Blood Cell Apoptosis/Necrosis: Some Clinical and Laboratory Aspects

The caspase-3 inhibitor (peptide Z-DEVD-FMK) affects the survival and function of platelets in platelet concentrate during storage

Background

Although apoptosis occurs in nucleated cells, studies show that this event also occurs in some anucleated cells such as platelets. During storage of platelets, the viability of platelets decreased, storage lesions were observed, and cells underwent apoptosis. We investigated the effects of caspase-3 inhibitor on the survival and function of platelets after different periods of storage.

Methods

Platelet concentrates were obtained from the Iranian Blood Transfusion Organization in plastic blood bags. Caspase-3 inhibitor (Z-DEVD-FMK) was added to the bags. These bags along with control bags to which no inhibitor was added were stored in a shaking incubator at 22℃ for 7 days. The effects of Z-DEVD-FMK on the functionality of platelets were analyzed by assessing their ability to bind to von Willebrand factor (vWF) and to aggregate in the presence of arachidonic acid and ristocetin. Cell survival was surveyed by MTT assay.

Results

At day 4 of storage, ristocetin-induced platelet aggregation was significantly higher in the inhibitor-treated (test) than in control samples; the difference was not significant at day 7. There was no significant difference in arachidonic acid-induced platelet aggregation between test and control samples. However, at day 7 of storage, the binding of platelets to vWF was significantly higher in test than in control samples. The MTT assay revealed significantly higher viability in test than in control samples at both days of study.

Conclusion

Treatment of platelets with caspase-3 inhibitor could increase their functionality and survival.

The platelet storage lesion

The continuous increase in the demand for platelet transfusion has necessitated the need to establish standards for determining the quality of platelets during storage. Bacterial contamination of platelet products and deleterious changes in structure and function referred to as the platelet storage lesion (PSL), have restricted the platelet shelf life to 5 days. The PSL and platelet health variables have been well studied and documented. The precise correlation between in vitro assays and in vivo platelet recovery and survival is yet to be established. This review presents an overview of the current understanding of PSL and the novel approaches being developed to negate the storage lesion.

The combined effect of platelet storage media and intercept pathogen reduction technology on platelet activation/activability and cellular apoptosis/necrosis: Lisbon-RBS experience

Platelets are known to undergo shape change, activation, a release reaction and apoptosis/necrosis during processing and storage, all of which are collectively known as the platelet storage lesion. Any additional processing may have some deleterious impact on platelet activability and functional integrity, which need to be investigated. This preliminary investigation was undertaken to establish the combined effects of standard platelet storage media and the intercept pathogen reduction technology on platelet activation and activability during 7 day storage, using buffy-coat derived platelets in standard storage media containing 35% plasma (N=24). P-selectin (CD62p) expression, a classical marker of platelet activation, and phosphatidylserine (PS) exposure on the platelet surface membrane, a hallmark of cellular necrosis/apoptosis, were both measured by flow cytometry. The results reveal significant increases in activation, from an average of 22.7% on day 1 before treatment to 31.6% on day 2 after treatment and 58.7% at the end of storage. Concomitantly, the basal expression of PS was slightly increased from 1.9% to 2.8% at day 2 after treatment and 7.3% at the end of storage. However, the functional reserve of platelets during storage, which reflects their capability to undergo activation and the release reaction when platelets were challenged with either calcium ionophore or thrombin, was relatively well maintained. These preliminary data confirm the earlier data on the use of intercept, and for the first time, based on the assessment of platelet functional integrity, suggest that platelet functional reserve is relatively well maintained, with little change in the formation of apoptotic cells.

Platelet storage lesion: an update on the impact of various leukoreduction processes on the biological response modifiers

Currently, platelet concentrates are produced either from pooled buffy which are leukoreduced during processing, by various types of WBC removal filters and several apheresis technologies, which are leukocyte-reduced during collection with or without filtration. It is therefore important to define the impact of various leukocyte-removal processes on the acceleration of platelet storage of lesion and cellular apoptosis/necrosis. This overview briefly highlights the effects of exposure to artificial surfaces, during apheresis leukoreduction processes and platelet storage bags on the development of the platelet storage lesion that may contribute to transfusion reactions. The results obtained from three plateletpheresis technologies are compared with data from a "like with like" study on buffy-coat-derived platelet concentrates, using three types of platelet filter/pack assemblies. Emphasis is placed on the combined preparative methods and storage bags on generation/removal of: kallikrein/kinin; activated complement, leukocytes and platelet-derived cytokines and the development of cellular injuries, measured by the release of Annexin V. There was no systematic evidence of significant cellular fragmentation caused by filtration, but the combined preparative methods and storage bags appears to have some impact on the rate of release of soluble HLA. Moreover, large variability was observed between and within groups, in terms of various laboratory markers of biocompatibility and major biological response modifiers, indicating that much still remains to be done on various aspects of quality improvement to fully abrogate platelet concentrates associated transfusion reactions.

