TNF-α Inhibits FoxO1 by Upregulating miR-705 to Aggravate Oxidative Damage in Bone Marrow-Derived Mesenchymal Stem Cells during Osteoporosis

Tumour necrosis factor α regulates the miR-27a-3p-Sfrp1 axis in a mouse model of osteoporosis

Osteoporosis is a metabolic bone disease that involves gradual loss of bone density and mass, thus resulting in increased fragility and risk of fracture. Inflammatory cytokines, such as tumour necrosis factor α (TNF-α), inhibit osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), and several microRNAs are implicated in osteoporosis development. This study aimed to explore the correlation between TNF-α treatment and miR-27a-3p expression in BMSC osteogenesis and further understand their roles in osteoporosis. An osteoporosis animal model was established using ovariectomized (OVX) mice. Compared with Sham mice, the OVX mice had a significantly elevated level of serum TNF-α and decreased level of bone miR-27a-3p, and in vitro TNF-α treatment inhibited miR-27a-3p expression in BMSCs. In addition, miR-27a-3p promoted osteogenic differentiation of mouse BMSCs in vitro, as evidenced by alkaline phosphatase staining and Alizarin Red-S staining, as well as enhanced expression of the osteogenic markers Runx2 and Osterix. Subsequent bioinformatics analysis combined with experimental validation identified secreted frizzled-related protein 1 (Sfrp1) as a downstream target of miR-27a-3p. Sfrp1 overexpression significantly inhibited the osteogenic differentiation of BMSCs in vitro and additional TNF-α treatment augmented this inhibition. Moreover, Sfrp1 overexpression abrogated the promotive effect of miR-27a-3p on the osteogenic differentiation of BMSCs. Furthermore, the miR-27a-3p-Sfrp1 axis was found to exert its regulatory function in BMSC osteogenic differentiation via regulating Wnt3a-β-catenin signalling. In summary, this study revealed that TNF-α regulated a novel miR-27a-3p-Sfrp1 axis in osteogenic differentiation of BMSCs. The data provide new insights into the development of novel therapeutic strategies for osteoporosis.

Multifunctional scaffolds for bone repair following age-related biological decline: Promising prospects for smart biomaterial-driven technologies

The repair of large bone defects due to trauma, disease, and infection can be exceptionally challenging in the elderly. Despite best clinical practice, bone regeneration within contemporary, surgically implanted synthetic scaffolds is often problematic, inconsistent, and insufficient where additional osteobiological support is required to restore bone. Emergent smart multifunctional biomaterials may drive important and dynamic cellular crosstalk that directly targets, signals, stimulates, and promotes an innate bone repair response following age-related biological decline and when in the presence of disease or infection. However, their role remains largely undetermined. By highlighting their mechanism/s and mode/s of action, this review spotlights smart technologies that favorably align in their conceivable ability to directly target and enhance bone repair and thus are highly promising for future discovery for use in the elderly. The four degrees of interactive scaffold smartness are presented, with a focus on bioactive, bioresponsive, and the yet-to-be-developed autonomous scaffold activity. Further, cell- and biomolecular-assisted approaches were excluded, allowing for contemporary examination of the capabilities, demands, vision, and future requisites of next-generation biomaterial-induced technologies only. Data strongly supports that smart scaffolds hold significant promise in the promotion of bone repair in patients with a reduced osteobiological response. Importantly, many techniques have yet to be tested in preclinical models of aging. Thus, greater clarity on their proficiency to counteract the many unresolved challenges within the scope of aging bone is highly warranted and is arguably the next frontier in the field. This review demonstrates that the use of multifunctional smart synthetic scaffolds with an engineered strategy to circumvent the biological insufficiencies associated with aging bone is a viable route for achieving next-generation therapeutic success in the elderly population.

Apoptotic vesicles rescue impaired mesenchymal stem cells and their therapeutic capacity for osteoporosis by restoring miR-145a-5p deficiency

Apoptotic vesicles (apoVs) play a vital role in various pathological conditions; however, we have yet to fully understand their precise biological effects in rescuing impaired mesenchymal stem cells (MSCs) and regulating tissue homeostasis. Here, we proved that systemic infusion of bone marrow MSCs derived from wild-type (WT) mice effectively improved the osteopenia phenotype and hyperimmune state in ovariectomized (OVX) mice. Importantly, the WT MSCs rescued the impairment of OVX MSCs both in vivo and in vitro, whereas OVX MSCs did not show the same efficacy. Interestingly, treatment with apoVs derived from WT MSCs (WT apoVs) restored the impaired biological function of OVX MSCs and their ability to improve osteoporosis. This effect was not observed with OVX MSCs-derived apoVs (OVX apoVs) treatment. Mechanistically, the reduced miR-145a-5p expression hindered the osteogenic differentiation and immunomodulatory capacity of OVX MSCs by affecting the TGF-β/Smad 2/3-Wnt/β-catenin signaling axis, resulting in the development of osteoporosis. WT apoVs directly transferred miR-145a-5p to OVX MSCs, which were then reused to restore their impaired biological functions. Conversely, treatment with OVX apoVs did not produce significant effects due to their limited expression of miR-145a-5p. Overall, our findings unveil the remarkable potential of apoVs in rescuing the biological function and therapeutic capability of MSCs derived from individuals with diseases. This discovery offers a new avenue for exploring apoVs-based MSC engineering and expands the application scope of stem cell therapy, contributing to the maintenance of bone homeostasis through a previously unrecognized mechanism.

Lycopene Promotes Osteogenesis and Reduces Adipogenesis through Regulating FoxO1/PPARγ Signaling in Ovariectomized Rats and Bone Marrow Mesenchymal Stem Cells

Recent interest in preventing the development of osteoporosis has focused on the regulation of redox homeostasis. However, the action of lycopene (LYC), a strong natural antioxidant compound, on osteoporotic bone loss remains largely unknown. Here, we show that oral administration of LYC to OVX rats for 12 weeks reduced body weight gain, improved lipid metabolism, and preserved bone quality. In addition, LYC treatment inhibited ROS overgeneration in serum and bone marrow in OVX rats, and in BMSCs upon H2O2 stimulation, leading to inhibiting adipogenesis and promoting osteogenesis during bone remodeling. At the molecular level, LYC improved bone quality via an increase in the expressions of FoxO1 and Runx2 and a decrease in the expressions of PPARγ and C/EBPα in OVX rats and BMSCs. Collectively, these findings suggest that LYC attenuates osteoporotic bone loss through promoting osteogenesis and inhibiting adipogenesis via regulation of the FoxO1/PPARγ pathway driven by oxidative stress, presenting a novel strategy for osteoporosis management.

Causal relationship between intervertebral disc degeneration and osteoporosis: a bidirectional two-sample Mendelian randomization study

Introduction

The relationship between intervertebral disc degeneration (IVDD) and osteoporosis (OP), diagnosed primarily using bone mineral density (BMD), remains unclear so far. The present study, therefore, aimed to investigate the potential relationship between osteoporosis and intervertebral disc degeneration using Mendelian randomization and genome-wide association analyses. Specifically, the impact of bone mineral density on the development of intervertebral disc degeneration was evaluated.

Materials and methods

The genome-wide association studies (GWAS) summary data of OP/BMDs and IVDD were collected from the FinnGen consortium, the GEFOS consortium, and MRC-IEU. The relationship between IVDD and OP was then explored using TSMR. The inverse-variance weighted (IVW) method was adopted as the primary effect estimate, and the reliability and stability of the results were validated using various methods, including MR-Egger, weighted median, simple mode, weighted mode, and MR-PRESSO.

Results

No significant causal relationship was observed between OP and IVDD (IVW, P > 0.05) or between femoral neck BMD (FA-BMD) and IVDD when OP and FA-BMD were used as exposures. However, increased levels of total body BMD (TB-BMD) and lumbar spine BMD (LS-BMD) were revealed as significant risk factors for IVDD (TB-BMD: IVW, OR = 1.201, 95% CI: 1.123-1.284, P = 8.72 × 10-8; LS-BMD: IVW, OR = 1.179, 95% CI: 1.083-1.284, P = 1.43 × 10-4). Interestingly, both heel BMD (eBMD) and femur neck BMD (FN-BMD) exhibited potential causal relationships (eBMD: IVW, OR = 1.068, 95% CI: 1.008-1.131, P = 0.0248; FN-BMD, IVW, OR = 1.161, 95% CI: 1.041-1.295, P = 0.0074) with the risk of IVDD. The reverse MR analysis revealed no statistically causal impact of IVDD on OP and the level of BMD (P > 0.05).

Conclusion

OP and the level of FA-BMD were revealed to have no causal relationship with IVDD. The increased levels of TB-BMD and LS-BMD could promote the occurrence of IVDD. Both eBMD and FN-BMD have potential causal relationships with the risk of IVDD. No significant relationship exists between IVDD and the risk of OP. Further research is warranted to comprehensively comprehend the molecular mechanisms underlying the impact of OP and BMD on IVDD and vice versa.

