Leonurine Protects Bone Mesenchymal Stem Cells from Oxidative Stress by Activating Mitophagy through PI3K/Akt/mTOR Pathway

Ultrasound-triggered functional hydrogel promotes multistage bone regeneration

The dysfunction of bone mesenchymal stem cells (BMSCs), caused by the physical and chemical properties of the inflammatory and repair phases of bone regeneration, contributes to the failure of bone regeneration. To meet the spatiotemporal needs of BMSCs in different phases, designing biocompatible materials that respond to external stimuli, improve migration in the inflammatory phase, reduce apoptosis in the proliferative phase, and clear the hurdle in the differentiation phase of BMSCs is an effective strategy for multistage repair of bone defects. In this study, we designed a cascade-response functional composite hydrogel (Gel@Eb/HA) to regulate BMSCs dysfunction in vitro and in vivo. Gel@Eb/HA improved the migration of BMSCs by upregulating the expression of chemokine (C-C motif) ligand 5 (CCL5) during the inflammatory phase. Ultrasound (US) triggered the rapid release of Ebselen (Eb), eliminating the accumulation of reactive oxygen species (ROS) in BMSCs, and reversing apoptosis under oxidative stress. Continued US treatment accelerated the degradation of the materials, thereby providing Ca2+ for the osteogenic differentiation of BMSCs. Altogether, our study highlights the prospects of US-controlled intelligent system, that provides a novel strategy for addressing the complexities of multistage bone repair.

Imbalance of early-life vitamin D intake targets ROS-mediated crosstalk between mitochondrial dysfunction and differentiation potential of MSCs associated the later obesity

BACKGROUND

Obesity is characterized by excessive fat accumulation, which is related with abnormal pluripotency of mesenchymal stem cells (MSCs). Recently, there is growing evidence that the disorder of maternal vitamin D (VD) intake is a well-known risk factor for long-term adverse health outcomes to their offspring. Otherwise, less is known of its repercussion and underlying mechanisms on the different differentiation potential of MSCs.

METHODS

Four-week-old female C57BL/6J mice were fed with different VD reproductive diets throughout the whole pregnancy and lactation. The characteristics of BMSCs from their seven-day male offspring, VDR knockdown establishment of HuMSCs and HuMSCs under the different VD interventions in vitro were confirmed by flow cytometry, RT-PCR, and immunofluorescence. The roles of VD on their mitochondrial dysfunction and differentiation potential were also investigated. Then their remaining weaned male pups were induced by administrating high-fat-diet (HFD) for 16 weeks and normal fat diet was simultaneously as controls. Their lipid accumulation and adipocytes hypertrophy were determined by histological staining and related gene expressions.

RESULTS

Herein, it was proved that imbalance of early-life VD intake could significantly aggravate the occurrence of obesity by inducing the adipogenesis through affecting the VD metabolism and related metabolites (P < 0.05). Moreover, abnormally maternal VD intake might be involved on the disorders of differentiation potential to inhibit the maintenance of MSCs stemness through increasing the productions of ROS, which was accompanied by impairing the expression of related genes on the adipo-osteogenic differentiation (P < 0.05). Moreover, it was along with increasing potential of adipogenic differentiation of MSCs as higher ROS in the state of VD deficiency, while excessive maternal VD status could conversely enhance the osteogenic differentiation with slightly lower ROS (P < 0.05). Furthermore, the underlying mechanisms might be involved on the mitochondria dysfunctional, especially the mitophagy, by activating the LC3b, P62 and etc. using in vivo and in vitro studies (P < 0.05).

CONCLUSION

These findings demonstrated that imbalance of early-life VD intake could target ROS-mediated crosstalk between mitochondrial dysfunction and differentiation potential of MSCs, which was significantly associated with the later obesity. Obviously, our results could open up an attractive modality for the benefits of suitable VD intake during the pregnancy and lactation.

Xinyang tablet alleviated cardiac dysfunction in a cardiac pressure overload model by regulating the receptor-interacting serum/three-protein kinase 3/FUN14 domain containing 1-mediated mitochondrial unfolded protein response and mitophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Xinyang tablet (XYT) has been used for heart failure (HF) for over twenty years in clinical practice, but the underlying molecular mechanism remains poorly understood.

