Abstract Background Insulin has been known to regulate bone metabolism, yet its specific molecular mechanisms during the proliferation and osteogenic differentiation of dental pulp stem cells (DPSCs) remain poorly understood. This study aimed to explore the effects of insulin on the bone formation capability of human DPSCs and to elucidate the underlying mechanisms. Methods Cell proliferation was assessed using a CCK-8 assay. Cell phenotype was analyzed by flow cytometry. Colony-forming unit-fibroblast ability and multilineage differentiation potential were evaluated using Toluidine blue, Oil red O, Alizarin red, and Alcian blue staining. Gene and protein expressions were quantified by real-time quantitative polymerase chain reaction and Western blotting, respectively. Bone metabolism and biochemical markers were analyzed using electrochemical luminescence and chemical colorimetry. Cell adhesion and growth on nano-hydroxyapatite/collagen (nHAC) were observed with a scanning electron microscope. Bone regeneration was assessed using micro-CT, fluorescent labeling, immunohistochemical and hematoxylin and eosin staining. Results Insulin enhanced the proliferation of human DPSCs as well as promoted mineralized matrix formation in a concentration-dependent manner. 10− 6 M insulin significantly up-regulated osteogenic differentiation-related genes and proteins markedly increased the secretion of bone metabolism and biochemical markers, and obviously stimulated mineralized matrix formation. However, it also significantly inhibited the expression of genes and proteins of receptors and receptor substrates associated with insulin/insulin-like growth factor-1 signaling (IIS) pathway, obviously reduced the expression of the phosphorylated PI3K and the ratios of the phosphorylated PI3K/total PI3K, and notably increased the expression of the total PI3K, phosphorylated AKT, total AKT and mTOR. The inhibitor LY294002 attenuated the responsiveness of 10− 6 M insulin to IIS/PI3K/AKT/mTOR pathway axis, suppressing the promoting effect of insulin on cell proliferation, osteogenic differentiation and bone formation. Implantation of 10− 6 M insulin treated DPSCs into the backs of severe combined immunodeficient mice and the rabbit jawbone defects resulted in enhanced bone formation. Conclusions Insulin induces insulin resistance in human DPSCs and effectively promotes their proliferation, osteogenic differentiation and bone formation capability through gradually inducing the down-regulation of IIS/PI3K/AKT/mTOR pathway axis under insulin resistant states.

Dental trauma is highly prevalent in children and adolescents, alongside tooth decay. This condition mainly induces pulp contamination, pulp necrosis, and tooth avulsion in the clinical context. The disturbance to root growth is prone to occur in immature permanent teeth. However, conventional endodontic treatment may not achieve favorable outcomes in these cases, necessitating conducting relevant exploration. Therefore, this study was performed to examine the impact of Annexin A1 (ANXA1) on the vascular repair of dental pulp using human dental pulp stem cells (DPSCs). Specifically, RNA sequencing (RNA-Seq) and functional clustering analyses were employed to identify key genes involved in pulp regeneration. ANXA1 was detected in DPSCs and may correlate with pulp restoration. However, it remains undefined about the potential of ANXA1 to promote the angiogenetic differentiation of DPSCs. The results of this study revealed that the addition of ANXA1 significantly enhanced the secretion of vascular endothelial growth factor-A (VEGF-A) in DPSCs. Moreover, the incubation of DPSCs with ANXA1 resulted in a higher expression level of endothelial markers and promoted vessel formation through the upregulation of the phosphorylated p38 (p-p38) pathway. The in vivo results corroborated that the ANXA1 group exhibited more blood vessels and an increased ratio of positive staining for CD31. In conclusion, these findings indicate that ANXA1 enhances the in vivo and in vitro vascularization of DPSCs, and the activation of p-p38 may play a pivotal role in mediating the differentiation process.