Traditional Chinese medicine in osteoporosis: from pathogenesis to potential activity

Osteoporosis characterized by decreased bone density and mass, is a systemic bone disease with the destruction of microstructure and increase in fragility. Osteoporosis is attributed to multiple causes, including aging, inflammation, diabetes mellitus, and other factors induced by the adverse effects of medications. Without treatment, osteoporosis will further progress and bring great trouble to human life. Due to the various causes, the treatment of osteoporosis is mainly aimed at improving bone metabolism, inhibiting bone resorption, and promoting bone formation. Although the currently approved drugs can reduce the risk of fragility fractures in individuals, a single drug has limitations in terms of safety and effectiveness. By contrast, traditional Chinese medicine (TCM), a characteristic discipline in China, including syndrome differentiation, Chinese medicine prescription, and active ingredients, shows unique advantages in the treatment of osteoporosis and has received attention all over the world. Therefore, this review summarized the pathogenic factors, pathogenesis, therapy limitations, and advantages of TCM, aiming at providing new ideas for the prevention and treatment of OP.

Differential DNA methylation landscape of miRNAs genes in mice liver fibrosis

BACKGROUND

Patients with chronic liver disease were found nearly all to have liver fibrosis, which is characterized by excess accumulation of extracellular matrix (ECM) proteins. While ECM accumulation can prevent liver infection and injury, it can destroy normal liver function and architecture. miRNA's own regulation was involved in DNA methylation change. The purpose of this study is to detect DNA methylation landscape of miRNAs genes in mice liver fibrosis tissues.

METHODS

Male mice (10-12 weeks) were injected CCl4 from abdominal cavity to induced liver fibrosis. 850 K BeadChips were used to examine DNA methylation change in whole genome. The methylation change of 16 CpG dinucleotides located in promoter regions of 4 miRNA genes were detected by bisulfite sequencing polymerase chain reaction (BSP) to verify chip data accuracy, and these 4 miRNA genes' expressions were detected by RT-qPCR methods.

RESULTS

There are 769 differential methylation sites (DMS) in total between fibrotic liver tissue and normal mice liver tissue, which were related with 148 different miRNA genes. Chips array data were confirmed by bisulfite sequencing polymerase chain reaction (R = 0.953; P < 0.01). GO analysis of the target genes of 2 miRNA revealed that protein binding, cytoplasm and chromatin binding activity were commonly enriched; KEGG pathway enrichment analysis displayed that TGF-beta signaling pathway was commonly enriched.

CONCLUSION

The DNA of 148 miRNA genes was found to have methylation change in liver fibrosis tissue. These discoveries in miRNA genes are beneficial to future miRNA function research in liver fibrosis.

Forkhead box O proteins: steering the course of stem cell fate

Stem cells are pivotal players in the intricate dance of embryonic development, tissue maintenance, and regeneration. Their behavior is delicately balanced between maintaining their pluripotency and differentiating as needed. Disruptions in this balance can lead to a spectrum of diseases, underscoring the importance of unraveling the complex molecular mechanisms that govern stem cell fate. Forkhead box O (FOXO) proteins, a family of transcription factors, are at the heart of this intricate regulation, influencing a myriad of cellular processes such as survival, metabolism, and DNA repair. Their multifaceted role in steering the destiny of stem cells is evident, as they wield influence over self-renewal, quiescence, and lineage-specific differentiation in both embryonic and adult stem cells. This review delves into the structural and regulatory intricacies of FOXO transcription factors, shedding light on their pivotal roles in shaping the fate of stem cells. By providing insights into the specific functions of FOXO in determining stem cell fate, this review aims to pave the way for targeted interventions that could modulate stem cell behavior and potentially revolutionize the treatment and prevention of diseases.

Protective effects of curcumin against osteoporosis and its molecular mechanisms: a recent review in preclinical trials

Osteoporosis (OP) is one of the most common metabolic skeletal disorders and is commonly seen in the elderly population and postmenopausal women. It is mainly associated with progressive loss of bone mineral density, persistent deterioration of bone microarchitecture, and increased fracture risk. To date, drug therapy is the primary method used to prevent and treat osteoporosis. However, long-term drug therapy inevitably leads to drug resistance and specific side effects. Therefore, researchers are constantly searching for new monomer compounds from natural plants. As a candidate for the treatment of osteoporosis, curcumin (CUR) is a natural phenolic compound with various pharmacological and biological activities, including antioxidant, anti-apoptotic, and anti-inflammatory. This compound has gained research attention for maintaining bone health in various osteoporosis models. We reviewed preclinical and clinical studies of curcumin in preventing and alleviating osteoporosis. These results suggest that if subjected to rigorous pharmacological and clinical trials, naturally-derived curcumin could be used as a complementary and alternative medicine for the treatment of osteoporosis by targeting osteoporosis-related mechanistic pathways. This review summarizes the mechanisms of action and potential therapeutic applications of curcumin in the prevention and mitigation of osteoporosis and provides reference for further research and development of curcumin.

Hmga1-overexpressing lentivirus protects against osteoporosis by activating the Wnt/β-catenin pathway in the osteogenic differentiation of BMSCs

Postmenopausal osteoporosis is associated with bone formation inhibition mediated by the impaired osteogenic differentiation potential of bone marrow mesenchymal stem cells (BMSCs). However, identifying and confirming the essential genes in the osteogenic differentiation of BMSCs and osteoporosis remain challenging. The study aimed at revealing the key gene that regulated osteogenic differentiation of BMSCs and led to osteoporosis, thus exploring its therapeutic effect in osteoporosis. In the present study, six essential genes related to the osteogenic differentiation of BMSCs and osteoporosis were identified, namely, fibrillin 2 (Fbn2), leucine-rich repeat-containing 17 (Lrrc17), heat shock protein b7 (Hspb7), high mobility group AT-hook 1 (Hmga1), nexilin F-actin-binding protein (Nexn), and endothelial cell-specific molecule 1 (Esm1). Furthermore, the in vivo and in vitro experiments showed that Hmga1 expression was increased during the osteogenic differentiation of rat BMSCs, while Hmga1 expression was decreased in the bone tissue of ovariectomized (OVX) rats. Moreover, the expression of osteogenic differentiation-related genes, the activity of alkaline phosphatase (ALP), and the number of mineralized nodules were increased after Hmga1 overexpression, which was partially reversed by a Wnt signaling inhibitor (DKK1). In addition, after injecting Hmga1-overexpressing lentivirus into the bone marrow cavity of OVX rats, the bone loss, and osteogenic differentiation inhibition of BMSCs in OVX rats were partially reversed, while osteoclast differentiation promotion of BMSCs in OVX rats was unaffected. Taken together, the present study confirms that Hmga1 prevents OVX-induced bone loss by the Wnt signaling pathway and reveals that Hmga1 is a potential gene therapeutic target for postmenopausal osteoporosis.

Conditioned media of deer antler stem cells accelerate regeneration of alveolar bone defects in rats

The destruction of periodontal alveolar bone (AB) caused by periodontitis is regarded as one of the major reasons for tooth loss. The inhibition of bone resorption and regeneration of lost AB are the desirable outcomes in clinical practice but remain in challenge. The use of mesenchymal stem cells (MSCs) is one current approach for achieving true restoration of AB defects (ABD). Antler stem cells (AnSC) are capable of renewing a huge mammalian bony appendage, the deer antler, suggesting an unparalleled potential for bone regeneration. Herein, we investigated the effectiveness of deer AnSCs conditioned medium (CM, AnSC-CM) for repair of surgically-created ABD using a rat model and sought to define the underlying mechanisms. The results showed that AnSC-CM effectively induced regeneration of AB tissue; the outcome was significantly better than human bone marrow mesenchymal stem cell conditioned medium (hBMSC-CM). AnSC-CM treatment upregulated osteogenic factors and downregulated osteoclastic differentiation factors; stimulated proliferation, migration and differentiation of resident MSCs toward osteogenic lineage cells; modulated macrophage polarization toward the M2 phenotype and suppressed osteoclastogenesis. That AnSC-CM resulted in better outcomes than hBMSC-CM in treating ABD was attributed to the cell compatibility as both AnSCs and AB tissue are neural crest-derived. In conclusion, the effects of AnSC-CM on AB tissue regeneration were achieved through both promotion of osteogenesis and inhibition of osteoclastogenesis. We believe that AnSC-CM is a candidate for effective treatment of ABD in dental clinical practice but will require investment in further development.

Mesenchymal stem cells: Emerging concepts and recent advances in their roles in organismal homeostasis and therapy

Stem cells play a crucial role in re-establishing homeostasis in the body, and the search for mechanisms by which they interact with the host to exert their therapeutic effects remains a key question currently being addressed. Considering their significant regenerative/therapeutic potential, research on mesenchymal stem cells (MSCs) has experienced an unprecedented advance in recent years, becoming the focus of extensive works worldwide to develop cell-based approaches for a variety of diseases. Initial evidence for the effectiveness of MSCs therapy comes from the restoration of dynamic microenvironmental homeostasis and endogenous stem cell function in recipient tissues by systemically delivered MSCs. The specific mechanisms by which the effects are exerted remain to be investigated in depth. Importantly, the profound cell-host interplay leaves persistent therapeutic benefits that remain detectable long after the disappearance of transplanted MSCs. In this review, we summarize recent advances on the role of MSCs in multiple disease models, provide insights into the mechanisms by which MSCs interact with endogenous stem cells to exert therapeutic effects, and refine the interconnections between MSCs and cells fused to damaged sites or differentiated into functional cells early in therapy.

