19 vs. 66.71 ± 3.47 and 58.79 ± 5.14%, respectively; p < 0.001). Also, there was a significantly higher product volume on the Trima compared with the Amicus and COM.TEC (395.56 vs. 363.11 and 386.4 ml, respectively; p = 0.008). Additionally, the CR was significantly lower with the COM.TEC compared with the Amicus and Trima (0.092 ± 0.011 vs. 0.099 ± 0.013 and 0.097 ± 0.013 plt × 10¹¹/min, respectively; p = 0.039). There was no significant differences in PLT yield between the three groups (p = 0.636).ConclusionsTrima single-needle device collected double dose platelets more efficiently than Amicus and COM.TEC double-needle devices. Blood volume processed, ACD-A volume, and median separation time was significantly higher with the COM.TEC. Also, the CR was significantly lower with the COM.TEC.     

Decreased levels of ferritin,mild thrombocytosis,and increased erythropoietin are sequential events among frequent plateletpheresis donors: Implication for a ferritin screen

BackgroundIt is generally recognized that repeat apheresis increases the risk for iron deficiency, thus may impact on the blood homeostasis. With regard to donor vigilance, we clarified the mid- to long-term effects of plateletapheresis by comparing the most frequent donors with the first-time ones in hematological and biochemical tests.MethodsLevels of erythropoietin (EPO), hemoglobin (Hb) and ferritin were analyzed in double-unit (500 mL whole blood or 6 × 10¹¹ apheresis platelets) donations in three male cohorts, with identifiers of first-time whole-blood donors (n = 30), first-time platelet donors transited from maximal whole blood to apheresis (n = 30) and frequent donors subjected to extreme plateletpheresis (n = 90), respectively. According to the number of donations, the last earnest cohort, who donate almost 24 times a year, was further subdivided into three groups– casual (76–120 life-time donations in 5 years), mediocre (121–168 within 7 years) and enthusiastic (≥169 within 7 years and a month).ResultsRegardless of the donation experience in whole blood or plateletpheresis, iron deficiency (serum ferritin concentrations <15 μg/L) was identified in all earnest cohorts. The ferritin means were significantly lower in plateletpheresis groups, with the lowest values in the enthusiastic group. EPO levels showed a significant inverse correlation with ferritin (p = 0.015, r = –0.224). Long-term earnest donors had the lowest iron stores accompanied by a later thrombocytosis and a final increase in EPO was revealed.ConclusionRegular ferritin screens are crucial to ensure a high level of donor health protection.     

Effects on donors of repeated leukocyte losses during plateletpheresis

All blood components collected by automated cytapheresis contain donor leukocytes. The possibility that repeated cytapheresis donation might lead to clinically important leukocyte losses and immunodeficiency has been a longstanding concern. Although convincing data do not exist to substantiate this concern, it is common practice to limit the number of annual cytapheresis donations per donor and to monitor donors for developing lymphocytopenia. Clinically significant immunodeficiency is unlikely to occur unless donors lose >1 × 10¹¹ lymphocytes within a few weeks period of time or unless donor lymphocyte counts fall persistently to <0.5 × 10⁹/L. Each plateletpheresis procedure, when performed using modern cell separators that are designed to produce a relatively “pure” platelet concentrate, leads to the loss of 1.0 × 10⁶ to 5.0 × 10⁷ leukocytes. Thus, automated plateletpheresis as performed in 1994 is extremely unlikely to cause clinically significant lymphocyte depletion and consequent immunodeficiency.     

