Glucocorticoid (GC) overuse is the main cause of osteonecrosis of the femoral head (ONFH). The dysfunction of bone marrow mesenchymal stem cells (BMSCs) plays an important role in ONFH pathogenesis. Physiological concentrations of GCs can induce the osteogenic differentiation of BMSCs; however, intervention with high concentrations of GC may lead to changes in aging and autophagy in certain cell types.

We generated an ONFH mouse model by injecting C57BL/6 J mice with MPS. BMSCs were harvested from the femora and tibiae of mice and were analyzed for osteogenesis, adipogenesis, senescence, and cell proliferation. In vitro, BMSCs were treated with different concentrations of GC for 48 h, followed by functional analyses to identify differentially expressed genes (DEGs) associated with ONFH. Additionally, various bioinformatics analyses were performed to identify differentially expressed genes in ONFH.

BMSCs from ONFH mice showed signs of aging, as indicated by increased SA-β-gal positive cells (4.4-fold) and upregulated p53 (2.6-fold) and p21 (2.0-fold) protein expression. It is also accompanied by changes in osteogenic/lipogenic differentiation ability. Bioinformatics analysis further verified these findings. High-dose GC stimulation significantly induced cellular senescence of BMSCs, as indicated by an increase in SA-β-gal positive cells (6.2-fold) and a decrease in autophagy levels. GC stimulation changes the differentiation fate of BMSCs.

Our results indicated that GC-induced ONFH was associated with changes in aging and autophagy in BMSCs. GC not only directly affected the osteogenic differentiation of BMSCs but also indirectly affected their differentiation fate through aging and autophagy changes.

Stem cells are crucial for maintaining bodily stability, but their regenerative abilities decline with age. This decline is marked by reduced proliferation and differentiation capacities of stem cells, as well as exhaustion of the stem cell pool. The accumulation of aged mesenchymal stem cells (MSCs) can reduce the tissue regeneration, but the molecular mechanisms influencing MSCs aging remain unclear. Moreover, collecting MSCs from elderly individuals is not suitable for observing the early response of MSCs to senescence stress, and the factors involved in early senescence remain unclear. In our previous study, we established a fast MSC aging model using D-galactose. We discovered that, while not affecting the "stemness" markers of mesenchymal stem cells, the expression of LncRNA NEAT1-206 was notably increased during the early stages of aging induction (within 4 days). And LncRNA NEAT1-206 was observed to be localized in the cytoplasmic matrix due to enhanced nuclear export. We found that the LncRNA NEAT1-206 could trigger autophagy through the WNT5A/Ca2+ signaling pathway, thereby decreasing senescence markers and enhancing the osteogenic differentiation of MSCs. This study elucidated the role that LncRNA NEAT1-206 as a potential key factor in conferring resistance to D-galactose-induced cell senescence at the early stage and promoting the osteogenic differentiation of MSCs. This study may provide a foundational understanding for delaying the MSCs aging process.

Global aging heightens the risk of oral disorders, among which periodontitis is the major cause of tooth loss in the aging population. The regeneration of damaged periodontal hard tissue is highly challenging due to the existence of the refractory local inflammation. Owing to the potent anti-inflammatory capabilities, regulatory T cells hold great promise in immunotherapies for tissue regeneration. However, the transferred regulatory T cells can alter their phenotypes and functions in local inflammatory milieu, significantly impairing their therapeutic efficacy. Herein, we introduce a novel regulatory T cell-based nanobiohybrid system bearing polyphenol-functionalized rapamycin nanocomplexes. The sustained in situ release of immunosuppressant rapamycin from the cell-attached nanocomplexes maintains the anti-inflammatory phenotype of regulatory T cells in the inflammatory milieu. The synergistic actions of the anti-inflammatory cytokines secreted and the immunosuppressant released guide a pro-resolving polarization of macrophages and enhance osteogenic differentiation of bone marrow-derived stromal cells. The stabilized phenotype of the regulatory T cells dramatically promoted the resolution of periodontal inflammation and the repair of the hard tissue (alveolar bone) in vivo. Overall, these studies highlight a potent regulatory T cell-based nanobiohybrid therapy to treat periodontitis by modulating periodontal immune microenvironment.

Exercise-induced mechanical load stimulates bone cells, including osteocytes, to promote bone formation. The bone response to loading is less effective with aging, but the cellular and molecular mechanisms responsible for the impaired mechanoresponsiveness remain unclear. Excessive mitochondrial reactive oxygen species (mtROS) and deficient autophagy are common aging mechanisms implicated in decreased bone formation in old mice. Here, we confirmed that the osteogenic effects of tibia compressive loading are lower in old versus young female mice. We also examined whether an increase in mtROS or decreased autophagy in osteoblast-lineage cells of adult female mice could mimic the deleterious effects of aging. To this end, we loaded mice lacking the antioxidant enzyme superoxide dismutase 2 (Sod2) or autophagy-related 7 (Atg7) in cells targeted by Osterix1 (Osx1)-Cre. Osteocytes in Atg7ΔOsx1 exhibited altered morphology and decreased osteocyte dendrite projections. Two weeks of loading increased cortical bone mass and bone formation rate at both periosteal and endosteal surfaces of Osx1-Cre control mice. Nonetheless, in both Atg7ΔOsx1 and Sod2ΔOsx1 mice the response to loading was identical to that observed in control mice, indicating that compromised Atg7-dependent autophagy or excessive mtROS are not sufficient to impair the bone response to tibial compressive loading. Thus, alternative mechanisms of aging might be responsible for the decreased response of the aged skeleton to mechanical stimuli. These findings also suggest that an intact osteocyte dendrite network is not required for the osteogenic response in this model of bone loading.