Patients with diabetic osteoporosis (DOP) often suffer from poor osseointegration of artificial implants, which is a challenge that affects implant outcomes. The osteogenic differentiation ability of human jaw bone marrow mesenchymal stem cells (JBMMSCs) is the key to implant osseointegration. Studies have shown that the microenvironment of hyperglycemia affects the osteogenic differentiation of mesenchymal stem cells (MSC), but the mechanism is still unclear. Therefore, the aim of this study was to isolate and culture JBMMSCs from surgically derived bone fragments from DOP patients and control patients to investigate the differences in their osteogenic differentiation ability and to elucidate its mechanisms. The results showed that the osteogenic ability of hJBMMSCs was significantly decreased in the DOP environment. Mechanism study showed that the expression of senescence marker gene P53 was significantly increased in DOP hJBMMSCs compared to control hJBMMSCs according to RNA-sequencing result. Further, DOP hJBMMSCs were found to display significant senescence using β-galactosidase staining, mitochondrial membrane potential and ROS assay, qRT-PCR and WB analysis. Overexpression of P53 in hJBMMSCs, knockdown of P53 in DOP hJBMMSCs, and knockdown followed by overexpression of P53 significantly affected the osteogenic differentiation ability of hJBMMSCs. These results suggest that MSC senescence is an important reason for decreasing osteogenic capacity in DOP patients. P53 is a key target in regulating hJBMMSCs aging, and knocking down P53 can effectively restore the osteogenic differentiation ability of DOP hJBMMSCs and promote osteosynthesis in DOP dental implants. It provided a new idea to elucidate the pathogenesis and treatment of diabetic bone metabolic diseases.

Aging is an irreversible natural phenomenon that occurs with age. Anti-aging medicine refers to the application of advanced science and medical technology to early detect, prevent, treat and reverse age-related dysfunctions and diseases. The research on aging and anti-aging has always been a hot spot in the field of medicine and life science. Stem cells are the basis of tissue regeneration and repair, and also the key to maintain the metabolism of the body. At present, it is generally accepted that there is a close relationship between stem cell aging and body aging. The aging process of the body must be accompanied by the aging of a variety of stem cells in the body, and similarly, stem cell aging will also accelerate the aging of the body. Numerous studies in recent years have shown that reversing stem cell aging plays an important role in body anti-aging, which is also an important research direction that is conducive to delaying the aging of the population. This article reviews the mechanism of stem cell aging, the methods of reversing stem cell aging, and the application and mechanism of stem cells in the anti-aging of the body, aiming to provide reference for the application of stem cells in the anti-aging and treatment of aging related diseases.

The alveolar bone marrow mesenchymal stem cells (ABM-MSCs) play an important role in oral bone healing and regeneration. Insulin is considered to improve impaired oral bones due to local factors, systemic factors and pathological conditions. However, the effect of insulin on bone formation ability of ABM-MSCs still needs to be elucidated. The aim of this study was to determine the responsiveness of rat ABM-MSCs to insulin and to explore the underlying mechanism. We found that insulin promoted ABM-MSCs proliferation in a concentration-dependent manner, in which 10-6 M insulin exerted the most significant effect. 10-6 M insulin significantly promoted the type I collagen (COL-1) synthesis, alkaline phosphatase (ALP) activity, osteocalcin (OCN) expression, and mineralized matrix formation in ABM-MSCs, significantly enhanced the gene and protein expressions of intracellular COL-1, ALP, and OCN. Acute insulin stimulation significantly promoted insulin receptor (IR) phosphorylation, IR substrate-1 (IRS-1) protein expression, and mammalian target of rapamycin (mTOR) phosphorylation, but chronic insulin stimulation decreased these values, while inhibitor NT219 could attenuate these responses. When seeded on β-tricalcium phosphate (β-TCP), ABM-MSCs adhered and grew well, during the 28-day culture period, ABM-MSCs+β-TCP +10-6 M insulin group showed significantly higher extracellular total COL-1 amino-terminus prolongation peptide content, ALP activity, OCN secretion, and Ca and P concentration. When implanted subcutaneously in severe combined immunodeficient mice for 1 month, the ABM-MSCs+β-TCP +10-6 M insulin group obtained the most bone formation and blood vessels. These results showed that insulin promoted the proliferation and osteogenic differentiation of ABM-MSCs in vitro, and enhance osteogenesis and angiogenesis of ABM-MSCs in vivo. Inhibition studies demonstrated that the insulin-induced osteogenic differentiation of ABM-MSCs was dependent of insulin/mTOR signaling. It suggests that insulin has a direct anabolic effect on ABM-MSCs.

