Cytochrome c and resveratrol preserve platelet function during cold storage

Comparative analysis of cold-stored apheresis platelet units in additive solution with or without pathogen reduction: Implications of cytochrome c supplementation

BACKGROUND

Platelets are limited in supply, and the preservation of platelet function during storage remains challenging. Novel storage approaches are being explored to improve platelet quality, extend shelf life, and reduce risk of infection. This study sought to elucidate platelet function in cold-stored apheresis units in additive solution (platelet additive solution [PAS]) and subjected to pathogen reduction (PR) as well as the impact of cytochrome c (cyt c) supplementation. We hypothesized that the PR would decrease stored platelet function, regardless of cyt c supplementation.

METHODS

Platelet apheresis units (PAS) were collected (N = 5 volunteers) and divided into PR or no PR (PAS) and supplemented with vehicle or cyt c (100 μM). Units were stored at 4°C for 15 days, sequential aliquots were removed, and platelet/mitochondrial respiratory function and biochemical parameters were analyzed.

RESULTS

There was no difference in platelet aggregation in response to adenosine diphosphate between PAS and PR platelets. Aggregation function in response to arachidonic acid was higher in PR versus PAS platelets. Maximum clot strength was not different between PAS and PR from Day 0 to Day 5 but declined in PR platelets on Days 10 and 15. Oxygen consumption declined at the same rate in PAS and PR platelets, while rate of lactate and TCO 2 decrease was greater in PR platelets than in PAS platelets. Supplementation with cyt c did not alter platelet function or biochemical parameters in PAS or PR platelets.

CONCLUSION

Platelet additive solution and PR platelets show similar declines in respiratory capacity, and biochemical parameters during cold storage, but PR platelets demonstrated significantly increased arachidonic acid-induced aggregation across all time points. Further understanding this mechanism may provide a means to prolong platelet shelf life.

The effect of modulating platelet reactive oxygen species by the addition of antioxidants to prevent clearance of cold-stored platelets

BACKGROUND

It is known that the rapid clearance of cold-stored platelets is attributed to various storage lesions, including an abnormal increase in reactive oxygen species when platelets are exposed to cold temperatures. As an antioxidant, N-acetylcysteine exhibits some significant effects on scavenging various reactive oxygen species and inhibiting cell damage and apoptosis.

AIMS

This study aimed to investigate the effects of N-acetylcysteine on reducing reactive oxygen species production and protecting cold-stored platelets from phagocytosis and clearance, and to determine the optimal concentration of N-acetylcysteine.

METHODS

Platelet concentrates were divided into three groups: room-temperature-stored platelets, cold-stored platelets, and cold-stored platelets with the addition of different concentrations of N-acetylcysteine. After five days of storage, reactive oxygen species production, lipid peroxidation levels, activation marker expressions, GPIb/ɑ desialylation with exposure of glycan residues and other quality parameters of platelets were measured and compared between the groups. Phagocytosis of platelets was detected by phorbol 12-myristate 13-acetate-activated THP-1 or Hep G2 cells. Moreover, the recovery of infused platelets was measured in severe combined immunodeficient mice at different timepoints.

RESULTS

After 5 days of storage, cytoplasmic reactive oxygen species significantly increased in chilled compared to non-chilled platelets; they were notably reduced with the addition of N-acetylcysteine, particularly at a concentration of 5 mM. Compared with chilled platelets, the P-selectin and phosphatidylserine expressions, as well as exposure of GPIb/ɑ glycan residues, were significantly reduced with 5 mM of N-acetylcysteine. Phagocytosis of platelets by THP-1 or Hep G2 cells was significantly lower in 5 mM of N-acetylcysteine compared to cold-stored platelets without N-acetylcysteine.

CONCLUSIONS

This study demonstrated correlations between reactive oxygen species production and their pro-oxidant effects on platelet clearance after cold storage. The addition of N-acetylcysteine at an appropriate concentration do not only protects chilled platelets from storage lesions caused by reactive oxygen species overproduction but also prevents platelet phagocytosis in vitro and clearance in vivo, thereby extending circulating time.

