The effect of gamma irradiation on platelet redox state during storage

Results of clinical effectiveness of conventional versus Mirasol-treated Apheresis Platelets in Patients with Hypoproliferative Thrombocytopenia (MiPLATE) trial

BACKGROUND

The Mirasol® Pathogen Reduction Technology System was developed to reduce transfusion-transmitted diseases in platelet (PLT) products.

STUDY DESIGN AND METHODS

MiPLATE trial was a prospective, multicenter, controlled, randomized, non-inferiority (NI) study of the clinical effectiveness of conventional versus Mirasol-treated Apheresis PLTs in participants with hypoproliferative thrombocytopenia. The novel primary endpoint was days of ≥Grade 2 bleeding with an NI margin of 1.6.

RESULTS

After 330 participants were randomized, a planned interim analysis of 297 participants (145 MIRASOL, 152 CONTROL) receiving ≥1 study transfusion found a 2.79-relative rate (RR) in the MIRASOL compared to the CONTROL in number of days with ≥Grade 2 bleeding (95% confidence interval [CI] 1.67-4.67). The proportion of subjects with ≥Grade 2 bleeding was 40.0% (n = 58) in MIRASOL and 30.3% (n = 46) in CONTROL (RR = 1.32, 95% CI 0.97-1.81, p = .08). Corrected count increments were lower (p < .01) and the number of PLT transfusion episodes per participant was higher (RR = 1.22, 95% CI 1.05-1.41) in MIRASOL. There was no difference in the days of PLT support (hazard ratio = 0.86, 95% CI 0.68-1.08) or total number of red blood cell transfusions (RR = 1.12, 95% CI 0.91-1.37) between MIRASOL versus CONTROL. Transfusion emergent adverse events were reported in 119 MIRASOL participants (84.4%) compared to 133 (82.6%) participants in CONTROL (p = NS).

DISCUSSION

This study did not support that MIRASOL was non-inferior compared to conventional platelets using the novel endpoint number of days with ≥Grade 2 bleeding in MIRASOL when compared to CONTROL.

X-rays Stimulate Granular Secretions and Activate Protein Kinase C Signaling in Human Platelets

X-rays can induce morphological as well as functional changes in cells. Platelets are anuclear cellular fragments originating from megakaryocytes and are the major regulators in hemostasis and thrombosis. Platelet products are irradiated to avoid medical complications associated with platelet transfusion. So far, gamma, UV, and laser radiation have been used for this purpose. However, scientists are divided about the effects of radiation on platelet quality. The present study was designed to explore the possible effects of X-rays in washed human platelets and understand the molecular mechanism behind them. In the present study, we exposed washed human platelets to 10 or 30 Gy X-rays at 0.25 Gy/min. Flow cytometry, aggregometry, and western blot were performed to investigate the effect of X-rays on platelet degranulation, integrin activation, platelet aggregation, and apoptosis. It was found that X-rays immediately induced granular secretions with no effect on GP IIb/IIIa activation. Not surprisingly, due to granule secretions in irradiated platelets, platelet aggregation was significantly reduced. In contrast to granular secretions and platelet aggregation, X-rays induced mitochondrial transmembrane potential depolarization in a time-dependent manner to induce apoptosis and activated protein kinase C (PKC) signaling. This study revealed and explained the molecular mechanism activated by X-rays in washed human platelets. Here we also introduced Gö 6983, a PKC inhibitor, as an agent that counteracts X-ray-induced changes and maintains the integrity of platelets.

Unveiling the mechanism of platelet dysfunction in Parkinson's disease: The effect of 6-hydroxydopamine on human blood platelets

INTRODUCTION

Parkinson's disease (PD) is a progressive neuronal illness often linked to increased cardiovascular complications, such as myocardial infarction, cardiomyopathy, congestive heart failure, and coronary heart disease. Platelets, which are the essential components of circulating blood, are considered potential players in regulating these complications, as platelet dysfunction is evident in PD. These tiny blood cell fragments are supposed to play a crucial role in these complications, but the underlying molecular processes are still obscure.

METHODS

To gain a better understanding of platelet dysfunction in PD, we investigated the impact of 6-hydroxydopamine (6-OHDA), an analog of dopamine that simulates PD by destroying dopaminergic neurons, on human blood platelets. The levels of intraplatelet reactive oxygen species (ROS) were assessed using H₂DCF-DA (20 μM), while mitochondrial ROS was evaluated using MitoSOX™ Red (5 μM), and intracellular Ca²⁺ was measured with Fluo-4-AM (5 μM). The data were acquired through the use of both a multimode plate reader and a laser-scanning confocal microscope.

