Puerarin Relieved Compression-Induced Apoptosis and Mitochondrial Dysfunction in Human Nucleus Pulposus Mesenchymal Stem Cells via the PI3K/Akt Pathway

Targeting ferroptosis to enhance the efficacy of mesenchymal stem cell-based treatments for intervertebral disc degeneration

Although mesenchymal stromal cell (MSC) implantation shows promise for repairing intervertebral disc (IVD) degeneration (IVDD), their limited retention within degenerative IVDs compromises therapeutic efficacy. The oxidative stress in the microenvironment of degenerated IVDs induces a surge in reactive oxygen species production within MSCs, disrupting the balance between oxidation and antioxidation, and ultimately inducing ferroptosis. Recent evidence has suggested that targeting ferroptosis in MSCs could enhance MSC retention, extend the survival of transplanted MSCs, and markedly delay the pathological progression of IVDD. By targeting ferroptosis, a novel approach emerges to boost the efficacy of MSC transplantation therapy for IVDD. In this review, current research on targeting ferroptosis in MSCs is discussed from various perspectives, including the targeting of specific genes and pathways, drug preconditioning, and hydrogel encapsulation. A detailed discussion on the effects of targeting ferroptosis in MSCs on the transplantation repair of degenerated IVDs is provided. Insights that could guide improvements in stem cell transplantation therapies are also offered. Significantly, this review presents specific ideas for our future foundational research. These insights outline promising avenues for future clinical translation and will contribute to developing and optimizing treatment strategies for MSC transplantation therapy, maximizing benefits for patients with lumbar IVDD.

Exploring the therapeutic potential of puerarin on intervertebral disc degeneration by regulating apoptosis of nucleus pulposus cells

Intervertebral disc degeneration (IVDD) stands as a prevalent chronic orthopedic ailment, profoundly impacting patients' well-being due to incapacitating low back pain. Studies have highlighted a close correlation between IVDD and the programmed cell death of nucleus pulposus (NP) cells orchestrated by interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and caspase-3 (CASP3). Puerarin, renowned for its anti-inflammatory attributes and its influence on IL-1β and TNF-α, emerges as a promising candidate for IVDD treatment. However, the precise mechanism by which it regulates apoptosis via these pathways remains ambiguous. This investigation utilizes bioinformatics to unveil the molecular intricacies of puerarin-mediated apoptosis regulation in IVDD, substantiated by preliminary in vitro experiments. Analysis exposes aberrant expression of pivotal apoptosis-associated proteins (IL-1β, TNF-α, CASP3, CASP8, and BCL2) in IVDD patients, with network pharmacology indicating puerarin's potential efficacy in IVDD treatment by modulating apoptosis and cellular senescence pathways. Further experiments elucidate puerarin's capacity to stimulate NP cell proliferation while inhibiting apoptosis, potentially contributing to IVDD mitigation. Western blot and PCR outcomes reveal escalated expression of apoptosis-related proteins (IL-1β, TNF-α, and CASP3) in lipopolysaccharide-treated NPCs, ameliorated by puerarin intervention. Molecular docking simulations demonstrate favorable binding properties of puerarin with apoptotic proteins, while flow cytometry analysis indicates its ability to diminish NPC apoptosis. These discoveries imply that puerarin might alleviate NPC apoptosis by modulating key targets, thereby potentially ameliorating IVDD. In summary, this study unveils the intrinsic mechanism of puerarin in regulating NPC apoptosis to alleviate IVDD, underscoring its therapeutic promise.

Protective effects of puerarin combined with bone marrow mesenchymal stem cells on nerve injury in rats with ischemic stroke

BACKGROUND

Bone marrow mesenchymal stem cells (BM-MSCs) transplantation shows promise for treating ischemic stroke, but the ischemic environment that follows cerebral infarction hinders the survival of transplanted cells. We aimed to study the effects of puerarin (Pue) in combination with BM-MSCs on cerebral ischemic injury.

METHODS

After middle cerebral artery occlusion (MCAO) models were prepared by suture-occluded method, rats were randomly allocated to the sham, MCAO, Pue (50 mg/kg), BM-MSCs (2×106), and BM-MSCs+Pue groups. The neurological function, infarct area, levels of inflammation-related factors, brain tissue damage, apoptosis, BrdU, Beclin1, and LC3 levels were then assessed.

RESULTS

Pue and BM-MSCs reduced the modified neurological severity score, cerebral infarction area, and serum inflammation-related factor levels for MCAO rats. Furthermore, Pue and BM-MSCs interventions ameliorated brain tissue damage, and repressed apoptosis of brain tissues in MCAO rats. Moreover, Pue or BM-MSCs enhanced BrdU expression, restrained LC3II/LC3I ratio and Beclin 1 expression in MCAO rats' brain tissues. Importantly, the combination of Pue and BM-MSCs exhibited more pronounced effects on aforementioned outcomes.

