Improved extension of platelet storage in a polyolefin container with higher oxygen permeability

Shelf-life, bioburden, water and oxygen permeability studies of laser welded SEBS/PP blended polymer

The most common material used for blood bags is PVC, which requires the addition of DEHP to increase its flexibility. DEHP is known to cross the polymer barrier and move into the stored blood and, ultimately, the patient's bloodstream. In this work, an alternative prototype composed of SEBS/PP was fabricated through blow-moulding and compared with the commercially available PVC-based blood bag which was designated as the control. The blow-moulded sample layers were welded together using CO2 lasers and optimized to obtain complete sealing of the sides. The samples' performance characteristics were analyzed using water permeability, oxygen permeability, shelf-life, and bioburden tests. The SEBS/PP sample exhibited the highest oxygen permeability rate of 1486.6 cc/m2/24 h after 40 days of ageing, indicating that the sample is conducive for red blood cell (RBC) respiration. On the other hand, the SEBS/PP sample showcased a lower water permeability rate of 0.098 g/h m2 after 40 days of aging, indicating a high-water barrier property and thus preventing water loss during storage. In comparison, the oxygen and water permeability rates of PVC-DEHP were found to be distinctly lower in performance (662.7 cc/m2/24 h and 0.221 g/h m2, respectively). In addition, shelf-life analyses revealed that after 40 days of ageing, polymer samples exhibited no visual damage or degradation. The optimal parameters to obtain adequate welding of the SEBS/PP were determined to be power of 60% (18 W), speed of 70 in/sec and 500 Pulse Per Inch (PPI). Furthermore, the bioburden estimates of SEBS/PP of 115 CFU are markedly lower compared to the bioburden estimate of PVC-DEHP of 213 CFU. The SEBS/PP prototype can potentially be an effective alternative to PVC-based blood bags, particularly for high-risk patients in order to reduce the likelihood of medical issues.

Modulation of Platelet-Surface Activation: Current State and Future Perspectives

Modulation of platelet-surface activation is important for many biomedical applications such as in vivo performance, platelet storage, and acceptance of an implant. Reducing platelet-surface activation is challenging because they become activated immediately after short contact with nonphysiological surfaces. To date, controversies and open questions in the field of platelet-surface activation still remain. Here, we review state-of-the-art approaches in inhibiting platelet-surface activation, mainly focusing on modification, patterning, and methodologies for characterization of the surfaces. As a future perspective, we discuss how the combination of biochemical and physiochemical strategies together with the topographical modulations would assist in the search for an ideal nonthrombogenic surface.

Influence of Oxidative Stress on Stored Platelets

Platelet storage and its availability for transfusion are limited to 5-6 days. Oxidative stress (OS) is one of the causes for reduced efficacy and shelf-life of platelets. The studies on platelet storage have focused on improving the storage conditions by altering platelet storage solutions, temperature, and materials. Nevertheless, the role of OS on platelet survival during storage is still unclear. Hence, this study was conducted to investigate the influence of storage on platelets. Platelets were stored for 12 days at 22°C. OS markers such as aggregation, superoxides, reactive oxygen species, glucose, pH, lipid peroxidation, protein oxidation, and antioxidant enzymes were assessed. OS increased during storage as indicated by increments in aggregation, superoxides, pH, conjugate dienes, and superoxide dismutase and decrements in glucose and catalase. Thus, platelets could endure OS till 6 days during storage, due to the antioxidant defense system. An evident increase in OS was observed from day 8 of storage, which can diminish the platelet efficacy. The present study provides an insight into the gradual changes occurring during platelet storage. This lays the foundation towards new possibilities of employing various antioxidants as additives in storage solutions.

In vitro evaluation of platelet concentrates suspended in additive solution and treated for pathogen reduction: effects of clumping formation

BACKGROUND

Platelet concentrates may demonstrate visual, macroscopic clumps immediately after collection following aphaeresis or production from whole blood, independently of the preparation method or equipment used. The relationship between the occurrence of clumping and their effect on in vitro quality of platelets was investigated.

MATERIAL AND METHODS

Platelet concentrates, suspended in SSP+ additive solution (Macopharma), were obtained by automated processing and also from routine processing. A total of twelve units were allocated to the test group (n=12) due to the presence of clumps. Platelet concentrates without clumps were used as controls (n=10). All platelet units were treated for pathogen reduction following storage under continuous agitation for in vitro testing over a 9-day storage period.

RESULTS

No significant differences were found throughout storage between the groups. The lactate dehydrogenase levels increased in both groups; this increase was higher in the test group on the last day of testing, without there being a significant difference on day 2. In contrast, pH values on day 2 were significantly different between the test and control groups. Platelet-derived cytokines increased comparably during storage.

DISCUSSION

The results confirm good in vitro quality and storage stability of platelets suspended in SSP+ and treated with the Intercept pathogen reduction system. The presence of "non-compacted" clumps in platelet concentrates does not appear to affect the in vitro quality of the platelets.