Assessing Platelet Mitochondrial Dysfunction in a Murine Model of Acute Acetaminophen Toxicity

INTRODUCTION

Acetaminophen (APAP) toxicity remains a significant cause of adult and pediatric liver failure in North America and Europe. Previous research has evaluated the impaired mitochondrial function associated with APAP toxicity. The primary aim of this study was to evaluate the effects of APAP toxicity on platelet mitochondrial function using platelet oxygen consumption in a murine model in vivo. Our secondary objectives were to determine the effect of 4-MP on platelet mitochondrial function and hepatic toxicity in the setting of APAP overdose, and to correlate platelet mitochondrial function with other markers of APAP toxicity.

METHODS

Male C57Bl/6 mice were randomized to receive APAP (300 or 500 mg/kg) or vehicle followed 90 minutes later by either 4-MP (50 mg/kg) or vehicle via intraperitoneal injection. Mice were euthanized 0, 12, or 24 hours later and platelets isolated from cardiac blood and counted. Platelet oxygen consumption (POC) was determined using a closed-system respirometer. Liver injury was assessed by measuring alanine transferase (ALT) and histological evaluation.

RESULTS

Injection of 500 mg/kg APAP led to increased POC versus pair-matched control (vehicle) (p < 0.001). Administration of 4-MP did not affect POC in control or 300 mg/kg APAP mice. In mice receiving 500 mg/kg APAP and 4-MP, POC decreased significantly compared to mice receiving 500 mg/kg APAP alone (p < 0.01). Serum and histological analysis confirmed APAP-induced hepatic damage in mice receiving 500 mg/kg APAP and these effects blunted by treatment with 4-MP.

CONCLUSIONS

Platelet oxygen consumption as a measure of mitochondrial function may be useful as a biomarker of hepatic APAP toxicity in the setting of moderate to severe overdose. Treatment with 4-MP decreases hepatic necrosis and may mitigate the harmful effects of APAP on platelet mitochondrial function detected via POC.

Platelet storage: Progress so far

There is a crucial need for platelet transfusion during an emergency-surgery and treatment of platelet disorders. The unavailability of donors has furthermore increased the demand for platelet storage. Platelets have limited shelf life due to bacterial contamination and storage lesions. Temperature, materials, oxygen availability, media, platelet processing and manufacturing methods influence the platelet quality and viability during storage. The conception of various platelet additive solutions along with the advent of plastic storage during the 1980s led to enormous developments in platelet storage strategies. Cold storage of platelets gained attention despite its inability to contribute to platelet survival post-transfusion as it offers faster haemostasis. Several developments in platelet storage strategies over the years have improved the quality and shelf-life of stored platelets. Despite the progress, the efficacy of platelets during storage beyond a week has not been achieved. Antioxidants as additives have been explored in platelet storage and have proven to enhance the efficacy of platelets during prolonged storage. However, the molecular interactions of antioxidants in platelets can provide a better understanding of their mechanism of action. Optimization of dosage concentrations of antioxidants is also a critical parameter to be considered as they tend to exhibit toxicity at certain levels. This review provides comprehensive insights into the critical factors affecting platelet storage and the evolution of platelet storage. It also emphasizes the role of antioxidants as additives in platelet storage solutions and their future prospects towards better platelet banking.

Platelet Aggregation, Mitochondrial Function and Morphology in Cold Storage: Impact of Resveratrol and Cytochrome c Supplementation

Donated platelets are critical components of hemostasis management. Extending platelet storage beyond the recommended guidelines (5 days, 22 °C) is of clinical significance. Platelet coagulation function can be prolonged with resveratrol (Res) or cytochrome c (Cyt c) at 4 °C. We hypothesized that storage under these conditions is associated with maintained aggregation function, decreased reactive oxygen species (ROS) production, increased mitochondrial respiratory function, and preserved morphology. Donated platelets were stored at 22 °C or 4 °C supplemented with 50 μM Res or 100 μM Cyt c and assayed on days 0 (baseline), 5, 7 and 10 for platelet aggregation, morphology, intracellular ROS, and mitochondrial function. Declining platelet function and increased intracellular ROS were maintained by Res and Cyt c. Platelet respiratory control ratio declined during storage using complex I + II (CI + CII) or CIV substrates. No temperature-dependent differences (4 °C versus 22 °C) in respiratory function were observed. Altered platelet morphology was observed after 7 days at 22 °C, effects that were blunted at 4 °C independent of exposure to Res or Cyt c. Storage of platelets at 4 °C with Res and Cyt c modulates ROS generation and platelet structural integrity.