Periodontal ligament stem cells (PDLSCs) bring new hope to patients with poor periodontium recovery and impaired regeneration. However, the complex inflammatory microenvironment continually inhibits stem cell function and hinders stem cell therapy effectiveness. Melatonin is a naturally occurring neurohormone that participates in the regulation of a large spectrum of biological functions. We investigated the effect of melatonin on periodontium regeneration both in vitro and in vivo. The results showed that melatonin promoted periodontitis recovery and enhanced the osteogenesis of inflamed PDLSCs (Inf-PDLSCs) depending on concentrations. Further mechanistic exploration indicated that autophagy activation played a significant role in enhancing the osteogenic differentiation of Inf-PDLSCs after melatonin treatment. Additionally, melatonin-induced upregulation of TEME110 participated in the initiation of autophagy activation and enhancement of osteogenesis in Inf-PDLSCs. Collectively, the results of our study provide evidence that melatonin-mediated osteogenesis of Inf-PDLSCs is important for periodontal tissue regeneration. Moreover, melatonin as a therapeutic drug for periodontitis treatment deserves further investigation.

BackgroundSystemic lupus erythematosus is a common autoimmune disease. Studies have suggested that defective stem cells could be involved in the pathogenesis of systemic lupus erythematosus, which leads to changes in the function of immune cells. By observing the cell morphology, autophagy, and senescence of bone marrow mesenchymal stem cells (BMSCs) from lupus mice and normal controls, this study investigated the role of IL-6 in autophagy and senescence of BMSCs and explored relevant mechanisms.MethodFemale MRL/lpr and C57 mice with similar weights and sizes at 20-22 weeks old were selected. BMSCs were isolated using the whole bone marrow adherent method. Quantitative real-time polymerase chain reaction, β-galactosidase staining, western blotting, and ELISA were used to detect autophagy and senescence.ResultCompared with BMSCs from normal mice, BMSCs from lupus mice exhibited low autophagy and premature senescence with a senescence-associated secretory phenotype. The addition of exogenous IL-6 increased the protein levels of p-STAT3 and Bcl-2, and in the IL-6-treated group, the premature senescence of cells increased and autophagy decreased.ConclusionThe biological functions of BMSCs from MRL/lpr lupus mice were impaired. IL-6 prevents autophagy and subsequently promotes the senescence of BMSCs by activating the IL-6/STAT3 pathway.

Osteoporosis (OP) is a bone metabolic disease caused by decreased bone mass leading to destruction of bone microstructure. Treatment of OP is characterized by a lifelong nature, causing extreme financial and psychological burdens to patients. Hormonal abnormalities, cellular autophagy, Ferroptosis, and oxidative stress are all part of the intricate and varied pathophysiology of OP. Recent research has revealed that mitochondrial dysfunction is a significant factor in the onset and progression of OP. By regulating bone marrow mesenchymal stem cell differentiation through various signaling pathways and cytokines, abnormal mitochondrial energy metabolism brought on by oxidative stress processes impacts osteoblast and osteoclast proliferation and differentiation, causing an imbalance in bone metabolism that ultimately results in OP. Therefore, one possible method to prevent and manage OP may be to use mitochondria as a carrier to trigger osteogenic differentiation of bone marrow mesenchymal stem cells from mitochondrial energy consumption, oxidative stress, autophagy, and osteoclast death. In order to offer some theoretical references and therapeutic approaches for the clinical prevention and treatment of OP, we will examine the pathophysiology of OP from mitochondrial dysfunction in this work.

Skeletal aging is characterized by a decrease in bone mass and an increase in marrowfat content. Advanced oxidation protein products (AOPPs) accumulate easily with aging and disrupt redox homeostasis. We examined whether AOPPs accumulation contributes to the bone-fat imbalance during skeletal aging.

Both young and aged mice were employed to assess the changes of AOPPs levels and its contribution to bone-fat imbalance during skeletal aging. Primary bone marrow mesenchymal stromal cells (MSCs) were used to examine the potential role of AOPPs in age-related switch between osteogenic and adipogenic differentiation. Aged mice were also gavaged by non-selective antioxidant N-acetyl-L-cysteine (NAC), followed by close monitoring of the changes in AOPPs levels and bone-fat metabolism. Furthermore, young mice were chronically exposed to AOPPs and then evaluated for the changes of bone mass and marrow adiposity.

The levels of AOPPs in serum and bone marrow were markedly higher in aged mice than that in young mice. Age-related accumulation of AOPPs was accompanied by reduced bone formation, increased marrow adiposity and deterioration of bone microstructure. Reduced AOPPs accumulation by antioxidant NAC leaded to improvement of the bone-fat imbalance in aged mice. Similarly, the bone-fat imbalance was induced by chronic AOPPs loading in young mice. Compared with MSCs from young mice, MSCs from aged mice tended to differentiate into adipocytes rather than osteoblasts and displayed cellular senescence. Exposure of primary MSCs to AOPPs resulted in the switch from osteogenic to adipogenic lineage and cellular senescence. AOPPs challenge also increased intracellular ROS generation by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and mitochondria. The antioxidant NAC, after scavenging ROS, ameliorated the AOPPs-induced lineage switch and senescence in MSCs by inhibiting the PI3K/AKT/mTOR pathway.

Our findings revealed the involvement of AOPPs in age-related switch between osteogenic and adipogenic differentiation, and illuminated a novel potential mechanism underlying bone-fat imbalance during skeletal aging.

Reducing AOPPs accumulation and its cascading effects on MSCs might be an attractive strategy for delaying skeletal aging.

Bone marrow mesenchymal stromal cells (BM-MSCs) are multipotent cells present in bone marrow; they play a crucial role in the process of bone formation. Cellular senescence is defined as a stable state of cell cycle arrest that impairs the functioning of cells. Research has shown that aging triggers a state of senescence in BM-MSCs, leading to a reduced capacity for osteogenic differentiation and the accumulation of senescent cells, which can accelerate the onset of various diseases. Therefore, it is essential to explore mechanisms and strategies for the rejuvenation of senescent BM-MSCs. Senile osteoporosis (SOP) is a metabolic bone disease characterized by reduced bone formation. The senescence of BM-MSCs is considered one of the most important factors in the occurrence and development of SOP. Therefore, the rejuvenation of BM-MSCs for the treatment of SOP represents a promising strategy. This work provides a summary of the functional alterations observed in senescent BM-MSCs and a systematic review of the mechanisms that facilitate the rejuvenation of senescent BM-MSCs. Additionally, we analyze the progress in and the limitations associated with the application of rejuvenated senescent BM-MSCs to treat SOP, with the aim of providing new insights for the prevention and treatment of SOP.

