Quality control of apheresis platelets: a multicentre study to evaluate factors that can influence pH measurement

Transforming research to improve therapies for trauma in the twenty-first century

Improvements have been made in optimizing initial care of trauma patients, both in prehospital systems as well as in the emergency department, and these have also favorably affected longer term outcomes. However, as specific treatments for bleeding are largely lacking, many patients continue to die from hemorrhage. Also, major knowledge gaps remain on the impact of tissue injury on the host immune and coagulation response, which hampers the development of interventions to treat or prevent organ failure, thrombosis, infections or other complications of trauma. Thereby, trauma remains a challenge for intensivists. This review describes the most pressing research questions in trauma, as well as new approaches to trauma research, with the aim to bring improved therapies to the bedside within the twenty-first century.

Association of blood donor characteristics with in vitro platelet storage properties

BACKGROUND AND OBJECTIVE

The study was planned to determine the association of blood donor characteristics with in vitro quality of platelets.

MATERIAL AND METHODS

In the prospective observational study, a total of 85 male whole blood donors in the age group of 18-30 and 45-65 years were enrolled using purposive sampling method. Serum total cholesterol, glycosylated hemoglobin (HbA1c), and LDH levels were performed on donor pre-donation sample. Buffy coat platelet concentrates were prepared from 450 mL quadruple blood bags. Samples from platelets were taken on day one and five of storage and biochemical properties were observed.

RESULTS

Median MPV was higher in platelets from older blood donors on day five (9.8 vs 9.4, p = 0.037). Median LDH levels were also higher in platelets on day one and five from older donors (Day one: 204.5 vs 147, p = <0.000; day five: 278 vs 224, p = 0.001 respectively). Platelets from donors with high HbA1c levels had lower median pH (Day one: 7.31 vs 7.37, p = 0.024) and higher median glucose levels on day one of storage (Day one: 358 vs 311, p = 0.001). Higher median lactate levels throughout the storage period were also seen in platelets from donors with higher HbA1c levels (Day one: 7 vs 5.7, p = 0.037; Day five: 16 vs 12.2, p = 0.032). Glucose consumption (108 vs 66, p = 0.025) and lactate production (9 vs 6.4, p = 0.019) was higher in platelets from donors with higher HbA1c levels.

CONCLUSION

In vitro platelet storage properties are affected by blood donor characteristics.

The impact of donor biological variation on the quality and function of cold-stored platelets

BACKGROUND AND OBJECTIVES

Room temperature-stored platelets (RTPs) maximize platelet viability but limit shelf life. The aims of this study were to investigate the impact of donor variability on cold-stored platelets (CSPs) and RTP, to determine whether RTP quality markers are appropriate for CSP.

MATERIALS AND METHODS

Double platelet donations (n = 10) were collected from consented regular male donors stored in 100% plasma. A full blood count, donor age, weight, height and body mass index (BMI) were collected at the time of donation. Platelet donations were split equally into two bags, and assigned to non-agitated CSP or agitated RTP. The quality and function of platelets were assessed throughout the standard 7 days of storage and at expiry (day 8). Non-parametric statistical analyses were used to analyse results given the small sample size.

RESULTS

As expected, there were significant differences between CSP and RTP throughout storage including a reduction in CSP concentration as well as a loss of swirling. Furthermore, a significant increase in CSP exhibiting activation and apoptotic markers was observed. Platelet concentrations were further impacted by donor BMI, and donors with the highest BMI (>29) had the lowest platelet concentration and activation response at the end of CSP storage.

CONCLUSION

Platelet quality and functionality play a vital role in transfusion outcomes; however, blood components are inherently variable. This study demonstrated, for the first time, the specific impact of donor BMI on CSP quality and function and highlights the requirement for novel quality markers for assessing CSPs.

Donor variation in stored platelets: Higher metabolic rates of platelets are associated with mean platelet volume, activation and donor health

BACKGROUND

Platelets (PLTs) differ in glycolytic activity, resulting in rapid acidification of 'poor' storing PLT concentrates (PCs) in plasma, or depletion of glucose when stored in PLT additive solution (PAS). We aimed to understand why PLT glycolysis rates vary between donors and how this affects storage performance.

