Generation of Platelet Microparticles after Cryopreservation of Apheresis Platelet Concentrates Contributes to Hemostatic Activity.

OBJECTIVE: In the last decade, substantial evidence has accumulated about the use of cryopreserved platelet concentrates, especially in trauma. However, little reference has been made in these studies to the morphological and functional changes of platelets. Recently platelets have been shown to be activated by cryopreservation processes and to undergo procoagulant membrane changes resulting in the generation of platelet-derived microparticles (PMPs), platelet degranulation, and release of platelet-derived growth factors (PDGFs). We assessed the viabilities and the PMP and PDGF levels of cryopreserved platelets, and their relation with thrombin generation. MATERIALS AND METHODS: Apheresis platelet concentrates (APCs) from 20 donors were stored for 1 day and cryopreserved with 6% dimethyl sulfoxide. Cryopreserved APCs were kept at -80 °C for 1 day. Thawed APCs (100 mL) were diluted with 20 mL of autologous plasma and specimens were analyzed for viabilities and PMPs by flow cytometry, for thrombin generation by calibrated automated thrombogram, and for PDGFs by enzyme-linked immunosorbent assay testing. RESULTS: The mean PMP and PDGF levels in freeze-thawed APCs were significantly higher (2763±399.4/µL vs. 319.9±80.5/µL, p<0.001 and 550.9±73.6 pg/mL vs. 96.5±49 pg/mL, p<0.001, respectively), but the viability rates were significantly lower (68.2±13.7% vs. 94±7.5%, p<.001) than those of fresh APCs. The mean endogenous thrombin potential (ETP) of freeze-thawed APCs was significantly higher than that of the fresh APCs (3406.1±430.4 nM.min vs. 2757.6±485.7 nM.min, p<0.001). Moreover, there was a significant positive poor correlation between ETP levels and PMP levels (r=0.192, p=0.014). CONCLUSION: Our results showed that, after cryopreservation, while levels of PMPs were increasing, significantly higher and earlier thrombin formation was occurring in the samples analyzed despite the significant decrease in viability. Considering the damage caused by the freezing process and the scarcity of evidence for their in vivo superiority, frozen platelets should be considered for use in austere environments, reserving fresh platelets for prophylactic use in blood banks.

Is one-size-fits-all strategy adequate for platelet storage?

BACKGROUND: Platelet suspensions (PSs) are stored at room temperature. However, recent reports show that PSs stored at 4 °C possess superior hemostatic properties. We compared the viabilities and thrombin generation capacities of PSs stored either at 4 °C or 22 °C hours. MATERIALS AND METHODS: Twenty units of apheresis derived platelets (ADPs) from 20 male donors and 20 units of random platelet suspensions (RPSs) from another 20 male donors were obtained. Half of the ADPs and half of the RPSs (10 units/per group) were stored at 4 °C, the other halves of ADPs and RPSs (10 units/per group) were stored in agitators at 22 °C for 48 hours. The flow cytometric viability tests and thrombin generation tests of the PSs were assessed. RESULTS: The viabilities of both ADPs and RPSs group platelets, stored either at 4 °C or 22 °C for 48 hours, were not statistically significantly different. The ADPs and RPSs stored at 4 °C generated significantly higher peak thrombin levels than the platelets stored at 22 °C. Moreover, the ADPs group stored at 4 °C showed significantly shorter time to thrombin generation and reach peak levels. CONCLUSION: The PSs stored at 4 °C showed higher and faster thrombin generation capacities than the room temperature PSs. Given the superior hemostatic properties of refrigerated platelets, creating different storage temperature capabilities for specific transfusion purposes may be a prudent approach, especially for improving the outcome of bleeding trauma casualties.

A strategical re-thinking on National Blood Donor Pool: Anti-HBc positivity related re-entry mechanisms.

BACKGROUND AND OBJECTIVES: Screening of blood donations for antibodies against hepatitis B core antigen (anti-HBc) is used to prevent transfusion transmitted hepatitis B virus (HBV) infection. In this study, we studied the magnitude of blood donor gain by using a re-entry mechanism in our Blood Bank of Gulhane Military Academy of Medicine. MATERIALS AND METHODS: Between January and May 2013, 5148 voluntary blood donors were screened by ELISA method for HBsAg, anti-HBc total and other screening markers, prospectively. Samples with repeated reactivity for the presence of anti-HBc were further tested with four supplemental assays. RESULTS: We detected 515 (10%) anti-HBc positive and 4612 (90%) anti-HBc negative cases in 5127 HBsAg negative serum samples. A total of 461 (89.5%) blood units were reactive for at least one additional serologic parameter and 54 were (10.5%) negative. Isolated anti-HBc positivity rate was 1.3% (69/5127). In the isolated anti-HBc positive samples, 54 were also anti-HBe and HBeAg negative. HBV DNA was not detected in any of the samples. CONCLUSION: Applying the EDQM criteria would decrease our blood donor loss from 10% to 5.4%. As alternative re-entry mechanisms have already been presented in the literature, institution of a new policy is needed to enhance the limited blood donor pool in our system.

Freezing of Apheresis Platelet Concentrates in 6% Dimethyl Sulfoxide: The First Preliminary Study in Turkey.