The Missing Pieces to the Cold-Stored Platelet Puzzle

Cold-stored platelets are making a comeback. They were abandoned in the late 1960s in favor of room-temperature stored platelets due to the need for longer post-transfusion platelet recoverability and survivability in patients with chronic thrombocytopenia. However, the current needs for platelet transfusions are rapidly changing. Today, more platelets are given to patients who are actively bleeding, such as ones receiving cardiac surgeries. It has been established that cold-stored platelets are more hemostatically effective, have reduced bacterial growth, and have longer potential shelf lives. These compelling characteristics led to the recent interest in bringing back cold-stored platelets to the blood systems. However, before reinstating cold-stored platelets in the clinics again, a thorough investigation of in vitro storage characteristics and in vivo transfusion effects is required. This review aims to provide an update on the recent research efforts into the storage characteristics and functions of cold-stored platelets using modern investigative tools. We will also discuss efforts made to improve cold-stored platelets to be a better and safer product. Finally, we will finish off with discussing the relevance of in vitro data to in vivo transfusion results and provide insights and directions for future investigations of cold-stored platelets.

Mitochondrial Respiration of Platelets: Comparison of Isolation Methods

Multiple non-aggregatory functions of human platelets (PLT) are widely acknowledged, yet their functional examination is limited mainly due to a lack of standardized isolation and analytic methods. Platelet apheresis (PA) is an established clinical method for PLT isolation aiming at the treatment of bleeding diathesis in severe thrombocytopenia. On the other hand, density gradient centrifugation (DC) is an isolation method applied in research for the analysis of the mitochondrial metabolic profile of oxidative phosphorylation (OXPHOS) in PLT obtained from small samples of human blood. We studied PLT obtained from 29 healthy donors by high-resolution respirometry for comparison of PA and DC isolates. ROUTINE respiration and electron transfer capacity of living PLT isolated by PA were significantly higher than in the DC group, whereas plasma membrane permeabilization resulted in a 57% decrease of succinate oxidation in PA compared to DC. These differences were eliminated after washing the PA platelets with phosphate buffer containing 10 mmol·L⁻¹ ethylene glycol-bis (2-aminoethyl ether)-N,N,N′,N′-tetra-acetic acid, suggesting that several components, particularly Ca²⁺ and fuel substrates, were carried over into the respiratory assay from the serum in PA. A simple washing step was sufficient to enable functional mitochondrial analysis in subsamples obtained from PA. The combination of the standard clinical PA isolation procedure with PLT quality control and routine mitochondrial OXPHOS diagnostics meets an acute clinical demand in biomedical research of patients suffering from thrombocytopenia and metabolic diseases.

Improved Cardiovascular Tolerance to Hemorrhage after Oral Resveratrol Pretreatment in Dogs

