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Introduction: Cell-based bone regenerative therapy exhibits considerable potential in the treatment of bone defects caused by trauma, disease, and congenital anomalies. The periosteum, a fibrous membrane covering the outer surface of bone, plays a crucial role in bone formation and regeneration by sourcing osteoprogenitor cells. The remarkable osteogenic potential of periosteal cells (PCs) has led to the effective clinical implementation of PC-based regenerative therapies and tissue engineering. The abundance of progenitor cells in cultured PCs is well established; however, the heterogeneity of the cell population and its impact on bone regeneration remain uncertain. In this study, we aimed to characterize the heterogeneity of cultured PCs via single-cell RNA-sequencing (scRNA-seq) and to examine their osteogenic potential in vivo. Methods: Human PCs cultivated using the tissue explant method were utilized in this study. scRNA-seq and real-time PCR were performed to examine the cellular heterogeneity and osteogenic capacity of the cultured PCs. Experimental bone formation by the cultured PCs was examined using the rat model of subcutaneous implantation. Results: ScRNA-seq analysis showed that the cultured PCs were categorized into three cell types (osteoprogenitor cells, mesenchymal stem cells, and fibroblasts) with specific gene expression patterns. In addition, the cellular population and osteogenic capacity differed between the central and peripheral regions in the culture dish. The PCs in the central region showed higher osteogenic potential than those in the peripheral region. Conclusions: This study revealed the diversity of the composition of the PCs and their distinct osteogenic capabilities in different regions in the culture dish. The findings may provide promising prospects for the development of more efficacious regenerative therapeutic applications using cultured PCs in the future.

Background The effect of oral microbiota on the intestinal microbiota has garnered growing attention as a mechanism linking periodontal diseases to systemic diseases. However, the salivary microbiota is diverse and comprises numerous bacteria with a largely similar composition in healthy individuals and periodontitis patients.Aim We explored how health-associated and periodontitis-associated salivary microbiota differently colonized the intestine and their subsequent systemic effects.Methods The salivary microbiota was collected from a healthy individual and a periodontitis patient and gavaged into C57BL/6NJcl[GF] mice. Gut microbial communities, hepatic gene expression profiles, and serum metabolites were analyzed.Results The gut microbial composition was significantly different between periodontitis-associated microbiota-administered (PAO) and health-associated oral microbiota-administered (HAO) mice. The hepatic gene expression profile demonstrated a distinct pattern between the two groups, with higher expression of lipid and glucose metabolism-related genes. Disease-associated metabolites such as 2-hydroxyisobutyric acid and hydroxybenzoic acid were elevated in PAO mice. These metabolites were significantly correlated with characteristic gut microbial taxa in PAO mice. Conversely, health-associated oral microbiota were associated with higher levels of beneficial serum metabolites in HAO mice.Conclusion The multi-omics approach used in this study revealed that periodontitis-associated oral microbiota is associated with the induction of disease phenotype when they colonized the gut of germ-free mice.

Background & AimsPeriodontitis increases the risk of nonalcoholic fatty liver disease (NAFLD); however, the underlying mechanisms are unclear. Here, we show that gut dysbiosis induced by oral administration of Porphyromonas gingivalis, a representative periodontopathic bacterium, is involved in the aggravation of NAFLD pathology.MethodsC57BL/6N mice were administered either vehicle, P. gingivalis, or Prevotella intermedia, another periodontopathic bacterium with weaker periodontal pathogenicity, followed by feeding on a choline-deficient, l-amino acid-defined, high-fat diet with 60 kcal% fat and 0.1% methionine (CDAHFD60). The gut microbial communities were analyzed by pyrosequencing the 16S ribosomal RNA genes. Metagenomic analysis was used to determine the relative abundance of the Kyoto Encyclopedia of Genes and Genomes pathways encoded in the gut microbiota. Serum metabolites were analyzed using nuclear magnetic resonance-based metabolomics coupled with multivariate statistical analyses. Hepatic gene expression profiles were analyzed via DNA microarray and quantitative polymerase chain reaction.ResultsCDAHFD60 feeding induced hepatic steatosis, and in combination with bacterial administration, it further aggravated NAFLD pathology, thereby increasing fibrosis. Gene expression analysis of liver samples revealed that genes involved in NAFLD pathology were perturbed, and the two bacteria induced distinct expression profiles. This might be due to quantitative and qualitative differences in the influx of bacterial products in the gut because the serum endotoxin levels, compositions of the gut microbiota, and serum metabolite profiles induced by the ingested P. intermedia and P. gingivalis were different.ConclusionsSwallowed periodontopathic bacteria aggravate NAFLD pathology, likely due to dysregulation of gene expression by inducing gut dysbiosis and subsequent influx of gut bacteria and/or bacterial products.

Obesity is an epidemic health issue with a rapid increase worldwide. It increases the risk of various diseases, including periodontal disease, an oral chronic infectious disease.