Studies on Safety and Efficacy of Platelets and Other Transfused Blood Products

Principal Investigator: J.G. Vostal, MD
Office / Division / Lab: OBRR / DH / LCH

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Overview

Public Health Issue: Over 9 million platelet products are collected in the US per year and transfused for therapeutic support of chronically and acutely thrombocytopenic patients. Unfortunately there are inherent risks to transfusion of platelets into patients, which include, but are not limited to, transfer of infectious pathogens and development of anti-platelet antibodies (alloimmunization). For example, platelet products pose the highest risk of transmitting bacterial sepsis out of any other transfusion product and lead to 5-10 deaths from contaminated platelets reported to the FDA per year. Bacterial contamination of platelets occurs at the time of collection and storage of platelets at room temperature permits proliferation of bacteria to very high levels. Even platelets stored under optimal conditions have a relatively short circulation time post-transfusion and require frequent transfusions to maintain adequate number of platelets for hemostasis. Reduction in the quality of platelets, either by inadequate storage or by processing methods that damage them, can lead to increased clearance of the transfused platelets prompting further transfusions and increasing the risk of adverse events. Ideally the number of transfusions should be kept to a minimum to reduce the risk of adverse events while assuring adequate hemostasis by providing sufficient numbers of functional platelets in circulation. This can be achieved by collecting and storing the platelets through means that produce the least amount of damage. Licensing of safe and effective novel processing and storage devices involves an evaluation of the extent of damage to the collected and stored platelets. For decades this evaluation has utilized human volunteers in Phase 2 clinical trials to determine the recovery and lifespan of infused radioactively labeled platelets. Damaged platelets have a decreased recovery and survival. Even though this is the current "gold standard" for platelet evaluation such studies are logistically and financially difficult to conduct and represent a major hurdle for development of novel methods for platelet collection and processing. In addition to traditional pathogens such as bacteria and viruses there are other infectious agents found in blood for which screening tests are not available. One such pathogen, now known to be transmitted by blood transfusion is variant Creutzfeldt Jakob disease (vCJD). vCJD falls into a family of incurable human and animal neurodegenerative diseases referred to as transmissible spongiform encephalaopathies (TSE). The current approach to decreasing risk of transfusion transmitted vCJD is donor deferral based on history of travel to countries with prevalent bovine spongiform encephalopathy disease in cattle. However this approach eliminates many donors who are not infected. A screening test for donors or a prion pathogen removal process applied to transfusion products would be beneficial in decreasing transmission of TSE diseases by transfusion. In addition it would increase the available donor pool as the travel history restrictions could be lifted.

Regulatory Contribution: The knowledge gained from on going research will be used to evaluate the quality of future platelet products and streamline the approval process. Understanding of TSE transmission by blood will be applied to evaluation and development of devices for removal or detection of vCJD infectivity in blood products.

Research Approach: The studies in LCH are aimed at development of an animal model that could predict in vivo viability of transfused platelet products in humans. Such a model may one day replace the use of human clinical trials that utilize radiolabeled platelets to define the kinetics of particular platelet products in circulation. We developed a rodent model that can identify minor to moderate levels of damage to human platelets. Currently we are defining the level of sensitivity for detection of damage he damage. Our plans are to run a side-by-side comparison of the animal model and human clinical trial to validate the ability of the model to detect platelet damage. Development of a validated animal model that provides similar information as a radiolabeled platelet clinical trial could speed up the development process of a variety of novel platelet products such as pathogen-reduced platelets, extended shelf life platelets and platelet substitutes that could be used in the battle field where conventional platelets are difficult to obtain and store. A test to screen blood for the presence of the vCJD infectious agent has not been developed yet. The infectious particle is a conformationaly altered form of naturally occurring prion protein. We are searching for biologic molecules that can bind prion protein with the yeast two hybrid expression system. Peptides from molecules that bind prion protein will be used to develop a detection method for the infectious prion proteins and serve as an affinity ligand to remove prion proteins from transfusion products.

Mission Relevance & Outcomes: An animal model that could detect damage to platelets by novel platelet collection or storage methods would greatly facilitate the evaluation process. Once validated against a concurrent human clinical trial the animal model could be used to predict which novel products would be worth developing into clinical products. For vCJD, a detection method would increase safety and availability of transfusion products by reducing donor deferrals. A molecule that binds to prion could be used to detect the presence of the altered prion or be used to reduce the load of prion molecules in a transfusion product by affinity purification.

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Publications

Biochim Biophys Acta 2008 Nov;1782(11):615-20
Human cellular prion protein interacts directly with clusterin protein.
Xu F, Karnaukhova E, Vostal JG

Apoptosis 2008 Aug;13(8):993-1004
Molecular mechanism underlying differential apoptosis between human melanoma cell lines UACC903 and UACC903(+6) revealed by mitochondria-focused cDNA microarrays.
Zhang Q, Wu J, Nguyen A, Wang BD, He P, Laurent GS, Rennert OM, Su YA

Blood Cells Mol Dis 2008 May-Jun;40(3):302-7
Reduced erythroid cell and erythropoietin production in response to acute anemia in prion protein-deficient (Prnp-/-) mice.
Zivny JH, Gelderman MP, Xu F, Piper J, Holada K, Simak J, Vostal JG

Transfusion 2007 Dec;47(12):2223-32
Divergent expression of cellular prion protein on blood cells of human and nonhuman primates.
Holada K, Simak J, Brown P, Vostal JG

Transfusion 2007 Aug;47(8):1540-9
In vivo recovery of human platelets in severe combined immunodeficient mice as a measure of platelet damage.
Piper JT, Gelderman MP, Vostal JG

Haematologica 2006 Aug;91(8):1126-9
Expression of cellular prion protein on platelets from patients with gray platelet or Hermansky-Pudlak syndrome and the protein's association with alpha-granules.
Holada K, Glierova H, Simak J, Vostal JG

J Trauma 2006 Jun;60(6 Suppl):S78-82
Efficacy evaluation of current and future platelet transfusion products.
Vostal JG

Transfus Med 2006 Feb;16(1):41-8
A multistate cluster of red blood cell transfusion reactions associated with use of a leucocyte reduction filter.
Alvarado-Ramy F, Kuehnert MJ, Alonso-Echanove J, Sledge L, Haley NR, Epstein J, Vostal J, Pearson M.

Cancer Res 2005 Aug 15;65(16):7370-7
Endogenous osteonectin/SPARC/BM-40 expression inhibits MDA-MB-231 breast cancer cell metastasis.
Koblinski JE, Kaplan-Singer BR, VanOsdol SJ, Wu M, Engbring JA, Wang S, Goldsmith CM, Piper JT, Vostal JG, Harms JF, Welch DR, Kleinman HK.

Br J Haematol 2004 Jun;125(6):804-13
Elevated circulating endothelial membrane microparticles in paroxysmal nocturnal haemoglobinuria.
Simak J, Holada K, Risitano AM, Zivny JH, Young NS, Vostal JG.