Resveratrol has been shown to preserve organ function and improve survival in hemorrhagic shock rat models. This study investigated whether seven days of oral resveratrol could improve hemodynamic response to hemorrhage and confer benefits on risk of acute kidney injury (AKI) without inducing coagulopathy in a canine model. Twelve greyhound dogs were randomly allocated to receive oral resveratrol (1000 mg/day) or placebo for seven days prior to inducing hemorrhage until a targeted mean blood pressure of ≤40 mmHg was achieved. AKI biomarkers and coagulation parameters were measured before, immediately following, and two hours after hemorrhage. Dogs were euthanized, and renal tissues were examined at the end of the experiment. All investigators were blinded to the treatment allocation. A linear mixed model was used to assess effect of resveratrol on AKI biomarkers and coagulation parameters while adjusting for volume of blood loss. A significant larger volume of blood loss was required to achieve the hypotension target in the resveratrol group compared to placebo group (median 64 vs. 55 mL/kg respectively, p = 0.041). Although histological evidence of AKI was evident in all dogs, the renal tubular injury scores were not significantly different between the two groups, neither were the AKI biomarkers. Baseline (pre-hemorrhage) maximum clot firmness on the Rotational Thromboelastometry (ROTEM^®) was stronger in the resveratrol group than the placebo group (median 54 vs. 43 mm respectively, p = 0.009). In summary, seven days of oral resveratrol did not appear to induce increased bleeding risk and could improve greyhound dogs’ blood pressure tolerance to severe hemorrhage. Renal protective effect of resveratrol was, however, not observed.

Platelet Dysfunction after Traumatic Brain Injury: A Review

Coagulopathy is a known sequela of traumatic brain injury (TBI) and can lead to increased morbidity and mortality. Platelet dysfunction has been identified as one of several etiologies of coagulopathy following TBI and has been associated with poor outcomes. Regardless of whether the platelet dysfunction occurs as a direct consequence of the injury or because of pre-existing medical comorbidities or medication use, accurate detection and monitoring of response to therapy is key to optimal patient care. Platelet transfusion has been proposed as a potential therapeutic intervention to treat platelet dysfunction, with several studies using platelet function assays to monitor response. The development of increasingly precise diagnostic testing is providing enhanced understanding of the specific derangement in the hemostatic process, allowing clinicians to provide patient-specific treatment plans. There is wide variability in the currently available literature on the incidence and clinical significance of platelet dysfunction following TBI, which creates challenges with developing evidence-based management guidelines. The relatively high prevalence of platelet inhibitor therapy serves as an additional confounding factor. In addition, the data are largely retrospective in nature. We performed a literature review to provide clarity on this clinical issue. We reviewed 348 abstracts, and included 97 manuscripts in our final literature review. Based on the currently available research, platelet dysfunction has been consistently demonstrated in patients with moderate-severe TBI. We recommend the use of platelet functional assays to evaluate patients with TBI. Platelet transfusion directed at platelet dysfunction may lead to improved clinical outcome. A randomized trial guided by implementation science could improve the applicability of these practices.

The impact of bilirubin ditaurate on platelet quality during storage

Bilirubin ditaurate (BRT), a conjugated bilirubin analogue, has demonstrated anti-platelet characteristics following acute ex vivo exposure. Scavenging of mitochondrial superoxide and attenuation of granule exocytosis suggested a potential benefit for including BRT for storage. With no reports of cytotoxicity following acute exposure, the impact of 35µM BRT on platelet function was investigated, in clinically suppled units, for up to seven days. Exposure to 35µM BRT significantly reduced mitochondrial membrane potential and increased glucose consumption until exhaustion after 72 hours. Platelet aggregation and activation was significantly impaired by BRT. Mitochondrial superoxide production and phosphatidylserine expression were significantly elevated following glucose exhaustion, with decreased viability observed from day five onwards. Lactate accumulation and loss of bicarbonate, support a metabolic disturbance, leading to a decline of quality following BRT inclusion. Although acute ex vivo BRT exposure reported potentially beneficial effects, translation from acute to chronic exposure failed to combat declining platelet function during storage. BRT exposure resulted in perturbations of platelet quality, with the utility of BRT during storage therefore limited. However, these are the first data of prolonged platelet exposure to analogues of conjugated bilirubin and may improve our understanding of platelet function in the context of conjugated hyperbilirubinemia.

The contribution of oxidative stress to platelet senescence during storage

BACKGROUND

Platelets for transfusion become senescent and dysfunctional during storage, resulting in a markedly short shelf life (5 days). We hypothesized that oxidative stress might account for this decline.

STUDY DESIGN AND METHODS

Human platelets were treated with or without antioxidants before storage, and samples were collected and analyzed at different time points. Platelet senescence was determined by senescence-associated β-galactosidase assay, and senescence-related platelet qualities were also analyzed.