STUDY DESIGN AND METHODS

Buffy coats from donors <45, 45-70 and >70 years were selected and single-donor PCs in plasma or PAS-E were prepared. PCs were stored for 8 days at 22 ± 2°C and sampled regularly for analysis. Mitochondrial activity was analyzed with an Oroboros oxygraph. Age groups, or subgroups divided into quartiles based on glucose consumption, were analyzed with ANOVA.

RESULTS

In each comparison, PCs of the different groups were not different in volume and cellular composition. PLTs with the highest glucose consumption had a higher initial mean platelet volume (MPV) and developed higher CD62P expression and Annexin A5 binding during storage. Higher glycolytic activity in these PLTs was not a compensation for lower mitochondrial ATP production, because mitochondrial ATP-linked respiration of fresh PLTs correlated positively with MPV (R²  = 0.71). Donors of high glucose-consuming PLTs had more health-related issues. Storage properties of PCs from donors over 70 were not significantly different compared to PCs from donors younger than 45 years.

CONCLUSIONS

High glucose-consuming PCs developing higher activation levels, not only displayed enhanced mitochondrial activity but were also found to contain larger PLTs, as determined by MPV. Storage performance of PLTs was found to be associated with donor health, but not with donor age.

Current challenges in platelet transfusion

The supply of platelets for transfusion is a logistical challenge due to the physiology of platelets and current measures of transfusion performance dictating storage at 22°C and a short product shelf-life (<7 days). Demand for platelets has increased in recent years and changes in the demographics of the population may enhance this further. Many studies have been conducted to understand what the optimal dose and trigger for transfusion should be, mainly in hematology patients who are the largest cohort that receive platelets, mostly to prevent bleeding. Emerging data suggests that for bleeding patients, where immediate hemostasis is a key consideration, the current standard product may not be optimal. Alternative platelet preparation methods/storage options that may improve the hemostatic properties of platelets are under active development. In parallel with research into alternative platelet products that might enhance hemostasis, better measures for assessing bleeding risk and platelet efficacy are needed.

Refrigeration of apheresis platelets in platelet additive solution (PAS-E) supports in vitro platelet quality to maximize the shelf-life

BACKGROUND

Refrigeration, or cold-storage, of platelets may be beneficial to extend the limited shelf-life of conventionally stored platelets and support transfusion protocols in rural and military areas. The aim of this study was to compare the morphologic, metabolic, and functional aspects of apheresis platelets stored at room-temperature (RT) or cold conditions, in either plasma or supplemented with platelet additive solution (PAS).

STUDY DESIGN AND METHODS

Double-dose apheresis platelets were collected in either 100% plasma or 40% plasma/60% PAS-E using the Trima apheresis platform. One component from each group was either stored at RT (20-24°C) or refrigerated (2-6°C). Platelets were tested over a 21-day period.

RESULTS

The platelet concentration decreased by approximately 30% in all groups during 21 days of storage (p > .05). Cold-storage reduced glycolytic metabolism, and the pH was maintained above the minimum specification (>6.4) for 21 days only when platelets were stored in PAS. The surface phenotype and the composition of the supernatant were differentially affected by temperature and storage solution. Functional responses (aggregation, agonist-induced receptor activation, clotting time) were improved during cold-storage, and the influence of residual plasma was assay dependent.

CONCLUSION

In vitro platelet quality is differentially affected by storage time, temperature, and solution. Cold-storage, particularly in PAS, better maintains key metabolic, phenotypic, and functional parameters during prolonged storage.

Current Understanding of the Relationship between Blood Donor Variability and Blood Component Quality

While differences among donors has long challenged meeting quality standards for the production of blood components for transfusion, only recently has the molecular basis for many of these differences become understood. This review article will examine our current understanding of the molecular differences that impact the quality of red blood cells (RBC), platelets, and plasma components. Factors affecting RBC quality include cytoskeletal elements and membrane proteins associated with the oxidative response as well as known enzyme polymorphisms and hemoglobin variants. Donor age and health status may also be important. Platelet quality is impacted by variables that are less well understood, but that include platelet storage sensitive metabolic parameters, responsiveness to agonists accumulating in storage containers and factors affecting the maintenance of pH. An increased understanding of these variables can be used to improve the quality of blood components for transfusion by using donor management algorithms based on a donors individual molecular and genetic profile.