Depletion of CCR2-positive cells reduces endocytic fibrin uptake.CCR2^+/RFP single-transgenic mice (N = 3) and CCR2^+/RFP;CCR2-depleter^+/0 bitransgenic littermates (N = 3), expressing the diphtheria toxin receptor selectively in CCR2-positive cells, were treated with diphtheria toxin and implanted with fluorescent fibrin. (A) Enumeration of CCR2-positive cells in fibrin implantation fields 24 hours after fibrin implantation. (B) Number of CCR2-positive (red bars) and CCR2-negative (gray bars, N = 3) cells 24 hours after implantation of fibrin into diphtheria toxin–treated CCR2^+/RFP transgenic mice (left bars) and CCR2^+/RFP;CCR2-depleter^+/0 bitransgenic littermates (right bars, N = 3). Crosshatched bars embedded within red and gray bars show fraction of, respectively, CCR2-positive and CCR2-negative cells that endocytose fibrin. Data in panel A are shown as individual data points and as mean values with standard deviations. Significance was determined by Student t test (2 tailed). (C-D) Representative examples of implantation fields of diphtheria toxin–injected CCR2^+/RFP single-transgenic mice (C) and CCR2^+/RFP;CCR2-depleter^+/0 bitransgenic littermates (D). Scale bars represent 10 μm.