CircRNA hsa_circ_0006859 inhibits the osteogenic differentiation of BMSCs and aggravates osteoporosis by targeting miR-642b-5p/miR-483-3p and upregulating EFNA2/DOCK3

Hsa_circ_0006859 has been found as a possible biomarker for postmenopausal osteoporosis (PMOP) with an effect on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), but the underlying mechanism is unclear. Bioinformatics analysis was used to identify dysregulated RNAs involved in osteoporosis based on public datasets. Function assays were used to determine the functions of hsa_circ_0006859 on cell proliferation and osteogenic differentiation in vitro. It was found that hsa_circ_0006859 was upregulated in OVX mice-derived BMSCs, but lowly expressed during osteogenic differentiation. Overexpressing hsa_circ_0006859 inhibited the cell proliferation and osteogenesis of BMSCs and hFOB 1.19 cells, vice versa. Bilateral ovariectomy (OVX) was used to induce PMOP in mice. The interactions among circ_0006859, miR-642b-5p/miR-483-3p, and EFNA2/DOCK3 were determined using the RIP assay. Silencing circ_0006859 relieved PMOP in mice. Mechanistically, circ_0006859 bound to miR-642b-5p/miR-483-3p directly, while miR-642b-5p and miR-483-3p respectively targeted EFNA2 and DOCK3. Hsa_circ_0006859 downregulated the expression of miR-642b-5p/miR-483-3p to upregulate EFNA2/DOCK3. Additionally, miR-642b-5p/miR-483-3p targeted EFNA2/DOCK3 to inhibit BMSCs osteogenic differentiation and facilitate osteoporosis progression by inactivating the Wnt signaling. In conclusion, hsa_circ_0006859 is involved in PMOP by targeting miR-642b-5p/EFNA2 and miR-483-3p/DOCK3 axes to maintain the Wnt-signaling pathway, which may be a novel possible therapeutic targets and biomarkers for PMOP.

miR-344d-3p regulates osteogenic and adipogenic differentiation of mouse mandibular bone marrow mesenchymal stem cells

Postmenopausal osteoporosis (POP) is a chronic disease of bone metabolism that occurs in middle-aged and elderly women. POP can cause abnormalities of the skeletal system in the whole body, and the jaw bone is also impacted, affecting the function of the oral and maxillofacial regions. Mandibular bone marrow mesenchymal stem cells (MBMSCs) play an important role in mandibular bone metabolism, and abnormal differentiation of MBMSCs can affect the metabolic balance between new and old bone. MicroRNAs (miRNAs) can induce the differentiation of MBMSCs. In this study, the changes in biological characteristics of mandible and MBMSCs in the bone microenvironment of postmenopausal osteoporosis were firstly analyzed, and then the key miRNAs screened from miRNAs gene chips were sorted out for verification and functional exploration. It was found that miR-344d-3p promoted the osteogenic differentiation of MC3T3-E1 and MBMSCs. It inhibited the adipogenic differentiation of 3T3-L1 and MBMSCs. In addition, Dnmt3a may be the target gene of miR-344d-3p. In conclusion, this study found new biological indicators related to bone metabolism, which are of great significance in the field of bone reconstruction.

Oxidative Stress and Inflammation in Osteoporosis: Molecular Mechanisms Involved and the Relationship with microRNAs

Osteoporosis is characterized by the alteration of bone homeostasis due to an imbalance between osteoclastic bone resorption and osteoblastic bone formation. Estrogen deficiency causes bone loss and postmenopausal osteoporosis, the pathogenesis of which also involves oxidative stress, inflammatory processes, and the dysregulation of the expression of microRNAs (miRNAs) that control gene expression at post-transcriptional levels. Oxidative stress, due to an increase in reactive oxygen species (ROS), proinflammatory mediators and altered levels of miRNAs enhance osteoclastogenesis and reduce osteoblastogenesis through mechanisms involving the activation of MAPK and transcription factors. The present review summarizes the principal molecular mechanisms involved in the role of ROS and proinflammatory cytokines on osteoporosis. Moreover, it highlights the interplay among altered miRNA levels, oxidative stress, and an inflammatory state. In fact, ROS, by activating the transcriptional factors, can affect miRNA expression, and miRNAs can regulate ROS production and inflammatory processes. Therefore, the present review should help in identifying targets for the development of new therapeutic approaches to osteoporotic treatment and improve the quality of life of patients.

The Role of Bone Cell Energetics in Altering Bone Quality and Strength in Health and Disease

PURPOSE OF REVIEW

Bone quality and strength are diminished with age and disease but can be improved by clinical intervention. Energetic pathways are essential for cellular function and drive osteogenic signaling within bone cells. Altered bone quality is associated with changes in the energetic activity of bone cells following diet-based or therapeutic interventions. Energetic pathways may directly or indirectly contribute to changes in bone quality. The goal of this review is to highlight tissue-level and bioenergetic changes in bone health and disease.

RECENT FINDINGS

Bone cell energetics are an expanding field of research. Early literature primarily focused on defining energetic activation throughout the lifespan of bone cells. Recent studies have begun to connect bone energetic activity to health and disease. In this review, we highlight bone cell energetic demands, the effect of substrate availability on bone quality, altered bioenergetics associated with disease treatment and development, and additional biological factors influencing bone cell energetics. Bone cells use several energetic pathways during differentiation and maturity. The orchestration of bioenergetic pathways is critical for healthy cell function. Systemic changes in substrate availability alter bone quality, potentially due to the direct effects of altered bone cell bioenergetic activity. Bone cell bioenergetics may also contribute directly to the development and treatment of skeletal diseases. Understanding the role of energetic pathways in the cellular response to disease will improve patient treatment.

Curcumin Prevents Diabetic Osteoporosis through Promoting Osteogenesis and Angiogenesis Coupling via NF-κB Signaling

Diabetic osteoporosis (DOP) is a metabolic disease which is characterized by impaired bone microarchitecture and reduced bone mineral density resulting from hyperglycemia. Curcumin, an effective component extracted from Curcuma longa, exhibits antioxidation, regulation of bone metabolism and hypoglycemic effects. The BMSC-mediated osteogenesis and angiogenesis coupling seems to be important in bone formation and regeneration. We aimed to explore the effect of curcumin on BMSC-mediated osteogenesis-angiogenesis coupling in high glucose conditions and underlying mechanisms. Our results showed that high glucose impaired the osteogenic and proangiogenic ability of BMSCs and that curcumin pretreatment rescued the BMSC dysfunction induced by high-concentration glucose. Inhibition of the high glucose-activated NF-κB signaling pathway has been found to contribute to the protective effects of curcumin on high glucose-inhibited coupling of osteogenesis and angiogenesis in BMSCs. Furthermore, accelerated bone loss and decreased type H vessels were observed in diabetic osteoporosis mice models. However, curcumin treatment prevented bone loss and promoted vessel formation in diabetic osteoporosis mice. Based on these results, we concluded that curcumin ameliorated diabetic osteoporosis by recovering the osteogenesis and angiogenesis coupling of BMSCs in hyperglycemia, partly through inhibiting the high glucose-activated NF-κB signaling pathway.

Differentially expressed genes and miRNAs in female osteoporosis patients

Osteoporosis is characterized by lowing bone mineral density. This study aimed to investigate the genes, miRNAs, pathways, and miRNA-gene interaction pairs involved in the pathogenesis of female osteoporosis. The differentially expressed genes (DEGs, GSE62402), differentially expressed miRNAs (DEmiRNAs, GSE63446), and differentially methylated genes (GSE62588) between females with low- and high-hip bone mineral density were identified. Genes common to DEGs, differentially methylated genes, DEmiRNAs' targets, and osteoporosis-related genes were retained and used to construct the miRNA-mRNA-pathway regulatory network. The expression of hub nodes was validated in microarray datasets (genes in GSE56116 and miRNAs in GSE93883). Thirty-four DEmiRNAs and 179 DEGs with opposite expression-methylation profiles were identified. Functional enrichment analysis showed that DEGs were associated with pathways including "hsa00380:Tryptophan metabolism," "hsa04670:Leukocyte transendothelial migration," "hsa04630:Jak-STAT signaling pathway," and "hsa04062:Chemokine signaling pathway." The miRNA-mRNA-pathway network included 10 DEGs, 9 miRNAs, and 4 osteoporosis-related pathways. The miRNA-gene-pathway axes including hsa-miR-27b-5p/3p-IFNAR1-hsa04630, hsa-miR-30a-5p/3p-IFNAR1-hsa04630, hsa-miR-30a-5p/3p-ALDH2-hsa00380, and hsa-miR-194-5p/3p-NCF2-hsa04670 were included in the network. Microarray validation showed that IFNAR1, NCF2, and ALDH2 were upregulated, and hsa-miR-30a-3p/5p, hsa-miR-194-3p/5p, hsa-miR-27b-3p/5p, and hsa-miR-34a-3p were downregulated in osteoporotic samples compared with control. Axes including hsa-miR-27b/30a-IFNAR1-Jak-STAT signaling pathway, hsa-miR-30a-ALDH2-Tryptophan metabolism, and hsa-miR-194-NCF2-Leukocyte transendothelial migration were involved in osteoporosis pathogenesis.

Regulation of osteogenic differentiation by the pro-inflammatory cytokines IL-1β and TNF-α: current conclusions and controversies

Treatment of complex bone fracture diseases is still a complicated problem that is urged to be solved in orthopedics. In bone tissue engineering, the use of mesenchymal stromal/stem cells (MSCs) for tissue repair brings hope to the medical field of bone diseases. MSCs can differentiate into osteoblasts and promote bone regeneration. An increasing number of studies show that the inflammatory microenvironment affects the osteogenic differentiation of MSCs. It is shown that TNF-α and IL-1β play different roles in the osteogenic differentiation of MSCs via different signal pathways. The main factors that affect the role of TNF-α and IL-1β in osteogenic differentiation of MSCs include concentration and the source of stem cells (different species and different tissues). This review in-depth analyzes the roles of pro-inflammatory cytokines in the osteogenic differentiation of MSCs and reveals some current controversies to provide a reference of comprehensively understanding.