Platelet preservation: agitation and containers

For platelets to maintain their in vitro quality and in vivo effectiveness, they need to be stored at room temperature with gentle agitation in gas-permeable containers. The mode of agitation affects the quality of the platelets, and a gentle method of agitation, either a circular or a flat bed movement, provides the best results. Tumblers or elliptical agitators induce platelet activation and subsequent damage. As long as the platelets remain in suspension, the agitation speed is not important. Agitation of the platelet concentrates ensures that the platelets are continuously oxygenated, that sufficient oxygen can enter the storage container and that excess carbon dioxide can be expelled. During transportation of platelet concentrates, nowadays over long distances where they are held without controlled agitation, platelets may tolerate a certain period without agitation. However, evidence is accumulating that during the time without agitation, local hypoxia surrounding the platelets may induce irreversible harm to the platelets. Over the decades, more gas-permeable plastics have been used to manufacture platelet containers. The use of different plastics and their influence on the platelet quality both in vitro and in vivo is discussed. The improved gas-permeability has allowed the extension of platelet storage from 3 days in the early 1980s, to currently at least 7 days. In the light of new developments, particularly the introduction of pathogen reduction techniques, the use of platelet additive solutions and the availability of improved automated separators, further (renewed) research in this area is warranted.

Overview on platelet preservation: better controls over storage lesion

Platelet storage lesion (PSL), correlating with reduced in vivo recovery/survival and hemostatic capacity after transfusion, is characterized essentially by morphological and molecular evidence of platelet activation and energy consumption in the medium. Processes that limit shelf-life are multifactorial, and include both necrosis and apoptosis. PSL is greatly influenced by factors including duration of storage, temperature, ratio of platelet number to media volume, solution composition with respect to energy content and buffering capacity, and gas permeability of the container. Recent progress for slowing PSL has been made with storage media that more effectively fuel ATP production and buffer the inevitable effects of metabolism. Improved oxygen-permeability of containers also helps to maintain aerobic-dominant glycolysis. Patients stand to benefit from platelet products of higher intrinsic quality that store well until the moment of transfusion.

Preservation of Platelets by Adding Epigallocatechin-3-O-Gallate to Platelet Concentrates

The effect of epigallocatechin-3- O-gallate (EGCG), a major component of green tea, on platelet preservation was evaluated. Single donor platelets ( N = 10) were collected and preserved by the standard method. EGCG was added to the platelet concentrates before preservation and then the functional and biochemical parameters were monitored throughout the storage period. After 6 days of preservation, the aggregability of the platelets was significantly maintained by addition of 50 and 100 μg/ml of EGCG. Platelet prothrombinase activity was also significantly retained by the addition of EGCG. The accumulation of P-selectin and RANTES in the plasma preserved with EGCG was less than those preserved without EGCG, which indicated that EGCG might inhibit platelet activation. Furthermore, EGCG reduced the increase of LDH in plasma during preservation and inhibited the activation of caspase-3 and cleavage of gelsolin, thereby showing that EGCG could inhibit the apoptosis of platelets. These results suggest that EGCG may play an effective role in preserving platelets by inhibiting the activation and apoptosis of platelets.

Survival and recovery of apheresis platelets stored in a polyolefin container with high oxygen permeability

BACKGROUND AND OBJECTIVES

Oxygen permeability is important in platelet storage media. We compared a new polyolefin container with enhanced oxygen permeability (PO-80; Kawasumi, Tokyo, Japan) to a widely used alternative (PL2410; Baxter Healthcare, Deerfield, IL, USA).

MATERIALS AND METHODS

In vitro characteristics of paired platelet concentrates (PCs; mean 4.2 x 10(11)/250 ml plasma/bag) stored in PO-80 or PL2410 were assessed through 9 days of storage. In vivo recovery and survival of 7-day-old autologous PCs were assessed according to the Murphy method.

RESULTS

Laboratory assessment of platelet quality favoured PO-80 during 9 days of storage with statistically significant differences in glucose consumption (2.75 vs. 4.93 mmol/10(12)/24 h in the interval 120-168 h), lactate generation (4.37 vs. 8.11 mmol/10(12)/24 h in the interval 120-168 h), pressure of oxygen (pO(2)) (59.3 vs. 38.1 mmHg at day 1), and HCO(3)(-) (14.7 vs. 13.4 mmol/l at day 1). Statistically significant differences were not seen in aggregation, hypotonic shock response or pH. In vivo assessment of autologous platelets stored 7 days in the PO-80 container revealed that recovery was 82.1% and survival was 81.0% of fresh control. Seven-day stored PCs in PO-80 were shown in vivo to be non-inferior to fresh platelets, with upper confidence limits (UCL(95)) in recovery and survival of stored PCs below the maximum acceptable difference (MAD); 15.3% UCL(95) < 20.4% MAD and 2.1 days UCL(95) < 2.1 days MAD.

CONCLUSIONS

The in vitro characteristics of PCs stored in a highly oxygen-permeable container were stable at least 7 days. The in vivo study supports the suitability of PO-80 for 7-day platelet storage.