Aging is an intricate and gradual process characterized by tissue and cellular dysfunction. Adipose-derived mesenchymal stem cells (ADMSCs) experience a functional decline as part of systemic aging. However, the alterations in ADMSCs across various anatomical sites throughout an individual's lifespan remain unclear. To shed light on these changes, we collected white adipose tissue and brown adipose tissue samples from the epididymis, perirenal, inguinal, and scapular regions of young, adult, and aged rats and subsequently isolated ADMSCs for RNA sequencing. As aging progressed, we observed a reduction in the number of ADMSCs at all anatomical sites. Marker genes of ADMSCs from different sites were identified. Aging triggered notable activation of inflammatory and immune responses while diminishing the ADMSC differentiation capacity and ability to maintain a normal tissue morphology. Furthermore, miR-195-5p and miR-497-3p, which promoted cell senescence and apoptosis while inhibiting proliferation and differentiation, were positively correlated with aging. These findings increase our understanding of ADMSC senescence and underscore the unique physiological changes and functions of ADMSCs across different anatomical sites during aging.NEW & NOTEWORTHY Dynamic changes in mRNAs and miRNAs of ADMSCs during aging are shown. As aging progressed, we observed a reduction in the number of ADMSCs at all anatomical sites. Aging leads to the activation of inflammatory and cellular dysfunction. miR-195-5p and miR-497-3p are positively correlated with aging, which promoted cell senescence and apoptosis while inhibiting proliferation and differentiation. ADMSCs associated with different anatomical sites have site-specific markers.

Heat stress is essential for improving the efficacy of mesenchymal stem cell (MSC)-based regeneration medicine. However, it is still unclear whether and how heat stress influences the differentiation of stem cells from apical papilla (SCAPs). This research aimed to explore the potential mechanism of glucose-regulated protein 78 (GRP78) in regulating differentiation under heat stress in SCAPs.

The proliferation ability was assessed using the 5-Ethynyl-2'- deoxyuridine (EdU) assay, cell counting kit assay (CCK-8), and flow cytometry (FCM). The osteogenic and odontogenic differentiation capacities were investigated through Western blot, quantitative reverse transcription polymerase chain reaction (qRT-PCR), alkaline phosphatase (ALP) staining and activity assay, alizarin red S (ARS) staining, as well as immunofluorescence staining. Western blot and transmission electron microscopy (TEM) were used to detect autophagy.

Heat stress enhanced the osteogenic and odontogenic differentiation of SCAPs, but it did not significantly affect proliferation. Besides, GRP78 has been confirmed to modulate the differentiation induced by heat stress. Autophagy triggered by GRP78 enhanced osteogenic and odontogenic differentiation of SCAPs, while the knockdown of GRP78 or the inhibitor of autophagy suppressed the differentiation.

Heat stress induces osteogenic and odontogenic differentiation of SCAPs through GRP78-mediated autophagy.

Mesenchymal stromal cells (MSCs) possess therapeutic properties, which can be blunted by obesity. Autophagy, a cellular recycling process, is essential for MSC function. We investigated the mechanisms by which obesity affects the properties of MSCs, with a focus on autophagy. Adipose tissue was obtained from kidney donors [body mass index (BMI) <30 kg/m2, non-obese] or individuals undergoing weight loss surgery (BMI ≥30 kg/m2, obese) for MSC harvesting (n = 11 each); samples were randomized to sequencing (seq; n = 5 each) or functional studies (n = 6 each). MSCs were sequenced to determine their epigenetic (5-hydroxymethylcytosine) and transcriptomic profiles across autophagy-related genes using hydroxymethylated DNA immunoprecipitation sequencing and mRNA-seq, respectively. Genes with shared trends in both datasets underwent Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR) validation. During functional studies, 2-h starvation was used to induce autophagy in vitro, enabling detection of changes in the protein expression of microtubule-associated protein 1A/1B-light chain-3 and in autophagic flux. Obesity amplified a starvation-induced reduction in autophagic flux in MSCs while promoting earlier generation of new autophagosomes during autophagy initiation. Integrated analysis of the two sequencing datasets revealed 124 differentially hydroxymethylated genes and 30 differentially expressed mRNAs. Among six overlapping autophagy-related genes, three exhibited same-direction trends. Of these, STX12 and SLC25A4 may be implicated in the impact of obesity on autophagic changes in MSCs. Therefore, human obesity may alter autophagy in adipose tissue-derived MSC, and thereby their metabolism and function.

The superficial zone cells in articular cartilage (SFZCs) have been identified as stem/progenitor chondrocytes and promoted cell self-renewal in the osteoarthritis (OA). Several studies emphasized the involvement of senescence and autophagy in OA. Interleukin-1β (IL-1β) is one of the main inflammatory mediators of OA, and whether it induces senescence and autophagy in SFZCs remains unclear. The present study aimed to investigate autophagy flux, mitochondrial function, and intracellular reactive oxygen species (ROS) that resulted in senescence in SFZCs induced by IL-1β.

Using western blotting, reverse transcription-quantitative PCR, immunofluorescence, intracellular ROS detection, mitochondrial staining, and determination of mitochondrial membrane potential, we tested senescence and autophagy markers in SFZCs induced by IL-1β in vitro. The consequences of mitochondrial function and ROS were also studied with IL-1β-induced senescence.

IL-1β treatment decreased SFZC proliferation, induced SFZC senescence, and reduced SFZCs' chondrogenic differentiation capacity. Moreover, IL-1β impaired autophagy flux, and the autophagy activator, rapamycin, attenuated the senescence of SFZCs. IL-1β-induced autophagy defect resulted in mitochondrial dysfunction and overproduction of ROS, and autophagy activation notably protected against mitochondrial dysfunction and reduced the levels of ROS. Moreover, antioxidant N-acetylcysteine reversed the senescence of IL-1β in SFZCs.

