Effect of enamel matrix derivative (EMD, Emdogain(R)) on the differentiation of cultured human periodontal ligament cells and mesenchymal stem cells

Park, Sang Gyu; Jue, Seong Suk; Kwon, Yong Dae; Choi, Byung Joon; Kim, Young Ran; Lee, Baek Soo

Abstract

INTRODUCTION: Enamel matrix derivative (EMD) is a protein which is secreted by Hertwig root sheath and plays a major role in the formation of cementum and attachment of peridontium. Several studies have shown that EMD promoted the proliferation and differentiation of preosteoblasts, osteoblasts and periodontal ligament cells in vitro; however, reports showing the inhibition of osteogenic differentiation by EMD also existed. This study was designed to simultaneously evaluate the effect of EMD on the two cell lines (human mesenchymal stem cells; hMSC, human periodontal ligament derived fibroblasts ; hPDLCs) by means of quantitative analysis of some bone related matrices (Alkaline phosphatase ; ALP , osteopontin ; OPN, osteocalcin ; OC).
MATERIALS AND METHODS
hMSCs and hPDLCs were expanded and cells in the 4~6 passages were adopted to use. hMSc and hPDLCs were cultured during 1,2,7, and 14 days with 0, 50 and 100 micro/ml of EMD, respectively. ALP activity was assessed by SensoLyte ALP kit and expressed as values of the relative optical density. Among the matrix proteins of the bony tissue, OC and OPN were assessed and quantification of these proteins was evaluated by means of human OC immunoassay kit and human OPN assay kit, respectively.
RESULTS
ALP activity maintained without EMD at 1,2nd day. The activity increased at 7th day but decreased at 14th day. EMD increased the activity at 14th day in the hPDLCs culture. In the hMSCs, rapid decrease was noted in 7th and 14th days without regard to EMD concentrations. Regarding the OPN synthesis in hPDLCs, marked decrease of OPN was noted after EMD application. Gradual decrease tendency of OPN was shown over time. In hMSCs, marked decrease of OPN was also noted after EMD application. Overall concentration of OPN was relatively consistent over time than that in hPDLCs. Regarding the OC synthesis, in both of hPDLCs and hMSCs, inhibition of OC formation was noted after EMD application in the early stages but EMD exerted minimal effect at the later stages.
CONCLUSION
In this experimental condition, EMD seemed to play an inhibitory role during the differentiation of hMSCs and hPDLCs in the context of OC and OPN formation. In the periodontium, there are many kinds of cells contributing to the regeneration of oral tissue. EMD enhanced ALP activity in hPDLCs rather than in hMSCs and this may imply that EMD has a positive effect on the differentiation of cementoblasts compared with the effect on hMSCs. The result of our research was consistent with recent studies in which the authors showed the inhibitory effect of EMD in terms of the differentiation of mineral colony forming cells in vitro. This in vitro study may not stand for all the charateristics of EMD; thus, further studies involving many other bone matrices and cellular attachment will be necessary.