RESULTS

Our findings showed that 6-OHDA treatment increased the production of ROS in human blood platelets. The increase in ROS was confirmed by the ROS scavenger, NAC, and was also reduced by inhibiting the NOX enzyme with apocynin. Additionally, 6-OHDA potentiated mitochondrial ROS production in platelets. Furthermore, 6-OHDA triggered the intraplatelet Ca²⁺ elevation. This effect was mitigated by the Ca²⁺ chelator BAPTA, which decreased the ROS production triggered by 6-OHDA in human blood platelets, while the IP₃ receptor blocker, 2-APB, reduced the formation of ROS induced by 6-OHDA.

CONCLUSION

Our findings suggest that the 6-OHDA-induced ROS production is regulated by the IP₃ receptor-Ca²⁺-NOX signaling axis in human blood platelets, where the platelet mitochondria also play a significant role. This observation provides a crucial mechanistic understanding of the altered platelet activities that are commonly observed in PD patients.

Gamma irradiation induces a pro-apoptotic state in longer stored platelets, without progressing to an overt apoptosis by day 7 of storage

BACKGROUND

Although gamma-irradiation to platelet products is a standard method to prevent the risk of TA-GVHD in vulnerable recipients, it induces some proteomic and redox changes, of which irradiation-induced ROS increments may potentiate platelet mitochondrial dysfunction. However, whether these changes cause platelet apoptosis, or affect their viability during storage, is the main subject of this study.

METHODS

PLT-rich plasma PC was split into two bags, one kept as control while other was subjected to gamma-irradiation. Within 7-days storage, cytosolic and mitochondrial levels of cytochrome c and pro-apoptotic molecules of Bak and Bax were evaluated by western-blotting. Intraplatelet active caspase (using FAM-DEVD-FMK) and PS-exposure were detected by flowcytometry. Caspase activity in platelet lysate was also confirmed by immunofluorescence detection of Caspase-3/7 Substrate N-Ac-DEVD-N'-MC-R110 while platelet viability was evaluated with MTT assays.

RESULTS

Cytosolic cytochrome c gradually increased while its mitochondrial content steadily declined during 7 days of storage. In a contrary trend, reverse patterns were observed for Bak and Bax expressions. Gamma-irradiated platelets showed higher release of mitochondrial cytochrome c that reflected by higher cytosolic cytochrome c levels on day 7 of storage. Concurrently mitochondrial pro-apoptotic Bak and Bax proteins increased on day 7 in irradiated products. However, gamma-irradiation didn't significantly increase caspase activity or PS-exposure, nor did it decrease platelet viability.

CONCLUSION

Here, consistent with studies on "gamma-irradiation-induced oxidative stress", we showed that gamma-ray also increases platelet pro-apoptotic signals during storage, although not strongly enough to affect platelet viability by overt apoptosis induction. Conclusively, whether supplementing ROS scavengers or antioxidants to irradiated platelets can improve their quality during storage may be of interest for future research.

Platelets Facilitate Wound Healing by Mitochondrial Transfer and Reducing Oxidative Stress in Endothelial Cells

As a critical member in wound healing, vascular endothelial cells (ECs) impaired under high levels of reactive oxygen species (ROS) would hamper neovascularization. Mitochondria transfer can reduce intracellular ROS damage under pathological condition. Meanwhile, platelets can release mitochondria and alleviate oxidative stress. However, the mechanism by which platelets promote cell survival and reduce oxidative stress damage has not been clarified. Here, first, we selected ultrasound as the best method for subsequent experiments by detecting the growth factors and mitochondria released from manipulation platelet concentrates (PCs), as well as the effect of manipulation PCs on the proliferation and migration of HUVECs. Then, we found that sonicate platelet concentrates (SPC) decreased the level of ROS in HUVECs treated with hydrogen peroxide in advance, increased mitochondrial membrane potential, and reduced apoptosis. By transmission electron microscope, we saw that two kinds of mitochondria, free or wrapped in vesicles, were released by activated platelets. In addition, we explored that platelet-derived mitochondria were transferred to HUVECs partly by means of dynamin-dependent clathrin-mediated endocytosis. Consistently, we determined that platelet-derived mitochondria reduced apoptosis of HUVECs caused by oxidative stress. What is more, we screened survivin as the target of platelet-derived mitochondria via high-throughput sequencing. Finally, we demonstrated that platelet-derived mitochondria promoted wound healing in vivo. Overall, these findings revealed that platelets are important donors of mitochondria, and platelet-derived mitochondria can promote wound healing by reducing apoptosis caused by oxidative stress in vascular endothelial cells. And survivin is a potential target. These results further expand the knowledge of the platelet function and provide new insights into the role of platelet-derived mitochondria in wound healing.

