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Education and Training:

B.A., Mathematics, Cum Laude, Washington State University, Pullman, Washington (1959)

M.D., George Washington University, Washington, DC (1963)

Rotating Internship, Mount Sinai Hospital, New York, New York (1963-64)

Resident in Medicine, Mount Sinai Hospital, New York, New York (1964-65)

Resident in Medicine,
Parkland Memorial Hospital, Dallas, TX (1965-67)

Senior Fellow in Medicine (Hematology/Oncology), University of Washington, Seattle, WA (1967-68)

Sherrill J. Slichter, M.D.
Professor of Medicine, Division of Hematology
University of Washington School of Medicine

Director, Platelet Transfusion Research,
Bloodworks NW

Office Address:
Bloodworks NW
Box 359190
921 Terry Avenue
Seattle, WA 98104-1256

Phone:   (206) 292-6541
Fax:       (866) 287-7209
E-mail:   sjslichter@BloodworksNW.org


Evaluation of the effects of pathogen reduction on platelet storage and prevention of platelet alloimmunization


      Evaluate methods of extending platelet storage times;

      Assess the effects of pathogen reduction procedures on platelet viability and function;

      Determine approaches to prevent platelet alloimmunization in a dog platelet transfusion model.


Extended Platelet Storage Studies:  Platelet storage is affected by the method of collection, the storage bag, and the storage solution. We have evaluated two different methods of harvesting platelets from whole blood; the so-called platelet-rich plasma method which involves a soft centrifugation of the whole blood to separate the blood into red cells and supernatant platelet-rich plasma. The platelet-rich plasma is then transferred to another bag where the platelets are hard-spun concentrating the platelets at the bottom of the bag, and then most of the supernatant plasma is transferred to another bag for transfusion as plasma. The platelets are re-suspended in a small amount of residual plasma or a storage solution. The alternate method of preparing platelet concentrates from whole blood is called the buffy coat method. In this method, the whole blood is hard-spun producing red cells at the bottom of the bag, a buffy coat layer that contains the white cells and platelets in the middle of the bag, and a supernatant plasma layer. The red cells are removed through ports in the bottom of the bag, plasma is taken off through ports at the top of the bag, and the remaining buffy coats from four to six whole blood collections are pooled, and a soft centrifugation is done to bring down the majority of the red and white cells. The supernatant pooled platelets are removed into another bag for storage in either plasma or a storage solution. Studies to determine how long whole blood prepared platelet concentrates can be stored are in progress. The parameters we are evaluating are how the preparation method, the storage bag, and the storage solution affect platelet viability during extended storage.

In addition to preparing platelets from whole blood, apheresis procedures can be used to harvest enough platelets from a single donor to constitute a transfusion dose. Our recent studies have indicated that by using a very gentle apheresis collection procedure, storing the platelets in a specific bag, and in a storage solution called Plasmalyte rather than residual plasma, we have been able to extend the storage time of apheresis platelets from the currently licensed 5 days to 12 days while still meeting FDA requirements for platelet quality after storage.

Pathogen Reduction Of Extended Stored Platelets:  Because platelets are stored at room temperature, the risk of bacterial contamination is quite high and is one of the major reasons for limiting platelet storage time to five days to reduce the overgrowth of any bacteria which may have entered the system, usually because of inadequate cleansing of the venapuncture site.  In order to allow licensing of extended stored platelets, a sensitive and specific point of release bacterial assay has to be used, and none are currently available.  Alternatively, a method of pathogen reduction can be used.  We have focused our efforts on working with a manufacturer who has developed a system of pathogen reduction to determine the effects of pathogen reduction on extended stored platelets.  It is known that there is some damage induced by the pathogen reduction process, and so it is unlikely that we will be able to achieve 12 days of storage and still meet FDA post-storage platelet viability measurements, but we are hopeful that we may be able to extend platelet storage times for at least nine to ten days.

