Exploring the impact of oral bacteria remnants on stem cells from the Apical papilla: mineralization potential and inflammatory response

Valeriia Zymovets; Olena Rakhimova; Philip Wadelius; Alexej Schmidt; Malin Brundin; Peyman Kelk; Maréne Landström; Nelly Romani Vestman

doi:10.3389/fcimb.2023.1257433

Exploring the impact of oral bacteria remnants on stem cells from the Apical papilla: mineralization potential and inflammatory response

Front Cell Infect Microbiol. 2023 Nov 27:13:1257433. doi: 10.3389/fcimb.2023.1257433. eCollection 2023.

Authors

Affiliations

¹ Department of Odontology, Umeå University, Umeå, Sweden.
² Department of Endodontics, Region of Västerbotten, Umeå, Sweden.
³ Department of Medical Biosciences, Pathology, Umeå University, Umeå, Sweden.
⁴ Section for Anatomy, Department of Integrative Medical Biology (IMB), Umeå University, Umeå, Sweden.
⁵ Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden.

^# Contributed equally.

Abstract

Introduction: Bacterial persistence is considered one of the main causal factors for regenerative endodontic treatment (RET) failure in immature permanent teeth. This interference is claimed to be caused by the interaction of bacteria that reside in the root canal with the stem cells that are one of the essentials for RET. The aim of the study was to investigate whether prolonged exposure of stem cells from the apical papilla (SCAP) to bacterial remnants of Fusobacterium nucleatum, Actinomyces gerensceriae, Slackia exigua, Enterococcus faecalis, Peptostreptococcaceae yurii, commonly found in infected traumatized root canals, and the probiotic bacteria Lactobacillus gasseri and Limosilactobacillus reuteri, can alter SCAP's inflammatory response and mineralization potential.

Methods: To assess the effect of bacterial remnants on SCAP, we used UV-C-inactivated bacteria (as cell wall-associated virulence factors) and bacterial DNA. Histochemical staining using Osteoimage Mineralization Assay and Alizarin Red analysis was performed to study SCAP mineralization, while inflammatory and osteo/odontogenic-related responses of SCAPs were assessed with Multiplex ELISA.

Results: We showed that mineralization promotion was greater with UV C-inactivated bacteria compared to bacterial DNA. Immunofluorescence analysis detected that the early mineralization marker alkaline phosphatase (ALP) was increased by the level of E. coli lipopolysaccharide (LPS) positive control in the case of UV-C-inactivated bacteria; meanwhile, DNA treatment decreased the level of ALP compared to the positive control. SCAP's secretome assessed with Multiplex ELISA showed the upregulation of pro-inflammatory factors IL-6, IL-8, GM-CSF, IL-1b, neurotrophic factor BDNF, and angiogenic factor VEGF, induced by UV-C-killed bacteria.

Discussion: The results suggest that long term stimulation (for 21 days) of SCAP with UV-C-inactivated bacteria stimulate their mineralization and inflammatory response, while DNA influence has no such effect, which opens up new ideas about the nature of RET failure.

Keywords: SCAP; bacterial DNA; bacterial remnants; inflammation; mineralization; oral bacteria.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Cell Differentiation / genetics
Cell Proliferation
Cells, Cultured
DNA, Bacterial
Escherichia coli* / genetics
Osteogenesis*
Stem Cells / physiology

Substances

DNA, Bacterial

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This research was funded by the Knut and AliceWallenberg Foundation (project number 7003503, the Region of Vasterbotten (Sweden) via ALF grant number 7004361(NV) and 98263 (ML), Kempestiftelserna Kempe SMK-1966 and the research fund of the County Council of Vasterbotten (Project Number: 7003459 and 7003589).