Objective: To explore new therapeutic strategies for periodontitis, this study prepared extracellular vesicles (EVs) derived from human umbilical cord mesenchymal stem cells (hUC-MSCs) loaded with saikosaponin D (SSD) and evaluated their efficacy in a mouse model of periodontitis. Methods: This study was approved by the Medical Ethics Committee and the Laboratory Animal Ethics Committee of the unit. hUC-MSCs at logarithmic growth phase were seeded into 96 well plates and then treated with various concentrations of SSD for 24 hours. The CCK-8 assay was used to determine the SSD concentration that preserves hUC-MSC viability. Flow cytometry (FCM) assessed SSD-induced apoptosis in hUC-MSCs and determined drug loading and loading efficiency. Nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM) characterized the morphology and size of hUC-MSCs-EVs and hUC-MSCs-SSD-EVs. C57BL/6J mice were divided into five groups with six mice per group: control group, periodontitis model group (PD), PD+SSD group (2 mg/kg), PD+hUC-MSCs-EVs group (10 μg/μL) and PD+hUC-MSCs-SSD-EVs group (10 μg/μL). Administration was performed 3 times a week for 4 consecutive weeks. Micro-CT and hematoxylin-eosin (HE) staining evaluated alveolar bone resorption in periodontal tissues of a mouse model of periodontitis. RT-qPCR measured inflammatory cytokine expression in periodontal tissues of a mouse model of periodontitis. Immunofluorescence analyzed macrophage M1/M2 polarization and runt-related transcription factor 2 (RUNX2) protein expression in periodontal tissues of a mouse model of periodontitis. Results: The CCK-8 assay showed that 10 μmol/L SSD had little effect on hUC-MSCs viability (P>0.05). FCM confirmed the successful loading of SSD into EVs with a loading efficiency of 11.40%. TEM and NTA revealed that hUC-MSCs-SSD-EVs presented round or oval membranous structures with diameters ranging from 200 to 300 nm. Micro CT and HE staining showed that, compared with the PD group, the distance from cementoenamel junction to alveolar bone crest (CEJ-ABC) was markedly shortened (P<0.01）.The alveolar bone of periodontitis‑model bone volume fraction (BV/TV) and trabecular number (Tb.N) were significantly elevated in the PD+hUC-MSCs-SSD-EVs group (P<0.01). RT-qPCR and IF results showed that hUC-MSCs-SSD-EVs in periodontal tissues markedly downregulated the expression of pro-inflammatory cytokines including interleukin-1β, interleukin-6, tumor necrosis factor-α, interleukin-12 and interleukin-22 (P<0.01), upregulated the expression of the anti-inflammatory factor interleukin-10 (P<0.01), promoted the polarization of macrophages from the M1 phenotype to the M2 phenotype, and elevated the protein expression level of RUNX2 (P<0.01). Conclusion hUC-MSC-SSD-EVs effectively alleviated inflammatory responses in a mouse model of maxillary periodontitis and reduced alveolar bone loss, providing a new idea for the treatment of periodontitis.

Periodontal bone defects, primarily caused by periodontitis, are highly prevalent in clinical settings and manifest as bone fenestration, dehiscence, or attachment loss, presenting a significant challenge to oral health. In regenerative medicine, harnessing developmental principles for tissue repair offers promising therapeutic potential. Of particular interest is the condensation of progenitor cells, an essential event in organogenesis that has inspired clinically effective cell aggregation approaches in dental regeneration. However, the precise cellular coordination mechanisms during condensation and regeneration remain elusive. Here, taking the tooth as a model organ, we employed single-cell RNA sequencing to dissect the cellular composition and heterogeneity of human dental follicle and dental papilla, revealing a distinct Platelet-derived growth factor receptor alpha (PDGFRA) mesenchymal stem/stromal cell (MSC) population with remarkable odontogenic potential. Interestingly, a reciprocal paracrine interaction between PDGFRA⁺ dental follicle stem cells (DFSCs) and CD31⁺ Endomucin⁺ endothelial cells (ECs) was mediated by Vascular endothelial growth factor A (VEGFA) and Platelet-derived growth factor subunit BB (PDGFBB). This crosstalk not only maintains the functionality of PDGFRA⁺ DFSCs but also drives specialized angiogenesis. In vivo periodontal bone regeneration experiments further reveal that communication between PDGFRA⁺ DFSC aggregates and recipient ECs is essential for effective angiogenic-osteogenic coupling and rapid tissue repair. Collectively, our results unravel the importance of MSC-EC crosstalk mediated by the VEGFA and PDGFBB-PDGFRA reciprocal signaling in orchestrating angiogenesis and osteogenesis. These findings not only establish a framework for deciphering and promoting periodontal bone regeneration in potential clinical applications but also offer insights for future therapeutic strategies in dental or broader regenerative medicine.
Receptor, Platelet-Derived Growth Factor alpha/metabolism* ; Humans ; Neovascularization, Physiologic/physiology* ; Dental Sac/cytology* ; Single-Cell Analysis ; Transcriptome ; Mesenchymal Stem Cells/metabolism* ; Bone Regeneration ; Animals ; Dental Papilla/cytology* ; Periodontium/physiology* ; Stem Cells/metabolism* ; Regeneration ; Angiogenesis

