The effect of systemic corticosteroid treatment on the immunolocalisation of Notch-1, Delta, CD105 and CD166 in rat articular cartilage.

We studied the immunolocalisation of the stem cell-specific markers Notch-1, Delta, CD105 and CD166 in rat articular cartilage and analysed the effect of systemic corticosteroid treatment on the patterns of distribution of cells labelling for these markers. Female Wistar rats were separated randomly into two groups: the control group (n=8) was injected with isotonic salt solution and the corticosteroid group (n=8) was injected with 10 mg/kg intramuscular corticosteroid (methylprednisolone) once a week for a period of 8 weeks. Femoral head specimens from each group were obtained at the end of the treatment and processed for routine histological and immunohistochemical examinations. Quantitative data were obtained by H-SCORE and statistical evaluations were performed. The immunolocalisation of all markers was more apparent in the superficial zone and decreased through the deeper zones in all groups. However, the intensity of labelling was much less obvious in the group treated with corticosteroid compared to control. H-SCORE analysis confirmed that in the group treated with corticosteroid, the intensity of Notch-1, Delta, CD105 and CD166 labelling had decreased significantly compared to control (p<0.05). In conclusion, based on the immunolocalisation of stem cell-specific markers Notch-1, Delta, CD105 and CD166, the data suggest that the stem cells may continue to exist in adult rat articular cartilage. It was also observed that systemic corticosteroid treatment may effect the immunolabelling intensity of these markers, suggesting that corticosteroid treatment may reduce the function and the regenerative capacity of these cells in articular cartilage. 2009 Elsevier GmbH. All rights reserved.