IL-1β promotes autophagy impairment and subsequently results in dysfunctional mitochondria and overproduction of ROS, which finally causes SFZC senescence.

Liuwei Dihuang pill (LWDH) has been used to treat postmenopausal osteoporosis (PMOP).

To explore the effects and mechanisms of action of LWDH in PMOP.

Forty-eight female Sprague-Dawley rats were divided into four groups: sham-operated (SHAM), ovariectomized (OVX), LWDH high dose (LWDH-H, 1.6 g/kg/d) and LWDH low dose (LWDH-L, 0.8 g/kg/d); the doses were administered after ovariectomy via gavage for eight weeks. After eight weeks, the bone microarchitecture was evaluated. The effect of LWDH on the differentiation of bone marrow mesenchymal stem cells (BMSCs) was assessed via osteogenesis- and lipogenesis-induced BMSC differentiation. The senescence-related biological indices were also detected using senescence staining, cell cycle analysis, quantitative real-time polymerase chain reaction and western blotting. Finally, the expression levels of autophagy-related proteins and Yes-associated protein (YAP) were evaluated.

LWDH-L and LWDH-H significantly modified OVX-induced bone loss. LWDH promoted osteogenesis and inhibited adipogenesis in OVX-BMSCs. Additionally, LWDH decreased the positive ratio of senescence OVX-BMSCs and improved cell viability, cell cycle, and the mRNA and protein levels of p53 and p21. LWDH upregulated the expression of autophagy-related proteins, LC3, Beclin1 and YAP, in OVX-BMSCs and downregulated the expression of p62.

LWDH improves osteoporosis by delaying the BMSC senescence through the YAP-autophagy axis.

Metabolic abnormalities and mild inflammation are hallmarks of aging and major driving factors for aging-related damage and bone metabolic diseases. Mitochondria are crucial links in energy metabolism and immune homeostasis regulation. Mitochondrial dysfunction is considered one of the pathogenic factors of aging-related osteoporosis, but its mechanism of action needs further research. Here, we demonstrated that the interaction between stimulator of interferon genes (STING)-mediated regulation of hexokinase 2 (Hk2)-voltage-dependent anion channel-1 (Vdac1) is a critical factor contributing to mitochondrial dysfunction and osteogenic abnormalities during aging. As the aging process progresses, factors related to aging cause an increase in STING expression, which disrupts the interaction between Hk2 and Vdac1. Dissociation of Hk2 from Vadc1 triggered the opening of the mitochondrial inner mitochondrial permeability transition pore (mPTP), leading to mitochondrial dysfunction and abnormal osteogenic differentiation, thereby disrupting bone homeostasis. In brief, this study demonstrates that STING acts as an intracellular metabolic Checkpoint, influencing mitochondrial function to promote the development of osteoporosis. These findings significantly enhance the development of STING-targeted treatments for aging-related osteoporosis.

Osteopenia and osteoporosis are common long-term complications of the cytotoxic conditioning regimen for hematopoietic stem cell transplantation (HSCT). We examined mesenchymal stem and progenitor cells (MSPCs), which include skeletal progenitors, from mice undergoing HSCT. Such MSPCs showed reduced fibroblastic colony-forming units frequency, increased DNA damage, and enhanced occurrence of cellular senescence, whereas there was a reduced bone volume in animals that underwent HSCT. This reduced MSPC function correlated with elevated activation of the small Rho guanosine triphosphate hydrolase CDC42, disorganized F-actin distribution, mitochondrial abnormalities, and impaired mitophagy in MSPCs. Changes and defects similar to those in mice were also observed in MSPCs from humans undergoing HSCT. A pharmacological treatment that attenuated the elevated activation of CDC42 restored F-actin fiber alignment, mitochondrial function, and mitophagy in MSPCs in vitro. Finally, targeting CDC42 activity in vivo in animals undergoing transplants improved MSPC quality to increase both bone volume and trabecular bone thickness. Our study shows that attenuation of CDC42 activity is sufficient to attenuate reduced function of MSPCs in a BM transplant setting.

Bone defects are highly prevalent diseases caused by trauma, tumors, inflammation, congenital malformations and endocrine abnormalities. Ideally effective and side effect free approach to dealing with bone defects remains a clinical conundrum. Klotho is an important protein, which plays an essential role in regulating aging and mineral ion homeostasis. More recently, research revealed the function of Klotho in regulating skeleton development and regeneration. Klotho has been identified in mesenchymal stem cells, osteoblasts, osteocytes and osteoclasts in different skeleton regions. The specific function and regulatory mechanisms of Klotho in long bone and craniofacial bone vary due to their different embryonic development, ossification and cell types, which remain unclear and without conclusion. Moreover, studies have confirmed that Klotho is a multifunctional protein that can inhibit inflammation, resist cancer and regulate the endocrine system, which may further accentuate the potential of Klotho to be the ideal molecule in inducing bone restoration clinically. Besides, as an endogenous protein, Klotho has a promising potential for clinical therapy without side effects. In the current review, we summarized the specific function of Klotho in long bone and craniofacial skeleton from phenotype to cellular alternation and signaling pathway. Moreover, we illustrated the possible future clinical application for Klotho. Further research on Klotho might help to solve the existing clinical difficulties in bone healing and increase the life quality of patients with bone injury and the elderly.

Skeletal stem cells (SSCs) and related progenitors with osteogenic potential, collectively termed skeletal stem and/or progenitor cells (SSPCs), are crucial for providing osteoblasts for bone formation during homeostatic tissue turnover and fracture repair. Besides mediating normal bone physiology, they also have important roles in various metabolic bone diseases, including osteoporosis. SSPCs are of tremendous interest because they represent prime future targets for osteoanabolic therapies and bone regenerative medicine. Remarkable progress has been made in characterizing various SSC and SSPC populations in postnatal bone. SSPCs exist in the periosteum and within the bone marrow stroma, including subsets localizing around arteriolar and sinusoidal blood vessels; they can display osteogenic, chondrogenic, adipogenic and/or fibroblastic potential, and exert critical haematopoiesis-supportive functions. However, much remains to be clarified. By the current markers, bona fide SSCs are commonly contained within broader SSPC populations characterized by considerable heterogeneity and overlap, whose common versus specific functions in health and disease have not been fully unravelled. Here, we review the present knowledge of the identity, fates and relationships of SSPC populations in the postnatal bone environment, their contributions to bone maintenance, the changes observed upon ageing, and the effect of metabolic diseases such as osteoporosis and diabetes mellitus.