BACKGROUND:Dental pulp stem cells (DPSCs) refer to a type of stem cells, which is characterized by great differentiation potential and is easy to obtain. DPSCs are able to be employed for treating immune diseases and tissue regeneration. However, the differentiation ability exhibited by aging DPSCs is reduced, thereby limiting the application. As speculated by the microarray analysis, different expressions of miRNAs might be involved in DPSC senescence, whereas comprehensive transcriptome level detection has been rare. OBJECTIVE AND METHODS:To gain insights into the molecular mechanisms involved, RNA-sequencing, pathway enrichment and Gene Ontology Analysis were conducted on aging and young DPSCs. RESULTS:In this study, the differences in long non-coding RNA (lncRNA) and messenger RNA (mRNA expressions) of the aging and young DPSCs were demonstrated, and the vital factors and the relevant pathways were speculated. On the whole, 18950 mRNAs and 21854 lncRNAs were detected, among which 14 mRNAs and 7 lncRNAs were differentially expressed. Furthermore, hsa-miR-6724-5p may be a vital node in the aging process of DPSCs, and its target genes was involved in the dopaminergic synapse. CONCLUSION:In brief, the aging of DPSCs was significantly dependent of differentially expressed genes (DEGs) which is related to dopaminergic synapse. However, the specific function and internal relationship of the DEGs should be verified in depth.

Background Juvenile Xanthogranuloma (JXG) is a non-hereditary, self-limiting disease which is usually presented in infancy or early childhood and in males over females. Case presentation We report a rare case of oral Juvenile Xanthogranuloma with recurrent progressive gingival hyperplasia and concomitant presentation of osteolysis in a 21-year-old adult male with no significant medical history. Patient presented with generalized gingival hyperplasia, osteolysis of the maxilla and mandible, and a round, firm, nodular mass with clear circumference on the left shoulder. Results of gingival tissue biopsy, karyotype, bone marrow biopsy and immunohistochemistry were suggestive of a diagnosis of Juvenile Xanthogranuloma with no association to hematologic malignancy. Unfortunately, patient declined treatment and elected to be transferred back to local hospital for future evaluation. Conclusions Juvenile Xanthogranuloma in adults can have atypical manifestations including generalized gingival hyperplasia and osteolysis of the maxilla and mandible. It should be differentiated between Langerhans cell histiocytosis, Papillon–Lefevre Syndrome, and Pyogenic Granulomas. Despite uncommon incidence, it should be included in differential diagnoses in cases of similar clinical presentations.

Objectives. In this study, a new type of dental implant by covering the surface of the titanium (Ti) implant with zinc-magnesium (Zn-Mg) alloy was designed, to study the antibacterial and antioxidant effects of Mg alloy on titanium (Ti) implants in oral implant restoration. Methods. Human gingival fibroblasts (HGFs), S. sanguinis, and F. nucleatum bacteria were used to detect the bioactivity and antibacterial properties of Mg alloy-coated Ti implants. In addition, B6/J mice implanted with different materials were used to further detect their antibacterial and antioxidant properties. Results. The results showed that Mg alloy could better promote the adhesion and proliferation and improve the alkaline phosphatase (ALP) activity of HGFs, which contributed to better improved stability of implant osseointegration. In addition, Mg alloy could better inhibit the proliferation of S. sanguinis, while no significant difference was found in the proliferation of F. nucleatum between the two implants. In the mouse model, the peripheral inflammatory reaction and oxidative stress of the Mg alloy implant were significantly lower than those of the Ti alloy implant. Conclusions. Zn-Mg alloy-coated Ti implants could better inhibit the growth of Gram-positive bacteria in the oral cavity, inhibit oxidative stress, and facilitate the proliferation activity of HGFs and the potential of osteoblast differentiation, thus, better increasing the stability of implant osseointegration.

