New approaches to counteract platelet shortages

Oct 17 2005

Availability of safe platelets is a fundamental blood transfusion challenge and can be especially problematic in times of emergency. Several studies presented at the annual American Association of Blood Banks (AABB) meeting today demonstrate new approaches to counteract platelet shortages by enhancing the safety of whole blood derived platelets, precluding the need to rely on only those obtained through apheresis.

"If platelets from whole blood are tested for bacteria using state-of-the-art culture detection methods, the risk of transfusing contaminated platelets would be significantly reduced and transfusion medicine specialists would no longer have to make a trade-off between clinical safety and availability," says Stein Holme, Ph.D., vice president, R&D Applications, Pall Corporation, one of the presenters at AABB. Bacterial contamination of platelets is the leading infectious cause of sickness and death from a blood transfusion.

Dr. Holme explains that there is currently a disparity in platelet safety. Apheresis (single donor) platelets, which are time-consuming and expensive to obtain, are tested for bacterial contamination using the most sensitive culture detection methods. Whereas whole blood derived platelets are typically tested using less sensitive and reliable methods such as dipsticks or pH meters. Hospitals resort to these less sensitive methods since whole blood derived platelets need to be individually sampled for bacterial contamination (five separate tests) prior to pooling into a standard therapeutic dose for transfusion. However, if whole blood derived platelets were first pooled and then tested for bacteria using a more sensitive detection method, only one testing sample would be required. This approach would increase the safety standard of transfused platelets and ensure that this valuable resource is more readily available. It would also be more cost-effective, as it would reduce the handling costs of hospitals.

Dr. Holme provided an overview of the results from a series of studies conducted by research institutions in the U.S. and Canada that demonstrate the value of prestoraged pooled platelets. In vivo studies showed that prestoraged pooled platelets have an equivalent clinical response (the number of platelets that continue to circulate in the human body post-transfusion) to platelets pooled at the time of transfusion. The pooled and stored platelets also showed equivalent quality based on standard quality criteria and measures.

Steven Young, Ph.D., Scientific Director Microbiology & Virology, Tricore Reference Laboratories, presented a study on bacteria detection of pooled platelet concentrates, which evaluated the ability of the Pall eBDS System to detect 10 different bacteria that can contaminate platelets. The results of this study found that the Pall eBDS System, one of the most sensitive culture methods, was effective in detecting bacteria (greater than 99 percent) in pooled platelets.

Dr. Young concludes, "The ability to store random donor platelets concentrates as a pool would provide significant benefits such as having a therapeutic dose ready in emergency situations, reducing pool outdating, and enabling a simplified method for bacteria detection."

This month Pall Corporation was granted FDA clearance to market the Pall AcrodoseTM PL System, which provides a therapeutic dose of leukoreduced platelets that are tested for bacteria contamination with the integrated Pall eBDS technology. The new system enables blood centers to pool whole blood derived platelets and conduct a single state-of-the-art bacterial contamination test to enhance platelet safety and availability. The resulting AcrodoseSM Platelets are transfusion-ready and reduce the cost burden to hospitals by eliminating the need for further processing and testing.

Adding to this body of knowledge, Joseph D. Sweeny, M.D., Medical Director Blood Bank, Miriam Hospital, and Associate Professor of Medicine, Brown University in Providence, Rhode Island, presented the results of a study on extending the shelf life of platelets from 5 days to 7 days. Platelets outdate and are disposed of in about five days. This study examined the logistics and storage properties of whole blood derived pooled platelets stored in additive solution. The study showed that there was good in vitro function and preservation of the platelets to day seven based on all measures studied, with white blood cell counts and platelet yield similar to apheresis products.

There are currently about 2.1 million platelet transfusions in the U.S. annually. Platelets are the blood component responsible for blood clotting functions, and are typically diminished in patients undergoing chemotherapy, treatments related to organ transplant or victims of severe burns. They are essential blood products in times of emergency such as radiation exposure during an environmental or WMD event to a major disease outbreak, such as the recent events in Calcutta, India, which resulted in severe platelet shortage due to a simultaneous outbreak of multiple diseases (dengue hemorrhagic fever, malaria and typhoid).

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