RECOVERY OF IN-VITRO FUNCTIONAL-ACTIVITY OF PLATELET CONCENTRATES STORED AT 4-DEGREES-C AND TREATED WITH 2ND-MESSENGER EFFECTERS

Background: The potential for bacterial contamination limits the stora ge of platelets at 22 degrees C to 5 days. Refrigerated storage at 4 d egrees C would abrogate this problem but would also result in a rapid loss of in vitro viability and functional activity and in vivo viabili ty. The inhibition of platelets during storage by a combination of spe cific, reversible, second-messenger effecters has been investigated to allow prolonged storage at 4 degrees C with significant retention of in vitro viability and functional activity. Study Design and Methods: The combination of effecters was added directly to platelet concentrat es, and this step was followed by storage at 4 degrees C. Control unit s were incubated at 4 degrees C without the effecters and at 22 degree s C according to standard blood-banking techniques. At 1, 5, and 9 day s, the units were tested for recovery of cell number, recovery of in v itro functional activity and viability, and expression of platelet sur face markers. Results: Treated platelets stored at 4 degrees C for 9 d ays, while spherical in shape, displayed no loss of cell number and ha d a recovery of viability and functional activity as compared with con trol platelets stored at 22 degrees C for 5 days, as follows: ADP and collagen aggregation responses of 250 and 100 percent, respectively; a 70-percent recovery of hypotonic shock response; and a 60-percent rec overy of extent of shape change. The treated platelets also expressed an equivalent amount of the surface marker glycoprotein Ib and a lower amount of the activation marker alpha-granule membrane protein-140 on the membrane surface. Conclusion: Second-messenger effecters added to platelets significantly maintained in vitro functional activity with storage at 4 degrees C. In vitro analysis demonstrates the potential f or extended 4 degrees C storage of platelets with numerical and functi onal recovery comparable to that achieved with current methods. Refrig erated storage of platelet concentrates has the potential to reduce th e risk of bacterial contamination.