Platelets photochemically treated with amotosalen HCl and ultraviolet A light correct prolonged bleeding times in patients with thrombocytopenia

In vitro evaluation of metabolic changes and residual platelet responsiveness in photochemical treated and gamma-irradiated single-donor platelet concentrates during long-term storage

BACKGROUND

Photochemical treatment (PCT) prevents replication of pathogens in platelet concentrates (PCs) by cross-linking nucleic acids and thus affects all cells containing DNA or RNA.

STUDY DESIGN AND METHODS

Fourteen double-dose single-donor PCs were divided into two study arms. The double-dose PCs were split in two identical units, PCT and conventional control PCs. Study Arm A consisted of seven PCT PCs with corresponding untreated controls, whereas Study Arm B consisted of seven PCT PCs with corresponding gamma-irradiated control. Metabolic changes and agonist-induced platelet (PLT) response were evaluated during storage for up to 12 days.

RESULTS

Higher rate of PLT destruction, illustrated by reduced PLT content, increased lactate dehydrogenase levels, and higher CD61+ microparticle formation rate, were observed after PCT. Generally PCT accelerated metabolic changes in PCs and reduced agonist-induced (collagen or thrombin receptor activator peptide [TRAP]) aggregation responses. Flow cytometric analysis of CD62P and CD42b (GPIbalpha) expression showed higher spontaneous PLT activation in PCT PCs from 5 days of storage. Correspondingly, a reduced capacity for up regulation of CD62P expression and down regulation of CD42b was observed in PCT PLTs after stimulation by the agonists ADP or TRAP.

CONCLUSION

Generally reduced in vitro PLT quality was observed after PCT during storage for up to 12 days, with marked reduction from 5 days of storage. Compared to conventional PCs, reduced agonist-induced aggregation and glycoprotein expression were observed after PCT during storage, corresponding to significantly higher level of spontaneous PLT activation in PCT PCs. Clinical studies of efficacy and safety of PCT PCs stored for more than 5 days are recommended.

Platelet Transfusion Therapy

This article provides guidelines for the appropriate use of platelet transfusions to reduce unnecessary transfusions, thereby avoiding transfusion-related risks to the patients and the costs of platelet therapy. Platelet products available for transfusion are whole blood derived platelet concentrates and apheresis platelets. Leukoreduced platelets can be used to reduce platelet alloimmunization, cytomegalovirus transmission, and febrile transfusion reactions, while gamma irradiation prevents transfusion-associated graftversus-host disease. Other topics discussed are the expected response to transfused platelets and reasons for poor responses related to alloimmunization, underlying disease state, clinical conditions, and drugs. Appropriate transfusion guidelines based on pretransfusion platelet count, platelet dose, and whether the transfusion is prophylactic or therapeutic are outlined. Identification, prevention, and management of adverse consequences of platelet transfusions and platelet refractoriness are discussed.

Leukoreduced buffy coat?derived platelet concentrates photochemically treated with amotosalen HCl and ultraviolet A light stored up to 7�days: assessment of hemostatic function under flow conditions

BACKGROUND

Amotosalen plus ultraviolet A light photochemical treatment (PCT) inactivates high titers of bacteria, and other pathogens, in platelet concentrates (PCs) potentially allowing the storage of platelets (PLTs) for up to 7 days. Adhesion and aggregation of PLTs to injured vascular surfaces are critical aspects of PLT hemostatic function.

STUDY DESIGN AND METHODS

Two ABO-identical leukoreduced buffy coat-derived PCs in additive solution were mixed and divided: one-half underwent PCT (PCT-PCs) and the other was kept as a control (C-PCs); both were stored under standard conditions. The total number of paired PCs studied was nine. Samples were taken on Day 1 (before PCT) and after 5 and 7 days of storage. The adhesion and aggregation capacities were evaluated under flow conditions in a ex vivo perfusion model.

RESULTS

Compared to control, PCT resulted in a decrease in PLT count of 6.5 percent (p = 0.004) and 10.2 percent (p = 0.008) after 5 and 7 days' storage, respectively (n = 9). PLT interaction with subendothelium was mainly in form of adhesion. The surface covered by PCT PLTs on Day 1 was 26.0 +/- 4.2 percent (mean +/- SEM). On Day 5, PCT-PCs showed a covered surface of 20.9 +/- 2.2 percent, and the C-PCs, 20.6 +/- 1.6 percent. After 7 days, PCT-PCs produced a nonsignificant higher PLT deposition compared to control (27.1 +/- 2.9% vs. 21.2 +/- 2.8%, p = 0.06).

CONCLUSION

PCT of PCs and storage up to 7 days was associated with a 10.2 percent decrease in PLT count due to processing losses compared to C-PC. PLT adhesive and aggregating capacities under flow conditions of PCT-PCs were similar to C-PCs and remained well preserved for up to 7 days of storage.

Emerging infectious diseases that threaten the blood supply

Following the devastating effects of blood-transmitted human immunodeficiency virus (HIV), blood establishments have become increasingly vigilant for the emergence or re-emergence of new threats to the safety of the blood supply. Many agents have fulfilled the broad definition of emerging blood-transmitted infections, including West Nile virus (WNV), Trypanosoma cruzi, Plasmodium spp., Babesia spp., parvovirus B19, dengue virus, and the prions that cause variant Creutzfeld-Jacob disease (vCJD). Other agents such as human herpes virus-8 (HHV-8-Kaposi's sarcoma virus) and Borellia (Lyme disease) and, perhaps, avian flu virus, are known to have a viremic phase, but have not yet been proved to be transfusion-transmitted. In the wake of these threats, transfusion services use a variety of donor screening interventions, including serologic assays, nucleic acid assays, and geographic exclusions based on potential exposure. The ultimate safeguard may be a pre-emptive pathogen inactivation strategy that will disrupt all nucleic acid-containing agents (though not prions). Considerable effort and resources have been invested in this arena, but currently no single technique is effective for inactivation of both liquid and cellular blood products and toxicity issues have not been completely resolved. The blood supply is remarkably safe with the risk of major pathogens such as hepatitis C virus (HCV) and HIV now reduced to less than one transmission per 2 to 3 million exposures. However, to approach near-zero infectious disease risk for emerging and re-emerging pathogens, new strategies such as pathogen inactivation or multi-pathogen microarray technology will need to be developed or refined.