Effects of Porphyromonas gingivalis Lipopolysacharide on Dental Follicle Progenitor Cells

The identification of dental follicle progenitor cells (DFPCs) has stimulated interest in their potential use in stem cell-based therapies to treat periodontitis. However, the inflammatory state of periodontal disease displays a major challenge to such therapeutical approaches. Objectives: In this study, we challenged human DFPCs with Porphyromonas gingivalis lipopolysaccharide (P.g-LPS) - a major etiological factor in periodontitis - and assayed the response of DFPCs in terms of viability and secretion of interleukin-6 (IL-6), a pleiotropic cytokine that is considered as an osteolytic factor involved in periodonitis. Methods: Human DFPCs were obtained from extracted wisdom teeth and characterized. Second passage cells were subsequently stimulated with different concentrations of P.g.-LPS (0 μg/ml, 1 μg/ml, 10 μg/ml and 50 μg/ml) respectively. After 24 hours of incubation cytotoxicity assays (MTT) were performed and concentration of secreted IL-6 in culture supernatants was determined by a specific enzyme-linked immunosorbent assay (ELISA). Human mesenchymal stem cells (MSCs) were used as a control group. Results: DFPCs were able to attach onto plastic surface, showed a typical fibroblast-like morphology and formed single-cell colonies. Furthermore, DFPCs could differentiate into adipocytes, osteoblasts and chondrocytes and were strongly positive to typical stem cell markers (CD29, CD44, CD73, CD90 and CD105). Interestingly, after LPS challenge no secretion of IL-6 was detected in the supernatants of DFPCs, while ELISA demonstrated the secretion of IL-6 by MSCs in a concentration-dependent manner. In terms of cytotoxicity, the challenge with LPS showed no statistically significant influence on both cell populations. Conclusion: The findings of this study indicate that P.g.-LPS do not affect DFPCs regarding their viability and IL-6 secretion.