CONCLUSION

The combination of Pue and BM-MSCs facilitated the recovery of neurological function in rats after cerebral ischemic damage, and the mechanisms may correlate with the repression of neuronal apoptosis, inflammation, and autophagy.

Targeting ferroptosis by natural products in pathophysiological conditions

Ferroptosis is a form of cell death that is induced by iron-mediated accumulation of lipid peroxidation. The involvement of ferroptosis in different pathophysiological conditions has offered new perspectives on potential therapeutic interventions. Natural products, which are widely recognized for their significance in drug discovery and repurposing, have shown great promise in regulating ferroptosis by targeting various ferroptosis players. In this review, we discuss the regulatory mechanisms of ferroptosis and its implications in different pathological conditions. We dissect the interactions between natural products and ferroptosis in cancer, ischemia/reperfusion, neurodegenerative diseases, acute kidney injury, liver injury, and cardiomyopathy, with an emphasis on the relevance of ferroptosis players to disease targetability.

Quercetin relieves compression-induced cell death and lumbar disc degeneration by stabilizing HIF1A protein

Background

Lumbar disc degeneration (LDD) is a prevalent condition characterized by the decreased viability and functional impairment of nucleus pulposus mesenchymal stem cells (NPMSCs). Shaoyao-Gancao decoction (SGD), a traditional Chinese medicine formula, has been used to treat LDD, but its active components and mechanisms are unclear.

Methods

An integrative network pharmacology and transcriptome analysis were conducted to identify bioactive compounds in SGD that could target LDD. NPMSCs were cultured under mechanical compression as a cellular model of LDD. A rat model of annulus fibrosus needle-puncture was established to induce intervertebral disc degeneration. The effects of quercetin, a predicted active component, on alleviating compression-induced NPMSC death and LDD were evaluated in vitro and in vivo.

Results

The analysis identified hypoxia-inducible factor 1-alpha (HIF1A) as a potential target of quercetin in LDD. HIF1A was upregulated in degenerated human disc samples and compression-treated NPMSCs. Quercetin treatment alleviated compression-induced oxidative stress, apoptosis, and loss of viability in NPMSCs by stabilizing HIF1A. The protective effects of quercetin were abrogated by HIF1A inhibition. In the rat model, quercetin ameliorated intervertebral disc degeneration.

Conclusion

Our study identified HIF1A as a protective factor against compression-induced cell death in NPMSCs. Quercetin, a bioactive compound found in the traditional Chinese medicine formula SGD, improved the survival of NPMSCs and alleviated LDD progression by stabilizing HIF1A. Targeting the HIF1A pathway through natural compounds like quercetin could represent a promising strategy for the clinical management of LDD and potentially other degenerative disc diseases.

SP1/CTR1-mediated oxidative stress-induced cuproptosis in intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is an age-related disease and is responsible for low back pain. Oxidative stress-induced cell death plays a fundamental role in IDD pathogenesis. Cuproptosis is a recently discovered form of programmed cell death dependent on copper availability. Whether cuproptosis is involved in IDD progression remains unknown. Herein, we established in vitro and in vivo models to investigate cuproptosis in IDD and the mechanisms by which oxidative stress interacts with copper sensitivity in nucleus pulposus cells (NPCs). We found that ferredoxin-1 (FDX1) content increased in both rat and human degenerated discs. Sublethal oxidative stress on NPCs led to increased FDX1 expression, tricarboxylic acid (TCA) cycle-related proteins lipoylation and aggregation, and cell death in the presence of Cu2+ at physiological concentrations, while FDX1 knockdown inhibited cell death. Since copper homeostasis is involved in copper-induced cytotoxicity, we investigated the role of copper transport-related proteins, including importer (CTR1) and efflux pumps (ATPase transporter, ATP7A, and ATP7B). CTR1 and ATP7A content increased under oxidative stress, and blocking CTR1 reduced oxidative stress/copper-induced TCA-related protein aggregation and cell death. Moreover, oxidative stress promoted the expression of specific protein 1 (SP1) and SP1-mediated CTR1 transcription. SP1 inhibition decreased cell death rates, preserved disc hydration, and alleviated tissue degeneration. This suggests that oxidative stress upregulates FDX1 expression and copper flux through promoting SP1-mediated CTR1 transcription, leading to increased TCA cycle-related protein aggregation and cuproptosis. This study highlights the importance of cuproptosis in IDD progression and provides a promising therapeutic target for IDD treatment.

