Stem Cell-Induced Pulp Regeneration Can Be Enhanced by Administration of CCL11-Neutralizing Antibody in the Ectopic Tooth Transplantation Model in the Aged Mice.

OBJECTIVE: Pulp regeneration by stem cell transplantation declines due to age-related reduction. We hypothesized that administration of a cytokine together with the cell transplantation may improve the stem cell niche microenvironment and promote regeneration. CCL11 is implicated as a factor in aging. This investigation was performed to investigate the changes in the quality of the regenerated pulp by administration of CCL11 antibody in the aged mice and elucidate the underlying mechanisms. MATERIALS AND METHODS: Mobilized dental pulp stem cell (MDPSC) transplants were characterized in an ectopic tooth root transplantation model in both the aged and young mice. The amount of regenerated pulp tissue was analyzed in the transplants with continuous administration of CCL11 antibody compared with those without the antibody administration. Blood CCL11 levels were assessed at the onset of the experiment. Furthermore, immunostaining of CD68 together with CD11c or CD206 for M1 and M2 macrophage, respectively, were performed. Each double-positive cell count of M1 and M2 macrophages and M1/M2 ratio in the transplants with administration were compared with those without administration both in the aged and young mice. RESULTS: The administration of CCL11 antibody enhanced pulp regeneration and significantly reduced the blood CCL11 level in the aged mice. As the number of M1 macrophages decreased, the M1/M2 ratio in the treated aged mouse was less than that in the untreated aged mouse. There was, however, significant difference between the treated aged mouse and the untreated young mouse. CONCLUSION: CCL11 antibody has the potential to enhance and stimulate pulp regeneration in the aged mice.

Observation of maxillary incisive canal using dry skulls between Hellman's dental age IA and IIIC.

The maxillary incisive canals were observed in childhood from infancy to school-aged children to clarify their development. Cone-beam computed tomography was performed to investigate 44 dry child skulls. Two-dimensional images of various planes in the maxillary incisive canal were reconstructed on a computer using 3-dimensional visualization and measurement software. Then, antero-posterior angulation, and antero-posterior and lateral axes of the maxillary incisive canal were measured at the inferior and middle levels. The mean difference of angulation between the inferior and middle levels was 2.3 degrees in IIC, and 11.1 degrees in IIIC. The mean ratio of the lateral axis to antero-posterior axis at the middle level was 2.54 in IIC, and 1.93 in IIIC. In conclusion, it was antero-posteriorly straight from IA to IIC, and, after IIIA, it curved at the middle level. The cross-sectional shape in IIC was depressed with a larger lateral axis.

Stimulation of angiogenesis, neurogenesis and regeneration by side population cells from dental pulp.

Mesenchymal stem cells (MSCs) have been used for cell therapy in various experimental disease models. However, the regenerative potential of MSCs from different tissue sources and the influence of the tissue niche have not been investigated. In this study, we compared the regenerative potential of dental pulp, bone marrow and adipose tissue-derived CD31(-) side population (SP) cells isolated from an individual porcine source. Pulp CD31(-) SP cells expressed the highest levels of angiogenic/neurotrophic factors and had the highest migration activity. Conditioned medium from pulp CD31(-) SP cells produced potent anti-apoptotic activity and neurite outgrowth, compared to those from bone marrow and adipose CD31(-) SP cells. Transplantation of pulp CD31(-) SP cells in a mouse hindlimb ischemia model produced higher blood flow and capillary density than transplantation of bone marrow and adipose CD31(-) SP cells. Motor function recovery and infarct size reduction were greater with pulp CD31(-) SP cells. Pulp CD31(-) SP cells induced maximal angiogenesis, neurogenesis and pulp regeneration in ectopic transplantation models compared to other tissue sources. These results demonstrate that pulp stem cells have higher angiogenic, neurogenic and regenerative potential and may therefore be superior to bone marrow and adipose stem cells for cell therapy.

Comparison of ß-adrenergic and glucocorticoid signaling on clock gene and osteoblast-related gene expressions in human osteoblast.