Clinical effect of buffy-coat vs. apheresis platelet concentrates in patients with severe thrombocytopenia after intensive chemotherapy

BACKGROUND AND OBJECTIVES

Therapeutic or prophylactic use of platelet concentrates (PC) is essential for patients with thrombocytopenia due to intensive chemotherapy for various malignancies. PC quality has been improved after introduction of storage containers that are more oxygen permeable than the second-generation PC containers. Consequently, shelf life of PCs at our blood bank has been extended to 6.5 days after monitoring each PC for bacterial contamination. In this prospective observational study, we compared apheresis PCs harvested by Amicus cell separator with buffy-coat (BC) PCs during storage for up to 6.5 days.

MATERIALS AND METHODS

All PCs were collected from healthy volunteer donors and were prepared for routine clinical use. A total of 446 transfusion episodes with 688 PCs for 77 adult patients with oncological and haematological diseases were registered during a 13-month period. Outcome measures were corrected count increment after 1 h (CCI-1), after 18-24 h (CCI-2), and transfusion intervals. Transfusions were carried out after storage from 1.5 to 6.5 days.

RESULTS

Both CCI and the transfusion intervals decreased statistically significantly by increasing storage time after transfusions with apheresis PCs or BC PCs. However, less than 4% of the variation in CCI and transfusion interval could be explained by platelet storage time. There were no significant differences between BC PCs and apheresis PCs, regarding CCI and transfusion intervals.

CONCLUSION

We can conclude that BC PCs are not inferior to apheresis PCs, and may serve the clinical purposes as well as apheresis PCs harvested by Amicus.

Metabolic energy reduction by glucose deprivation and low gas exchange preserves platelet function after 48 h storage at 4 °C

INTRODUCTION

We showed earlier that metabolically suppressed platelets (MSP) prepared by incubation in glucose-free, antimycin A medium at 37 degrees C better sustained storage at 4 degrees C than untreated controls at 22 degrees C. However, the use of the mitochondrial inhibitor antimycin A is incompatible with platelet transfusion.

OBJECTIVES

The aim of this study was to investigate how energy-reduced (ER) platelets could be prepared in the absence of antimycin A.

STUDY DESIGN AND METHODS

Platelets in gas-impermeable bags in glucose-free medium were kept at 22 degrees C for 4 h to reduce energy stores and thereafter stored at 4 degrees C (ER22-4). Controls were energy-reduced platelets without prior incubation at 22 degrees C (ER4), and MSPs in test tubes and untreated platelets in gas-permeable bags with glucose and stored at 22 degrees C (C22) and 4 degrees C (C4).

RESULTS

After 48 h storage, ER22-4 were superior to C22 with respect to pH preservation (6 x 4 +/- 0 x 4 vs. 5 x 0 +/- 0 x 4, n= 4), platelet count (800 +/- 225 vs. 650 +/- 150 x 10(9)), thrombin receptor-activating peptide-induced aggregation (50 +/- 15 vs. 10 +/- 5%) and glycoprotein (GP)Ib alpha expression (60 +/- 15% vs. 28 +/- 15). GPIb alpha expression was higher in ER22-4 than in ER4, indicating that energy suppression preserved GPIb alpha during cold storage.

CONCLUSION

Metabolic suppression without the use of antimycin A could be mimicked by storage of platelets in glucose-free medium in gas-impermeable bags. Energy suppression preserved GPIb alpha expression during storage at 4 degrees C.

Platelet glycolytic flux increases stimulated by ultraviolet-induced stress is not the direct cause of platelet morphology and activation changes: possible implications for the role of glucose in platelet storage

BACKGROUND

Stress-enhanced platelet (PLT) storage lesions include increased glycolysis, discoid-to-sphere morphology change, and spontaneous PLT activation. It is not clear if reduction in glycolysis can alleviate storage lesion development.

STUDY DESIGN AND METHODS

Apheresis PLT concentrates were exposed to 17.2 J/mL UV light and 50 microM riboflavin, followed by storage with various concentrations of 2-deoxyglucose (2-DOG) for 5 days. The control had no UV or 2-DOG exposure.

RESULTS

Lactate production and glucose consumption were increased significantly to 0.1371 +/- 0.0281 and 0.0724 +/- 0.0151 mmol per 10(12) cells per hour for UV-treated PLTs, respectively, when compared to control samples. UV treatment induced a decline in pH to 6.55 +/- 0.26 for treated PLTs on Day 5, hypotonic shock response (HSR) 33 +/- 25 percent, extent of shape change (ESC) to 3.8 +/- 3.6 percent, swirl 1.0 +/- 1.0 and increased P-selectin expression 85.2 +/- 9.4 percent. Addition of 2-DOG up to 20 mmol per L significantly reduced lactate production to 0.0515 +/- 0.0045 mmol per 10(12) cells per hour (p < 0.05) and glucose consumption to 0.0293 +/- 0.0060 mmol per 10(12) cells per hour and increased pH to 7.35 +/- 0.09 in a dose-dependent manner. 2-DOG, however, had no effects on HSR, ESC, swirl, and P-selectin expression. Furthermore, an exaggeration of UV-stressed PLT aggregation by addition of 2-DOG was also observed.

CONCLUSIONS

Increased glycolytic flux is not a direct cause for PLT morphology change and spontaneous activation during storage lesion development. Reduction of glucose utilization may increase PLT loss during storage.