Enamel matrix derivative (EMD: Emdogain®) is well recognized in periodontology where it is used as a local adjunct to periodontal surgery to stimulate regeneration of periodontal tissues lost to periodontal disease. The biological effect of EMD is through stimulation of local growth factor secretion and cytokine expression in the treated tissues, inducing a regenerative process that mimics odontogenesis.
In this study we want to identify the effect of EMD on the newly discovered adipokine/cytokine resistin, and try to identify the bioactive fraction of EMD.
Normal human osteoblasts (NHO), mesenchymal stem cells (MSC) and monocytes were incubated with EMD at various concentrations ranging from 10-100 µg/ml and harvested after 6 hours, 1, 2, 3, and 7 days. EMD were divided in 13 fractions on a size exclusion column. The effect of each fraction, containing material equivalent to the content found in 10 µg/ml EMD, were tested on NHO cells after 1, 2 and 3 days incubation and compared to the effect of EMD (10 µg/ml) and untreated cells.
2 mg EMD was injected intramuscular (gluteus maximus) of rats every 3th day for 14 days. Resistin levels in blood samples were measured after 1, 3, 6 and 14 days.
The levels of resistin in cell culture medium were measured by Luminex, an immunobased fluorescent technique, and the level of resistin in rat plasma was measured by the Rat resistin ELISA kit (UM-104101). Further, the total protein content and ALP activity in the cell culture medium were measured.
In NHO and MSC cells treated with EMD, the resistin concentration in cell culture medium was highly increased compare to untreated cells. We were not able to identify a specific EMD fraction causing the same increase in resistin as EMD. We observed no significant changes in resistin levels in monocytes treated with EMD.
In rats injected with EMD intramuscularly, we found a significant increase in circulating resistin levels, compared to rats receiving saline.
Our results indicate that cells of mesenchymal origin respond to EMD with increased resistin secretion, whereas cells of hematopoietic origin do not.