Gamma and X-ray irradiation do not affect the in vitro quality of refrigerated apheresis platelets in platelet additive solution (PAS-E)

BACKGROUND

Platelet refrigeration (cold storage) provides the advantages of an extended shelf life and reduces the risk of bacterial growth, compared to platelets stored at room temperature (RT). However, processing modifications, such as irradiation, may further improve the safety and/or alter the quality of cold-stored platelets. Platelet components are irradiated to prevent transfusion-associated graft versus host disease (TA-GvHD) in high-risk patients; and while irradiation has little effect on the quality of RT-stored platelet components, there is no data assessing the effect irradiation has following cold storage.

STUDY DESIGN AND METHODS

Triple-dose apheresis platelets were collected in 40% plasma/60% PAS-E, using the TRIMA apheresis platform, and refrigerated (2-6°C) within 8 h of collection. On day 2, one of each component was gamma or X-ray irradiated or remained non-irradiated. Platelets were tested over 21 days.

RESULTS

The platelet concentration decreased by approximately 20% in all groups during 21 days of storage (p > .05). Irradiation (gamma or X-ray) did not affect platelet metabolism, and the pH was maintained above the minimum specification (>6.4) for 21 days. The surface phenotype and the composition of the supernatant was similar in non-irradiated and irradiated platelets, regardless of the source of radiation. Functional responses (aggregation and clot formation) were not affected by irradiation.

DISCUSSION

Gamma and X-ray irradiation do not affect the in vitro quality of platelet components stored in the cold for up to 21 days. This demonstrates the acceptability of irradiating cold-stored platelets, which has the potential to improve their safety for at-risk patient cohorts.

The in vitro quality of X-irradiated platelet components in PAS-E is equivalent to gamma-irradiated components

BACKGROUND

Blood components are irradiated to inactivate lymphocytes in an effort to prevent transfusion-associated graft versus host disease. Although gamma irradiators are commonly used, they are subjected to rigorous health, safety, and compliance regulations, compared with X-irradiators which have the advantage of only emitting radiation while the machine is switched on. While the effects of gamma irradiation on platelet components are well known, there is little or no data comparing the effects of X- and gamma-irradiation on the quality of these components. Therefore, this study examined the in vitro quality of platelet components (pooled and apheresis) following X- or gamma-irradiation.

STUDY DESIGN AND METHODS

Whole-blood-derived (pooled) and apheresis platelet components in platelet additive solution (n = 20 pairs for each type) were irradiated (X vs. gamma). In vitro platelet quality was tested prior to irradiation (day 1) and subsequently on days 2, 5, and 7. Non-irradiated components were tested on day 5 in parallel as reference controls. Metabolic parameters, surface expression of glycoproteins and activation markers (CD62P and annexin-V binding), and agonist-induced aggregation were measured.

RESULTS

All components met Council of Europe specifications. There were no statistical differences in any in vitro quality measurements between X- and gamma-irradiated pooled or apheresis platelet components.

CONCLUSION

X- and gamma-irradiation have similar effects on the in vitro quality of stored blood components, indicating that either technology represents a suitable option for irradiation of platelet components.

Platelet transfusion practice and related transfusion reactions in a large teaching hospital

BACKGROUND

Platelet transfusion practice varies widely since many aspects of platelet concentrate (PC) use have not been definitively determined. The objectives of this retrospective study were to present platelet transfusion practice and evaluate PC and patient characteristics, as well as their association with transfusion reaction (TR) rate.

MATERIAL AND METHODS

Platelet transfusions over a 5-year period were analysed regarding PC characteristics (the ABO and RhD compatibility, product type, and storage duration), patient characteristics (most responsible diagnosis, age, and gender), and TR type.

RESULTS

A total of 46,351 PCs were transfused: 76.4% whole blood-derived (WBD) and 23.6% single donor apheresis (SDA). Three thousand seven hundred seventy-six patients received platelet transfusions: 24.7% paediatric and 75.3% adult patients, 79.6% outpatients and 20.4% inpatients. As much as 63.1% of all transfused PCs were fresh (stored for≤3 days), 98.0% ABO-identical, and 87.3% of all PCs given to RhD- patients were RhD-. PCs were mainly transfused to haemato-oncology (76.8%) and cardiovascular surgery patients (6.5%). Overall, 84 (0.18%) TRs were reported, with allergic TRs (ATRs) being the most common. Although PC ABO compatibility and storage duration, as well as patient age and gender, showed differences in TR rate, only the use of PCs in platelet additive solution (PAS) showed a statistically significant reduction of TRs (P<0.001).

CONCLUSION

Transfusion practice at the University Hospital Centre Zagreb resulted in almost all patients receiving ABO and RhD identical PCs, and most of them were fresh PCs. The most important factor affecting the incidence of TRs was platelet storage solution. The use of PAS effectively reduced the rate of TRs, particularly allergic TRs.