Prevention of Platelet Alloimmunization In a Dog Platelet Transfusion Model: Our prior studies in a dog platelet transfusion model identified UV-B irradiated platelets as being equivalent to filter-leukoreduced platelets in preventing platelet alloimmunization.  Our data on UV-irradiation in the dog being equivalent to leukoreduction was confirmed in a very large prevention of platelet alloimmunization trial in AML patients undergoing induction chemotherapy.  This study validated the usefulness of the dog as a pre-clinical model in identifying methods that were not only successful in the dog but also in patients in preventing alloimmunization.  In our most recent studies, we have identified that combining leukocyte reduction with pathogen reduction resulted in prevention of platelet alloimmunization in 20 out of 21 (95%) recipient dogs who received 8 weekly platelet transfusions that had been both filter leukoreduced and pathogen inactivated.  This compares to a 14% incidence of preventing alloimmunization with standard, non-modified platelets, a 14% protection rate using only pathogen reduction, a 45% and a 66% prevention rate for filtered leukoreduced platelets.  Therefore, it is anticipated that this combined filtration leukoreduction/pathogen reduction system may be completely effective in preventing platelet alloimmunization when used in thrombocytopenic patients.


Slichter SJ, Fish D, Abrams VK, Gaur L, Nelson K, Bolgiano D. Evaluation of different methods of leukoreduction of donor platelets to prevent alloimmune platelet refractoriness and induce tolerance in a canine transfusion model. Blood 2005;105(2):847-854.

Slichter SJ, Davis K, Enright H, Braine H, Gernsheimer T, Kao KJ, Kickler T, Lee E, McFarland J, McCullough J, Rodey G, Schiffer C, Woodson R. Factors affecting post-transfusion platelet increments, platelet refractoriness, and platelet transfusion intervals in thrombocytopenic patients. Blood 2005;105(10):4106-4114.

Slichter SJ, Kaufman R, Assmann SF, McCullough J, Triulzi DJ, Strauss RG, Gernsheimer TB, Ness PM, Brecher ME, Josephson CD, Konkle BA, Woodson RD, Ortel TL, Hillyer CD, Skerrett DL, McCrae KR, Sloan SR, Uhl L, George JN, Aquino VM, Manno C, McFarland JG, Hess JR, Leissinger C, Granger S. Dose of prophylactic platelet transfusions and prevention of hemorrhage. N Engl J Med 2010;362(7):600-613.

Slichter SJ, Bolgiano D, Kao K-J, Kickler TS, McFarland J, McCullough J, Woodson R. Persistence of lymphocytotoxic antibodies in patients in the Trial to Reduce Alloimmunization to platelets: Implications for using modified blood products. Transfus Med Rev 2011;25(2):102-110.

Slichter SJ, Bolgiano D, Corson J, Jones MK, Christoffel T. Extended storage of platelet-rich plasma prepared platelet concentrates in plasma or Plasmalyte. Transfusion 2010;50(10);2199-2209.

Dumont LJ, Dumont DF, Unger ZM, Siegel A, Szczepiorkowski ZM, Corson JS, Jones MK, Christoffel T, Pellham E, Bailey SL, Slichter SJ; for the BEST Collaborative. A randomized controlled trial comparing autologous radiolabeled in vivo platelet recoveries and survivals of 7-day stored platelet-rich plasma and buffy coat platelets from the same subjects. Transfusion 2011;51(6):1241-1248.

Slichter SJ. New thoughts on the correct dosing of prophylactic platelet transfusions to prevent bleeding. Curr Opin Hematol. 2011;18(6):427-435.

Schubert P, Culibrk B, Karwal S, Slichter SJ, Devine DV. Optimization of platelet concentrate quality: Application of proteomic technologies to donor management. J Proteomics 2012;76:329-336.

Slichter SJ, Pellham E, Bailey SL, Christoffel T. Filtration leukoreduction followed by pathogen-reduction (Mirasol treatment) prevents alloimmune platelet refractoriness in a dog platelet transfusion model. Blood 2012;120(21):271.

Slichter SJ, Bolgiano D, Corson J, Jones MK, Christoffel T, Pellham E. Extended storage of apheresis platelets in plasma. Vox Sang 2013;104(4):324-330.

Slichter SJ. Eliminate prophylactic platelet transfusions? Invited Editorial. N Engl J Med 2013;368(19):1837-1838.

Slichter SJ, Corson J, Jones MK, Christoffel T, Pellham E, Bailey SL, Bolgiano D. Extended storage of apheresis platelets in Plasmalyte. Blood, submitted.

Slichter SJ, Bolgiano D, Corson J, Jones MK, Christoffel T, Bailey SL, Pellham E. Extended storage of buffy-coat platelet concentrates in plasma or Plasmalyte. Transfusion, submitted.