| Project/Area Number |
22K21011
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| Research Category |
Grant-in-Aid for Research Activity Start-up
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| Allocation Type | Multi-year Fund |
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| Review Section |
0907:Oral science and related fields
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| Research Institution | Niigata University |
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Principal Investigator |
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| Project Period (FY) |
2022-08-31 – 2025-03-31
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| Project Status |
Granted (Fiscal Year 2023)
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| Budget Amount *help |
¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2023: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2022: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | dental pulp / odontoblast / immune cells / injuries / CpG-ODNs / TLR9 / macrophages / healing / dendritic cells |
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| Outline of Research at the Start |
The complex mechanisms of dental tissue natural self-repair and regeneration remain to be clarified. In this study we aim to investigate the cellular cross-talk among odontoblasts, pulpal stem/progenitor cells, and immune cells induced by the effect of a novel and potent immunomodulator (CpG-ODNs) following external injuries to the tooth. Considering the future results, we will propose a new treatment called "dendritic cell activation therapy", aimed to improve the prognosis of severely injured teeth towards their subsequent regeneration and further translation to the clinical setting.
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| Outline of Annual Research Achievements |
To our knowledge, the present study is the first ever conducted analyzing the in vivo effects of synthetic CpG-ODNs during the pulpal healing process using murine tooth injury models. However, our study failed to provide significant differences between experimental and clinically used solutions (HBSS and DW), as CpG-ODNs solutions did not show clear advantages on the different phases of the pulpal repair process.
Interestingly, and despite the occurrence of severe inflammatory reactions in the dental pulp of CpG-ODNs groups, and low rates of cell proliferation at Week 1, newly-formed hard tissue was observed in the dental pulp of all experimental groups at Week 2. CpG-ODNs tended to stimulate TLR9 immunoexpression and total macrophage activity (F4/80) in the coronal and root dental pulp, even at Week 2; suggesting a possible effect on the activation of M1 macrophages. Likewise, a positive tendency towards CpG-ODNs was found related to M2 macrophages activity, as they may induce certain effect on anti-inflammatory responses in the afflicted pulpal tissue.
From our in vitro data, we found that high concentrations for longer treatment periods seem to affect the viability of cultured pulpal cells of immune lineage.
In summary, The treatment with CpG-ODNs at its lowest tested concentration (0.1mM) seems to modulate the healing of the dental pulp after injuries. Also, a positive trend for the expression of immune cells markers was found towards the experimental groups.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The current project has reached the final stage. All the data obtained from our mice dental pulp primary cultures was analyzed and is ready to be reported. We are finishing the quantitative analyses of our immune cell markers from the in vivo stage. We considered that the amount of data generated by our in vivo and in vitro experimental designs is valuable to be published. Based on this, the additional in vivo experiments using doxycycline-induced TetOP-H2B-GFP reporter and WT mice would not be necessary to perform, as they may lead to same results already obtained and increase the number of experimental animals for the present study.
Recently, we have presented our data in the 129th meeting of the Japanese Association of Anatomists in Okinawa. Furthermore, we are moving forward to prepare the first manuscript with our most outstanding results from our in vivo and in vitro data.
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| Strategy for Future Research Activity |
During the final stage of this project, we aim to analyze in vitro the variations of the gene expression on samples collected following in vivo experiments using the same injury model, intentionally-delayed tooth replantation. However, we will use only CpG-ODNs at its lowest concentrations and one control group. The goal is to compare the expression of certain markers that are critical during the healing processs in samples taken from mice with samples from mice primary cell culture. We want to clarify the expression of TLR9 and its signalling pathway.
The data collected from the previous set of experiments will be summarized in a manuscript that is under preparation, and expected to be submitted by next June. In addition, a second manuscript with the description of our last data set is expected to be submitted by the end of 2024.
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