Cross-contamination of the human salivary gland HSG cell line with HeLa cells: A STR analysis study.

OBJECTIVES: The human salivary gland (HSG) cell line, labeled as a submandibular ductal cell line, is commonly used as in vitro models to study radiation therapy, Sjögren's syndrome, pleomorphic adenoma, mucocele, epithelial-to-mesenchymal transition, and epigenetics. However, the American Type Culture Collection (ATCC) has recently released a list of cross-contaminated cell lines that included HSG. Despite this notice, some research laboratories still use HSG as a salivary cell model. Therefore, this study examined the authenticity of HSG sampled from three different laboratories. METHODS: DNA was extracted from HSG and additional salivary cell lines (NS-SV-AC, NS-SV-DC, A253, HSY) and submitted for cell line authentication with short tandem repeat (STR) analysis. RESULTS: All HSG samples had STR profiles indicating >80% match with HeLa in both the ATCC and Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ) databases. This confirmed that HSG sampled from three different laboratories and HSY shared a common ancestry (host) with HeLa, whereas NS-SV-AC, NS-SV-DC, and A253 had unique STR profiles. CONCLUSION: Short tandem repeat analysis revealed that HSG was contaminated by the HeLa cell line. Furthermore, because genotyping of the original HSG cell line was not performed during its establishment, it will be difficult to authenticate an uncontaminated sample of HSG.

A meta-analysis of retention systems for implant-supported prostheses in partially edentulous jaws.

STATEMENT OF PROBLEM: Choosing an appropriate retention system for patients with partial edentulism and dental implants is impeded by a paucity of evidence. The available evidence is extrapolated from either completely edentulous or mixed study populations. PURPOSE: The purpose of this systematic review was to assess the effects of different retention systems used for implant-supported prostheses in patients with partially edentulous jaws by measuring the rates of failure, survival, and event-free situations. MATERIAL AND METHODS: An electronic database search supplemented by a manual search was conducted to identify the best, good, and fair quality studies reporting at least 10 participants with a 1-year follow-up (PROSPERO-CRD 42015024649). Summary estimates of the survival, failure, and event-free proportions were obtained using a random effects model with a 95% confidence interval. RESULTS: Among the 896 citations from 3875 titles identified by the search, 104 studies reporting over 5317 participants with 9568 reconstructions and a total exposure time of 46553.18 years were included in the analysis. Screw-retained single crowns showed twofold minor complication even rates (8.5%; 95% confidence interval [CI]: 5.5-12.9) compared with cement-retained single crowns (4.2%. 95% CI; 3.2-5.4). None of the retention systems were more advantageous than the others in relation to failure and event-free outcomes. However, the summary of the findings suggests that cement-retained single crowns, splinted crowns, and cantilever-fixed partial dentures performed better (with fewer events) than screw-retained restorations in the long term. CONCLUSIONS: Results suggest that cement retention may be an appropriate system for implant-supported restorations in partial edentulism. However, high-quality prospective studies and cost evaluation are recommended to confirm the evidence.

A Simplified and Systematic Method to Isolate, Culture, and Characterize Multiple Types of Human Dental Stem Cells from a Single Tooth.

This chapter describes a simplified method that allows the systematic isolation of multiple types of dental stem cells such as dental pulp stem cells (DPSC), periodontal ligament stem cells (PDLSC), and stem cells of the apical papilla (SCAP) from a single tooth. Of specific interest is the modified laboratory approach to harvest/retrieve the dental pulp tissue by minimizing trauma to DPSC by continuous irrigation, reduction of frictional heat from the bur rotation, and reduction of the bur contact time with the dentin. Also, the use of a chisel and a mallet will maximize the number of live DPSC for culture. Steps demonstrating the potential for multiple cell differentiation lineages of each type of dental stem cell into either osteocytes, adipocytes, or chondrocytes are described. Flow cytometry, with a detailed strategy for cell gating and analysis, is described to verify characteristic markers of human mesenchymal multipotent stromal cells (MSC) from DPSC, PDLSC, or SCAP for subsequent experiments in cell therapy and in tissue engineering. Overall, this method can be adapted to any laboratory with a general setup for cell culture experiments.

Osteogenic Potential of Dental Mesenchymal Stem Cells in Preclinical Studies: A Systematic Review Using Modified ARRIVE and CONSORT Guidelines.

Background and Objective. Dental stem cell-based tissue engineered constructs are emerging as a promising alternative to autologous bone transfer for treating bone defects. The purpose of this review is to systematically assess the preclinical in vivo and in vitro studies which have evaluated the efficacy of dental stem cells on bone regeneration. Methods. A literature search was conducted in Ovid Medline, Embase, PubMed, and Web of Science up to October 2014. Implantation of dental stem cells in animal models for evaluating bone regeneration and/or in vitro studies demonstrating osteogenic potential of dental stem cells were included. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were used to ensure the quality of the search. Modified ARRIVE (Animal research: reporting in invivo experiments) and CONSORT (Consolidated reporting of trials) were used to critically analyze the selected studies. Results. From 1914 citations, 207 full-text articles were screened and 137 studies were included in this review. Because of the heterogeneity observed in the studies selected, meta-analysis was not possible. Conclusion. Both in vivo and in vitro studies indicate the potential use of dental stem cells in bone regeneration. However well-designed randomized animal trials are needed before moving into clinical trials.