Radial extracorporeal shockwave (r-ESW) and bone marrow stromal cells (BMSCs) have been reported to alleviate senile osteoporosis (SOP), but its regulatory mechanism remains unclear. In this study, we firstly isolated human BMSCs from bone marrow samples and treated with varying r-ESW doses. And we found that r-ESW could enhance the proliferation of SOP-BMSCs in a dose-dependent manner by EdU assay. Subsequently, the impact of r-ESW on the proliferation, apoptosis and multipotency of BMSCs was assessed. And the outcomes of flow cytometry, Alizarin red S (ARS), and tube formation test demonstrated that the optimal shockwave obviously boosted SOP-BMSCs osteogenesis and angiogenesis but exhibited no significant impact on cell apoptosis. Additionally, the signaling of Piezo1 and CaMKII/CREB was examined by Western blotting, qPCR and immunofluorescence. And the results showed that r-ESW promoted the expression of Piezo1, increased intracellular Ca2+ and activated the CaMKII/CREB signaling pathway. Then, the application of Piezo1 siRNA hindered the r-ESW-induced enhancement ability of osteogenesis coupling with angiogenesis of SOP-BMSCs. The use of the CaMKII/CREB signaling pathway inhibitor KN93 suppressed the Piezo1-induced increase in osteogenesis and angiogenesis in SOP-BMSCs. Finally, we also found that r-ESW might alleviate SOP in the senescence-accelerated mouse prone 6 (SAMP6) model by activating Piezo1. In conclusion, our research offers experimental evidence and an elucidated underlying molecular mechanism to support the use of r-ESW as a credible rehabilitative treatment for senile osteoporosis.

Autophagy is a recycling pathway in which damaged or dysfunctional proteins, protein aggregates, and organelles are delivered to lysosomes for degradation. Insufficiency of autophagy is thought to contribute to several age-related diseases including osteoporosis. Consistent with this, elimination of autophagy from the osteoblast lineage reduces bone formation and causes low bone mass. However, whether increasing autophagy would benefit bone health is unknown. Here, we increased expression of the endogenous Transcription Factor EB gene ( Tfeb ) in osteoblast lineage cells in vivo via CRISPR activation. Tfeb overexpression stimulated autophagy and lysosomal biogenesis in osteoblasts. Tfeb overexpressing male mice displayed a robust increase in femoral and vertebral cortical thickness at 4.5 months of age. Histomorphometric analysis revealed that the increase in femoral cortical thickness was due to increased bone formation at the periosteal surface. Tfeb overexpression also increased femoral trabecular bone volume. Consistent with these results, bone strength was increased in Tfeb overexpressing mice. Female Tfeb overexpressing mice also displayed a progressive increase in bone mass over time and at 12 months of age had high cortical thickness and trabecular bone volume. This increase in vertebral trabecular bone volume was due to elevated bone formation. Osteoblastic cultures showed that Tfeb overexpression increased proliferation and osteoblast formation. Overall, these results demonstrate that stimulation of autophagy in osteoblast lineage cells promotes bone formation and strength and may represent an effective approach to combat osteoporosis.

Age-related osteoporosis is a prevalent bone metabolic disorder distinguished by an aberration in the equilibrium between bone formation and resorption. The reduction in the stemness of Bone Marrow Mesenchymal Stem Cells (BMSCs) plays a pivotal role in the onset of this ailment. Comprehending the molecular pathways that govern BMSCs stemness is imperative for delineating the etiology of age-related osteoporosis and devising efficacious treatment modalities. The study utilized single-cell RNA sequencing and miRNA sequencing to investigate the cellular heterogeneity and stemness of BMSCs. Through dual-luciferase reporter assays and functional experiments, the regulatory effect of miR-183 on CTNNB1 (β-catenin) was confirmed. Overexpression and knockdown studies were conducted to explore the impact of miR-183 and β-catenin on stemness-related transcription factors Oct4, Nanog, and Sox2. Cell proliferation assays and osteogenic differentiation experiments were carried out to validate the influence of miR-183 and β-catenin on the stemness properties of BMSCs. Single-cell analysis revealed that β-catenin is highly expressed in both high stemness clusters and terminal differentiation clusters of BMSCs. Overexpression of β-catenin upregulated stemness transcription factors, while its suppression had the opposite effect, indicating a dual regulatory role of β-catenin in maintaining BMSCs stemness and promoting bone differentiation. Furthermore, the confluence of miRNA sequencing analyses and predictions from online databases revealed miR-183 as a potential modulator of BMSCs stemness and a novel upstream regulator of β-catenin. The overexpression of miR-183 effectively diminished the stemness characteristics of BMSCs by suppressing β-catenin, whereas the inhibition of miR-183 augmented stemness. These outcomes align with the observed alterations in the expression levels and functional assessments of transcription factors associated with stemness. This study provides evidence for the essential involvement of β-catenin in preserving the stemness of BMSCs, as well as elucidating the molecular mechanism through which miR-183 selectively targets β-catenin to modulate stemness. These results underscore the potential of miR-183 and β-catenin as molecular targets for augmenting the stemness of BMSCs. This strategy is anticipated to facilitate the restoration of bone microarchitecture and facilitate bone tissue regeneration by addressing potential cellular dysfunctions, thereby presenting novel targets and perspectives for the management of age-related osteoporosis.

