Correlation of in vitro platelet quality measurements with in vivo platelet viability in human subjects

BACKGROUND AND OBJECTIVES: Changes in in vitro platelet quality parameters during platelet storage are associated with a decrease of in vivo platelet viability after platelet transfusion. Many attempts have been made to identify the most predictable in vitro parameters for in vivo performance. We used a riboflavin-based ultraviolet (UV) light treatment process designed to inactivate pathogens and white blood cell (WBC) contaminants in blood products as a model system in which to study the correlation of in vitro cell quality with in vivo viability. MATERIALS AND METHODS: Platelet products (n = 18) were collected by a standard Trima apheresis procedure and treated with one of three dose levels of UV light (0, 7.2 or 12.4 J/ml) in the presence of 50 microm riboflavin. Lactate production, glucose consumption and P-selectin expression, pH, pCO(2), pO(2), hypotonic shock response and swirl were measured during 5 days of platelet storage post-UV/RB treatment. Aliquots of these products were radiolabelled on day 5 of storage and were subsequently used to determine platelet recovery and survival time in autologous subjects. RESULTS: The responses of in vitro cell quality were observed to occur in a UV dose-dependent manner. Lactate production and pH were identified as the parameters most strongly correlated with platelet in vivo recovery, which ranged from 5 to 82%. The correlation coefficients (r) for lactate production and pH with in vivo recovery in human subjects were 0.9090 and 0.8831 with P-values of 0.007 and 0.031, respectively. Lactate production and pH were also found to be correlated with platelet survival time, with correlation coefficients of 0.8063 and 0.8384 (the P values were 0.01 and 0.001, respectively). CONCLUSIONS: Using conditions of riboflavin-based UV light treatment, lactate production and pH were identified as having the highest correlations with recovery and survival of radiolabelled platelets in healthy subjects.