Background: Allergic contact stomatitis (ACS) is common among people with allergic constitution and who have allergy reaction to specific allergen such as drugs, food, and materials because of immune dysfunction. With the development of materials science, the increasing diversity of cosmetics and food additives has gradually raised the incidence rate of ACS. Now systemic and local therapy are adopted in the therapy of ACS. However, the systemic therapy would drop the drugs' concentration after it reaches the treatment area through the layers of human barriers, while the locally-used drugs such as collutory may not be suitable for patients with skin lesion. Kangfuxin contains a variety of biological extracts which is anti-inflammatory and curative and can produce connective tissues whether its skin or mucous membrane. It can be used not only in non-oral diseases such as gastric ulcer or gynecological diseases, but also in the treatment of recurrent aphthous ulcer and many kinds of stomatitis and has shown good anti-inflammatory and curative effects. This study aimed to explore the effectiveness of Kangfuxin solution as a local-used adjuvant drug to treat ACS. Case Description: We present a 22-year-old male with ACS whose complaint at the first visit was severe pain, accompanied by salivation, tongue enlargement, bleeding, tonsil enlargement, and symptoms of difficulty in eating, fatigue, and dizziness. After the physical and laboratory examination, we found no abnormalities other than a history of eating the kiwi fruit, which is a common allergen. Thus, he was diagnosed as ACS. In this case, we provided a pharmacologic therapeutic intervention of chlorpheniramine (one tablet, three times a day) and Kangfuxin solution (gargle for 15 min, three times a day) with advice that no exposure to the allergen. On the third day, the patient felt no significant relief of symptoms, while one week after the first visit, the symptoms had obviously alleviated and most of the red lip erosion disappeared. The patient recovered completely with no discomfort in ten days after the initial visit. Conclusions: This study investigated the therapeutic effect of Kangfuxin solution combined with chlorpheniramine on ACS.

Dental pulp stem cells (DPSCs) are ideal seed cells for the regeneration of dental tissues. However, DPSC senescence restricts its clinical applications. Metformin (Met), a common prescription drug for type 2 diabetes, is thought to influence the aging process. This study is aimed at determining the effects of metformin on DPSC senescence. Young and aging DPSCs were isolated from freshly extracted human teeth. Flow cytometry confirmed that DPSCs expressed characteristic surface antigen markers of mesenchymal stem cells (MSCs). Cell Counting Kit-8 (CCK-8) assay showed that a concentration of 100 μM metformin produced the highest increase in the proliferation of DPSCs. Metformin inhibited senescence in DPSCs as evidenced by senescence-associated β-galactosidase (SA-β-gal) staining and the expression levels of senescence-associated proteins. Additionally, metformin significantly suppressed microRNA-34a-3p (miR-34a-3p) expression, elevated calcium-binding protein 39 (CAB39) expression, and activated the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway. Dual-luciferase reporter assay confirmed that CAB39 is a direct target for miR-34a-3p. Furthermore, transfection of miR-34a-3p mimics promoted the senescence of DPSCs, while metformin treatment or Lenti-CAB39 transfection inhibited cellular senescence. In conclusion, these results indicated that metformin could alleviate the senescence of DPSCs by downregulating miR-34a-3p and upregulating CAB39 through the AMPK/mTOR signaling pathway. This study elucidates on the inhibitory effect of metformin on DPSC senescence and its potential as a therapeutic target for senescence treatment.