Three Classes of Antioxidant Defense Systems and the Development of Postmenopausal Osteoporosis

Osteoporosis is a common bone imbalance disease that threatens the health of postmenopausal women. Estrogen deficiency accelerates the aging of women. Oxidative stress damage is regarded as the main pathogenesis of postmenopausal osteoporosis. The accumulation of reactive oxygen species in the bone microenvironment plays a role in osteoblast and osteoclast apoptosis. Improving the oxidative state is essential for the prevention and treatment of postmenopausal osteoporosis. There are three classes of antioxidant defense systems in the body to eliminate free radicals and peroxides including antioxidant substances, antioxidant enzymes, and repair enzymes. In our review, we demonstrated the mechanism of antioxidants and their effect on bone metabolism in detail. We concluded that glutathione/oxidized glutathione (GSH/GSSG) conversion involved the PI3K/Akt-Nrf2/HO-1 signaling pathway and that the antioxidant enzyme-mediated mitochondrial apoptosis pathway of osteoblasts was necessary for the development of postmenopausal osteoporosis. Since the current therapeutic effects of targeting bone cells are not significant, improving the systemic peroxidation state and then regulating bone homeostasis will be a new method for the treatment of postmenopausal osteoporosis.

Exercise to Mend Aged-tissue Crosstalk in Bone Targeting Osteoporosis & Osteoarthritis

Aging induces alterations in bone structure and strength through a multitude of processes, exacerbating common aging- related diseases like osteoporosis and osteoarthritis. Cellular hallmarks of aging are examined, as related to bone and the marrow microenvironment, and ways in which these might contribute to a variety of age-related perturbations in osteoblasts, osteocytes, marrow adipocytes, chondrocytes, osteoclasts, and their respective progenitors. Cellular senescence, stem cell exhaustion, mitochondrial dysfunction, epigenetic and intracellular communication changes are central pathways and recognized as associated and potentially causal in aging. We focus on these in musculoskeletal system and highlight knowledge gaps in the literature regarding cellular and tissue crosstalk in bone, cartilage, and the bone marrow niche. While senolytics have been utilized to target aging pathways, here we propose non-pharmacologic, exercise-based interventions as prospective "senolytics" against aging effects on the skeleton. Increased bone mass and delayed onset or progression of osteoporosis and osteoarthritis are some of the recognized benefits of regular exercise across the lifespan. Further investigation is needed to delineate how cellular indicators of aging manifest in bone and the marrow niche and how altered cellular and tissue crosstalk impact disease progression, as well as consideration of exercise as a therapeutic modality, as a means to enhance discovery of bone-targeted therapies.

Lansoprazole-induced osteoporosis via the IP3R- and SOCE-mediated calcium signaling pathways

Background

Many clinical studies have shown a correlation between proton pump inhibitors (PPIs) and osteoporosis or fractures. The purpose of this study was to establish a murine model of chronic oral PPI administration to verify whether PPIs caused bone metabolic impairment and investigate the relevant molecular mechanism underlying the effects of PPIs on MC3T3-E1 murine osteoblasts.

Methods

A lansoprazole-induced bone loss model was used to investigate the damaging effects of PPIs. In vivo, immunohistochemistry, Hematoxylin–Eosin (HE) staining, micro-CT analysis, and blood biochemical analyses were used to evaluate the effect of lansoprazole on bone injury in mice. In vitro, the effects of lansoprazole and related signaling pathways in MC3T3-E1 cells were investigated by CCK-8 assays, EdU assays, flow cytometry, laser confocal microscopy, patch clamping, reverse transcription-quantitative polymerase chain reaction and Western blotting.

Results

After 6 months of lansoprazole gavage in ICR mice, the micro-CT results showed that compared with that in the vehicle group, the bone mineral density (BMD) in the high-dose group was significantly decreased (P < 0.05), and the bone microarchitecture gradually degraded. Biochemical analysis of bone serum showed that blood calcium and phosphorus were both decreased (P < 0.01). We found that long-term administration of lansoprazole impaired skeletal function in mice. In vitro, we found that lansoprazole (LPZ) could cause calcium overload in MC3T3-E1 cells leading to apoptosis, and 2-APB, an inhibitor of IP3R calcium release channel and SOCE pathway, effectively blocked increase in calcium caused by LPZ, thus protecting cell viability.

Conclusions

Longterm administration of LPZ induced osteoporotic symptoms in mice, and LPZ triggered calcium increases in osteoblasts in a concentration-dependent manner. Intracellular calcium ([Ca²⁺]_i) persisted at a high concentration, thereby causing endoplasmic reticulum stress (ERS) and inducing osteoblast apoptosis.

Epigenetic therapy attenuates oxidative stress in BMSCs during ageing

Oxidative stress, a hallmark of ageing, inhibits the osteogenic differentiation of bone marrow-derived mesenchymal stem cells in long bone. The dysfunction of the cellular antioxidant defence system is a critical cause of oxidative stress, but the mechanism of the decline of antioxidant defence in senescent stem cells remains elusive. Here, we found that EZH2, an epigenetic regulator of histone methylation, acted as a suppressor of the antioxidative defence system in BMSCs from the femur. The increased EZH2 led to a decrease in the levels of antioxidant enzymes and exaggerated oxidative damage in aged BMSCs, resulting in the defect of bone formation and regeneration. Mechanistically, EZH2 enhanced the modification of H3K27me3 on the promoter of Foxo1 and suppressed its function to activate the downstream genes in antioxidant defence. Moreover, epigenetic therapy targeting EZH2-mediated H3K27me3 modification largely recovered the antioxidant defence in BMSCs and attenuate oxidative damage, leading to the recovery of the osteogenesis in old BMSCs. Taken together, our findings revealed novel crosstalk between histone epigenetic modification and oxidative stress during stem cell ageing, suggesting a possibility of epigenetic therapy in the recovery of BMSCs senescence and treatment of age-related bone disease.

Remodeling the periodontitis microenvironment for osteogenesis by using a reactive oxygen species-cleavable nanoplatform

Modestly removing the excessive reactive oxygen species (ROS) plays a crucial role in regulating the microenvironment of periodontitis and provides favorable conditions for osteogenesis. However, the current strategy for scavenging ROS is not controllable, substantially limiting the outcomes in periodontitis. Herein, we introduced a controllable ROS-scavenging nanoplatform by encasing N-acetylcysteine (NAC, (a well-known ROS scavenger) into tailor-made ROS-cleavable amphiphilic polymer nanoparticles (PEG-ss-PCL NPs) as an intracellular delivery carrier. The existing ROS in the inflammatory microenvironment facilitated polymer degradation via breakage of thioketal bonds, and then led to encapsulated NAC release. NAC eliminated all ROS induced by lipopolysaccharide (LPS), while PssL-NAC adjusted the ROS level slightly higher than that of the control group. The percentage of apoptotic cells cultured with NAC and PssL-NAC decreased observably compared with that of cells cultured with 10 µg/ml LPS. The microenvironment regulated by PssL-NAC was highly suitable for osteogenic differentiation based on PCR and Western blot results, which showed higher expression levels of BMP2, Runx2, and PKA. Analysis of ALP activity and Alizarin red S staining showed consistent results. Additionally, the injection of PssL-NAC into the periodontitis area could alleviate the tissue destruction induced by ligation of the maxillary second molar. PssL-NAC showed a better ability to decrease osteoclast activity and inflammation, consequently improving the restoration of destroyed tissue. Our study suggests that ROS-responsive polymer nanoparticles loaded with NAC (PssL-NAC) can be new promising materials for the treatment of periodontitis. STATEMENT OF SIGNIFICANCE: More and more studies indicate that periodontal tissue damage is closely related to the high reactive oxygen species (ROS) environment. Excessive ROS will aggravate periodontal tissue damage and is not conducive to tissue repair. However, as an essential signal molecule in human physiological activities, ROS absence is also useless for tissue repair. In this study, we proposed to improve ROS imbalance in the environment of periodontitis as a strategy to promote periodontal regeneration and successfully synthesized a smart drug-releasing nanoplatform that can respond to ROS. Besides, we validated its ability to regulate the ROS environment and promote osteogenesis through experimental data in vivo and in vitro.

Atractylenolide III alleviates sepsis-mediated lung injury via inhibition of FoxO1 and VNN1 protein

PURPOSE

To evaluate the influence of atractylenolide (Atr) III on sepsis-induced lung damage.

METHODS

We constructed a mouse sepsis model through cecal ligation and puncture. These mice were allocated to the normal, sepsis, sepsis + Atr III-L (2 mg/kg), as well as Atr III-H (8 mg/kg) group. Lung injury and pulmonary fibrosis were accessed via hematoxylin-eosin (HE) and Masson's staining. We used terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and flow cytometry for detecting sepsis-induced lung cell apoptosis. The contents of the inflammatory cytokines in lung tissue were measured via enzyme-linked immunosorbent assay (ELISA).

RESULTS

Atr III-H did not only reduce sepsis-induced lung injury and apoptosis level, but also curbed the secretion of inflammatory factors. Atr III-H substantially ameliorated lung function and raised Bcl-2 expression. Atr III-H eased the pulmonary fibrosis damage and Bax, caspase-3, Vanin-1 (VNN1), as well as Forkhead Box Protein O1 (FoxO1) expression.

