Effect of cyclosporin A on proliferation and differentiation of human periodontal ligament cells

Objective. Cyclosporin A (CsA) is widely used to prevent rejection after organ transplantation. However, it also causes several side-effects, including gingival overgrowth and bone resorption. Cellular mechanisms underlying the effect of CsA on periodontal tissue remain unclear. In this study, we investigated the effect of CsA on the proliferation and expression of characteristic markers in periodontal ligament cells (PDLs). Material and methods. The proliferation and viability of PDLs were measured by direct cell counting and 3,4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide assay, respectively. mRNA expression levels of the specific proteins alkaline phosphatase (ALP), osteocalcin (OC) and collagen type 1 (Coll-1) were quantified using real-time polymerase chain reaction. Finally, ALP activity of PDLs was investigated using a specific colorimetric assay. Results. We found that proliferation of PDLs was stimulated by 0.01-0.1 mu g/ml CsA and unaffected by 1 mu g/ml CsA. The viability of PDLs was increased by 0.1 mu g/ml CsA and not affected by 0.01 mu g/ml and 1 mu g/ml CsA. Furthermore, the mRNA expression levels of ALP, OC and Coll-1 in PDLs were significantly increased upon stimulation with 0.1 mu g/ml CsA for 24 h or by stimulation with 0.01 mu g/ml CsA for 48 h. In contrast, significantly lower expression levels of all three proteins in PDLs were observed upon stimulation with 1 mu g/ml CsA for 48 h. The ALP activity of PDLs exhibited a similar pattern of changes upon CsA stimulation. Conclusion. Our data demonstrated that CsA may influence both the proliferation and differentiation of human PDLs, which may play an important role in the homeostasis of periodontal tissue.