What’s happening? The expanding role of apheresis platelet support in neonatal alloimmune thrombocytopenia: Current status and future trends

Despite some unresolved problems that may be associated with platelet transfusion, such as alloimmunisation, refractoriness, bacterial contamination, and the potential side effects related to the development of some biological response modifiers during storage, platelet therapy remains the most effective treatment for the management and prevention of severe thrombocytopenia and hemorrhage [Seghatchian J, Snyder EL, Krailadsiri P, editors. Platelet therapy: current status and future trends. Amsterdam, The Netherlands: Elsevier; 2000]. This appears to be particularly the case in neonatal alloimmune thrombocytopenia (NAIT), which arises due to an incompatibility of the platelet specific antigens between the pregnant mother and her baby. Over 80% of severe NAIT cases in the Caucasian population occur when the mother and baby differ in their HPA-1 epitope (HPA-1a negative and positive respectively) leading, in 10% of cases, to the production of anti-HPA-1a which can cross the placenta and cause NAIT in utero or post-partum. Anti-HPA-5b is the second most cause of NAIT, although severe cases occur only after the first pregnancy. Clinical manifestations of NAIT vary from mild (petechia and bruises) to severe (intracranial haemorrhage with possible death or life long morbidity). A recent study in Scotland indicated that the cost per case of severe NAIT detected during screening of pregnant women, where anti-HPA-1a is detected for the first time, would amount to $98,771 [Turner M, Bessos H, et al. Prospective epidemiological study of the outcome and cost effectiveness of antenatal screening to detect neonatal alloimmune thrombocytopenia (NAIT) due to anti-HPA-1a. Transfusion, in press. Yet, unlike the case with Rhesus hemolytic disease of the new born, the cost-effectiveness of HPA-1 screening in NAIT remains unresolved, as does the most optimal mode of treatment. Therefore, in the absence of a consensus on the screening and optimal management of NAIT, the availability and provision of HPA-1a/5b negative apheresis platelets based on current practice (transfusionguidelines.org.uk) appear to be a clinically effective treatment in NAIT. In that vein, an increasing number of blood transfusion centres are screening blood donors in order to secure panels of donors for the prompt provision of HPA-1a/5b negative apheresis platelets. However, evidence is also accumulating that while platelets derived from various apheresis technologies currently in use may be equivalent in terms of cellular contents (thus meeting specifications), they may differ in terms of the platelet storage lesion, microvesiculation and the development of platelet-derived cytokines and some other biological response modifiers [Seghatchian J. Platelet storage lesion: the influence of various leukoreduction procedures on generation/retention of some biological response modifiers, microvesiculation, distribution of membrane-bound/soluble Prion and the rate of HLA-CLASS1 release. Trans Apher Sci, in press. This manuscript summarises strategy and progress both in the improvement of apheresis platelet quality and provision in NAIT.

The application of a new quantitative assay for the monitoring of integrin-associated protein CD47 on red blood cells during storage and comparison with the expression of CD47 and phosphatidylserine with flow cytometry

BACKGROUND

After the introduction of universal leukoreduction, the role of factors other than white blood cells in red cell (RBC) storage lesion is attracting increasing attention. These include changes in the levels of CD47 and phosphatidylserine (PS) markers on RBCs during storage. The aim of this study was to monitor these changes with both flow cytometry (FACS) and a newly developed quantitative enzyme-linked immunosorbent assay (ELISA).

STUDY DESIGN AND METHODS

A new quantitative ELISA (monoclonal antibody immobilization of RBC antigens [MAIRA]) was developed. The assay yielded consistent linear curves that enabled the measurement of CD47 expression on RBCs. In addition, FACS was used to measure both CD47 expression and PS on RBCs (n = 3 units) during storage (Days 4, 10, 24, and 31).

RESULTS

A significant reduction in CD47 expression was observed both by MAIRA assay and by FACS by Days 24 and 31 (p < 0.01), and the correlation between the two assays was significant (p < 0.01). In addition, a significant increase in PS was observed by the same storage days with FACS (p < 0.01).

CONCLUSION

The MAIRA assay appears to be suitable for the quantitative measurement of RBC markers during storage. Significant changes in CD47 and PS levels were observed during storage, which may have detrimental immunomodulatory and hemostatic effects on the transfused RBCs.

Red cell storage lesion: The potential impact of storage-induced CD47 decline on immunomodulation and the survival of leucofiltered red cells

Red blood cells undergo major biochemical and biomechanical changes during storage that could effect their post transfusion performance. Biochemical effects include changes in 2,3-diphosphoglycerate (2,3-DPG), ATP, and calcium levels, as well as metabolic modulation and release of Annexin V, a cytosolic component of blood cells, as a global marker of cellular injury and fragmentation. Biomechanical changes include alterations in cellular membrane, shape changes, phospholipid content, phospholipid asymmetry, and antigenic markers. Although the extent of these changes under various storage conditions has been well documented, their clinical effects remain unclear. In the current era of universal leucodepletion, the immunomodulatory effects of some essential markers such as CD47 and phosphatidyl serine become the focus of interest as highlighted in this manuscript.

Clinical implications of red blood cell and platelet storage lesions: an overview

Both red blood cells and platelets undergo lesions upon storage which affect their function and possibly their clinical outcome. Some of these lesions are reversible, others not. Improved additive solutions and leukocyte depletion can delay the appearance of storage lesions. In addition, cellular apoptosis leads to numerous mitochondrial and surface changes during storage which have the potential to induce immune suppression by tuning down the innate immune system. This overview highlights some laboratory and clinical aspects of red cell and platelet storage lesions.