Inhibition of metalloproteinase activity improves posttransfusion recovery of CCCP-treated and aged platelets. (A) Upper panel: survival of washed platelets incubated for 60 minutes with CCCP in the presence or absence of GM6001. Lower panel: survival of platelets aged in plasma in the presence or absence of GM6001. Upon treatment, platelets were labeled with calcein and infused into mice. Blood was drawn at different time points and analyzed by flow cytometry. Results are shown as percent calcein-labeled platelets ± SEM, n = 5. (B) Washed platelets were incubated for 60 minutes with DMSO, CCCP, or GM6001/CCCP, stained for their mitochondrial potential with JC-1,49 and analyzed immediately. JC-1 is a carbocyanine that, in its monomeric form, exhibits an emission maximum at 527 nm (Fl1). High mitochondrial potential promotes a directional uptake of JC-1 into the matrix and subsequent formation of J-aggregates (emission maximum: 590 nm, Fl2). Results are representative of 3 separate experiments. (C, D) Platelets were treated as indicated, stained with annexin V-FITC or RB40.34-FITC (anti-P-selectin) and analyzed on a FACScalibur. Results are representative of 5 experiments.