New vistas in oral biology and regenerative medicine using immortalized odontogenic cell lines: a systematic review

Aim: To identify the immortalized cell lines of odontogenic origin, their immortalization methods and future directions. Methods: This systematic-review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered in Open Sciences Framework (DOI 10.17605/OSF.IO/MZ3T6). A broad-based search strategy was utilized using MeSH terms and keywords relate to the research question on five databases without any restrictions of languages and the year of publication. A search of the literature and reference searching were also done. The screening of the titles and abstracts were performed as per the defined inclusion criteria. A self-designed, pilot-tested form was used for data extraction and Toxicological Data Reliability Assessment Tool (ToxRTool) was used for the assessment of the risk of bias (ROB) in the included studies. Results: A total of 382 studies were screened and full texts of 45 articles were evaluated as per the inclusion and exclusion criteria. Finally, a total of 26 articles were included for the qualitative analysis. There were 13 studies related to cells of dental pulp or progenitor cells, 11 related to the cells of periodontium, and two related to ameloblasts. Among the included studies, 11 studies had been done on cells of animal origin (mouse, rat, cow and pig) while 15 had used cells of human origin. The most common method used for the immortalisation of cell lines was transfection of the cells with Simian virus (SV40) used in 14 of the 26 studies included in the systematic review. Another method was transduction with hTERT gene and transfection with human papilloma virus16 (HPV16). Among the included studies, 11 had low, 12 had moderate and 3 had high risk of bias. Conclusion: The present systematic review observed that the majority of work has been done on the odontogenic cells of human origin, especially in the cells of periodontium, with transfection by SV40 and HPV16 virus sequence being the commonest methods of immortalization. These cells have been envisaged for understanding the molecular biological characteristics and cellular pathways and along with their applications in regenerative medicine.