OBJECTIVE: Transfusion of platelet suspensions is an essential part of patient care for certain clinical indications. In this pioneering study in Turkey, we aimed to assess the in vitro hemostatic functions of platelets after cryopreservation. MATERIALS AND METHODS: Seven units of platelet concentrates were obtained by apheresis. Each apheresis platelet concentrate (APC) was divided into 2 equal volumes and frozen with 6% dimethyl sulfoxide (DMSO). The 14 frozen units of APCs were kept at -80 °C for 1 day. APCs were thawed at 37 °C and diluted either with autologous plasma or 0.9% NaCl. The volume and residual numbers of leukocytes and platelets were tested in both before-freezing and post-thawing periods. Aggregation and thrombin generation tests were used to analyze the in vitro hemostatic functions of platelets. Flow-cytometric analysis was used to assess the presence of frozen treated platelets and their viability. RESULTS: The residual number of leukocytes in both dilution groups was <1x106. The mean platelet recovery rate in the plasma-diluted group (88.1±9.5%) was higher than that in the 0.9% NaCl-diluted group (63±10%). These results were compatible with the European Directorate for the Quality of Medicines quality criteria. Expectedly, there was no aggregation response to platelet aggregation test. The mean thrombin generation potential of post-thaw APCs was higher in the plasma-diluted group (2411 nmol/L per minute) when compared to both the 0.9% NaCl-diluted group (1913 nmol/L per minute) and the before-freezing period (1681 nmol/L per minute). The flow-cytometric analysis results for the viability of APCs after cryopreservation were 94.9% and 96.6% in the plasma and 0.9% NaCl groups, respectively. CONCLUSION: Cryopreservation of platelets with 6% DMSO and storage at -80 °C increases their shelf life from 7 days to 2 years. Besides the increase in hemostatic functions of platelets, the cryopreservation process also does not affect their viability rates.

In vitro efficacy of frozen erythrocytes: implementation of new strategic blood stores to alleviate resource shortage (issue revisited).

BACKGROUND/AIM: Currently, the provision of blood products largely depends on walking blood banks and limited amounts of stored blood with short shelf lives. We aimed to compare the efficacy of erythrocyte concentrate (ECs) by pre- and postfreezing in vitro tests. MATERIALS AND METHODS: In our study, 10 ECs were glycerolized, frozen, thawed, and then deglycerolized using the Naval Blood Research Laboratory method. In addition to using the standard tests, ATP and 2,3-DPG levels and the viability of erythrocytes were also determined. RESULTS: The prefreezing mean viability rates of erythrocytes changed from 89.7 ± 13.7% to 98.6 ± 1.8% after thawing and deglycerolization. Prefreezing and day 0 ATP levels (1.64 ± 0.15 µmol/g Hb and 1.81 ± 0.14 µmol/g Hb, respectively) were similar. The 2,3-DPG levels decreased from 18.09 ± 4.78 µmol/g Hb measured before the procedure to 10.41 ± 4.58 µmol/g Hb on day 0. The mean hemolysis rates and supernatant Hb levels changed from 0.21 ± 0.11% to 0.36 ± 0.12% and 1 ± 0.5 g/L to 1.5 ± 0.5 g/L, respectively. CONCLUSION: The test results showed the efficacy of the frozen-thawed ECs to be used in humans for a broad spectrum of clinical indications. As a part of a contingency plan, national frozen blood reserves need to be established.

Seroprevalence and genotyping of hepatitis B, hepatitis C and HIV among healthy population and Turkish soldiers in Northern Cyprus.

AIM: To compare the prevalence of hepatitis viral markers among soldiers from Turkey, blood donors from Northern Cyprus, and soldiers from Northern Cyprus. METHODS: Hepatitis B surface antigen (HBsAg), anti-HCV and anti-human immunodeficiency virus (HIV) seroprevalence, HBV DNA, HCV RNA and HCV genotyping among soldiers from Turkey (group I), civil blood donors from Northern Cyprus (group II), and soldier candidates from Northern Cyprus (group III) were studied and compared to one another. In total, 17545 cases (13546 males and 3999 females with a mean age of 34.5 +/- 10.3 year, group I = 11234, group II = 5057, and group III = 1254) were included into the study. RESULTS: Among all cases, HBsAg positivity rates were 2.46%, anti-HCV was 0.46% and anti-HIV was 0.00%. HBV DNA was 2.25%, HCV RNA was 0.33% in all groups. HBsAg positivity rates were 2.16% in group I, 3.00% in group II and 2.71% in group III. There was a significant difference between group I and group II (c2 = 6.11, P = 0.047 < 0.05). Anti-HCV positivity rates were 0.45% in group I, 0.45% in group II, and 0.56% in group III. Genotypes of HCV were 1b and 1a in group I, 1b, 1a and 2 in group II, and 1b, 1a in group III. HBsAg carrier rates were 2.20% in females and 2.53% in males. Anti-HCV prevalence was 0.38% in females and 0.48% in males. HBsAg positivity rates were 2.53% in individuals younger than 50, and 1.47% in older than 50. There was a significant difference between the two groups (c2 = 23.48, P = 0.001). CONCLUSION: Prevalences of HBsAg, HCV and HIV infections in Northern Cyprus population are similar to those of Turkey.