In vivo recoveries and survivals of murine platelets. (A) In vivo recovery and survival of galactosylated murine platelets. Enzymatic galactosylation of murine platelets does not restore the survival of platelets stored at 4°C for 48 hours and transfused into mice (▴), compared with platelets incubated with the control donor sugar UDP-glucose (▵) (n = 6). The survival of washed 4-hour-chilled platelets glycosylated with UDP-galactose (●) and UDP-glucose (○) in plasma, respectively, is also shown as well as the survival of fresh platelets (■) (n = 6). (B) In vivo recovery and survival of unmodified cold-stored murine platelets. Survival of unmodified murine platelets stored as PRP at 4°C for 4 hours (×; n = 4), 24 hours (▵; n = 6), and 48 hours (○; n = 6). For comparison, the survival of fresh platelets is also shown (□; n = 3). (Inset) Platelets refrigerated for 48 hours retain CMFDA fluorescence. Platelets were stained with CMFDA and the platelet-associated fluorescence was measured immediately (control, solid line) and after 48 hours at 4°C (48 hours, 4°C, dashed line). (C) In vivo recovery and survival of murine platelets in wild-type and α_Mβ₂ integrin receptor knockout mice. The 48-hour, cold-stored murine platelets do not circulate in α_Mβ₂ integrin receptor knockout mice. CMFDA-labeled galactosylated platelets stored for 48 hours at 4°C (closed symbols) or fresh platelets (used as a control) (open symbols) were transfused into mice lacking the αMβ2 integrin receptor (MAC-1 KO) (▴, ▵) or into wild-type (WT) mice (●, ○), respectively (n = 3).