Dental stem/progenitor cells are a promising cell sources for alveolar bone (AB) regeneration because of their same embryonic origin and superior osteogenic potential. However, their molecular processes during osteogenic differentiation remain unclear. The objective of this study was to identify the responsiveness of dental follicle cells (DFCs) and AB marrow-derived mesenchymal stem cells (ABM-MSCs) to recombinant human bone morphogenetic protein-2 (rhBMP-2). These cells expressed vimentin and MSC markers and did not express cytokeratin and hematopoietic stem cell markers and showed multilineage differentiation potential under specific culture conditions. DFCs exhibited higher proliferation and colony-forming unit-fibroblast efficiency than ABM-MSCs; rhBMP-2 induced DFCs to differentiate toward a cementoblast/osteoblast phenotype and ABM-MSCs to differentiate only toward a osteoblast phenotype; and rhBMP-2-induced DFCs exhibited higher osteogenic differentiation potential than ABM-MSCs. These cells adhered, grew, and produced extracellular matrix on nanohydroxyapatite/collagen/poly(l-lactide) (nHAC/PLA). During a 14-day culture on nHAC/PLA, the extracellular alkaline phosphatase (ALP) activity of DFCs decreased gradually and that of ABM-MSCs increased gradually; rhBMP-2 enhanced their extracellular ALP activity, intracellular osteocalcin (OCN), and osteopontin (OPN) protein expression; and DFCs exhibited higher extracellular ALP activity and intracellular OCN protein expression than ABM-MSCs. When implanted subcutaneously in severe combined immunodeficient mice for 3 months, DFCs+nHAC/PLA+rhBMP-2 obtained higher percentage of bone formation area, OCN, and cementum attachment protein expression and lower OPN expression than ABM-MSCs+nHAC/PLA+rhBMP-2. These results showed that DFCs possessed superior proliferation and osteogenic differentiation potential in vitro, and formed higher quantity and quality bones in vivo. It suggested that DFCs might exhibit a more sensitive responsiveness to rhBMP-2, so that DFCs enter a relatively mature stage of osteogenic differentiation earlier than ABM-MSCs after rhBMP-2 induction. The findings imply that these dental stem/progenitor cells are alternative sources for AB engineering in regenerative medicine, and developing dental tissue may provide better source for stem/progenitor cells.

The microenvironment, or niche, regulates stem cell fate and improves differentiation efficiency. Human umbilical cord mesenchymal stem cells (hUC-MSCs) are ideal cell source for bone tissue engineering. However, the role of the microenvironments in hUC-MSC-based bone regeneration is not yet fully understood. This study is aimed at investigating the effects of the in vitro culture microenvironment (hUC-MSCs, nano-hydroxyapatite/collagen/poly (L-lactide) (nHAC/PLA), osteogenic media (OMD), and recombinant human bone morphogenetic protein-7 (rhBMP-7)) and the in vivo transplanted microenvironment (ectopic and orthotopic) on bone regeneration ability of hUC-MSCs. The isolated hUC-MSCs showed self-renewal potential and MSCs’ characteristics. In the in vitro two-dimensional culture microenvironment, OMD or OMD with rhBMP-7 significantly enhanced hUC-MSCs’ osteocalcin immunofluorescence staining, alkaline phosphatase, and Alizarin red staining; OMD with rhBMP-7 exhibited the highest ALP secretion and mineralized matrix formation. In the in vitro three-dimensional culture microenvironment, nHAC/PLA supported hUC-MSCs’ adhesion, proliferation, and differentiation; the microenvironment containing OMD or OMD and rhBMP-7 shortened cell proliferation progression and made osteogenic differentiation progression advance; rhBMP-7 significantly attenuated the inhibiting effect of OMD on hUC-MSCs’ proliferation and significantly enhanced the promoting effect of OMD on gene expression and protein secretion of osteogenic differentiation markers, calcium and phosphorous concentration, and mineralized matrix formation. The in vitro three-dimensional culture microenvironment containing OMD and rhBMP-7 induced hUC-MSCs to form the most new bones in ectopic or orthotopic microenvironment as proved by microcomputed tomography and hematoxylin and eosin staining, but bone formation in orthotopic microenvironment was significantly higher than that in ectopic microenvironment. The results indicated that the combination of in vitro hUC-MSCs+nHAC/PLA+OMD+rhBMP-7 microenvironment and in vivo orthotopic microenvironment provided a more optimized niche for bone regeneration of hUC-MSCs. This study elucidates that hUC-MSCs and their local microenvironment, or niche, play an important role in hUC-MSC-based bone regeneration. The endogenously produced BMP may serve an important regulatory role in the process.

