DEVELOPMENT AND CHARACTERIZATION OF A TRANSFORMED HUMAN PERIODONTAL-LIGAMENT CELL-LINE

PERIODONTAL LIGAMENT (PDL) CELLS ARE THOUGHT to be important for estab lishing and maintaining a stable interface between tone and teeth. In addition, PDL cells are thought to play critical roles in both the pat hogenesis of periodontal disease and the regeneration ai periodontal l igament tissues; The purpose of this study was to develop a continuous or stable human PDL cell line as an in vitro model for the investigat ion of cellular-mechanisms involved in periodontal regeneration and de struction. Human PDL cells, derived rom a primary cell culture, were t ransfected with simian virus 40 (SV40) T antigen-containing virus with a neomycin resistance gene. The transformed cells expressed the SV40 T antigen mRNA as assayed by reverse transcription polymerase chain re action (RT-PCR). This cell line was also characterized for morphologic al changes and growth characteristics compared to primary PDL cell cul tures. The transformed cells were shown to form a multilayer pattern a nd distinct colonies on tissue culture surfaces. However, no colony fo rmation was found in soft agar. The transformed PDL cell line was foun d to have a greater rate of proliferation in 10% fetal bovine serum th an primary culture, and continued to proliferate in low serum concentr ations capable of producing quiescence in primary cells. Interleukin-1 beta (IL-1 beta) was shown to produce a 7-fold elevation in collagena se (MMP-I) mRNA levels, consistent with primary PDL cells. In addition , IL-1 beta was shown to produce a decrease in alkaline phosphatase ac tivity in a concentration-dependent manlier: The transformed cell line has been maintained for over 30 generations of cell culture. in concl usion, a stable human PDL cell line has been established to serve as a model for future in vitro investigations into periodontal pathogenic mechanism and to evaluate therapies directed at the regeneration of pe riodontal ligament.