Characterization of a clonal human periodontal ligament stem cell line exposed to methacrylate resin-, bioactive glass-, or silicon-based root canal sealers

[Abstract] The aim of this study was to characterize a clonal human periodontal ligament (PDL) stem cell line (line 2 - 23 cells) cultured with root canal sealers based on methacrylate resin (SuperBond sealer; SB), bioactive glass (Nishika Canal Sealer BG; BG), or silicon (GuttaFlow 2; GF). The sealers were set in rubber molds to form sealer discs. Line 2 - 23 cells were cultured with or without the discs for 3 days. The cell viability was evaluated by direct cell counting and MTT assay. Inflammation-, PDL-, collagen-, and cell cycle-related gene expression was investigated by real-time RT-PCR. Collagen production was analyzed by Picro Sirius Red staining. Calcium ion concentration in the culture was measured by a QuantiChrom calcium assay kit. Line 2 - 23 cells survived when cultured with GF discs, but decreased cell viability was observed with SB and BG discs. The expression of inflammation-related genes was higher in cells cultured with SB discs, and expression of PDL-related genes was lower in cells exposed to SB and BG discs. These discs also down-regulated collagen production in line 2 - 23 cells. BG discs increased calcium ion concentration in the culture medium. Cells exposed to GF discs exhibited the same inflammation-, PDL-, collagen-, and cell cycle-related gene expression and collagen production as untreated cells. These results suggested that the characteristics of line 2 - 23 cells cultured with GF discs was highly resemble to untreated cells throughout the 3 days of the culture model.