Biological differences between fibroblasts derived from peripheral and central areas of keloid tissues

Background: Clinical observations indicate that the bulging and reddish peripheral areas of keloids are more elevated than their central areas. Moreover, the peripheral areas of keloids undergo aggressive growth and invasion into normal skin, beyond the boundaries of the initial wound. The aim of this study was to investigate the biological differences between peripheral and central keloid areas. Methods: Six patients suffering from keloids on the anterior chest were selected for this study. Fibroblasts were harvested from both central and peripheral keloid areas. Cell cycle distribution and apoptosis induction were analyzed by flow cytometry and with an antibody to Fas. The expression of apoptosis-related proteins (Fas, Bcl-2, and p53) was measured by flow cytometry. Results: Fibroblasts derived from both central and peripheral parts of keloids displayed significant resistance to Fas-mediated apoptosis. Analysis of cell cycle distribution indicated that approximately 60 percent of fibroblasts derived from the peripheral parts of keloids were in the proliferative periods of the cell cycle (G, and S phase). However, the majority of fibroblasts derived from keloid centers were in Go or G, phase. Fas and Bcl-2 expression did not differ significantly between the two groups, but p53 expression was much higher in fibroblasts derived from central parts than from peripheral parts. Conclusion: It is suggested that differences in cell cycle distribution and p53 protein expression may account for the different growth characteristics of keloid peripheries and centers.