Most living organisms exhibit circadian rhythms that are generated by endogenous circadian clocks, the master one being present in the suprachiasmatic nuclei (SCN). Output signals from the SCN are believed to transmit standard circadian time to peripheral tissue through sympathetic nervous system and humoral routes. Therefore, the authors examined the expression of clock genes following treatment with the ß-adrenergic receptor agonist, isoprenaline, or the synthetic glucocorticoid, dexamethasone, in cultured human osteoblast SaM-1 cells. Cells were treated with 10(-6) M isoprenaline or 10(-7) M dexamethasone for 2 h and gene expressions were determined using real-time polymerase chain reaction (PCR) analysis. Treatment with isoprenaline or dexamethasone induced the circadian expression of clock genes human period 1 (hPer1), hPer2, hPer3, and human brain and muscle Arnt-like protein 1 (hBMAL1). Isoprenaline or dexamethasone treatment immediately increased hPer1 and hPer2 and caused circadian oscillation of hPer1 and hPer2 with three peaks within 48 h. hPer3 expression had one peak after isoprenaline or dexamethasone treatment. hBMAL expression had two peaks after isoprenaline or dexamethasone treatment, the temporal pattern being in antiphase to that of the other clock genes. Dexamethasone treatment delayed the oscillation of all clock genes for 2-6 h compared with isoprenaline treatment. The authors also examined the expression of osteoblast-related genes hα-1 type I collagen (hCol1a1), halkaline phosphatase (hALP), and hosteocalcin (hOC). Isoprenaline induced oscillation of hCol1a1, but not hALP and hOC. On the other hand, dexamethasone induced oscillation of hCol1a1 and hALP, but not hOC. Isoprenaline up-regulated hCol1a1 expression, but dexamethasone down-regulated hCol1a1 and hALP expression in the first phase.

Regeneration of dental pulp following pulpectomy by fractionated stem/progenitor cells from bone marrow and adipose tissue.

Pulp stem/progenitor cells can induce complete pulp regeneration. However, due to the limited availability of pulp tissue with age, there is a need to examine other sources for fractions of side population (SP) cells. In the present investigation bone marrow and adipose tissues of the same individual were evaluated as alternate sources. Pulp CD31(-) SP cells have higher migration activity and higher expression of angiogenic/neurotrophic factors than bone marrow and adipose CD31(-) SP cells. Adipose tissue CD31(-) SP cell transplantation yielded the same amount of regenerated tissue as pulp derived cells. However, bone marrow CD31(-) SP cell transplantation yielded significantly less regenerated tissue in pulpectomized root canals in dogs. The rate of matrix formation was much higher in adipose CD31(-) SP cell transplantation compared to pulp CD31(-) SP cell transplantation on day 28. Microarray analysis demonstrated similar qualitative and quantitative patterns of mRNA expression characteristic of pulp in the regenerated tissues from all three cell sources. Expression of many angiogenic/neurotrophic factors in the transplanted cells demonstrated trophic effects. Our results demonstrate that bone marrow and adipose CD31(-) SP cells might be suitable alternative cell sources for pulp regeneration.

Remineralization of primary tooth enamel from individuals with Down syndrome.

PURPOSE: The purpose of this study was to clarify the characteristics of primary tooth enamel of Down syndrome patients (DSPs). We examined 9 primary teeth of Down syndrome children and 11 primary teeth of normally developed children to investigate the remineralization processes of enamel by transverse microradiography and X ray micro analyzer (XMA). METHODS: Mineral loss, lesion depth, maximum mineral value, minimum mineral value, depth of maximum mineral value, and depth of minimum mineral value were used to analyze transverse microradiography (TMR). In addition, we calculated the percentage of enamel remineralization. RESULTS: All the parameters in the 2 groups showed marked recovery. The results indicated that the Down syndrome group was significantly remineralized the same way as the control group. According to the comparison of mineral content distribution by XMA, the content distribution of magnesium was different between the 2 groups. CONCLUSION: While recovery through remineralization of primary teeth was similar between Down syndrome children and normally developed children, the mechanism of remineralization process may be different between the 2 groups; consequently, magnesium may be considered as one of the factors affecting recovery.