RESULTS

Sign of senescence became evident after Day 3 and continued to increase over time. We also found that chemical induction of platelet activation did not affect senescence level, whereas apoptosis inducers showed a stimulative effect on platelet senescence. Moreover, this effect was not prevented by a pan-caspase inhibitor. Meanwhile, cellular and mitochondrial reactive oxygen species were found elevated during storage, and treatments with antioxidants successfully prevented this increase and also mitigated senescence levels of stored platelets. Finally, resveratrol, a natural antioxidant, was utilized as a novel storage additive to safely extend platelet shelf time. We showed that the addition of resveratrol efficiently postponed platelet senescence and ameliorated platelet storage lesion.

CONCLUSIONS

Platelets during storage became senescent and dysfunctional over time, and we found that oxidative stress might account for this decline. The addition of antioxidants effectively postponed senescence and ameliorated platelet storage lesion, which might provide a valuable reference to future platelet storage methodologies.

Resveratrol promotes trophoblast invasion in pre-eclampsia by inducing epithelial-mesenchymal transition

Impairment spiral arteries remodelling was considered to be the underlying cause of pathogenesis of pre‐eclampsia (PE). Resveratrol (RE) was reported that it could modulate cellar phenotype to ameliorate diverse human diseases. However, the biological function of RE in PE remains poorly understood. In this report, we investigated the effect of RE on trophoblast phenotype both in vivo and in vitro. We conducted MTT and transwell assays to explore cell proliferation and invasion events in HTR‐8/SVneo. In mice model, the clinical characteristics of PE were established through the injection of NG‐nitro‐l‐arginine methyl ester (L‐NAME). Furthermore, related experiments were performed to detect cellar phenotype‐associated signalling pathway, including epithelial‐mesenchymal transition (EMT) and Wnt/β‐catenin. Cell assays indicated that RE could increase trophoblasts migration and invasion. In addition, hypertension and proteinuria were markedly ameliorated by RE compared with the controls in PE mice model. Moreover, treatment by RE in trophoblasts or in PE model, we found that RE activated EMT progress through the regulation of E‐cadherin, β‐catenin, N‐cadherin, vimentin expression, and further altered the WNT‐related gene expression, including WNT1, WNT3 and WNT5B. Our findings demonstrated that RE might stimulate the invasive capability of human trophoblasts by promoting EMT and mediating the Wnt/β‐catenin pathway in PE.

Evaluation of platelet activation in leukocyte-depleted platelet concentrates during storage

Structural and functional changes in platelets during storage can lead to the loss of platelet reactivity and response. Our aim was to evaluate leukocyte-depleted platelet concentrates on storage days 0, 3 and 5, obtained by in-line filtration. In non-filtered platelet concentrates (NF-PC) group, 180 whole blood units were collected with quadruple blood bags and then compared to another group of 180 whole blood units (leukocyte-depleted platelet concentrates [LD-PC]), collected in Imuflex Whole Blood Filter Saving Platelets (WB-SP) bags with an integrated leukoreduction filter, with regard to the platelet quality and characteristics. The efficacy of the two techniques for platelet concentrate preparation was evaluated by white blood cell (WBC) and platelet count on day 0. The partial pressure of oxygen (pO2), pH, platelets positive for P-selectin (CD62P), CD63, cluster of differentiation 42b (CD42b), phosphatidylserine (PS), and mitochondrial membrane potential (MMP) were analyzed during the storage in both groups. A significantly lower WBC count and higher platelet count was observed in LD-PC compared to NF-PC group, indicating the overall efficacy of the first technique. During the 5-day storage, pH and pO2 decreased in both groups. In LD-PC group, higher pH, increased pO2 and decreased platelet surface expression of CD62P, CD63 and PS were observed compared to NF-PC group. In both groups, the percentage of CD42b positive platelets and MMP did not change significantly during the 5-day period. The assessment of different markers of platelet activation may be an effective tool in evaluating the quality of platelets during storage. A better understanding of platelet activation may provide new insights for developing a novel therapeutic approach in the manipulation of platelet aggregation.