Cost effectiveness of quality assurance in plateletpheresis

BACKGROUND AND OBJECTIVES: A quality assurance system (QAS) is part of modern blood banking facilities. Quality control of single donor platelet (SDP) concentrates includes the determination of the platelet (PLT) yield and the white blood cell (WBC) contamination. Improvements in modern apheresis technology allow the collection of high PLT yields and leukoreduced products. Double dose SDPs can be split and WBC-reduced products may be labelled as leukodepleted thereby reducing costs. MATERIAL AND METHODS: 3309 SDPs obtained with the Amicus, AS 104, AS.TEC 204 and MCS + blood cell separators were retrospectively analysed for their PLT yield. SDPs with > or = 4.0 x 10(11) PLTs were considered as double dose SDPs and split. WBCs were determined microscopically in 170 SDPs. SDPs with a leukocyte content < 1.0 x 10(6) were labelled as leukodepleted and no further WBC filtration was recommended. RESULTS: PLT yield was statistically higher in SDPs from the Amicus device, 84.8% of these products could be split. Double dose concentrates were collected in 22.7% with the MCS + machine and in 4.8% with the AS 104/AS.TEC 204 blood cell separators. The savings for disposables was $150,041 and for infectious disease testing $75,766. After the subtraction of the costs for PLT determinations in all SDPs $215,880 could be saved. WBC contamination was statistically lowest in in-line filtered SDPs from the MCS + device (median 0.29 x 10(5), range 0.22-9.96 x 10(5)) and all of these products were considered as fulfilling the criterion of leukodepeletion so that we were able to save $17,135 for bedside filters. Median WBC content was 0.75 x 10(5) (range 0.35-22.5 x 10(5)) in SDPs from the Amicus and 0.9 x 10(5) (range 0.27-99.8 x 10(5)) in SDPs from the AS 104/AS.TEC 204 devices, respectively. CONCLUSION: Blood cell separators of the newest generation allow the collection of leukodepleted double dose SDPs. An intensified QAS in plateletpheresis allows the decision whether a product can be split and/or released as leukodepleted. By this means we were able to save a total of $233,015 per year.     

Phosphatidylserine exposure in platelet concentrates during the storage period: differences between the platelets collected with different cell separators.

BACKGROUND AND OBJECTIVES: Platelet alterations occur during the production and storage of platelet concentrates, the so called "storage lesion". We studied the platelet alterations during the storage period in apheresis concentrates, employing flow cytometry for phosphatidylserine (PS) detection on platelets during the five days of storage. MATERIAL AND METHODS: Twenty-seven single donor platelet concentrates harvested with the Cobe Trima, Baxter Amicus, or Haemonetics MCS+ were analyzed for PS exposure by flow cytometry on the day of production (day 1) and on days 3 and 5 of storage. Furthermore PS expression was analyzed in platelet donors' blood samples withdrawn before plateletpheresis. RESULTS: PS expression on platelets gave the following median values: in blood donors before apheresis it was 1.12% (0.13-1.78) in platelets concentrates on the first day (2 h after apheresis) 2.06% (0.66-15.2), the third day 6.57% (1.98-51.13) and the fifth day 23.04% (3.86-80.23). All differences between median values of PS expression in blood samples before apheresis, and platelets concentrates on days 1, 3 and 5 of storage, are statistically significant. The expression of PS in platelet concentrates was analyzed in relation to the blood cell separator used for the collection procedure and showed the following results: on day 1 the median values of PS in platelet concentrates collected with the three different blood cell separators, Trima, Cobe and MCS, did not show statistically significant differences. On day 3, the platelets concentrates collected with the Trima and with the MCS showed differences that were statistically significant. Those were respectively 10.59% (4.56-51.13) and 3.53% (1.98-12.61), p = 0.005. The PS expression in platelet concentrates collected with the Trima and MCS showed differences that are also statistically significant on day 5 at respectively 32.4% (9.61-80.23) and 8.57% (3.86-48.42), p = 0.005. CONCLUSIONS: PS exposure in platelet concentrates on days 3 and 5 rise to levels that could compromise the quality of the platelet units. Improvements in standardized platelet quality controls, and in platelet collection systems are required to reduce the storage lesions in platelets concentrates.     

An alternative method for custom prime: A case report of successful peripheral blood stem cell harvesting from two low-weight child donors

Allogeneic peripheral blood stem cell (APBSCs) transplantation is an effective treatment for hematological malignancies. However low-weight donor children meet some complications. In the current report, PBSCs were harvested from a 14-month-old child (9.8 Kg) for a 6 years old sibling recipient suffering from pre-B type of acute lymphoblastic leukemia (ALL) and also 24 months old male child donor (12 Kg) for a haploidentical recipient suffering from acute myeloid leukemia (AML-M4EO). The PBSC harvesting was performed using Spectra? Optia^® apheresis software with continuous mononuclear cell (CMNC) procedure. The results were completely promising and both recipients underwent an acceptable transplantation.     