CONCLUSIONS

Atr III alleviates sepsis-mediated lung injury via inhibition of FoxO1 and VNN1 protein.

Effects of strontium-incorporated micro/nano rough titanium surfaces on osseointegration via modulating polarization of macrophages

Macrophages perform multiple functions in both inflammation and wound healing, and are one of the fore front cells during implant osseointegration that influence subsequent process. Essential trace element modification may effectively modulate titanium implant surface biological properties. In this work, strontium (Sr) incorporated micro/nano rough titanium surfaces (Sr-SLA) was fabricated by hydrothermal treatment, and immunoreaction of macrophages was further investigated. In vitro results revealed that Sr doping inhibited inflammatory response of macrophages, further attenuated the inhibitory effect on following bone marrow derived cells (BMSCs) osteogenic differentiation. The regulation of macrophages by Sr-SLA likely involved ERK signaling pathway. Consistently, the in vivo study showed that compared with titanium surface sand-blasted with large grit and double acid-etched (SLA) implants, Sr-SLA implants could enhance new bone formation accompanied with more alternatively activated M2 macrophages infiltration and less classically activated M1 macrophages infiltration. These results reveal the immunomodulatory ability of Sr-SLA of adjusting the functional status of macrophages through inhibiting M1 polarization while promoting M2 polarization.

Silencing Proteasome 26S Subunit ATPase 2 (PSMC2) Protects the Osteogenic Differentiation In Vitro and Osteogenesis In Vivo

Osteoporosis is a commonly seen degenerative bone disorder in the elderly and postmenopausal women, with a low bone mineral density as a major risk factor. The osteogenic potential of bone marrow stromal cells (BMSCs) showed to be impaired during osteoporosis. We established a postmenopausal osteoporosis model in ovariectomized (OVX) mice and found the upregulation of proteasome 26S subunit ATPase 2 (PSMC2) in OVX mice. PSMC2 silencing improved OVX-impaired biomechanical properties of mice femur, OVX-decreased BMD, and OVX-destroyed bone structure. Histopathological analysis indicated that PSMC2 silencing improved bone trabecular structure and increased the contents of collagen fibers and newly formed bone or cartilage in OVX mice. In the meantime, PSMC2 silencing increased Runx2, PI3K, Wnt3a, and β-catenin protein contents while reduced CTSK protein. Within BMSCs isolated from OVX mice, PSMC2 silencing promoted BMSC osteogenic differentiation and elevated osteogenic markers' protein contents, including HOXA10, Runx2, OCN, OPN, and COL1A2. In conclusion, PSMC2 expression is upregulated in the postmenopausal osteoporosis model in OVX mice. PSMC2 silencing promotes the osteogenic differentiation of BMSCs in vitro, promotes bone formation, and inhibits bone resorption in vivo.

Baicalein ameliorates osteoporosis via AKT/FOXO1 signaling

In this study, we used bioinformatics and an in vitro cellular model of glucocorticoid-induced osteoporosis to investigate mechanisms underlying the beneficial effects of baicalein (BN) against osteoporosis. STITCH database analysis revealed 30 BN-targeted genes, including AKT1, CCND1, MTOR, and PTEN. Functional enrichment analysis demonstrated that BN-targeted genes were enriched in 49 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. MIRWALK2.0 database analysis identified 110 enriched KEGG pathways related to osteoporosis. A Venn diagram demonstrated that 26 KEGG pathways were common between osteoporosis and BN-targeted genes. The top 5 common KEGG pathways were prostate cancer, bladder cancer, glioma, pathways in cancer, and melanoma. BN-targeted genes in the top 5 shared KEGG pathways were involved in PI3K-AKT, MAPK, p53, ErbB, and mTOR signaling pathways. In addition, glucocorticoid-induced osteoporosis in MC3T3-E1 cells was partially reversed by BN through inhibition of AKT, which, by upregulating FOXO1, enhanced expression of bone turnover markers (ALP, OCN, Runx2, and Col 1) and extracellular matrix mineralization. These findings demonstrate that BN suppresses osteoporosis via an AKT/FOXO1 signaling pathway.

A narrative overview of utilizing biomaterials to recapitulate the salient regenerative features of dental-derived mesenchymal stem cells

Tissue engineering approaches have emerged recently to circumvent many limitations associated with current clinical practices. This elegant approach utilizes a natural/synthetic biomaterial with optimized physiomechanical properties to serve as a vehicle for delivery of exogenous stem cells and bioactive factors or induce local recruitment of endogenous cells for in situ tissue regeneration. Inspired by the natural microenvironment, biomaterials could act as a biomimetic three-dimensional (3D) structure to help the cells establish their natural interactions. Such a strategy should not only employ a biocompatible biomaterial to induce new tissue formation but also benefit from an easily accessible and abundant source of stem cells with potent tissue regenerative potential. The human teeth and oral cavity harbor various populations of mesenchymal stem cells (MSCs) with self-renewing and multilineage differentiation capabilities. In the current review article, we seek to highlight recent progress and future opportunities in dental MSC-mediated therapeutic strategies for tissue regeneration using two possible approaches, cell transplantation and cell homing. Altogether, this paper develops a general picture of current innovative strategies to employ dental-derived MSCs combined with biomaterials and bioactive factors for regenerating the lost or defective tissues and offers information regarding the available scientific data and possible applications.

Immunometabolic Endothelial Phenotypes: Integrating Inflammation and Glucose Metabolism

[Figure: see text].

miR-4286 functions in osteogenesis and angiogenesis via targeting histone deacetylase 3 and alleviates alcohol-induced bone loss in mice

Objectives

Alcohol consumption is one of the leading factors contributing to premature osteopenia. MicroRNA (miRNA) coordinates a cascade of anabolic and catabolic processes in bone homeostasis and dynamic vascularization. The aim was to investigate the protective role of miR‐4286 in alcohol‐induced bone loss and its mechanism.

Materials and Methods

The effect of miR‐4286 and alcohol on bone mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) was explored via multiple in vitro assays, including cell proliferation, QPCR, Western blot, osteogenesis, angiogenesis etc miR‐4286 directly regulated HDAC3 was investigated by luciferase reporter assay, and the function of HDAC3 was also explored in vitro. Moreover, alcohol‐induced bone loss in mice was established to reveal the preventive effect of miR‐4286 by radiographical and histopathological assays.

Results

In vitro, ethanol dramatically inhibited the proliferation and osteogenesis of BMSCs, and substantially impaired the proliferation and vasculogenesis of HUVECs. However, a forced overexpression of miR‐4286 within BMSCs and HUVECs could largely abolish inhibitory effects by alcohol. Furthermore, alcohol‐induced inhibition on osteogenic and vasculogenic functions was mediated by histone deacetylase 3 (HDAC3), and dual‐luciferase reporter assay showed that HDAC3 was the direct binding target of miR‐4286. In vivo, micro‐CT scanning and histology assessment revealed that miR‐4286 could prevent alcohol‐induced bone loss.

Conclusions

We firstly demonstrated that miR‐4286 might function via intimate osteogenesis‐angiogenesis pathway to alleviate alcohol‐induced osteopenia via targeting HDAC3.

MiRNA-1271-5p regulates osteogenic differentiation of human bone marrow-derived mesenchymal stem cells by targeting forkhead box O1 (FOXO1)

Forkhead box O1 (FOXO1) is a key regulator of osteogenesis. The aim of this study was to identify the mechanisms of microRNAs (miRNAs) targeting FOXO1 in osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs). Three miRNA target prediction programs were used to search for potential miRNAs that target FOXO1. Quantitative real-time polymerase chain reaction was conducted to detect the expression of miR-1271-5p and FOXO1 during osteogenic differentiation. Target gene prediction and screening, luciferase reporter assay was used to verify the downstream target gene of miR-1271-5p. The expression levels of FOXO1 and Runx2 were detected by RT-qPCR and Western blot analysis. Alkaline phosphatase (ALP) activity and matrix mineralization were detected by biochemical methods. The expression levels of Runx2, ALP, and osteocalcin were detected by RT-qPCR. Our results showed that miR-1271-5p was downregulated during osteogenic induction. And the expression levels of miR-1271-5p were higher in osteoporotic tissues than that in adjacent nonosteoporotic tissues. The expression levels of FOXO1 were lower in osteoporotic tissues than that in adjacent nonosteoporotic tissues. And a negative correlation was found between miR-1271-5p and FOXO1 in osteoporotic tissues. Overexpression of miR-1271-5p downregulated FOXO1 and inhibited osteogenic differentiation in hMSCs. Overexpression of miR-1271-5p downregulated the expression of osteogenic markers and reduced ALP activity. In addition, ectopic expression of FOXO1 reversed the effect of miR-1271-5p on osteogenic differentiation. In conclusion, miR-1271-5p functioned as a therapeutic target of osteogenic differentiation in hMSCs by inhibiting FOXO1, which provides valuable insights into the use of miR-1271-5p as a target in the treatment of osteoporosis and other bone metabolic diseases.

