Washed/replaced-platelet concentrates (W/R-PC) have been used to prevent non-hemolytic transfusion reactions. The manufacturing process of W/R-PC varies across institutions. Additive solution M-sol has been reported to retain the stability of platelet function. In this preclinical study, we developed a standard operating procedure (SOP) for manufacturing replaced-platelet concentrates (R-PC) with M-sol and analyzed the quality of these R-PC at a single institution.
The following parameters of R-PC with M-sol (n=8) manufactured according to the SOP were analyzed: pH and Na⁺, K⁺, Cl^-, and Mg²⁺concentrations. Functional testing of R-PC one day after manufacture consisted of the number of platelets, glucose level, P-selectin positivity, and swirling. In addition, we also performed both bacterial and endotoxin tests of the products.
The values (mean) of R-PC parameters were as follows: pH (7.51), Na⁺ (150.9mmol/l), K⁺ (2.71mmol/l), Cl^- (77.9mmol/l), Mg²⁺ (1.39mmol/l), glucose (17.6mmol/10¹²PLTs), and P-selectin (5.50%). A trend was observed for changes in the values of pH, K⁺, and glucose of the R-PC until the seventh day. The process of R-PC manufacturing was validated by setting the recovery of platelets as 90.8±3.2%, reduction of plasma protein as 93.3±1.6%, and presence of distinct swirling of all R-PC. Quality was confirmed by the negative results of bacterial tests in 14-day cultures and undetectable endotoxin levels.
We propose that the R-PC standard met the criteria validated by the preclinical study. These findings indicate that this SOP can be used to manufacture M-sol and R-PC for clinical use at individual institutions.

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Platelet-derived microparticles (PDMPs) produced during storage of autologous blood may be involved in unfavorable complications after transfusion as a result of their ability induce to inflammatory events. We have already demonstrated that the increase of microparticles seen in unfiltered autologous blood is almost entirely suppressed by pre-storage leukofiltration. To evaluate the clinical impact of filtering autologous blood, we studied whether pre-storage leukoreduction reduces clinical symptoms, edema and leg pain after orthopedic surgery. This comparison trial took place at a single university medical center. Based on date of birth, patients were assigned to receive either leukoreduced (LR) or non-leukoreduced (N-LR) autologous blood, as processed and stored in approved autologous collection sets. As indices of symptoms after surgery, edema and leg pain after post-operative day 3 were investigated. Symptoms in the joint which underwent surgery were excluded. Most patients were pretreated with heparin or factor Xa inhibitor for DVT prophylaxis. Six hundred and fifteen patients were enrolled, of whom 49 were excluded, leaving 566 for analysis in this study (LR group: 279, N-LR group: 287). The fraction of cases with edema and/or leg pain after autologus blood transfusion in the LR group (n=94, 34%) versus N-LR group (n=132, 46%) achieved statistical significance (Chi-square test, p<0.01). The same results were obtained in the subgroup of patients who underwent hipjoint surgery (p=0.01). These results suggest that pre-storage leucoreduction of autologous blood reduces complications such as edema and leg pain after orthopedic surgery.

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We established a system for recording and monitoring transfusion-adverse effects in patients by developing an electronic input system which uses forms of the electronic medical record (EMR) system at our hospital, CIS^TM(IMB Japan). Input is performed by selecting check boxes or drop-down menus. Adopting this new system enabled us to rapidly acquire detailed information on all transfusion-adverse effects. The system also enabled us to obtain the occurrence frequency of adverse events on a per patient and per bag basis. Patients who received transfusions from Jan 2008 to Dec 2009 were enrolled in the new system. A total of 5,156 bags of red blood cells (RCC, Red Cell Concentrates) were transfused to 1,154 patients, 1,795 bags of fresh frozen plasma (FFP) to 261 patients, and 3,394 bags of platelets (PC) to 350 patients. The number of patients with transfusion-adverse events was 20 (1.7%) for RCC, 12 (4.6%) for FFP, and 50 (14.2%) for PC. These incidences were higher in the Departments of Hematology (22.2%) and Pediatrics (23.7%) than in other clinical departments. Furthermore, occurrence was more frequent with transfusion per patient than that per bag. Pre-administration of an antihistamine agent or corticosteroid was not sufficient to prevent adverse events in patients who received PC transfusions. However, three patients who received a washed PC transfusion experienced no adverse events. Therefore, washed PC might be promising for decreasing the probability of adverse events. In summary, the EMR system is useful for gathering and analyzing adverse event data.

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Platelets (PLTs) washed with additive solution are useful for reducing adverse reactions induced by PLT concentrate (PC) transfusion. Since plasma contains certain complement components that inhibit bacterial growth, decreasing the plasma concentration by washing PC may promote bacterial growth in washed PLTs. Here, we compared bacterial growth in PLTs washed with M-sol with that in PLT rich plasma during a 7-day storage period.
Bacterial culture was inoculated into PRP (Day 0). After storage at 22-24°C on a flatbed shaker for 24 hours, PRP including bacteria was divided into two equal aliquots (control group and test group) on Day 1. After centrifugation of the test group, as much of the supernatant as possible was removed, and then the pellet was suspended in M-sol. Both groups were stored in polyolefin bags as described above until Day 7. To count bacterial colonies, aliquots were sampled from both groups and plated on agar plates.
Compared with that in PRP, the growth of Streptococcus dysgalactiae and Escherichia coli was promoted in washed PLTs, while that of Staphylococcus epidermidis and Staphylococcus aureus was suppressed. The growth of Bacillus cereus in washed PLTs was comparable with that in PRP. There was no growth of Propionibacterium acnes or Serratia marcescens in either PRP or washed PLTs during 7 days of storage.
Consideration should be given to the presence of bacterial strains that are more prone to grow in PLTs washed with M-sol than in PRP.

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