Concentrated Growth Factors Combined with Lipopolysaccharide Stimulate the In Vitro Regenerative and Osteogenic Activities of Human Dental Pulp Stem Cells by Balancing Inflammation

The effects of mineral trioxide aggregate and second-generation autologous growth factor on pulpotomy via TNF-α and NF-kβ/p65 pathways

This study aims to investigate the effect of Mineral Trioxide Aggregate (MTA), a bioactive endodontic cement, and Concentrated Growth Factor (CGF), a second-generation autologous growth factor, on pulpotomy-induced pulp inflammation. The study utilized the maxillary anterior central teeth of thirty-six young male Sprague Dawley rats. Forty-eight teeth were randomly assigned to two groups (12 rats/group; 24 teeth/group) based on the capping material (MTA or CGF). Subsequently, two subgroups (MTAG and CGFG) were formed per group (12 teeth/group) based on the time following pulpotomy (2-weeks and 4-weeks). The central teeth of the 12 animals assigned to the control group (CG) were not manipulated in any way, both in the 2-week group and in the 4-week group. Tissue samples extracted from rats at the end of the experiment were stained with H&E for histopathological analysis. For immunohistochemical analysis, primary antibodies for TNF-α and NF-kβ/65 were incubated. Data obtained from semi-quantitative analysis were assessed for normal distribution using Skewness-Kurtosis values, Q-Q plot, Levene's test, and the Shapiro-Wilk test on statistical software. A P value < 0.05 was considered significant. When compared with the control group, both MTAG and CGFG showed increased edematous and inflammatory areas. In MTAG, edematous and inflammatory areas decreased significantly from the 2nd week (2(2-2), 2(1-2)) to the 4th week (1(1-1), 1(0-1)), while in CGFG, edematous areas decreased (2(2-3), 1.5(1-2)), and inflammatory areas increased significantly (2(2-3), 3(2-2.5)). When compared with the control group, TNF-α and NF-kβ/p65 positivity were higher in both MTAG and CGFG. In MTAG, TNF-α [2(1.5-2)] and NF-kβ/p65 [1.5(1-2)] positivity decreased significantly from the 2nd week to the 4th week [TNF-α: 1(1-1), NF-kβ/p65: 1(1-2)], while no significant change was observed in CGFG. In conclusion, this study revealed a reduction in cells showing TNF-α and NF-kβ/p65 positivity in the MTA treatment group compared to the CGF group. Although MTA demonstrated more favorable results than CGF in mitigating pulpal inflammation within the scope of this study, further experimental and clinical investigations are warranted to obtain comprehensive data regarding CGF.

Effects of Novel Nanoparticulate Bioceramic Endodontic Material on Human Dental Pulp Stem Cells In Vitro

OBJECTIVES

This study aimed to investigate the in vitro effects of root canal filling and repair paste (nRoot BP) on human dental pulp stem cells (hDPSCs).

METHODS

The effects of nRoot BP and iRoot BP Plus on the adhesion, proliferation, migration, and differentiation of hDPSCs were examined in vitro for 72 hours. The adhesion of cells was observed using immunofluorescence rhodamine ghost pen cyclic peptide staining and scanning electron microscopy (SEM). Cell density and changes in migration area were measured under a fluorescence inverted microscope. Fluorescent quantitative PCR was performed to detect genes related to odontogenesis and osteogenesis.

RESULTS

Cells adhering to the surfaces of nRoot BP and iRoot BP Plus exhibited similar irregular polygonal morphologies, with cells extending irregular pseudopods to adhere to the materials. CCK-8 results indicated that the density of living cells for nRoot BP and iRoot BP Plus was lower than that of the blank control group at 3 and 5 days of culture. There was no significant difference in cell migration between the groups (P > .05). The migration ability of iRoot BP Plus and nRoot BP was similar to that of the control group. Both nRoot BP and iRoot BP Plus increased the expression of the RUNX2 gene, but there was no significant difference between the groups (P < .05). Furthermore, both nRoot BP and iRoot BP Plus downregulated the expression of the DSPP gene, with no significant difference between them (P > .05).