Collection of MNCs and progenitor cells by two separators for PBPC transplantation: a randomized crossover trial

BACKGROUND: Efficient collection of progenitor cells is essential for PBPC transplantation. Two apheresis machines (Amicus, Baxter Healthcare; and Spectra, Gambro BCT, software version 4.7) were compared prospectively by a crossover trial. STUDY DESIGN AND METHODS: Apheresis collections were performed for two consecutive days on patients for autologous and donors for allogeneic PBPC transplantation. The patients and donors, receiving a G-CSF, were randomized into two groups. In Group I, PBPCs were collected by the Amicus on the 1st day and the Spectra on the 2nd day, and the reverse order was used with Group II. A total of 60 apheresis procedures of 30 (16 in Group I and 14 in Group II) among 40 patients and donors enrolled were performed and evaluated. RESULTS: The nucleated cell counts, MNC counts, CD34+ PBPC counts, and amounts of CFU-GM collected per procedure were similar with the Amicus and the Spectra. On the other hand, the decrease of peripheral blood platelet counts of patients and donors was more prominent from using Spectra than Amicus (p < 0.0001). Components collected by the Amicus had fewer platelets than those collected by the Spectra (p < 0.0001). The efficiencies of collecting nucleated cells, MNCs, and CD34+ PBPCs were not different between the machines (p > 0.05). However, the efficiency of collecting platelets was significantly higher with Spectra than with Amicus (p < 0.0001). The Amicus took longer than the Spectra to process the same volume (p < 0.05). CONCLUSION: Amicus is superior to Spectra in avoiding apheresis-induced thrombocytopenia caused by platelets contaminating the collected samples. Therefore, the Amicus is useful for patients with thrombocytopenia or with a less-than-normal platelet count.     

Quantifying loss of CD34+ cells collected by apheresis after processing for freezing and post-thaw

Introduction: CD34⁺ cells collected for autologous bone marrow transplantation (BMT) are usually quantified in the apheresis product after collection, but the necessity to repeat these measures post-thaw is controversial.Methods: We examined the loss of CD34⁺ cells after collection, preparation for freezing and post-thaw in apheresis products collected for BMT.Results: Median number of CD34⁺ cells collected per unit was 1.61 × 10⁶/kg, viability: 97–100%. This number decreased to 1.38 × 10⁶/kg, viability: 96–100% before freezing and was 1.17 × 10⁶/kg post-thaw. Viability decreased to 86–98%. The relative loss of viable PBHPC showed an inverse correlation with the ratio “CD34⁺ cells/total nucleated cells” (r = ?0.45; p = <0.0005). This relative loss was largest in patients with Hodgkin’s lymphoma.Conclusion: Cryopreservation and thawing of PBHPCs in leukapheresis products provokes a small but significant stem cell loss. So, quantification of viable CD34⁺ cells post-thaw is important, especially in poorly mobilizing patients. Besides, the ratio “CD34⁺ cells/total nucleated cells” after leukapheresis is an important parameter for prediction of neutrophil recovery after BMT.     

Microparticle detection to guide platelet management for the reduction of platelet refractoriness in children – A study proposal

Microparticles have been shown to shed from a variety of viable cells as a consequence of inflammatory processes, activation or physical stress. Seventy to 90% of circulating microparticles are thought to be platelet-derived. The content of microparticles in blood collected from normal blood donors is highly variable and transfers into the final blood component. Elevated microparticle content (MPC) in donor blood might indicate an asymptomatic clinical condition of the donor which might affect the transfusion recipient, particularly pediatric patients. ThromboLUX is a new technology designed to routinely test biological samples for microparticle content. We compared MPC in platelet-rich plasma (PRP) of apheresis donors and the corresponding INTERCEPT-treated apheresis products (N = 24). The MPCs in donor and product samples were correlated (r = 0.74, P < 0.001). Microparticles were significantly reduced after plasma replacement and INTERCEPT treatment. These findings are supported by phase contrast microscopy. Platelet transfusions given to patients with fever or systemic inflammation are less efficacious. In addition, transfusing heterogeneous platelets – concentrates with high MPC and activated platelets – to patients whose immune systems are activated might tip them over a threshold and cause platelet refractoriness. Restricting prophylactic platelet transfusions to homogeneous products – concentrates with resting platelets and therefore low MPC – may reduce the risk of refractoriness in cancer patients, especially children with immature immunity. To test this hypothesis we introduce an evaluation protocol for platelet management, i.e., keeping a split inventory of homogeneous and heterogeneous platelets, and using only homogeneous platelets for prophylaxis as a strategy to reduce refractoriness.