Expression levels of CCL19, CCL21 and CCR7 in fibroblasts and their role in fibroblast proliferation. (A) Morphology of in vitro cultured fibroblasts via light microscopy. The original magnification is × 100. (B) A representative image of the expression of the fibroblast marker CD90 and CCR7 in AS LT fibroblasts. (C) RT-PCR and nucleic acid gel electrophoresis analyses revealed the expression of CCL19, CCL21 and CCR7 in 3 AS and 3 OA ligament fibroblast cultures. Blank corresponds to a control well containing no template cDNA. (D) ELISA revealed the secretion of CCL19 in 3 AS and 3 OA fibroblast cultures, and the experiments were repeated three times in duplicate. The data were calculated as the average value (CCL19 concentration) ± Standard deviation (SD). (E) Incubation of fibroblasts in various concentrations of CCL19 and CCL21 for 48 h. Cell proliferation was analyzed via the CCK8 assay as described in the Methods section. Cells cultured under standard growth conditions (growth medium) were used as the negative control. Additionally, mesangial (M) cells were used as the positive control. Changes in the proliferative activity were expressed as the values relative to the negative controls. Each result represents the mean ± SD of 4 parallel incubations for each condition. Comparable results were obtained from three independent experiments.