Objective:To study the whole bone marrow cellular composition of jaw and long bones, and further analyze the heterogeneity of mesenchymal stem cells (MSCs) derived from these two tissue, aiming at exploring the differences in functional characteristics of bone MSCs from different lineage sources.Methods:The Seurat package of R language was used to analyze the mandibular and femur whole bone marrow single-cell RNA-sequencing (scRNA-seq) datasets in the literature, and the subpopulations were annotated by reference to the marker genes reported by previous studies. The differentially expressed genes between mandible-derived MSCs (M-MSCs) and femur-derived MSCs (F-MSCs) were calculated, and cell-cell communication analysis between M-MSCs or F-MSCs with other cell populations was performed. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed on up-regulated and down-regulated differentially expressed genes of M-MSCs, and Gene Set Enrichment Analysis (GSEA) was performed on M-MSCs or F-MSCs.Results:cRNA-seq analysis showed that the mandible and femur had the same bone marrow cell composition, but there were differences in the proportion of specific cell populations. Also, there were significantly differentially expressed genes between M-MSCs and F-MSCs. In addition, cell-cell communication analysis revealed differences in numbers of ligand-receptor pairs between M-MSCs or F-MSCs with other cell populations. Furthermore, GO, KEGG and GSEA analysis showed that M-MSCs had higher extracellular matrix production potential than F-MSCs, but had lower ability to regulate other cells in the bone marrow, especially immune cells.Conclusions:M-MSCs and F-MSCs showed distinct differences in the gene expression pattern and up-regulated signaling pathways, which may be closely related to the developmental sources and functional characteristics of jaw and long bones.

Mesenchymal stem cells, under spatiotemporal regulation of genes and microenvironment, are capable of spontaneously aggregating into dense regions, a phenomenon known as mesenchymal condensation. Mesenchymal condensation is an evolutionarily conserved developmental event that is critical in initiating morphogenesis of teeth and systemic organs. Mesenchymal stem cells hold the intrinsic ability to self-assemble in culture, and the generation of stem cell aggregates based on this property that mimics developmental mesenchymal condensation has become a potent and promising approach in regenerative medicine. This review discusses the mesenchymal condensation principles and its role as well as mechanism in tooth morphogenesis, as well as the engineering strategies for constructing mesenchymal stem cell aggregates and their application experience in tooth regeneration. It aims to start from the perspective of "development-inspired regeneration" and provide insights into understanding stem cell developmental biology and establishing new organ regenerative strategies.

