Stem cells of the dental pulp.

Stem cells of the dental pulp are a population of postnatal stem cells with multilineage differentiation potential. These cells are derived from the neural ectomesenchyme, similar to most craniofacial tissues, and specific niches in the pulp have been identified. Since the isolation of dental pulp stem cells (DPSC) and stem cells from exfoliating deciduous teeth (SHED), numerous studies have attempted to define and characterize these cells, and embryonic stem cell features have been reported in both DPSC and SHED. These cells have a vast repertoire of differentiation - osteogenic, odontogenic, myogenic, adipogenic, neurogenic, and melanocytic, and have even demonstrated transdifferentiation to corneal cells and islet cells of pancreas. The combined advantages of multipotency/pluripotency and the relative ease of access of pulp tissue for autologous use render DPSC/ SHED attractive options in regenerative dentistry and medicine. This review gives a bird's eye view of current knowledge with respect to stem cells from the dental pulp.

Immunohistochemical detection of human telomerase reverse transcriptase in oral cancer and pre-cancer.

Purpose: Telomerase is a specialized ribonucleoprotein complex that stabilizes telomeres by adding "TAG" repeats to the end of chromosomes. The catalytic subunit of telomerase is human telomerase reverse transcriptase (hTERT), whose expression is the critical determinant of telomerase activity. Telomeres and telomerases play an important role in the longevity of cell and are known to conform "immortalization" on neoplastic cells. Although there exists a lot of information on telomerase in oral cancer, very little is known about their expression in leukoplakia and oral submucous fibrosis (OSF). This study addresses this lacuna. Materials and Methods: In this preliminary study, immunohistochemistry (IHC) was used to detect the expression of hTERT protein in oral squamous cell carcinoma (OSCC) (n=30), leukoplakia (n=15), OSF (n=15) and normal oral mucosa (n=10). The cellular localization of immunostain, intensity of stain, mean nuclear labeling index (LI) and mean nuclear labeling score (LS) of hTERT protein were studied. A total number of 1000 cells were counted in each slide. All the data were analyzed using SPSS software version 10.0.2. The cellular localization of cytoplasmic/nuclear/both of hTERT stain, staining intensity and LI were compared across the groups using Pearson's χ2 test. The mean LI and LS for OSF, leukoplakia, OSCC and normal were compared using analysis of variance (ANOVA). A P-value <0.05 was considered to be statistically significant. Results: The mean nuclear LI increased from OSF (22.46±4.53), through normal (28.3±12.3) to OSCC (47.56±21.30) (P=0.002) and from normal (28.3±12.3), through leukoplakia (44.06±14.6), to OSCC (47.56±21.30) (P=0.00). The mean nuclear labeling score was observed to increase from OSF (37.8±15), through normal (64.9±30.7), to OSCC samples (106.9±29.77) (P=0.00) and from normal (64.9±30.7), through leukoplakia (85.6±25.1) to OSCC samples (106.9±29.77) (P=0.00). Conclusion: There was increased expression of hTERT protein in OSCC and leukoplakia samples when compared to normal oral mucosa. The cellular localization, LI and LS in OSF were significantly different from OSCC and leukoplakia.