Isolation, Characterization and MicroRNA-based Genetic Modification of Human Dental Follicle Stem Cells.

To date, several stem cell types at different developmental stages are in the focus for the treatment of degenerative diseases. Yet, certain aspects, such as initial massive cell death and low therapeutic effects, impaired their broad clinical translation. Genetic engineering of stem cells prior to transplantation emerged as a promising method to optimize therapeutic stem cell effects. However, safe and efficient gene delivery systems are still lacking. Therefore, the development of suitable methods may provide an approach to resolve current challenges in stem cell-based therapies. The present protocol describes the extraction and characterization of human dental follicle stem cells (hDFSCs) as well as their non-viral genetic modification. The postnatal dental follicle unveiled as a promising and easily accessible source for harvesting adult multipotent stem cells possessing high proliferation potential. The described isolation procedure presents a simple and reliable method to harvest hDFSCs from impacted wisdom teeth. Also this protocol comprises methods to define stem cell characteristics of isolated cells. For genetic engineering of hDFSCs, an optimized cationic lipid-based transfection strategy is presented enabling highly efficient microRNA introduction without causing cytotoxic effects. MicroRNAs are suitable candidates for transient cell manipulation, as these small translational regulators control the fate and behavior of stem cells without the hazard of stable genome integration. Thus, this protocol represents a safe and efficient procedure for engineering of hDFSCs that may become important for optimizing their therapeutic efficacy.

Extraction of mandibular premolars and molars: comparison between local infiltration via pressure syringe and inferior alveolar nerve block anesthesia.

OBJECTIVES: The purpose of this study was to evaluate the anesthetic efficiency of local infiltration anesthesia administered with a pressure syringe (P-INF) via a special technique versus direct block anesthesia of the inferior alveolar nerve (IANB) for tooth extraction in the posterior mandible. MATERIALS AND METHODS: In a prospective randomized study, 101 teeth in 101 patients were extracted in the posterior mandible under local anesthesia whereby two different administration techniques were used (P-INF n = 48; IANB n = 53). Primary objectives were comparisons of anesthetic success rate (yes/no) and efficacy (full/sufficient vs. insufficient). Secondary objectives were patients' pain perception during treatment, pain of injection (numerical rating scale), need for second injections (always IANB), time until onset of anesthetic action (min), and duration of local numbness (min). RESULTS: IANB was successful in all cases, whereas initial P-INF achieved 35% of success only. Furthermore, IANB reached significant higher values of anesthetic efficacy compared to P-INF (P < 0.001). Concerning pain of injection, patients rated IANB to be more painful (P = 0.039). Second injections were significantly more often necessary for P-INF (P = 0.006) whereas duration until onset of action as well as the duration of local numbness were found to be equal. CONCLUSIONS: For anesthetic efficacy as well as anesthetic success, block anesthesia of the inferior alveolar nerve (IANB) turned out to be more proficient to local infiltration via special delivering system with a special technique. CLINICAL RELEVANCE: Infiltration, even when performed with 4% articaine and a pressure syringe system, is not a suitable method of anesthesia in the posterior mandible.