Abstract. Dental pulp stem cells (DPSCs) have the potential to form bone, nerve and fat, and are a candidate for use in regenerative medicine. Previous studies indicated that total flavonoids from Drynaria fortunei show a stimulative effect on the proliferation and osteogenic differentiation of osteoblastic MC3T3-E1 cells in vitro. This study aimed to investigate the effect of total flavonoids from Drynaria fortunei on the proliferation and osteogenic differentiation of rat DPSCs, and to further clarify the mechanisms involved. DPSCs were isolated by enzymatic digestion and identified using the CD44, CD29 and CD34 markers by immunohistochemistry, and exposed to 0.01, 0.05 and 0.1 g/l total flavonoids from Drynaria fortunei media. Total flavonoids from Drynaria fortunei promoted the proliferation of DPSCs in a dose-dependent manner and this effect may depend on the shortening of the G0/G1 phase and promotion of the S phase. Compared with the control group, the levels of alkaline phosphatase (ALP) and the expression of osteogenic genes increased with the concentrations of total flavonoids from Drynaria fortunei, and the volume and number of calcified nodules in the Drynaria groups was bigger compared to the control group. These results suggest that total flavonoid from Drynaria fortunei directly stimulates DPSC proliferation and osteogenic differentiation, and may serve as a new promising candidate drug for dental tissue engineering and bone regeneration.

Bone regeneration remains a great clinical challenge. Low intensity near-infrared (NIR) light showed strong potential to promote tissue regeneration, offering a promising strategy for bone defect regeneration. However, the effect and underlying mechanism of NIR on bone regeneration remain unclear. We demonstrated that bone regeneration in the rat skull defect model was significantly accelerated with low-intensity NIR stimulation. In vitro studies showed that NIR stimulation could promote the osteoblast differentiation in bone mesenchymal stem cells (BMSCs) and MC3T3-E1 cells, which was associated with increased ubiquitination of the core circadian clock protein Cryptochrome 1 (CRY1) in the nucleus. We found that the reduction of CRY1 induced by NIR light activated the bone morphogenetic protein (BMP) signaling pathways, promoting SMAD1/5/9 phosphorylation and increasing the expression levels of Runx2 and Osterix. NIR light treatment may act through sodium voltage-gated channel Scn4a, which may be a potential responder of NIR light to accelerate bone regeneration. Together, these findings suggest that low-intensity NIR light may promote in situ bone regeneration in a CRY1-dependent manner, providing a novel, efficient and non-invasive strategy to promote bone regeneration for clinical bone defects.

Atherosclerosis (AS) is an inflammatory vascular disease that constitutes a major underlying cause of cardiovascular diseases (CVD) and stroke. Infection is a contributing risk factor for AS. Epidemiological evidence has implicated individuals afflicted by periodontitis displaying an increased susceptibility to AS and CVD. This review concisely outlines several prevalent periodontal pathogens identified within atherosclerotic plaques, including Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum. We review the existing epidemiological evidence elucidating the association between these pathogens and AS-related diseases, and the diverse mechanisms for which these pathogens may engage in AS, such as endothelial barrier disruption, immune system activation, facilitation of monocyte adhesion and aggregation, and promotion of foam cell formation, all of which contribute to the progression and destabilization of atherosclerotic plaques. Notably, the intricate interplay among bacteria underscores the complex impact of periodontitis on AS. In conclusion, advancing our understanding of the relationship between periodontal pathogens and AS will undoubtedly offer invaluable insights and potential therapeutic avenues for the prevention and management of AS.