Advanced age is a major risk factor for age-related degenerative tendinopathy. During aging, tendon stem/progenitor cell (TSPC) function declines owing to the transition from a normal quiescent state to a senescent state. Extracellular vesicles (EVs) from young stem cells are reported to possess anti-aging functions. However, it remains unclear whether EVs from young TSPCs (TSPC-EVs) can rejuvenate senescent TSPCs to delay age-related degeneration. Here, this study finds that TSPC-EVs can mitigate the aging phenotypes of senescent TSPCs and maintain their tenogenic capacity. In vitro studies reveal that TSPC-EVs can reinstall autophagy in senescent TSPCs to alleviate cellular senescence, and that the re-establishment of autophagy is mediated by the PI3K/AKT pathway. Mechanistically, this study finds that thrombospondin 1, a negative regulator of the PI3K/AKT pathway, is enriched in TSPC-EVs and can be transported to senescent TSPCs. Moreover, in vivo studies show that the local delivery of TSPC-EVs can rejuvenate senescent TSPCs and promote their tenogenic differentiation, thereby rescuing tendon regeneration in aged rats. Taken together, TSPC-EVs as a novel cell-free approach have promising therapeutic potential for aging-related degenerative tendinopathy.

Bone aging and decreased autophagic activity are related but poorly explored in the jawbone. This study aimed to characterize the aging jawbones and jawbone-derived stromal cells (JBSCs) and determine the role of autophagy in jawbone mass decline. We observed that the jawbones of older individuals and mice exhibited similar age-related bone loss. Furthermore, leptin receptor (LepR)-lineage cells served as the primary source for in vitro cultured and expanded JBSCs, referred to as LepR-Cre+/JBSCs. RNA-sequencing data from the jawbones and LepR-Cre+/JBSCs showed the upregulated expression of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway during aging. Through single-cell transcriptomics, we identified a decrease in the proportion of osteogenic lineage cells and the activation of the PI3K/AKT pathway in LepR-lineage cells in aging bone tissues. Reduced basal autophagic activity, diminished autophagic flux, and decreased osteogenesis occurred in the jawbones and LepR-Cre+/JBSCs from older mice (O-mice; O-JBSCs). Pharmacologic and constitutive autophagy activation alleviated the impaired osteogenesis in O-JBSCs. In addition, the suppression of mTOR-induced autophagy improved the aging phenotype of O-JBSCs. The activation of autophagy in LepR-Cre+/JBSCs using chemical autophagic activators reduced the alveolar bone resorption in O-mice. Therefore, our study demonstrated that ATG molecules and pathways are crucial in jawbone aging, providing novel approaches to understanding age-related jawbone loss.

Rheumatoid Arthritis (RA) is a heterogeneous autoimmune disease with multiple unidentified pathogenic factors. The inconsistency between molecular subgroups poses challenges for early diagnosis and personalized treatment strategies. In this study, we aimed to accurately distinguish RA patients at the transcriptome level using bioinformatics methods.

We collected a total of 362 transcriptome datasets from RA patients in three independent samples from the GEO database. Consensus clustering was performed to identify molecular subgroups, and clinical features were assessed. Differential analysis was employed to annotate the biological functions of specifically upregulated genes between subgroups.

Based on consensus clustering of RA samples, we identified three robust molecular subgroups, with Subgroup III representing the high-risk subgroup and Subgroup II exhibiting a milder phenotype, possibly associated with relatively higher levels of autophagic ability. Subgroup I showed biological functions mainly related to viral infections, cellular metabolism, protein synthesis, and inflammatory responses. Subgroup II involved autophagy of mitochondria and organelles, protein localization, and organelle disassembly pathways, suggesting heterogeneity in the autophagy process of mitochondria that may play a protective role in inflammatory diseases. Subgroup III represented a high-risk subgroup with pathological processes including abnormal amyloid precursor protein activation, promotion of inflammatory response, and cell proliferation.

The classification of the RA dataset revealed pathological heterogeneity among different subgroups, providing new insights and a basis for understanding the molecular mechanisms of RA, identifying potential therapeutic targets, and developing personalized treatment approaches.

Bone marrow stromal/stem cells (BMSCs) are generally considered as common progenitors for both osteoblasts and adipocytes in the bone marrow, but show preferential differentiation into adipocytes rather than osteoblasts under aging, thus leading to senile osteoporosis. Accumulated evidences indicate that rejuvenation of BMSCs by autophagic enhancement delays bone aging. Here we synthetized and demonstrated a novel autophagy activator, CXM102 that could induce autophagy in aged BMSCs, resulting in rejuvenation and preferential differentiation into osteoblasts of BMSCs. Furthermore, CXM102 significantly stimulated bone anabolism, reduced marrow adipocytes, and delayed bone loss in middle-age male mice. Mechanistically, CXM102 promoted transcription factor EB (TFEB) nuclear translocation and favored osteoblasts formation both in vitro and in vivo. Moreover, CXM102 decreased serum levels of inflammation and reduced organ fibrosis, leading to a prolonger lifespan in male mice. Our results indicated that CXM102 could be used as an autophagy inducer to rejuvenate BMSCs and shed new lights on strategies for senile osteoporosis and healthyspan improvement.

Maintenance of mitochondrial homeostasis is crucial for ensuring healthy mitochondria and normal cellular function. This process is primarily responsible for regulating processes that include mitochondrial OXPHOS, which generates ATP, as well as mitochondrial oxidative stress, apoptosis, calcium homeostasis, and mitophagy. Bone mesenchymal stem cells express factors that aid in bone formation and vascular growth. Positive regulation of hematopoietic stem cells in the bone marrow affects the differentiation of osteoclasts. Furthermore, the metabolic regulation of cells that play fundamental roles in various regions of the bone, as well as interactions within the bone microenvironment, actively participates in regulating bone integrity and aging. The maintenance of cellular homeostasis is dependent on the regulation of intracellular organelles, thus understanding the impact of mitochondrial functional changes on overall bone metabolism is crucially important. Recent studies have revealed that mitochondrial homeostasis can lead to morphological and functional abnormalities in senescent cells, particularly in the context of bone diseases. Mitochondrial dysfunction in skeletal diseases results in abnormal metabolism of bone-associated cells and a secondary dysregulated microenvironment within bone tissue. This imbalance in the oxidative system and immune disruption in the bone microenvironment ultimately leads to bone dysplasia. In this review, we examine the latest developments in mitochondrial respiratory chain regulation and its impacts on maintenance of bone health. Specifically, we explored whether enhancing mitochondrial function can reduce the occurrence of bone cell deterioration and improve bone metabolism. These findings offer prospects for developing bone remodeling biology strategies to treat age-related degenerative diseases.