LRRc17 controls BMSC senescence via mitophagy and inhibits the therapeutic effect of BMSCs on ovariectomy-induced bone loss

Senescence of bone marrow-derived mesenchymal stem cells (BMSCs) has been widely reported to be closely correlated with aging-related diseases, including osteoporosis (OP). Moreover, the beneficial functions of BMSCs decline with age, limiting their therapeutic efficacy in OP. In the present study, using RNA sequencing (RNA-Seq), we found that leucine-rich repeat containing 17 (LRRc17) expression in BMSCs was highly positively correlated with age. Therefore, we investigated whether LRRc17 knockdown could rejuvenate aged MSCs and increase their therapeutic efficacy in OP. Consistent with the RNA-Seq results, the protein expression of LRRc17 in senescent BMSCs was significantly increased, whereas LRRc17 knockdown inhibited cell apoptosis and reduced the expression of age-related proteins and G2 and S phase quiescence. Furthermore, LRRc17 knockdown shifted BMSCs from adipogenic to osteogenic differentiation, indicating the critical role of LRRc17 in BMSC senescence and differentiation. Additionally, similar to rapamycin (RAPA) treatment, LRRc17 knockdown activated mitophagy via inhibition of the mTOR/PI3K pathway, which consequently reduced mitochondrial dysfunction and inhibited BMSC senescence. However, the effects of LRRc17 knockdown were significantly blocked by the autophagy inhibitor hydroxychloroquine (HCQ), demonstrating that LRRc17 knockdown prevented BMSC senescence by activating mitophagy. In vivo, compared with untransfected aged mouse-derived BMSCs (O-BMSCs), O-BMSCs transfected with sh-LRRc17 showed effective amelioration of ovariectomy (OVX)-induced bone loss. Collectively, these results indicated that LRRc17 knockdown rejuvenated senescent BMSCs and thus enhanced their therapeutic efficacy in OP by activating autophagy.

Exosomes derived from circRNA Rtn4-modified BMSCs attenuate TNF-α-induced cytotoxicity and apoptosis in murine MC3T3-E1 cells by sponging miR-146a

Osteoporosis is the most common and complex skeletal disorder worldwide. Exosomes secreted by bone marrow-derived mesenchymal stromal cells (BMSCs) are considered as an ideal seed source for bone tissue regeneration. However, the role of exosomes secreted by BMSCs (BMSCs-Exos) in osteoporosis and its underlying mechanisms remain unclear. In the present study, the expression of microRNA (miRNA)-146a and circular RNA (circRNA) Rtn4 (circ-Rtn4) was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), and their protein expression was determined by Western blotting. Enzyme-linked immunosorbent assay was performed to detect caspase-3 activity. Cell viability and apoptosis were assessed using 3-(4,5-Dimethylthiazol-2yl-)-2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry analysis, respectively. Luciferase reporter assay was exploited for target validation. Results showed that tumor necrosis factor-α (TNF-α) dose-dependently increased miR-146a expression, inhibited cell viability, and promoted cell apoptosis, as indicated by increased caspase-3, cleaved caspase-3, and Bcl-2-associated X protein (Bax) expression as well as caspase-3 activity. However, miR-146a silencing or co-culture with BMSCs-Exos blocked these effects. Moreover, co-culture with exosomes-derived from circ-Rtn4-modified BMSCs (Rtn4-Exos) attenuated TNF-α-induced cytotoxicity and apoptosis in MC3T3-E1 cells, as evidenced by the decrease in caspase-3, cleaved caspase-3, and Bax protein expression and caspase-3 activity. In addition, miR-146a was identified as a target of circ-Rtn4, and Rtn4-Exos exerted their function in TNF-α-treated MC3T3-E1 cells by sponging miR-146a. Hence, our findings suggested that Rtn4-Exos attenuated TNF-α-induced cytotoxicity and apoptosis in murine MC3T3-E1 cells by sponging miR-146a, suggesting that Rtn4-Exos may serve as novel candidates for treating osteoporosis.

Bioadaptation of implants to In vitro and In vivo oxidative stress pathological conditions via nanotopography-induced FoxO1 signaling pathways to enhance Osteoimmunal regeneration

Varieties of pathological conditions, including diabetes, are closely related to oxidative stress (OS), but the osseointegration or bioadaptation of implants to OS and the related mechanism remain poorly explored. In this study, the antioxidation and osteoimmune regeneration of titanium implants with micro/nanotopographies were evaluated under H₂O₂-, lipopolysaccharide (LPS)- and hyperglycemia-mediated cellular OS models and in diabetic rats as a representative animal model of OS. TiO₂ nanotube (TNT) coating on titanium implants directly induced superior osteogenic differentiation of bone mesenchymal stem cells (MSCs) and osseointegration compared with microscale sand blasted-acid etched topography (SLA) under OS, attributed to higher superoxide dismutase 2 activity, the neutralization of intracellular reactive oxygen species (ROS), and less apoptosis. Mechanistically, the oxidation resistance on TNT is driven by upregulated forkhead box transcription factor O1 (FoxO1), which is abolished after knockdown of FoxO1 via shRNA in MSCs. Indirectly, TNT also alleviates OS in macrophages, therefore inducing a higher portion of the M2 phenotype under OS with increased secretion of the anti-inflammatory cytokine IL-10, further promoting the osseoimmunity capacity compared with SLA. The current study not only suggests the potential application of TiO₂ nanotube-coated titanium implants in compromised conditions but also provides a systematic evaluation strategy for the future development of bone biomaterials.

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H₂O₂, lipopolysaccharide and hyperglycemia induced cellular oxidative stress models.

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TiO₂ nanotubes promote oxidation resistance and osteogenesis under oxidative stress.

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TiO₂ nanotubes activate forkhead box transcription factor O1 to enhance osteogenesis.

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TiO₂-nanotube-coated implants promote osseointegration in diabetic rats.

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TiO₂ nanotubes induce anti-inflammatory osteoimmunity under oxidative stress.

Targeting reactive oxygen species in stem cells for bone therapy

Reactive oxygen species (ROS) have emerged as key players in regulating the fate and function of stem cells from both non-hematopoietic and hematopoietic lineages in bone marrow, and thus affect the osteoblastogenesis-osteoclastogenesis balance and bone homeostasis. Accumulating evidence has linked ROS and associated oxidative stress with the progression of bone disorders, and ROS-based therapeutic strategies have appeared to achieve favorable outcomes in bone. We review current knowledge of the multifactorial roles and mechanisms of ROS as a target in bone pathology. In addition, we discuss emerging ROS-based therapeutic strategies that show potential for bone therapy. Finally, we highlight the opportunities and challenges facing ROS-targeted stem cell therapeutics for improving bone health.

Moringa oleifera leaf extracts protect BMSC osteogenic induction following peroxidative damage by activating the PI3K/Akt/Foxo1 pathway

Objective

We aimed to investigate the therapeutic effects of Moringa oleifera leaf extracts on osteogenic induction of rat bone marrow mesenchymal stem cells (BMSCs) following peroxidative damage and to explore the underlying mechanisms.

Methods

Conditioned medium was used to induce osteogenic differentiation of BMSCs, which were treated with H₂O₂, Moringa oleifera leaf extracts-containing serum, or the phosphatidyl inositol-3 kinase (PI3K) inhibitor wortmannin, alone or in combination. Cell viability was measured using the MTT assay. Cell cycle was assayed using flow cytometry. Expression levels of Akt, phosphorylated (p)Akt, Foxo1, and cleaved caspase-3 were analyzed using western blot analysis. The mRNA levels of osteogenesis-associated genes, including alkaline phosphatase (ALP), collagen І, osteopontin (OPN), and Runx2, were detected using qRT-PCR. Reactive oxygen species (ROS) and malondialdehyde (MDA) levels, as well as superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and ALP activity were detected using commercially available kits. Osteogenic differentiation capability was determined using alizarin red staining.

Results

During osteogenic induction of rat BMSCs, H₂O₂ reduced cell viability and proliferation, inhibited osteogenesis, increased ROS and MDA levels, and decreased SOD and GSH-PX activity. H₂O₂ significantly reduced pAkt and Foxo1 expression, and increased cleaved caspase-3 levels in BMSCs. Additional treatments with Moringa oleifera leaf extracts partially reversed the H₂O₂-induced changes. Wortmannin partially attenuated the effects of Moringa oleifera leaf extracts on protein expression of Foxo1, pAkt, and cleaved caspase-3, as well as mRNA levels of osteogenesis-associated genes.

Conclusion

Moringa oleifera leaf extracts ameliorate peroxidative damage and enhance osteogenic induction of rat BMSCs by activating the PI3K/Akt/Foxo1 pathway.

Do polyunsaturated fatty acids protect against bone loss in our aging and osteoporotic population?

Age-related bone loss is inevitable in both men and women and there will soon be more people of extreme old age than ever before. Osteoporosis is a common chronic disease and as the proportion of older people, rate of obesity and the length of life increases, a rise in age-related degenerating bone diseases, disability, and prolonged dependency is projected. Fragility fractures are one of the most severe complications associated with both primary and secondary osteoporosis and current treatment strategies target weight-bearing exercise and pharmacological intervention, both with limited long-term success. Obesity and osteoporosis are intimately interrelated, and diet is a variable that plays a significant role in bone regeneration and repair. The Western Diet is characterized by its unhealthy components, specifically excess amounts of saturated fat intake. This review examines the impact of saturated and polyunsaturated fatty acid consumption on chronic inflammation, osteogenesis, bone architecture, and strength and explores the hypothesis that dietary polyunsaturated fats have a beneficial effect on osteogenesis, reducing bone loss by decreasing chronic inflammation, and activating bone resorption through key cellular and molecular mechanisms in our aging population. We conclude that aging, obesity and a diet high in saturated fatty acids significantly impairs bone regeneration and repair and that consumption of ω-3 polyunsaturated fatty acids is associated with significantly increased bone regeneration, improved microarchitecture and structural strength. However, ω-6 polyunsaturated fatty acids were typically pro-inflammatory and have been associated with an increased fracture risk. This review suggests a potential role for ω-3 fatty acids as a non-pharmacological dietary method of reducing bone loss in our aging population. We also conclude that contemporary amendments to the formal nutritional recommendations made by the Food and Nutrition Board may be necessary such that our aging population is directly considered.