AIMS OF THE STUDY

In the present study, we aimed to explore the protective effects of XYT in HF in vivo and in vitro.

MATERIALS AND METHODS

Transverse aortic constriction was performed in vivo to establish a mouse model of cardiac pressure overload. Echocardiography, tissue staining, and real-time quantitative PCR (qPCR) were examined to evaluate the protective effects of XYT on cardiac function and structure. Adenosine 5'-triphosphate production, reactive oxygen species staining, and measurement of malondialdehyde and superoxide dismutase was used to detect mitochondrial damage. Mitochondrial ultrastructure was observed by transmission electron microscope. Immunofluorescence staining, qPCR, and Western blotting were performed to evaluate the effect of XYT on the mitochondrial unfolded protein response and mitophagy, and to identify its potential pharmacological mechanism. In vitro, HL-1 cells and neonatal mouse cardiomyocytes were stimulated with Angiotensin II to establish the cell model. Western blotting, qPCR, immunofluorescence staining, and flow cytometry were utilized to determine the effects of XYT on cardiomyocytes. HL-1 cells overexpressing receptor-interacting serum/three-protein kinase 3 (RIPK3) were generated by transfection of RIPK3-overexpressing lentiviral vectors. Cells were then co-treated with XYT to determine the molecular mechanisms.

RESULTS

In the present study, XYT was found to exerta protective effect on cardiac function and structure in the pressure overload mice. And it was also found XYT reduced mitochondrial damage by enhancing mitochondrial unfolded protein response and restoring mitophagy. Further studies showed that XYT achieved its cardioprotective role through regulating the RIPK3/FUN14 domain containing 1 (FUNDC1) signaling. Moreover, the overexpression of RIPK3 successfully reversed the XYT-induced protective effects and significantly attenuated the positive effects on the mitochondrial unfolded protein response and mitophagy.

CONCLUSIONS

Our findings indicated that XYT prevented pressure overload-induced HF through regulating the RIPK3/FUNDC1-mediated mitochondrial unfolded protein response and mitophagy. The information gained from this study provides a potential strategy for attenuating mitochondrial damage in the context of pressure overload-induced heart failure using XYT.

Leonurine: a comprehensive review of pharmacokinetics, pharmacodynamics, and toxicology

Leonurine is an alkaloid unique to the Leonurus genus, which has many biological activities, such as uterine contraction, anti-inflammation, anti-oxidation, regulation of cell apoptosis, anti-tumor, angiogenesis, anti-platelet aggregation, and inhibition of vasoconstriction. This paper summarizes the extraction methods, synthetic pathways, biosynthetic mechanisms, pharmacokinetic properties, pharmacological effects in various diseases, toxicology, and clinical trials of leonurine. To facilitate a successful transition into clinical application, intensified efforts are required in several key areas: structural modifications of leonurine to optimize its properties, comprehensive pharmacokinetic assessments to understand its behavior within the body, thorough mechanistic studies to elucidate how it works at the molecular level, rigorous safety evaluations and toxicological investigations to ensure patient wellbeing, and meticulously conducted clinical trials to validate its efficacy and safety profile.

Application of Antioxidant Compounds in Bone Defect Repair

Bone defects caused by trauma, tumor resection, and infections are significant clinical challenges. Excessive reactive oxygen species (ROS) usually accumulate in the defect area, which may impair the function of cells involved in bone formation, posing a serious challenge for bone repair. Due to the potent ROS scavenging ability, as well as potential anti-inflammatory and immunomodulatory activities, antioxidants play an indispensable role in the maintenance and protection of bone health and have gained increasing attention in recent years. This narrative review aims to give an overview of the main research directions on the application of antioxidant compounds in bone defect repair over the past decade. In addition, the positive effects of various antioxidants and their biomaterial delivery systems in bone repair are summarized to provide new insights for exploring antioxidant-based strategies for bone defect repair.