[This retracts the article DOI: 10.2147/IJN.S148001.].

目的:探讨种植体周围健康状态与微生物菌落的特性.方法:将42颗种植体分为成功(Success,S)、状况良好(Satisfactory survival,S.S)和状况一般(Compromised survival,C.S)组,记录探诊深度和种植体边缘骨吸收.从种植体近颊、颊、远颊取龈沟液样本,通过16S rRNA基因测序分析种植体周围健康状态与微生物菌落的特性.采用SPSS 25.0软件对数据进行统计学分析.结果:三组种植体边缘骨吸收量和平均探诊深度均有显著性差异(P＜0.001),S组和S.S组显著小于C.S组.16S rRNA基因测序发现S.S组菌落多样性高于S组和C.S组,与S组有显著差异(P＜0.05).三组龈沟液微生物群主要由链球菌属(Streptoccus)、卟啉单胞菌属(Porphyromonas)、马赛菌属(Massilia)、罗氏菌属(Rothia)、不动杆菌(Acinetobacter)、普雷沃菌属(Prevotella)、梭杆菌属(Fusobacterium)和密螺旋体属(Treponema)构成.种植体周围健康状况由良好发展到一般时,棒状杆菌属相对丰度逐渐降低,致病菌产线菌属(Filifactor)和Lentimicrobium相对丰度逐渐升高,丛毛单胞菌属(Comamonas)相对丰度显著减少,且三组之间差异显著(P＜0.05);短波单胞菌属(Brevun-dimonas)相对丰度在S.S组最高,显著高于S组和C.S组(P＜0.05).结论:种植体周围健康状况由良好发展到一般时,种植体周围炎症由轻到重,微生物多样性由高到低.种植体周围健康状况一般时微生物致病菌相对丰度较高,这表明龈沟液微生物菌落在种植体周围健康状态中具有潜在作用.

The present study aimed to evaluate the stem cell markers, characteristics and biological functions of cancer stem-like side population (SP) cells in human oral cancer. SP cells were isolated from the human oral squamous cell carcinoma Tca8113 cell line by Hoechst 33342 fluorescence dye and flow cytometry. The colony forming and proliferative capability of SP and non-SP cells were detected using a live-cell analysis system in vitro. The number of cells expressing stem cell markers was compared between SP cells and non-SP cells by flow cytometry. Reverse transcription-quantitative polymerase chain reaction and western blotting were used to detect the mRNA and protein expression levels of stem cell genes, respectively. Differential expression of microRNAs (miRNAs) in SP and non-SP cells was determined by microarray hybridization and an miRNA regulation network was produced. With regard to the proliferation capability, SP cells reached 60.0% confluence after 40 h of growth compared with 35.1% confluence for non-SP cells (P<0.05). The number of colonies in SP cells was 43.1±9.2 compared with 33.0±8.2 of non-SP cells (P<0.05). The aldehyde dehydrogenase-1 (ALDH1)-positive cell number in the SP cells was increased by 10 times compared with the non-SP cells (P<0.01). The mRNA and protein expression levels of ALDH1, SRY-box 2, POU class 5 homeobox 1 and Nanog homeobox in SP cells were significantly higher compared with non-SP cells (P<0.05). Microarray hybridization demonstrated that 21 miRNAs were upregulated and 13 miRNAs were downregulated in SP cells compared with non-SP cells. SP cells in Tca8113 demonstrated greater capability of proliferation and colony formation compared with non-SP cells in vitro. Stem cell markers were overexpressed in SP cells compared with non-SP cells.