Involvement of CB2 signalling pathway in the development of osteoporosis by regulating the proliferation and differentiation of hBMSCs

The aim of the present study was to explore the potential mechanism underlying the involvement of CB2 in osteoporosis. Micro‐CT was utilized to examine femur bone architecture. Also, real‐time PCR and Western blot analysis were utilized to detect the effect of 2‐AG on the expression of CB2 and Notch, or the interaction between CB2 and Notch 2. 2‐AG treatment up‐regulated BMD, Tb.Sp and SMI in OVX mice, whereas proportion of bone volume in total volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N) and bone mineral density (BMD) were decreased in 2‐AG‐treated OVX mice. Accordingly, 2‐AG administration up‐regulated Notch 1 expression in OVX mice but had no effect on CB2 and Notch 2 expression. Meanwhile, 2‐AG administration promoted the differentiation of hBMSCs in OVX mice, while exhibiting no effect on the proliferation of hBMSCs. Furthermore, in the cellular models, 2‐AG treatment also up‐regulated Notch 1 expression but had no effect on CB2 and Notch 2 expression, while Notch 1 shRNA had no effect on CB2 and Notch 2 expression. 2‐AG promoted cell proliferation and differentiation, which were inhibited by Notch 1 shRNA. NICD had no effect on CB2 level but increased Notch 1 expression, and CB2 shRNA decreased CB2 and Notch 1 expression. Finally, CB2 shRNA inhibited cell proliferation and differentiation, whereas NICD promoted proliferation and differentiation of hBMSCs. Our results provided further evidence for the association of CB2 gene with BMD and osteoporosis, and identified CB2 as a promising target for the treatment of osteoporosis.

Adverse Impact of Heavy Metals on Bone Cells and Bone Metabolism Dependently and Independently through Anemia

Mounting evidence is revealing that heavy metals can incur disordered bone homeostasis, leading to the development of degenerative bone diseases, including osteoporosis, osteoarthritis, degenerative disk disease, and osteomalacia. Meanwhile, heavy metal-induced anemia has been found to be intertwined with degenerative bone diseases. However, the relationship and interplay among these adverse outcomes remain elusive. Thus, it is of importance to shed light on the modes of action (MOAs) and adverse outcome pathways (AOPs) responsible for degenerative bone diseases and anemia under exposure to heavy metals. In the current Review, the epidemiological and experimental findings are recapitulated to interrogate the contributions of heavy metals to degenerative bone disease development which may be attributable dependently and independently to anemia. A few likely mechanisms are postulated for anemia-independent degenerative bone diseases, including dysregulated osteogenesis and osteoblastogenesis, imbalanced bone formation and resorption, and disturbed homeostasis of essential trace elements. By contrast, remodeled bone microarchitecture, inhibited erythropoietin production, and disordered iron homeostasis are speculated to account for anemia-associated degenerative bone disorders upon heavy metal exposure. Together, this Review aims to elaborate available literature to fill in the knowledge gaps in understanding the detrimental effects of heavy metals on bone cells and bone homeostasis through different perspectives.

lncRNA Xist Regulates Osteoblast Differentiation by Sponging miR-19a-3p in Aging-induced Osteoporosis

The switch between osteogenic and adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) plays a key role in aging-induced osteoporosis. In this study, miR-19a-3p was obviously downregulated in BMSCs from aged humans and mice. Overexpressed miR-19a-3p evidently reduced aging-induced bone loss in mice and promoted osteogenic differentiation of BMSCs, while silenced miR-19a-3p manifestly increased aging-induced bone loss in mice and repressed osteogenic differentiation of BMSCs. Hoxa5 was significantly downregulated in the BMSCs from aged mice and contribute to miR-19a-3p-induced osteoblast differentiation as a direct target gene of miR-19a-3p. Furthermore, lncRNA Xist was found as a sponge of miR-19a-3p to repress BMSCs osteogenic differentiation. In conclusion, our study reveals the critical role of the lncRNA Xist/miR-19a-3p/Hoxa5 pathway in aging-induced osteogenic differentiation of BMSCs, indicating the potential therapeutic target for osteoporosis.

Data-Independent Acquisition-Based Quantitative Proteomic Analysis Reveals the Protective Effect of Apigenin on Palmitate-Induced Lipotoxicity in Human Aortic Endothelial Cells

The ingestion of excessive free fatty acid could induce lipotoxicity in tissues and then lead to the initiation of many metabolism diseases. In this work, the protective effect of apigenin on palmitate-induced lipotoxicity in human aortic endothelial cells (HAEC) was investigated. Compared with 150 μM palmitate treatment alone, pretreatment with 10 μM apigenin for 6 h significantly increased the cell viability from 71.55 ± 3.62 to 91.06 ± 4.30% and improved mitochondrial membrane potential to the normal level (101.62 ± 11.72% of control). In addition, the production of nitric oxide was markedly elevated by apigenin cotreatment from 7.10 ± 3.95 to 94.20 ± 21.86%. The data-independent acquisition-based proteomic approach was used to study the protective mechanism, and the results revealed that 242 proteins were differently expressed in cells treated with palmitate and 93 proteins were reversed after apigenin supplementation. Apigenin realized its protective function mainly via regulating pathways such as IL-17, TNF, Fox O, cell adhesion, and endoplasmic reticulum protein processing. Collectively, these data demonstrated that apigenin supplement may serve as an alternative nutritional intervention to protect HAEC against lipotoxicity.

Short- and long-term treatment with TNF-α inhibits the induction of osteoblastic differentiation in cyclic tensile-stretched periodontal ligament fibroblasts

Background

Cyclic tensile stretching (CTS) induces osteoblastic differentiation of periodontal ligament fibroblasts (PDLF). On the other hand, increased concentrations of tumour necrosis factor-α (TNF-α) are found in inflammatory conditions, leading to periodontal disease and tooth loss. Accordingly, our aim was to investigate the short- and long-term effect of TNF-α on the response of human PDLF to CTS and its implication on osteoblastic differentiation.

Methods

PDLF were either pre-incubated for 4 hours or were repeatedly exposed to TNF-α for up to 50 days and then subjected to CTS. Gene expression was determined by quantitative real-time polymerase chain reaction. Activation of mitogen-activated protein kinase (MAPK) was monitored by western analysis and cell proliferation by bromodeoxyuridine incorporation. Intracellular reactive oxygen species were determined by the 2´, 7´-dichlorofluorescein-diacetate assay and osteoblastic differentiation by Alizarin Red-S staining after an osteo-inductive period of 21 days.

Results

CTS of PDLF induced an immediate upregulation of the c-fos transcription factor and, further downstream the overexpression of alkaline phosphatase and osteopontin, two major osteoblast marker genes. A 4-hour pre-incubation with TNF-α repressed these effects. Similarly, long-term propagation of PDLF along with TNF-α diminished their osteoblastic differentiation capacity and suppressed cells’ CTS-elicited responses. The observed phenomena were not linked with TNF-α-induced premature senescence or oxidative stress. While CTS induced the activation of MAPKs, involved in mechanotransduction, TNF-α treatment provoked a small delay in the phosphorylation of extracellular signal-regulated kinase and c-Jun N-terminal kinase.

Conclusion

Increased concentrations of TNF-α, such as those recorded in many inflammatory diseases, suppress PDLF’s immediate responses to mechanical forces compromising their osteoblastic differentiation potential, possibly leading to tissue’s impaired homeostasis.

MicroRNA-532-5p is implicated in the regulation of osteoporosis by forkhead box O1 and osteoblast differentiation

Background

MicroRNAs (miRNAs) are critical regulators in osteogenesis and cartilage formation. This study was designed to investigate whether miR-532-5p plays a role in the regulation of osteoporosis.

Methods

Osteoporotic fractures (OP group, n = 10) or osteoarthritis without osteoporosis (control group, n = 10) were selected as subjects in this study. Quantitative analysis of gene expression was performed by RT-PCR. Western blot was used to determine the expression levels of protein forkhead O1 (FOXO1). Bioinformatics analyses and luciferase reporter assay were used to verify the downstream target of miR-532-5p.

Results

Compared with the non-osteoporotic controls, miR-532-5p was upregulated in osteoporotic samples, and expression of miR-532-5p was downregulated in the osteogenic C2C12 cell model. Overexpression of miR-532-5p resulted in decreased expression levels of key osteoblast markers, including alkaline phosphatase (ALP), osteocalcin (OC), and collagen type I alpha 1 (COL1A1). The inhibitory results of miR-532-5p were reversed. MiR-532-5p contained a putative FOXO1 binding site. Moreover, miR-532-5p inhibited the expression of FOXO1, and overexpression of FOXO1 inhibited the effect of miR-532-5p on osteoblast markers.

Conclusions

MiR-532-5p can provide references to osteoporosis by regulating the expression of FOXO1 and osteoblast differentiation. MiR-532-5p might serve as a therapeutic target for osteoporosis.