Garcinol prevents oxidative stress-induced bone loss and dysfunction of BMSCs through NRF2-antioxidant signaling

There are multiple published data showing that excessive oxidative stress contributes to bone loss and even bone tissue damage, and it is also correlated with the pathophysiology of bone degenerative diseases, including osteoporosis (OP). Garcinol, a polyisoprenylated benzophenone derivative, has been recently established as an anti-oxidant agent. However, it remains elusive whether Garcinol protects bone marrow mesenchymal stem cells (BMSCs) and bone tissue from oxidative stress-induced damage. Here, we explored the potential effects of Garcinol supplementation in ameliorating oxidative stimulation-induced dysfunction of BMSCs and bone loss in osteoporotic mice. In this study, we verified that Garcinol exerted potent protective functions in the hydrogen peroxide (H2O2)-induced excessive oxidative stress and dysfunction of BMSCs. Besides, Garcinol was also identified to improve the reduced bone mass and abnormal lineage commitment of BMSCs in the condition of OP by suppressing the oxidative stimulation. Subsequent analysis revealed that nuclear factor erythroid 2-related factor 2 (NRF2) might be a key regulator in the sheltering effects of Garcinol on the H2O2-regulated oxidative stress, and the protective functions of Garcinol was mediated by NRF2-antioxidant signaling. Collectively, Garcinol prevented oxidative stress-related BMSC damage and bone loss through the NRF2-antioxidant signaling, which suggested the promising therapeutic values of Garcinol in the treatment of oxidative stress-related bone loss. Therefore, Garcinol might contribute to treating OP.

Mitochondrial dysfunction and therapeutic perspectives in osteoporosis

Osteoporosis (OP) is a systemic skeletal disorder characterized by reduced bone mass and structural deterioration of bone tissue, resulting in heightened vulnerability to fractures due to increased bone fragility. This condition primarily arises from an imbalance between the processes of bone resorption and formation. Mitochondrial dysfunction has been reported to potentially constitute one of the most crucial mechanisms influencing the pathogenesis of osteoporosis. In essence, mitochondria play a crucial role in maintaining the delicate equilibrium between bone formation and resorption, thereby ensuring optimal skeletal health. Nevertheless, disruption of this delicate balance can arise as a consequence of mitochondrial dysfunction. In dysfunctional mitochondria, the mitochondrial electron transport chain (ETC) becomes uncoupled, resulting in reduced ATP synthesis and increased generation of reactive oxygen species (ROS). Reinforcement of mitochondrial dysfunction is further exacerbated by the accumulation of aberrant mitochondria. In this review, we investigated and analyzed the correlation between mitochondrial dysfunction, encompassing mitochondrial DNA (mtDNA) alterations, oxidative phosphorylation (OXPHOS) impairment, mitophagy dysregulation, defects in mitochondrial biogenesis and dynamics, as well as excessive ROS accumulation, with regards to OP (Figure 1). Furthermore, we explore prospective strategies currently available for modulating mitochondria to ameliorate osteoporosis. Undoubtedly, certain therapeutic strategies still require further investigation to ensure their safety and efficacy as clinical treatments. However, from a mitochondrial perspective, the potential for establishing effective and safe therapeutic approaches for osteoporosis appears promising.

The inhibition of FTO attenuates the antifibrotic effect of leonurine in rat cardiac fibroblasts

BACKGROUND

Myocardial fibrosis (MF) is a common pathological condition in cardiovascular diseases that often causes severe cardiac dysfunction. MF is characterized by changes in cardiomyocytes, cardiac fibroblasts (CFs), levels of collagen (Col) -1, -3, and overdeposition of the extracellular matrix. Our previous research showed that leonurine (LE) effectively inhibits collagen synthesis and differentiation of CFs, but the mechanism is not fully elucidated. Recent evidence indicates that fat mass and obesity-associated proteins (FTO) regulates the occurrence and development of MF. This study aimed to explore the role of FTO in the antifibrotic effects of LE.

METHODS

Neonatal rat CFs were isolated, and induced using angiotensin II (Ang II) to establish a cell model of MF. Cell viability, wound healing and transwell assays were used to detect cell activity and migration ability. The protein and mRNA levels of MF-related factors were measured following stimulation with Ang II and LE under normal conditions or after FTO knockdown. The RNA methylation level was measured by dot blot assay.

RESULTS

The results showed that LE (20, 40 μM) was not toxic to normal CFs. LE reduced the proliferation, migration and collagen synthesis of Ang II-induced CFs. Further investigation showed that FTO was downregulated by Ang II stimulation, whereas LE reversed this effect. FTO knockdown facilitated the migration of CFs, upregulated the protein levels of Col-3, α-SMA and Col-1 in Ang II and LE-stimulated CFs, and enhanced the fluorescence intensity of α-SMA. Furthermore, LE reduced N6-methyladenosine (m6A) RNA methylation, which was partially blocked by FTO knockdown. FTO knockdown also reduced the expression levels of p53 protein in Ang II and LE-stimulated CFs.