Background: Human umbilical cord mesenchymal stem cells (hUC-MSCs) have been suggested as an alternative source of MSCs. However, the studies on its bone formation ability in oral maxillo-facial bone defect are rare. This study investigated the bone formation ability of recombinant human bone morphogenetic protein-7 (rhBMP-7)-induced hUC-MSCs combined with nano-hydroxyapatite/collagen/poly(L-lactide) (nHAC/PLA) in the back of nude mice and jaw bone defect of rabbit. Methods: The characteristics of hUC-MSCs were analyzed by plastic adherence, cell phenotype and multilineage differentiation potential. Cell proliferation was examined using a CCK-8 assay. Osteogenic differentiation was evaluated by quantitative calcium concentration, phosphorous concentration, alkaline phosphatase (ALP) activity, osteocalcin (OCN) concentration, mineral formation, and the mRNA levels of ALP, OCN and bone morphogenetic protein (BMP)-2. Scanning electron microscopy was used to observe cell adhesion, growth and differentiation. Bone formation was assessed by immunohistochemical staining, micro-CT and hematoxylin and eosin staining. Results: The isolated hUC-MSCs expressed CD105, CD90 and CD73, did not express CD45, CD34, CD11a and HLA-DR, exhibited self-renewal potential, and favored osteogenesis and adipogenesis. The exogenously-added rhBMP-7 attenuated the inhibitory effect of the serum-free osteogenic media (OMD) on the proliferation of hUC-MSCs combined with nHAC/PLA, increased the promoting effect of OMD on osteogenic differentiation of hUC-MSCs in two or three-dimensional culture, and enhanced its heterotopic bone formation and jaw bone defect repair abilities. Furthermore, the bone formation of in situ bone defect was significantly superior to heterotopic bone formation. Conclusions: That the microenvironment formed by the regenerative engineered constructs and the in situ bone defect microenvironment closely matched that of the bone tissue in its native state may be essential for sufficient and timely bone regeneration. The endogenously-produced BMPs may serve an important regulatory role in the process. These results paved the way for developing allogeneic hUC-MSCs-based constructs for clinical jaw bone regenerative therapeutic applications.

目的:探讨高正加速度(+Gz)对嚼肌肌细胞的影响及黄芪(Astragalusmembranaceus,AM)的防护作用.方法:30只SD大鼠随机分成对照组、+10Gz组、+10Gz+高浓度AM组(+10Gz+HAM)、+10Gz+中浓度AM组(+10Gz+MAM)、+10Gz+低浓度AM组(+10Gz+LAM),每组6只;腹腔注射不同浓度AM注射液14天后,于模拟加速度动物离心机行+10Gz暴露;光镜下观察咀嚼肌组织学变化;RT-PCR法检测Bcl-2和Bax的mRNA表达水平;Western Blot法检测细胞色素C及caspase-3的蛋白表达水平.结果:+10Gz组嚼肌血管扩张,肌纤维变细、扭曲、横纹消失、甚至坏死,各AM组嚼肌组织学改变程度明显减轻,且与AM浓度相关;+10Gz组嚼肌细胞BaxmRNA表达显著升高、Bcl-2mRNA表达显著降低、caspase-3和细胞色素C蛋白表达显著升高;预先应用AM可以抑制上述mRNA和蛋白的异常表达,并且呈剂量依赖性.结论:高正加速度可致嚼肌损伤、肌细胞凋亡,黄芪可能通过抑制细胞凋亡相关基因和蛋白的异常表达,保护嚼肌免受+Gz值暴露的伤害.