Tumor necrosis factor α reduces gonadotropin-releasing hormone release through increase of forkhead box protein O1 activity

It has been found that hypothalamus helps to control aging, and hypothalamus-driven programmatic aging is associated with nuclear factor-κB (NF-κB)-mediated decrease of gonadotropin-releasing hormone (GnRH). However, the molecular mechanism(s) underlying aging-associated hypothalamic GnRH decline are largely unknown. Forkhead box O (FOXO), a family of transcription factors, has been demonstrated to be associated with aging. GnRH neuronal cell line GT1-7 was used in this study to determine whether FOXO1 was involved in tumor necrosis factor α (TNF-α)-induced decrease of GnRH. Our data showed that FOXO1 activity was increased by TNF-α through inhibition of its phosphorylation. Increased FOXO1 activity inhibited gnrh1 gene and activated NF-κB, thereby impairing the secretion of GnRH from GT1-7 cells. The increase of FOXO1 activity contributes to TNF-α-induced decrease of GnRH release, which may underscore the significance of this event to the development of aging and therapeutic interventions against age-dependent pathologies.

Genome-wide identification of long noncoding RNAs and their competing endogenous RNA networks involved in the odontogenic differentiation of human dental pulp stem cells

BACKGROUND

Long noncoding RNAs (lncRNAs) play an important role in the multiple differentiations of mesenchymal stem cells (MSCs). However, few studies have focused on the regulatory mechanism of lncRNAs in the odontogenic differentiation of human dental pulp stem cells (hDPSCs).

METHODS

hDPSCs were induced to differentiate into odontoblasts in vitro, and the expression profiles of lncRNAs, microRNAs (miRNAs), and messenger RNAs (mRNAs) in differentiated and undifferentiated cells were obtained by microarray. Bioinformatics analyses including Gene Ontology (GO) analysis, pathway analysis, and binding site prediction were performed for functional annotation of lncRNA. miRNA/odontogenesis-related gene networks and lncRNA-associated ceRNA networks were constructed. Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was used to verify the expression of selected genes. RNA fluorescence in situ hybridization (FISH), qRT-PCR, and western blot analysis were used to explore the location and function of lncRNA-G043225. Dual-luciferase reporter assay was performed to confirm the binding sites of miR-588 with G043225 and Fibrillin 1 (FBN1).

RESULTS

We identified 132 lncRNAs, 114 miRNAs, and 172 mRNAs were differentially expressed. GO analysis demonstrated that regulation of the neurogenic locus notch homolog (Notch), Wnt, and epidermal growth factor receptor (ERBB) signaling pathways and activation of mitogen-activated protein kinase (MAPK) activity were related to odontogenic differentiation. Pathway analysis indicated that the most significant pathway was the forkhead box O (FoxO) signaling pathway, which is related to odontogenic differentiation. Two odontogenesis-related gene-centered lncRNA-associated ceRNA networks were successfully constructed. The qRT-PCR validation results were consistent with the microarray analysis. G043225 mainly locating in cytoplasm was proved to promote the odontogenic differentiation of hDPSCs via miR-588 and FBN1.

CONCLUSION

This is the first study revealing lncRNA-associated ceRNA network during odontogenic differentiation of hDPSCs using microarray, and it could provide clues to explore the mechanism of action at the RNA-RNA level as well as novel treatments for dentin regeneration based on stem cells.

miR-136-3p targets PTEN to regulate vascularization and bone formation and ameliorates alcohol-induced osteopenia

Alcohol consumption is regarded as one of the leading risk factors for secondary osteopenia. Coupled angiogenesis and osteogenesis via distinct type-H vessels orchestrates subtle biological processes of bone homeostasis. The dysfunction of angiogenesis and osteogenesis contributes to decreased bone mass during the development of osteopenia. Herein, we identified microRNA-136-3p was remarkedly downregulated in the mouse model of alcohol-induced osteopenia. Following the alcohol administration, downregulated microRNA-136-3p significantly suppressed vascularization and osteogenic differentiation in human umbilical vein endothelial cells (HUVECs) and bone mesenchymal stem cells (BMSCs), respectively. Furthermore, microRNA-136-3p could target phosphatase and tensin homolog deleted on chromosome ten (PTEN) in both HUVECs and BMSCs, thus substantially modulating the capacity of vessel formation and osteogenic differentiation. In the mouse model, microRNA-136-3p Agomir ameliorated alcohol-induced osteopenia, with the concomitant restoration of bone mass and type-H vessel formation. For the first time, this study demonstrated the pivotal role of microRNA-136-3p/PTEN axis in regulations of vascularization and bone formation, which might become the potential therapeutic target of alcohol-induced bone loss.

Fibroblast growth factor-2 ameliorates tumor necrosis factor-alpha-induced osteogenic damage of human bone mesenchymal stem cells by improving oxidative phosphorylation

Tumor necrosis factor-alpha (TNF-α) has been shown to have an inhibitory effect on the osteogenic differentiation of mesenchymal stem cells. The metabolic switch from glycolysis to oxidative phosphorylation (OXPHOS) is vital for energy supply during osteogenic differentiation. However, the metabolic switch is inhibited under inflammatory stimulation. FGF2 has shown that it can improve osteogenic differentiation and promote autoimmune inflammation. In this study, we investigated whether FGF2 can ameliorate TNF-a-inhibited osteogenic damage by improving OXPHOS. Effects of TNF-α or FGF2 on the proliferation and osteogenic differentiation of hBMSCs were evaluated by MTT assay, qRT-PCR, and ALP activity tests. The function of FGF2 on the TNF-a-inhibited metabolic switch was determined by Mito Stress test. The results showed that TNF-α was able to inhibit the osteogenic differentiation and OXPHOS of hBMSCs. FGF2 has no obvious function in improving the osteogenic-related genes, but it can ameliorate the impaired osteogenesis and OCR value caused by TNF-α. These findings suggest that FGF2 can prevent the impaired osteogenic differentiation and metabolic switch of hBMSCs under inflammatory stimulation, which might enhance the regeneration capacity of hBMSCs.

Melatonin restores the osteoporosis-impaired osteogenic potential of bone marrow mesenchymal stem cells by preserving SIRT1-mediated intracellular antioxidant properties

Postmenopausal osteoporosis (OP) is one of the most common bone diseases that affects millions of aging women. Reduced osteogenesis and increased oxidative stress have been implicated in bone marrow mesenchymal stem cells (BMMSCs) derived from OP patients. Melatonin has shown positive effects on osteoblast differentiation and bone formation; however, it was unknown whether melatonin could restore OP-impaired osteogenic potential of BMMSCs and what the underlying mechanisms entailed. The objective of this study is to investigate (1) whether melatonin can restore the impaired osteogenic potential of OP BMMSCs by preserving their antioxidant functions, and if so, (2) whether intravenous administration of melatonin can prevent OP-induced bone loss in ovariectomized (OVX) rats. Ovariectomies were performed in female rats and BMMSCs were isolated from the osteoporotic rats 3 months later. In vitro treatment with melatonin successfully improved the osteogenic differentiation of OP BMMSCs, as evidenced by increased levels of matrix mineralization and osteoblast-specific genes. In melatonin-treated OP BMMSCs, intracellular oxidative stress was significantly attenuated, while levels of intracellular antioxidant enzymes were noticeably up-regulated - particularly superoxide dismutase 2 (SOD2) and glutathione peroxidase 1 (GPX1). Silent information regulator type 1 (SIRT1) was involved in the melatonin-mediated recovery of osteogenesis and antioxidant functions. Meanwhile, in vivo injections of melatonin via the tail vein successfully ameliorated the bone micro-architecture in ovariectomized rat femurs. Further experiments confirmed that BMMSCs derived from melatonin-treated OVX rats exerted well-preserved antioxidant properties and osteogenic potential. Our findings demonstrate that the administration of melatonin is a promising strategy for treating patients with postmenopausal OP by preserving the antioxidant properties and osteogenic potential of their BMMSCs.

Recombinant Klotho Protects Human Periodontal Ligament Stem Cells by Regulating Mitochondrial Function and the Antioxidant System during H2O2-Induced Oxidative Stress

Human periodontal ligament stem cells (hPDLSCs) are a favourable source for tissue engineering, but oxidative stress conditions during cell culture and transplantation could affect stem cell viability and stemness, leading to failed regeneration. The aim of this study was to evaluate the antioxidant and protective effects of Klotho, an antiageing protein, against cell damage and the loss of osteogenesis in hPDLSCs in H₂O₂-induced oxidative environments. H₂O₂ was used as an exogenous reactive oxygen species (ROS) to induce oxidative stress. Recombinant human Klotho protein was administered before H₂O₂ treatment. Multitechniques were used to assess antioxidant activity, cell damage, and osteogenic ability of hPDLSCs in oxidative stress and the effects of Klotho on hPDLSCs. Mitochondrial function was analyzed by an electron microscopy scan of cellular structure, mitochondrial DNA copy number, and cellular oxygen consumption rate (OCR). Furthermore, we explored the pathway by which Klotho may function to regulate the antioxidant system. We found that pretreatment with recombinant human Klotho protein could enhance SOD activity and reduce intracellular oxidative stress levels. Klotho reduced H₂O₂-induced cellular damage and eventually maintained the osteogenic differentiation potential of hPDLSCs. Notably, Klotho promoted mitochondrial function and activated antioxidants by negatively regulating the PI3K/AKT/FoxO1 pathway. The findings suggest that Klotho protein enhanced the antioxidative ability of hPDLSCs and protected stem cell viability and stemness from H₂O₂-induced oxidative stress by restoring mitochondrial functions and the antioxidant system.