CONCLUSIONS

Our findings suggest that the inhibition of FTO may attenuate the antifibrotic effect of LE in CFs, suggesting that FTO may serve as a key protein for anti-MF of LE.

Soy isoflavones induces mitophagy to inhibit the progression of osteosarcoma by blocking the AKT/mTOR signaling pathway

BACKGROUND

Soy isoflavones (SI) is a natural bioactive substance exhibiting beneficial effects on human health. This study aims to elucidate the therapeutic potential of SI in the treatment of osteosarcoma (OS) and to investigate the underlying mechanisms, particularly focusing on mitophagy.

METHODS

The effects of SI on the proliferation, apoptosis, migration, and invasion of U2OS cells were analyzed. Mitophagy was assessed through multiple parameters: mitochondrial autophagosomes, mitochondrial membrane potential, autophagy-related proteins, reactive oxygen species (ROS), and oxygen consumption rate (OCR). Protein levels related to apoptosis, autophagy, and the AKT/mTOR pathway were analyzed using western blot. The therapeutic efficacy of SI was further identified using a mouse tumor xenograft model. Cell apoptosis and proliferation in tumor xenografts were detected by TUNEL staining and immunohistochemistry (IHC), respectively.

RESULTS

SI dose-dependently suppressed the viability, colony formation, migration, and invasion of U2OS cells, and enhanced the apoptosis. SI also dose-dependently induced mitophagy in OS cells, evidenced by an increase in autophagosomes and ROS levels, a decrease in mitochondrial membrane potential and OCR, and concomitant changes in autophagy-related proteins. Mdivi-1, an inhibitor of mitophagy, reversed the anti-tumor effects of SI on U2OS cells. In addition, SI blocked the AKT/mTOR pathway in U2OS cells. SC-79, an AKT agonist, reversed the effect of SI on inducing mitophagy. Moreover, SI also promoted cell apoptosis and mitophagy in tumor xenografts in vivo.

CONCLUSIONS

SI induces mitophagy in OS cells by blocking the AKT/mTOR pathway, contributing to the inhibition of OS.

Promotion of NAD+ recycling by the hypoxia-induced shift in the lactate dehydrogenase isozyme profile reduces the senescence of human bone marrow-derived endothelial progenitor cells

Expansion of bone marrow-derived endothelial progenitor cells (EPCs) in vitro to obtain required cell numbers for therapeutic applications faces the challenge of growing cell senescence under the traditional normoxic culture condition. We previously found that 1% O2 hypoxic culture condition is favorable for reducing senescence of EPCs, but the mechanisms underlying the favorability are still unclear. Here, we found that, compared with normoxia, hypoxia induced a shift in lactate dehydrogenase (LDH) isozyme profile, which manifested as decreased LDH2 and LDH1 and increased LDH5, LDH4 and total LDHs. Moreover, under hypoxia, EPCs presented higher LDH activity, which could promote the conversion of pyruvate to lactate, as well as a higher level of NAD+, Bcl2 interacting protein 3 (BNIP3) expression and mitophagy. Additionally, under hypoxia, knock-down of the LDHA subunit increased the LDH2 and LDH1 levels and knock-down of the LDHB subunit increased the LDH5 level, while the simultaneous knock-down of LDHA and LDHB reduced total LDHs and NAD+ level. Inhibition of NAD+ recycling reduced BNIP3 expression and mitophagy and promoted cell senescence. Taken together, these data demonstrated that 1% O2 hypoxia induces a shift in the LDH isozyme profile, promotes NAD+ recycling, increases BNIP3 expression and mitophagy, and reduces EPC senescence. Our findings contribute to a better understanding of the connection between hypoxic culture conditions and the senescence of bone marrow-derived EPCs and provide a novel strategy to improve in vitro expansion of EPCs.

