title: Porphyromonas gingivalis can invade periodontal ligament stem cells.
abstract: BACKGROUND
  Porphyromonas gingivalis is strongly associated with the development, progression, severity and recurrence of periodontitis. Periodontal ligament stem cells (PDLSCs) play an important role in the maintenance of periodontal tissue self-renewal and repair. The purpose of this study was to investigate the ability of P. gingivalis to infect PDLSCs using an in vitro monolayer model.
  
  
  METHODS
  We separated and cultured primary PDLSCs using the tissue block with limiting dilution method. The efficiency of P. gingivalis (ATCC 33277) infection of PDLSCs was measured using agar plate culture and quantitative polymerase chain reaction (q-PCR) methods. PDLSCs infected with P. gingivalis were also observed by transmission electron microscopy.
  
  
  RESULTS
  We assessed stem cell properties including cell morphology, clone formation, growth activity, cell surface antigens and multiple differentiation capacity. The infection rates of P. gingivalis in PDLSC at MOIs of 50, 100, 200, and 500 were 5.83%, 8.12%, 7.77% and 7.53% according to the agar plate culture method. By q-PCR, the efficiencies of P. gingivalis infection of PDLSCs at MOIs of 50, 100, 200, and 500 were 6.74%, 10.56%, 10.36% and 9.78%, respectively. Overall, the infection efficiency based on q-PCR was higher than that according to agar plate culture. Using transmission electron microscopy, we verified that P. gingivalis (ATCC 33277) could infect and invade PDLSCs after 2 h of incubation, and endocytic vacuoles were not found surrounding the internalized bacteria.
  
  
  CONCLUSIONS
  In conclusion, our data demonstrate that P. gingivalis can invade PDLSCs.
authors.affiliation: Department of Periodontics, School of Stomatology, China Medical University, Shenyang, 110002, China. chunlingpan@163.com.
authors.forename: Chunling
authors.identifier: http://orcid.org/0000-0002-3835-9719
authors.initials: C
authors.lastname: Pan
authors.affiliation: Department of Periodontics, School of Stomatology, China Medical University, Shenyang, 110002, China.
authors.forename: Junchao
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Periodontics, School of Stomatology, China Medical University, Shenyang, 110002, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Periodontics, School of Stomatology, China Medical University, Shenyang, 110002, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Song
authors.affiliation: Department of Periodontics, School of Stomatology, China Medical University, Shenyang, 110002, China.
authors.forename: Lisi
authors.initials: L
authors.lastname: Tan
authors.affiliation: Department of Periodontics, School of Stomatology, China Medical University, Shenyang, 110002, China.
authors.forename: Haijiao
authors.initials: H
authors.lastname: Zhao
mesh_terms: D000293:Adolescent; D000328:Adult; D000954:Antigens, Surface; D016866:Bacteroidaceae Infections / Q000382:microbiology; D002453:Cell Cycle; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D054884:Host-Pathogen Interactions; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D046529:Microscopy, Electron, Transmission; D010513:Periodontal Ligament / Q000254:growth & development / Q000382:microbiology* / Q000473:pathology; D010518:Periodontitis / Q000382:microbiology* / Q000473:pathology; D016966:Porphyromonas gingivalis / Q000235:genetics / Q000472:pathogenicity*; D013234:Stem Cells / Q000473:pathology; D055815:Young Adult
chemical_list: D000954:Antigens, Surface
keywords: Periodontal ligament stem cells; Periodontitis; Porphyromonas gingivalis