Trophic Effects of Dental Pulp Stem Cells on Schwann Cells in Peripheral Nerve Regeneration.

Recently, mesenchymal stem cells have demonstrated a potential for neurotrophy and neurodifferentiation. We have recently isolated mobilized dental pulp stem cells (MDPSCs) using granulocyte-colony stimulating factor (G-CSF) gradient, which has high neurotrophic/angiogenic potential. The aim of this study is to investigate the effects of MDPSC transplantation on peripheral nerve regeneration. Effects of MDPSC transplantation were examined in a rat sciatic nerve defect model and compared with autografts and control conduits containing collagen scaffold. Effects of conditioned medium of MDPSCs were also evaluated in vitro. Transplantation of MDPSCs in the defect demonstrated regeneration of myelinated fibers, whose axons were significantly higher in density compared with those in autografts and control conduits only. Enhanced revascularization was also observed in the MDPSC transplants. The MDPSCs did not directly differentiate into Schwann cell phenotype; localization of these cells near Schwann cells induced several neurotrophic factors. Immunofluorescence labeling demonstrated reduced apoptosis and increased proliferation in resident Schwann cells in the MDPSC transplant compared with control conduits. These trophic effects of MDPSCs on proliferation, migration, and antiapoptosis in Schwann cells were further elucidated in vitro. The results demonstrate that MDPSCs promote axon regeneration through trophic functions, acting on Schwann cells, and promoting angiogenesis.

Isolation of a stable subpopulation of mobilized dental pulp stem cells (MDPSCs) with high proliferation, migration, and regeneration potential is independent of age.

Insights into the understanding of the influence of the age of MSCs on their cellular responses and regenerative potential are critical for stem cell therapy in the clinic. We have isolated dental pulp stem cells (DPSCs) subsets based on their migratory response to granulocyte-colony stimulating factor (G-CSF) (MDPSCs) from young and aged donors. The aged MDPSCs were efficiently enriched in stem cells, expressing high levels of trophic factors with high proliferation, migration and anti-apoptotic effects compared to young MDPSCs. In contrast, significant differences in those properties were detected between aged and young colony-derived DPSCs. Unlike DPSCs, MDPSCs showed a small age-dependent increase in senescence-associated ß-galactosidase (SA-ß-gal) production and senescence markers including p16, p21, Interleukin (IL)-1ß, -6, -8, and Groα in long-term culture. There was no difference between aged and young MDPSCs in telomerase activity. The regenerative potential of aged MDPSCs was similar to that of young MDPSCs in an ischemic hindlimb model and an ectopic tooth root model. These results demonstrated that the stem cell properties and the high regenerative potential of MDPSCs are independent of age, demonstrating an immense utility for clinical applications by autologous cell transplantation in dental pulp regeneration and ischemic diseases.

A novel combinatorial therapy with pulp stem cells and granulocyte colony-stimulating factor for total pulp regeneration.

Treatment of deep caries with pulpitis is a major challenge in dentistry. Stem cell therapy represents a potential strategy to regenerate the dentin-pulp complex, enabling conservation and restoration of teeth. The objective of this study was to assess the efficacy and safety of pulp stem cell transplantation as a prelude for the impending clinical trials. Clinical-grade pulp stem cells were isolated and expanded according to good manufacturing practice conditions. The absence of contamination, abnormalities/aberrations in karyotype, and tumor formation after transplantation in an immunodeficient mouse ensured excellent quality control. After autologous transplantation of pulp stem cells with granulocyte-colony stimulating factor (G-CSF) in a dog pulpectomized tooth, regenerated pulp tissue including vasculature and innervation completely filled in the root canal, and regenerated dentin was formed in the coronal part and prevented microleakage up to day 180. Transplantation of pulp stem cells with G-CSF yielded a significantly larger amount of regenerated dentin-pulp complex compared with transplantation of G-CSF or stem cells alone. Also noteworthy was the reduction in the number of inflammatory cells and apoptotic cells and the significant increase in neurite outgrowth compared with results without G-CSF. The transplanted stem cells expressed angiogenic/neurotrophic factors. It is significant that G-CSF together with conditioned medium of pulp stem cells stimulated cell migration and neurite outgrowth, prevented cell death, and promoted immunosuppression in vitro. Furthermore, there was no evidence of toxicity or adverse events. In conclusion, the combinatorial trophic effects of pulp stem cells and G-CSF are of immediate utility for pulp/dentin regeneration, demonstrating the prerequisites of safety and efficacy critical for clinical applications.