Advances in the study of traditional Chinese medicine affecting bone metabolism through modulation of oxidative stress

Bone metabolic homeostasis is dependent on coupled bone formation dominated by osteoblasts and bone resorption dominated by osteoclasts, which is a process of dynamic balance between bone formation and bone resorption. Notably, the formation of bone relies on the development of bone vasculature. Previous studies have shown that oxidative stress caused by disturbances in the antioxidant system of the whole organism is an important factor affecting bone metabolism. The increase in intracellular reactive oxygen species can lead to disturbances in bone metabolism, which can initiate multiple bone diseases, such as osteoporosis and osteoarthritis. Traditional Chinese medicine is considered to be an effective antioxidant. Cumulative evidence shows that the traditional Chinese medicine can alleviate oxidative stress-mediated bone metabolic disorders by modulating multiple signaling pathways, such as Nrf2/HO-1 signaling, PI3K/Akt signaling, Wnt/β-catenin signaling, NF-κB signaling, and MAPK signaling. In this paper, the potential mechanisms of traditional Chinese medicine to regulate bone me-tabolism through oxidative stress is summarized to provide direction and theoretical basis for future research related to the treatment of bone diseases with traditional Chinese medicine.

Mechanisms of action and synergetic formulas of plant-based natural compounds from traditional Chinese medicine for managing osteoporosis: a literature review

Osteoporosis (OP) is a systemic skeletal disease prevalent in older adults, characterized by substantial bone loss and deterioration of microstructure, resulting in heightened bone fragility and risk of fracture. Traditional Chinese Medicine (TCM) herbs have been widely employed in OP treatment owing to their advantages, such as good tolerance, low toxicity, high efficiency, and minimal adverse reactions. Increasing evidence also reveals that many plant-based compounds (or secondary metabolites) from these TCM formulas, such as resveratrol, naringin, and ginsenoside, have demonstrated beneficial effects in reducing the risk of OP. Nonetheless, the comprehensive roles of these natural products in OP have not been thoroughly clarified, impeding the development of synergistic formulas for optimal OP treatment. In this review, we sum up the pathological mechanisms of OP based on evidence from basic and clinical research; emphasis is placed on the in vitro and preclinical in vivo evidence-based anti-OP mechanisms of TCM formulas and their chemically active plant constituents, especially their effects on imbalanced bone homeostasis regulated by osteoblasts (responsible for bone formation), osteoclasts (responsible for bone resorption), bone marrow mesenchymal stem cells as well as bone microstructure, angiogenesis, and immune system. Furthermore, we prospectively discuss the combinatory ingredients from natural products from these TCM formulas. Our goal is to improve comprehension of the pharmacological mechanisms of TCM formulas and their chemically active constituents, which could inform the development of new strategies for managing OP.

Remnant Cholesterol as an Independent Predictor of Periodontitis: A Population-Based Study

Objective

Numerus studies present that remnant cholesterol (RC) as a risk factor participates in the progression of multiple diseases. The aim of this study was to assess the relationship between cholesterol and periodontitis in the US population to find a reliable lipid predictor for periodontitis.

Materials and Methods

Clinical data was retrieved from the National Health and Nutrition Examination Survey (NHANES) database between 2009 and 2014. The logistic regression was conducted to examine the corelationship between RC and various clinical features. Meanwhile, the dose-response relationship was measured through restricted cubic spline analysis. And the propensity score matching (PSM) was established to further investigate the potential relationship between RC and periodontitis.

Results

A number of 4,829 eligible participants were included in this study. It was found that the increased RC is associated with the higher risk of periodontitis after adjusting the potential confounding factors with the adjusted odds ratios (aOR) of 1.403 (95% confidence intervals (CI): 1.171-1.681, P < 0.001, univariate analysis) and 1.341 (95% CI: 1.105-1.629, P = 0.003, multivariate analysis) in the highest grade. There were significant differences in the relationship between RC and various clinical features including age, gender, body mass index (BMI), race, hypertension, and diabetes mellitus (all P < 0.001). Besides, the calculated thresholds for predicting periodontitis were 19.99 (before propensity score matching (PSM)) and 20.91 (after PSM) mg/dL.

Conclusions

In this study, RC was identified to be positively associated with the occurrence of periodontitis, which suggests that RC can be considered as a predictor for periodontitis.

