Enhanced Shear-induced Platelet Aggregation Due to Low-temperature Storage
ARMY INST OF SURGICAL RESEARCH FORT SAM HOUSTON TX
Pagination or Media Count:
BACKGROUND Refrigeration of platelets PLTs offers an attractive alternative to the currently practiced storage at room temperature since it may mitigate problems associated with bacterial contamination and extend storage lifetime. Refrigeration causes a number of biophysical and biochemical changes in PLTs and decreases PLT circulation time in vivo. However, the effect of refrigeration on PLT hemostatic functions under physiologic and pathophysiologic shear conditions has not been adequately characterized. STUDY DESIGN AND METHODS Washed PLTs prepared from either fresh PLT-rich plasma PRP or PRP stored at 4 C for 2 days was mixed with exogenous von Willebrand factor VWF and fibrinogen and sheared in a cone-and-plate viscometer. PLT aggregation, activation, and VWF binding after shear and glycoprotein GP Iba receptor expression and ristocetin-induced PLT agglutination were measured. RESULTS PLTs stored at 4 C for 2 days aggregated significantly more than fresh PLTs particularly at high shear rates 10,000sec, and this increase was independent of PLT concentration or suspension viscosity. Further, refrigerated PLTs showed a greater increase in GP Iba dependent PLT activation under shear and also bound more VWF than fresh PLTs. However, the GP Iba expression levels as measured by three different antibodies were significantly lower in refrigerated PLTs than in fresh PLTs, and refrigeration resulted in a modest decrease in ristocetin-induced PLT agglutination. CONCLUSION The combined results demonstrate that refrigeration increases PLT aggregation under high shear, but not static, conditions and also increases shear-induced VWF binding and PLT activation. Clinically, enhanced shear-induced PLT aggregation due to low temperature storage may be a beneficial strategy to prevent severe bleeding in trauma.
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