Objective:To explore the biological process of liver tissue-derived extracellular vesicle (LT-EV) in promoting osteogenic differentiation of mesenchymal stem cells and healing of jaw defects to provide a feasible treatment method for the clinical treatment of jaw bone defects.Methods:Enzymatic hydrolysis and differential centrifugation were used to extract LT-EV, scanning electron microscopy, Western blotting, and nanoparticle tracking analyzers were used to identify and characterize LT-EV, and further to explore the biological functions of LT-EV through proteomics and Kyoto Encyclopedia of Genes and Genomes. Flow cytometry was used to detect LT-EV plasma concentration and to calculate the plasma half-life of LT-EV. Small animal in vivo imaging system was used to detect the biological distribution of LT-EV 24 hours after injection. Six C57BL/6 mice were divided into control group and LT-EV group (3 mice in each group) by simple random sampling method. All mice underwent jaw bone defect surgery and tail vein injection every 7 days (the control group was injected with phosphoric buffer saline, LT-EV group was injected with LT-EV), micro-CT was used to evaluate the degree of mouse jaw bone healing 28 days after surgery, HE staining was used to analyze the multi-organ biosafety of LT-EV, and immunofluorescence staining was used to detect the jaw bone expression of osteogenic marker proteins in the defect area. Human jaw bone mesenchymal stem cells (hJBMSC) induced by osteogenic differentiation were treated with LT-EV (obtained from orthognathic surgery patients provided by the Department of Traumatology and Orthognathic Surgery of School of Stomatology of The Fourth Military Medical University resected normal jaw bone fragments), and the difference in osteogenic differentiation ability between the hJBMSC group and the control group (phosphate buffer saline treatment) was compared, and the in vitro bone differentiation promoting effect of LT-EV was verified through alkaline phosphatase (ALP) staining and real-time fluorescence quantitative PCR. Results:The yield of LT-EV was high, and proteomics and Kyoto Encyclopedia of Genes and Genomes showed that LT-EV contained a series of proteins that regulated cell biological functions. LT-EV injected into the tail vein could reach the mouse jaw bone defect area and promote the regeneration and repair of the jaw bone defect [the bone volume fractions of the LT-EV group and the control group were (36.06±4.20)% and (18.58±5.61)%, respectively; t=4.32, P=0.013], and had good biosafety. LT-EV could promote osteogenic differentiation of hJBMSC in vitro. Compared to the control group, ALP staining and osteogenic gene expression levels were significantly enhanced after osteogenic differentiation of hJBMSC ( P<0.05). Conclusions:LT-EV exhibits a high yield, ease of acquisition, high biological safety, and excellent bone-promoting effects. It holds promise as a novel cell-free therapy strategy for regenerating craniofacial bone defects.

In the various diseases of oral and maxillofacial system,the incidence of tissue defects is high and harmful,the reconstruction of the morphology and function is difficult,which seriously affects the physiological and mental health of the patients.Dental and maxillofacial regeneration based on stem cells and tissue engineering technology is a potential way for the treatment of dental and maxillofacial defects,and is also the focus of current international competition.Based on the possible mechanism of stem cells regulating organ development,this paper reviews the current status of dental and maxillofacial regeneration and translation,and proposes future direction in this field in order to pro-mote the sustainable development of dental and maxillofacial regeneration and translation.

Objective:To analyze the immune microenvironment characteristics of human dental follicle tissues from the third molars and to explore the mutual communication and the effects of innate immune cells and adaptive immune cells within the dental follicle.Methods:Sequencing data(GSA-Human:HRA008022)in the GSA database were analyzed.Bioinformatics tools were employed for gene identification and GO enrichment analysis was performed to define the biological function of innate and adaptive immune cells.CellChat analysis was used for explaining intercellular communication among immune cell populations.Results:Using t-SNE dimen-sionality reduction analysis for immune cell populations,innate immune cell populations were obtained,including innate lymphoid cells,dendritic cells,mast cells and macrophages,and adaptive immune cell populations including T cells and B cells.Pearson corre-lation analysis showed that innate immune cells,specifically innate lymphoid cells and macrophages,had a strong correlation with adap-tive immune cell populations.GO enrichment analysis revealed mutual coordination among innate immune cell populations and regulato-ry effects on adaptive immune cell populations.Further CellChat analysis indicated biological signal transmission between innate and a-daptive immune cell populations,with CLEC,MIF,ADGRE5,COLLAGEN and MIF signaling pathways is the most significant.Con-clusion:Dental follicle tissues are rich in immune cells and innate immune cell populations interact with adaptive immune cells to regulate immune responses and participate in maintaining the homeostasis of dental follicle.