Cell death regulation: A new way for natural products to treat osteoporosis

Osteoporosis is a common metabolic bone disease that results from the imbalance of homeostasis within the bone. Intra-bone homeostasis is dependent on a precise dynamic balance between bone resorption by osteoclasts and bone formation by mesenchymal lineage osteoblasts, which comprises a series of complex and highly standardized steps. Programmed cell death (PCD) (e.g., apoptosis, autophagy, ferroptosis, pyroptosis, and necroptosis) is a cell death process that involves a cascade of gene expression events with tight structures. These events play a certain role in regulating bone metabolism by determining the fate of bone cells. Moreover, existing research has suggested that natural products derived from a wide variety of dietary components and medicinal plants modulate the PCDs based on different mechanisms, which show great potential for the prevention and treatment of osteoporosis, thus revealing the emergence of more acceptable complementary and alternative drugs with lower costs, fewer side effects and more long-term application. Accordingly, this review summarizes the common types of PCDs in the field of osteoporosis. Moreover, from the perspective of targeting PCDs, this review also discussed the roles of currently reported natural products in the treatment of osteoporosis and the involved mechanisms. Based on this, this review provides more insights into new molecular mechanisms of osteoporosis and provides a reference for developing more natural anti-osteoporosis drugs in the future.

Mitophagy—A New Target of Bone Disease

Bone diseases are usually caused by abnormal metabolism and death of cells in bones, including osteoblasts, osteoclasts, osteocytes, chondrocytes, and bone marrow mesenchymal stem cells. Mitochondrial dysfunction, as an important cause of abnormal cell metabolism, is widely involved in the occurrence and progression of multiple bone diseases, including osteoarthritis, intervertebral disc degeneration, osteoporosis, and osteosarcoma. As selective mitochondrial autophagy for damaged or dysfunctional mitochondria, mitophagy is closely related to mitochondrial quality control and homeostasis. Accumulating evidence suggests that mitophagy plays an important regulatory role in bone disease, indicating that regulating the level of mitophagy may be a new strategy for bone-related diseases. Therefore, by reviewing the relevant literature in recent years, this paper reviews the potential mechanism of mitophagy in bone-related diseases, including osteoarthritis, intervertebral disc degeneration, osteoporosis, and osteosarcoma, to provide a theoretical basis for the related research of mitophagy in bone diseases.

Leukemia Inhibitory Factor Facilitates Self-Renewal and Differentiation and Attenuates Oxidative Stress of BMSCs by Activating PI3K/AKT Signaling

Objective. Transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) remains a hopeful therapeutic approach for bone defect reconstruction. Herein, we investigated the effects and mechanisms of leukemia inhibitory factor (LIF) in the function and viability of hypoxic BMSCs as well as bone defect repair. Methods. The effects of LIF on apoptosis (flow cytometry, TUNEL staining), mitochondrial activity (JC-1 staining), proliferation (colony formation, EdU staining), and differentiation (CD105, CD90, and CD29 via flow sorting) were examined in hypoxic BMSCs. LIF, LIFR, gp130, Keap1, Nrf2, antioxidant enzymes (SOD1, catalase, GPx-3), bone-specific matrix proteins (ALP, BSP, OCN), PI3K, and Akt were detected via immunoblotting or immunofluorescent staining. BMSCs combined with biphasic calcium phosphate scaffolds were implanted into calvarial bone defect mice, and the therapeutic effect of LIF on bone defect was investigated. Results. Hypoxic BMSCs had increased apoptosis and oxidative stress and reduced mitochondrial activity. Additionally, LIF, LIFR, and gp130 were upregulated and PI3K/Akt activity was depressed in hypoxic BMSCs. Upregulated LIF alleviated apoptosis and oxidative stress and heightened mitochondrial activity and PI3K/Akt signaling in hypoxic BMSCs. Additionally, LIF overexpression promoted self-renewal and osteogenic differentiation of BMSCs with hypoxic condition. Mechanically, LIF facilitated self-renewal and differentiation as well as attenuated oxidative stress of BMSCs through enhancing PI3K/AKT signaling activity. Implantation of LIF-overexpressed BMSC-loaded BCP scaffolds promoted osteogenesis as well as alleviated oxidative stress and apoptosis through PI3K/Akt signaling. Conclusion. Our findings demonstrate that LIF facilitates self-renewal and differentiation and attenuates oxidative stress of BMSCs by PI3K/AKT signaling.