Interaction of long-term stored platelets with vascular subendothelium

Platelets stored as platelet-rich plasma under mildly alkaline conditions in vitro maintain morphologic integrity and functional capability for 2 to 3 weeks. We used the Baumgartner method to assess the ability of long-term stored platelets to interact with exposed vascular subendothelium. After 3 days in storage the size and number of thrombi on damaged surfaces decreased. However, the percentage of vascular surface covered was not reduced significantly until the cells had been stored for 14 days. Treatment of vascular segments with chymotrypsin to increase thrombogenicity caused platelets stored for 14 days to adhere and form aggregates on denuded surfaces in a manner similar to that of fresh platelets, but the ability to develop thrombi remained depressed. Thus long-term storage that maintains physical and functional integrity also preserves a reasonable capacity of platelets to interact with damaged blood vessels.