The relationship between mechanical force and alveolar bone remodeling is an important issue in orthodontics because tooth movement is dependent on the response of bone tissue to the mechanical force induced by the appliances used. Mechanical cyclical stretch plays an essential role in the cell osteogenic differentiation involved in bone remodeling. However, the underlying mechanisms are unclear, particularly the molecular pathways regulated by mechanical stimulation. In the present study, we reported a dynamic change of p21 level in response to mechanical cyclical stretch, and shRNA-p21 in bone marrow mesenchymal stem cells (BMSCs) induced osteogenic differentiation. The mechanism was mediated through TWIST/E2A/p21 axis. These results supported the mechanical stimulation-induced osteogenic differentiation is negatively regulated by p21.

As a bone implant material, porous tantalum (Ta) has better corrosion resistance and more suitable elastic modulus than titanium. Surface nanomodification can accelerate the integration of Ta implants with bone tissue, which has broad application prospects in the field of dental implantology. Due to mechanical stress and load wear, nanoscale Ta fragments are inevitably exfoliated from the implant surface and brought into direct contact with osteoblasts surrounding the implant. These wear fragments may affect the biological characteristics of osteoblasts and thus the stability of implants. To date, the interaction of nanoscale Ta fragments with osteoblasts has not been clearly investigated. In the current study, we used the mouse osteoblast cell line MC3T3-E1 to explore the effects of Ta nanoparticles (Ta-NPs) on the cytotoxicity, oxidative stress and autophagy of osteoblasts. We found that a low concentration (12.5 μg/mL) of Ta-NPs can promote the proliferation of osteoblasts, while the Ta-NPs began to induce a decrease in cell viability at concentrations ≥25 μg/mL. Increased cell mortality, reactive oxygen species (ROS) production and decreased mitochondrial membrane potential (MMP) occurred in a dose-dependent manner after Ta-NP treatment. Moreover, with Ta-NP stimulation, the ratio of LC3-II/LC3-I increased, and the level of p62 protein was reduced. However, the degradation of p62 was not continuously increased when the concentration of Ta-NPs was ≥25 μg/mL. These results indicate that Ta-NPs induced osteoblast damage via oxidative stress. Autophagy activation may be a key factor in the cellular response to Ta-NP toxicity and could have an important impact on determining the survival or death of osteoblasts.

OBJECTIVE:The fabrication of bioactive coatings on metallic implants to enhance osseointegration has become a topic of general interest in orthopedics and dentistry. Hydroxyapatite (HA) coating has been shown to induce bone formation and promote bone-implant integration. Unfortunately, poor mechanical performance has hindered this from becoming a favorable coating material. The majority of present studies have focused in incorporating different elements into HA coatings to improve mechanical properties. In recent years, tantalum (Ta) has received increasing attention due to its excellent biocompatibility and corrosion resistance. The aim of on the present study was to investigate the fabrication and biological performance of Ta-incorporated HA coatings.METHODS:Ta-incorporated HA coatings were fabricated using the plasma spray technique on a titanium substrate, and the surface characteristics and mechanical properties were examined. In addition, the effects of Ta-incorporated HA coatings on the biological behavior of mesenchymal stem cells (BMSCs) were investigated.RESULTS:Ta-incorporated HA coatings with microporous structure had higher roughness and wettability. In addition, the bonding strength of Ta/HA coatings with the substrate was substantially superior to HA coatings. Furthermore, Ta-incorporated HA coatings not only facilitated initial cell adhesion and faster proliferation, but also promoted the osteogenic differentiation of BMSCs.CONCLUSION:These results indicate that the incorporation of Ta could improve mechanical performance and increase the osteogenic activity of HA coatings. The Ta-incorporated HA coating fabricated by plasma spraying is expected to be a promising bio-coating material for metallic implants.