CONCLUSIONS

nRoot BP exhibited a slight inhibition of hDPSC proliferation but did not affect the adhesion and migration of hDPSCs. The impact of nRoot BP on the osteogenic and odontogenic differentiation of hDPSCs was similar to that of iRoot BP Plus.

Dental Stem Cells and Lipopolysaccharides: A Concise Review

Dental tissue stem cells (DTSCs) are well known for their multipotent capacity and regenerative potential. They also play an important role in the immune response of inflammatory processes derived from caries lesions, periodontitis, and gingivitis. These oral diseases are triggered by toxins known as lipopolysaccharides (LPS) produced by gram-negative bacteria. LPS present molecular patterns associated with pathogens and are recognized by Toll-like receptors (TLRs) in dental stem cells. In this review, we describe the effect of LPS on the biological behavior of DTSCs. We also focus on the molecular sensors, signaling pathways, and emerging players participating in the interaction of DTSCs with lipopolysaccharides. Although the scientific advances generated provide an understanding of the immunomodulatory potential of DTSCs, there are still new reflections to explore with regard to their clinical application in the treatment of oral inflammatory diseases.

The Migration and the Fate of Dental Pulp Stem Cells

Human dental pulp stem cells (hDPSCs) are adult mesenchymal stem cells (MSCs) obtained from dental pulp and derived from the neural crest. They can differentiate into odontoblasts, osteoblasts, chondrocytes, adipocytes and nerve cells, and they play a role in tissue repair and regeneration. In fact, DPSCs, depending on the microenvironmental signals, can differentiate into odontoblasts and regenerate dentin or, when transplanted, replace/repair damaged neurons. Cell homing depends on recruitment and migration, and it is more effective and safer than cell transplantation. However, the main limitations of cell homing are the poor cell migration of MSCs and the limited information we have on the regulatory mechanism of the direct differentiation of MSCs. Different isolation methods used to recover DPSCs can yield different cell types. To date, most studies on DPSCs use the enzymatic isolation method, which prevents direct observation of cell migration. Instead, the explant method allows for the observation of single cells that can migrate at two different times and, therefore, could have different fates, for example, differentiation and self-renewal. DPSCs use mesenchymal and amoeboid migration modes with the formation of lamellipodia, filopodia and blebs, depending on the biochemical and biophysical signals of the microenvironment. Here, we present current knowledge on the possible intriguing role of cell migration, with particular attention to microenvironmental cues and mechanosensing properties, in the fate of DPSCs.

Japanese Laws and the Current Status of Regenerative Medicine in the Tohoku Region

AIM

The aim of this study was to review Japanese laws regarding regenerative medicine and the current status of clinical application of regenerative medicine, to learn about the advantages and problems, and to thereby serve as a reference for measures necessary for the development of regenerative medicine.

BACKGROUND

Regenerative medicine started in 1957 with the transplantation of hematopoietic stem cells, followed by the establishment of embryonic stem cells in 1981 and induced pluripotent stem cells in 2006, and continues to evolve progressively. At the same time, however, problems have emerged due to lax legal regulations, such as the use of treatments that lack scientific evidence.

REVIEW RESULTS

The Japanese government enacted two laws to regulate regenerative medicine: the Law to Ensure the Safety of Regenerative Medicine and the Amend the Pharmaceutical Affairs Law in 2013. These laws were enacted with the aim of providing safe regenerative medicine promptly and smoothly and developing many regenerative medicine products. In these laws, regenerative medicine is defined as medical treatment that restores lost functions of damaged organs and tissues with the help of cellular and tissue-based products. Nowadays, there are two major methods of regenerative medicine. One representative method involves the transplantation of devices that activates self-regenerative ability by introducing living cells into patients' body. The other method is the activation and differentiation of endogenous stem cells with cell growth and differentiation factors.

CONCLUSION

The current status of regenerative medicine in the Tohoku region after the enactment of these laws is described in detail. This clarified the advantages and disadvantages associated with regenerative medicine as it is currently practiced in Japan.

CLINICAL SIGNIFICANCE

Development of regenerative medicine in dentistry will be advanced by learning about its clinical application in medicine.