Identification of novel function of vimentin for quality standard for regenerated pulp tissue.

INTRODUCTION: Pulp stem/progenitor cells have been successfully transplanted after pulpectomy in dogs and have led to pulp regeneration. The regenerated pulp tissue was investigated by the qualitative and quantitative protein expression patterns in comparison with those of normal pulp. There is an unmet need for a quality standard for regenerated pulp tissue. METHODS: Three distinct human CD105(+) stem/progenitor cells from dental pulp, bone marrow, and amnion were compared by 2-dimensional electrophoresis and the differential proteomic expression profiles. The protein identified with high confidence in pulp CD105(+) cells was examined by immunohistochemistry and real-time reverse-transcription polymerase chain reaction in regenerated pulp tissue compared with normal pulp. Its migration effect was further examined in pulp CD105(+) cells using small interfering RNA techniques to knock down the protein. RESULTS: Nine protein spots were detected solely in pulp CD105(+) cells; one of these was identified as vimentin. The expression of vimentin messenger RNA was highest in pulp tissue among a variety of human tissues and higher in pulp CD105(+) cells compared with other CD105(+) cells and unfractionated total pulp cells. Pulp cells and endothelial cells were positively stained with vimentin in regenerated pulp tissue similarly as those in normal pulp tissue. The expression of vimentin in regenerated pulp was similar to normal pulp. RNA interference knock down of vimentin expression in pulp CD105(+) cells significantly reduced the migration activity. CONCLUSIONS: The highest expression of vimentin in pulp tissue among other tissues and its migration effect in pulp stem cells suggest that it is a quality standard for pulp regeneration and pulp cell function.

Stress change on the temporomandibular joint in mandibular prognathism subjects with asymmetry after orthognathic surgery.

The purpose of this study was to evaluate changes in stress on the temporomandibular joint (TMJ) in 80 Japanese subjects (21 males and 59 females, mean age 23.7 years) with mandibular prognathism, with and without asymmetry after orthognathic surgery using the rigid bodies spring model (RBSM). The asymmetric group consisted of 40 subjects whose Mx-Md midline was more than 3 degrees. The remaining 40 subjects formed the symmetric group. The geometry of the stress analysis model was based on frontal cephalograms of the subjects. Menton (Me), the centre point of occlusal force on a line connecting the bilateral buccal cusps of the second molars, and the most lateral, superior, and medial points on the condyle were plotted on a computer display and stress on the condyle was calculated with the two-dimensional RBSM program, Fortran. The degree (force partition) of the resultant force, the direction (angulation), and the displacement (X, Y) of each condyle were calculated and the horizontal displacement (u), the vertical displacement (v), and rotation displacement (theta) of the mandibular body at Me were calculated pre- and post-operatively. The data was analysed using paired and unpaired t-tests. For the vertical (v) and rotational (theta) displacement, the post-operative value was smaller than the pre-operative value (v: P < 0.001, theta: P = 0.0063) in the asymmetric group. For angulation and the X-component, the post-operative value was smaller than that pre-operatively on the deviated (angulation: P = 0.0074, X-component: P = 0.0003) and non-deviated (angulation: P = 0.0024, X-component: P = 0.001) side in the asymmetric group. However, there was no significant difference between the pre- and post-operative value for any parameter in the symmetric group. These findings suggest that surgical correction of mandibular prognathism, with and without asymmetry, could induce an improvement in stress balance on the TMJ in the frontal aspect.

Determination of the emission probabilities of the principal gamma-rays for 134Cs to a high precision.

While multi-gamma-ray emitting nuclides such as 75Se, 134Cs and 152Eu have reasonably well-defined decay scheme, some inconsistencies still remain. Detailed evaluations and weighted-mean analyses result in the recommendation of gamma-ray emission probabilities with small uncertainties, although significant deviations exist in the measured values. Therefore, the gamma-ray emission probabilities of 134Cs have been measured to a high precision after an extremely accurate calibration of detection efficiency. The resulting data agree extremely well with the evaluated values in IAEA-TECDOC-619 (IAEA, X-ray and gamma-ray standards for detector calibration, IAEA-TECDOC-619, IAEA, Vienna, 1991).