Figure 1. Tumor necrosis factor-alpha (TNF-α) and Advanced glycation endproduct (AGE) induce apoptosis in pericytes in vitro. Primary bovine retinal pericytes were incubated with the indicated concentration of (A) TNF-α (0–20 ng/ml) or (B) carboxymethyllysine (CML)-collagen or unmodified collagen (0–400 μg/ml) . Cells were lysed after 24 h and apoptosis was measured by ELISA measurement of histone-associated cytoplasmic DNA. C: Caspase-3 activity was measured by fluorometric assays in lysates from cultured primary bovine retinal pericytes incubated with CML-collagen, unmodified collagen (200 μg/ml), or TNF-α (20 ng/ml) for 24 h. Each value represents the mean of five replicates±standard error of the mean. The experiment was performed three times with similar results. *, p<0.05 significantly differs from control unstimulated cells or unmodified control collagen.