Osteoporosis (OP) is a systemic metabolic bone disease that is characterized by decreased bone mineral density and microstructural damage to bone tissue. Recent studies have demonstrated significant advances in the research of programmed cell death (PCD) in OP. However, there is no bibliometric analysis in this research field. This study searched the Web of Science Core Collection (WoSCC) database for literature related to OP and PCD from 2000 to 2023. This study used VOSviewers 1.6.20, the "bibliometrix" R package, and CiteSpace (6.2.R3) for bibliometric and visualization analysis. A total of 2905 articles from 80 countries were included, with China and the United States leading the way. The number of publications related to PCD in OP is increasing year by year. The main research institutions are Shanghai Jiao Tong University, Chinese Medical University, Southern Medical University, Zhejiang University, and Soochow University. Bone is the most popular journal in the field of PCD in OP, and the Journal of Bone and Mineral Research is the most co-cited journal. These publications come from 14,801 authors, with Liu Zong-Ping, Yang Lei, Manolagas Stavros C, Zhang Wei, and Zhao Hong-Yan having published the most papers. Ronald S. Weinstein was co-cited most often. Oxidative stress and autophagy are the current research hot spots for PCD in OP. This bibliometric study provides the first comprehensive summary of trends and developments in PCD research in OP. This information identifies the most recent research frontiers and hot directions, which will provide a definitive reference for scholars studying PCD in OP.

The regenerative ability of limb bones after injury decreases during aging, but whether a similar phenomenon occurs in jawbones and whether autophagy plays a role in this process remain unclear. Through retrospective analysis of clinical data and studies on a mouse model of jawbone defects, we confirmed the presence of delayed or impaired bone regeneration in the jawbones of old individuals and mice. Subsequently, osteoblasts (OBs) derived from mouse jawbones were isolated, showing reduced osteogenesis in senescent osteoblasts (S-OBs). We observed a reduction in autophagy within both aged jawbones and S-OBs. Additionally, pharmacological inhibition of autophagy in normal OBs (N-OBs) led to cell aging and decreased osteogenesis, while autophagic activation reversed the aging phenotype of S-OBs. The activator rapamycin (RAPA) increased the autophagy level and bone regeneration in aged jawbones. Finally, we found that fatty acid-binding protein 3 (FABP3) was degraded by autolysosomes through its interaction with sequestosome 1 (P62/SQSTM1). Autophagy inhibition within senescent jawbones and S-OBs led to the excessive accumulation of FABP3, and FABP3 knockdown partially rescued the decreased osteogenesis in S-OBs and alleviated age-related compromised jawbone regeneration. In summary, we confirmed that autophagy inhibition plays an important role in delaying bone regeneration in aging jawbones. Autophagic activation or FABP3 knockdown can partially rescue the osteogenesis of S-OBs and the regeneration of aging jawbones, providing insight into jawbone aging.

The number of adult orthodontic patients is increasing, and studies have shown that autophagy is involved in regulating orthodontic tooth movement and plays an important role in aging-related changes. Therefore, we aimed to explore the role of autophagy in aging-related changes during orthodontic tooth movement by establishing a rat orthodontic tooth movement model.

Forty-five 6-week-old and sixty-five 8-month-old male Sprague-Dawley rats were selected to represent adolescents and adults and establish orthodontic tooth movement model. They were sacrificed on days 0,1,3,7 and 14. Immunohistochemistry, immunofluorescence and tartrate resistant acid phosphatase (TRAP) staining were applied to measure the expression level of osteogenesis, autophagy, aging factors and osteoclast number in periodontal membrane of left upper first molar during orthodontic tooth movement. Then, we regulated the autophagy level by injecting autophagy activator rapamycin during orthodontic tooth movement and measured these factors and tooth movement distance by micro-computed tomography.

Aging factor levels in the periodontal membrane were higher in adult rats than in adolescent rats and the autophagy factor levels were lower. The levels of osteogenic factors were lower on the tension side in adult rats than in adolescent rats. The peak osteoclast number on the pressure side occurred later in adult rats than in adolescent rats. The injection of rapamycin increased autophagy, accelerated orthodontic tooth movement in adult rats, and reduced the levels of aging factors. The levels of osteogenic factors were higher and reached those in adolescent rats at some time points. The number of osteoclasts increased significantly in the early stage.

Autophagy may play a substantial role in regulating aging-related changes in orthodontic tooth movement.

One of the major diseases affecting people globally is colorectal cancer (CRC), which is primarily caused by a lack of effective medical treatment and a limited understanding of its underlying mechanisms. Cellular autophagy functions to break down and eliminate superfluous proteins and substances, thereby facilitating the continual replacement of cellular elements and generating vital energy for cell processes. Non-coding RNAs and exosomal ncRNAs have a crucial impact on regulating gene expression and essential cellular functions such as autophagy, metastasis, and treatment resistance. The latest research has indicated that specific ncRNAs and exosomal ncRNA to influence the process of autophagy in CRC cells, which could have significant consequences for the advancement and treatment of this disease. It has been determined that a variety of ncRNAs have a vital function in regulating the genes essential for the formation and maturation of autophagosomes. Furthermore, it has been confirmed that ncRNAs have a considerable influence on the signaling pathways associated with autophagy, such as those involving AMPK, AKT, and mTOR. Additionally, numerous ncRNAs have the potential to affect specific genes involved in autophagy. This study delves into the control mechanisms of ncRNAs and exosomal ncRNAs and examines how they simultaneously influence autophagy in CRC.