Sympathetic cues via the adrenergic signaling critically regulate bone homeostasis and contribute to neurostress-induced bone loss, but the mechanisms and therapeutics remain incompletely elucidated. Here, we reveal an osteoclastogenesis-centered functionally important osteopenic pathogenesis under sympatho-adrenergic activation with characterized microRNA response and efficient therapeutics. We discovered that osteoclastic miR-21 was tightly regulated by sympatho-adrenergic cues downstream the β2-adrenergic receptor (β₂AR) signaling, critically modulated osteoclastogenesis in vivo by inhibiting programmed cell death 4 (Pdcd4), and mediated detrimental effects of both isoproterenol (ISO) and chronic variable stress (CVS) on bone. Intriguingly, without affecting osteoblastic bone formation, bone protection against ISO and CVS was sufficiently achieved by a (D-Asp₈)-lipid nanoparticle-mediated targeted inhibition of osteoclastic miR-21 or by clinically relevant drugs to suppress osteoclastogenesis. Collectively, these results unravel a previously underdetermined molecular and functional paradigm that osteoclastogenesis crucially contributes to sympatho-adrenergic regulation of bone and establish multiple targeted therapeutic strategies to counteract osteopenias under stresses.
Adrenergic Agents/pharmacology* ; Apoptosis Regulatory Proteins/pharmacology* ; Bone Diseases, Metabolic/metabolism* ; Humans ; Liposomes ; MicroRNAs/genetics* ; Nanoparticles ; Osteoclasts ; Osteogenesis/physiology* ; RNA-Binding Proteins/pharmacology*

OBJECTIVETo investigate whether vitamin C can promote the proliferation ability of bone marrow mesenchymal stem cells (BMMSCs) derived from aging mice.

METHODSThe senescence-accelerated mouse prone 6 (SAMP6) mice and senescence-accelerated mouse resistant 1 (SAMR1) mice were used as the test group and the control group, respectively, and the SAMP6 mice were examined by micro-CT to verify the senescent phenotype. BMMSCs were harvested from the two mouse lines and cultured in vitro, and the cells from SAMP6 mice were subjected to treatment with different concentrations of vitamin C. The proliferation ability of the cells from the two mouse lines was tested using MTT assay and growth curves, and TeloTAGGG Telomerase PCR ELISA was used to measure the telomerase activity; PCR and Western blotting were performed to detect the expression level of telomerase reverse transcriptase (TERT) in the cells.

RESULTSThe SAMP6 mice displayed a bone senescent phenotype. The proliferation ability of BMMSCs derived from SAMP6 mice and their telomerase activity were significantly lower than those derived from SAMR1 mice (P<0.05). Vitamin C treatment significantly enhanced the proliferation ability of BMMSCs derived from SAMP6 mice in a dose-dependent manner (P<0.05) and increased telomerase activity and TERT expression in the cells (P<0.05). At the concentration of 100 µg/mL, vitamin C produced the strongest effect in promoting the proliferation of BMMSCs from SAMP6 mice, while at the concentration of 1000 µg/ml, growth suppression occurred in the cells.

CONCLUSIONVitamin C can promote the proliferation of BMMSCs from aging mice possibly by increasing the cellular telomerase activity.

Aging ; Animals ; Ascorbic Acid ; chemistry ; Bone Marrow Cells ; cytology ; Cell Proliferation ; Cells, Cultured ; Culture Media ; chemistry ; Hematopoietic Stem Cells ; Mesenchymal Stromal Cells ; cytology ; Mice ; Telomerase ; metabolism

Objective To investigate whether vitamin C can promote the proliferation ability of bone marrow mesenchymal stem cells (BMMSCs) derived from aging mice. Methods The senescence-accelerated mouse prone 6 (SAMP6) mice and senescence-accelerated mouse resistant 1 (SAMR1) mice were used as the test group and the control group, respectively, and the SAMP6 mice were examined by micro-CT to verify the senescent phenotype. BMMSCs were harvested from the two mouse lines and cultured in vitro, and the cells from SAMP6 mice were subjected to treatment with different concentrations of vitamin C. The proliferation ability of the cells from the two mouse lines was tested using MTT assay and growth curves, and TeloTAGGG Telomerase PCR ELISA was used to measure the telomerase activity;PCR and Western blotting were performed to detect the expression level of telomerase reverse transcriptase (TERT) in the cells. Results The SAMP6 mice displayed a bone senescent phenotype. The proliferation ability of BMMSCs derived from SAMP6 mice and their telomerase activity were significantly lower than those derived from SAMR1 mice (P<0.05). Vitamin C treatment significantly enhanced the proliferation ability of BMMSCs derived from SAMP6 mice in a dose-dependent manner (P<0.05) and increased telomerase activity and TERT expression in the cells (P<0.05). At the concentration of 100μg/mL, vitamin C produced the strongest effect in promoting the proliferation of BMMSCs from SAMP6 mice, while at the concentration of 1000μg/ml, growth suppression occurred in the cells. Conclusion Vitamin C can promote the proliferation of BMMSCs from aging mice possibly by increasing the cellular telomerase activity.