Adipose tissue, an indispensable organ, fulfils the pivotal role of energy storage and metabolism and is instrumental in maintaining the dynamic equilibrium of energy and health of the organism. Adipocyte hypertrophy and adipocyte hyperplasia (adipogenesis) are the two primary mechanisms of fat deposition. Mature adipocytes are obtained by differentiating mesenchymal stem cells into preadipocytes and redifferentiation. However, the mechanisms orchestrating adipogenesis remain unclear. Autophagy, an alternative cell death pathway that sustains intracellular energy homeostasis through the degradation of cellular components, is implicated in regulating adipogenesis. Furthermore, adipose tissue functions as an endocrine organ, producing various cytokines, and certain inflammatory factors, in turn, modulate autophagy and adipogenesis. Additionally, autophagy influences intracellular redox homeostasis by regulating reactive oxygen species, which play pivotal roles in adipogenesis. There is a growing interest in exploring the involvement of autophagy, inflammation, and oxidative stress in adipogenesis. The present manuscript reviews the impact of autophagy, oxidative stress, and inflammation on the regulation of adipogenesis and, for the first time, discusses their interactions during adipogenesis. An integrated analysis of the role of autophagy, inflammation and oxidative stress will contribute to elucidating the mechanisms of adipogenesis and expediting the exploration of molecular targets for treating obesity-related metabolic disorders.

Recently, environmental temperature has been shown to regulate bone homeostasis. However, the mechanisms by which cold exposure affects bone mass remain unclear. In our present study, we observed that exposure to cold temperature (CT) decreased bone mass and quality in mice. Furthermore, a transplant of exosomes derived from the plasma of mice exposed to cold temperature (CT-EXO) can also impair the osteogenic differentiation of BMSCs and decrease bone mass by inhibiting autophagic activity. Rapamycin, a potent inducer of autophagy, can reverse cold exposure or CT-EXO-induced bone loss. Microarray sequencing revealed that cold exposure increases the miR-25-3p level in CT-EXO. Mechanistic studies showed that miR-25-3p can inhibit the osteogenic differentiation and autophagic activity of BMSCs. It is shown that inhibition of exosomes release or downregulation of miR-25-3p level can suppress CT-induced bone loss. This study identifies that CT-EXO mediates CT-induced osteoporotic effects through miR-25-3p by inhibiting autophagy via targeting SATB2, presenting a novel mechanism underlying the effect of cold temperature on bone mass.

The world population is increasingly aging, deeply affecting our society by challenging our healthcare systems and presenting an economic burden, thus turning the spotlight on aging-related diseases: exempli gratia, osteoporosis, a silent disease until you suddenly break a bone. The increase in bone fracture risk with age is generally associated with a loss of bone mass and an alteration in the skeletal architecture. However, such changes cannot fully explain increased fragility with age. To successfully tackle age-related bone diseases, it is paramount to comprehensively understand the fundamental mechanisms responsible for tissue degeneration. Aging mechanisms persist at multiple length scales within the complex hierarchical bone structure, raising the need for a multiscale and multidisciplinary approach to resolve them. This paper aims to provide an overarching analysis of aging processes in bone and to review the most prominent outcomes of bone aging. A systematic description of different length scales, highlighting the corresponding techniques adopted at each scale and motivating the need for combining diverse techniques, is provided to get a comprehensive description of the multi-physics phenomena involved.

The long noncoding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1) plays a crucial role in tumorigenesis and is frequently employed as a prognostic biomarker. However, its involvement in the osteogenic differentiation of oral stem cells, particularly human dental follicle stem cells (hDFSCs), remains unclear. Our investigation revealed that the absence of SNHG1 enhances the osteogenic differentiation of hDFSCs. Furthermore, the downregulation of SNHG1 induces autophagy in hDFSCs, leading to a reduction in intracellular oxidative stress levels. Notably, this effect is orchestrated through the epigenetic regulation of EZH2. Our study unveils a novel function of SNHG1 in governing the osteogenic differentiation of hDFSCs, offering fresh insights for an in-depth exploration of the molecular mechanisms underlying dental follicle development. These findings not only provide a foundation for advancing the understanding of SNHG1 but also present innovative perspectives for promoting the repair and regeneration of periodontal supporting tissue, ultimately contributing to the restoration of periodontal health and tooth function.

Skeletal disorders can seriously threaten the health and the performance of poultry, such as tibial dyschondroplasia (TD) and osteoporosis (OP). Oligomeric proanthocyanidins (OPC) are naturally occurring polyphenolic flavonoid compounds that can be used as potential substances to improve the bone health and the growth performance of poultry. Eighty 7-day-old green-eggshell yellow feather layer chickens were randomly divided into 4 groups: basal diet and basal diet supplementation with 25, 50, and 100 mg/kg OPC. The results have indicated that the growth performance and bone parameters of chickens were significantly improved supplementation with OPC in vivo, including the bone volume (BV), the bone mineral density (BMD) and the activities of antioxidative enzymes, but ratio of osteoprotegerin (OPG)/receptor activator of NF-κB (RANK) ligand (RANKL) was decreased. Furthermore, primary bone marrow mesenchymal stem cells (BMSCs) and bone marrow monocytes/macrophages (BMMs) were successfully isolated from femur and tibia of chickens, and co-cultured to differentiate into osteoclasts in vitro. The osteogenic differentiation derived from BMSCs was promoted treatment with high concentrations of OPC (10, 20, and 40 µmol/L) groups in vitro, but emerging the inhibition of osteoclastogenesis by increasing the ratio of OPG/RANKL. In contrary, the osteogenic differentiation was also promoted treatment with low concentrations of OPC (2.5, 5, and 10 µmol/L) groups, but osteoclastogenesis was enhanced by decreasing the ratio of OPG/RANKL in vitro. In addition, OPG inhibits the differentiation and activity of osteoclasts by increasing the autophagy in vitro. Dietary supplementation of OPC can improve the growth performance of bone and alter the balance of osteoblasts and osteoclasts, thereby improving the bone health of chickens.