Puerarin alleviates oxaliplatin-induced neuropathic pain by promoting Nrf2/GPX4-mediated antioxidative response

Oxaliplatin (OXA) as the platinum-based agent induces the cumulative neuropathy including functional impairment and neuropathic pain. OXA treatment triggered oxidative stress and inflammatory reaction in the spinal cord. Puerarin as a natural product has the neuroprotective effect on neuropathic pain. Hence, the roles and mechanisms of Pue on OXA induced neuropathic pain were studied. In this study, OXA-induced neuropathic pain mouse model was constructed by oxaliplatin injection for 5 consecutive days and two cycles. Pue (10 mg/kg) was administered intraperitoneally for seven consecutive days. The changes of behavior, morphology and levels of related proteins were detected. As a result, OXA-induced mice exhibited as the increased pain hypersensitivity, the impaired motor coordination, the activated NLRP3 inflammasome mediated inflammation and the suppressed nuclear factor erythroid 2-related factor 2 (Nrf2) mediated antioxidative reaction in the spinal cord (P<0.05 vs Control). After Pue administration, the mechanical pain threshold, thermal pain latency, spontaneous pain number and motor latency were improved (P<0.05 vs OXA). In the spinal cord, Pue administration reduced the levels of inflammatory elements, increased the levels of antioxidative elements and decreased the levels of oxidative factors (P<0.05 vs OXA). Furthermore, Pue also bind with Nrf2 and increased the association of Nrf2 to glutathione peroxidase 4 (GPX4). In summary, Pue alleviates oxaliplatin induced neuropathic pain by enhancing Nrf2/GPX4-mediated antioxidant response and suppressing inflammatory reaction in the spinal cord.

Diabetes cardiomyopathy: targeted regulation of mitochondrial dysfunction and therapeutic potential of plant secondary metabolites

Diabetic cardiomyopathy (DCM) is a specific heart condition in diabetic patients, which is a major cause of heart failure and significantly affects quality of life. DCM is manifested as abnormal cardiac structure and function in the absence of ischaemic or hypertensive heart disease in individuals with diabetes. Although the development of DCM involves multiple pathological mechanisms, mitochondrial dysfunction is considered to play a crucial role. The regulatory mechanisms of mitochondrial dysfunction mainly include mitochondrial dynamics, oxidative stress, calcium handling, uncoupling, biogenesis, mitophagy, and insulin signaling. Targeting mitochondrial function in the treatment of DCM has attracted increasing attention. Studies have shown that plant secondary metabolites contribute to improving mitochondrial function and alleviating the development of DCM. This review outlines the role of mitochondrial dysfunction in the pathogenesis of DCM and discusses the regulatory mechanism for mitochondrial dysfunction. In addition, it also summarizes treatment strategies based on plant secondary metabolites. These strategies targeting the treatment of mitochondrial dysfunction may help prevent and treat DCM.

Effects of puerarin on the intervertebral disc degeneration and biological characteristics of nucleus pulposus cells

CONTEXT

Intervertebral disc degeneration (IDD) is the pathological basis of spinal degenerative diseases. Puerarin (PU) is an isoflavonoid with functions and medicinal properties.

OBJECTIVE

To explore the effect of PU on IDD and its potential mechanism of action.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats were divided into sham, IDD, low PU, and high PU groups. Rat nucleus pulposus cells (NPCs) were isolated and divided into control, IL-1β, 100 and 200 μmol/mL PU, TAK-242 (TLR4 inhibitor), or 200 μmol/mL PU + LPS (TLR4 activator) groups. The water content, inflammatory factors, proliferation activity, TLR4/NF-κB pathway activity, apoptosis rate, protein expression of apoptosis, and histology of the extracellular matrix (ECM) were analysed.

RESULTS

In vivo: Compared with the IDD group, disorganization of intervertebral disc tissue was significantly improved, water content (2.80 ± 0.24 mg, 3.91 ± 0.31 mg vs. 2.02 ± 0.21 mg) and expression levels of collagen II and aggrecan were significantly increased, and the levels of inflammatory factors and the expression levels of TLR4, MyD88, and p-p65 were significantly decreased in IDD rats treated with PU. In vitro: Compared with the IL-1β group, the proliferation activity of IL-1β-treated NPCs and the expression of collagen II and aggrecan were significantly increased, while the apoptosis rate, levels of inflammatory factors, and the expression levels of TLR4, MyD88, and p-p65 were significantly decreased in IL-1β-treated NPCs treated with PU. LPS reversed the biological function changes of IL-1β-treated NPCs induced by PU.

CONCLUSIONS

PU can delay the progression of IDD by inhibiting activation of the TLR4/NF-κB pathway.

Melatonin alleviates oxidative stress-induced injury to nucleus pulposus-derived mesenchymal stem cells through activating PI3K/Akt pathway

BACKGROUND

The changes in the microenvironment of degenerative intervertebral discs cause oxidative stress injury and excessive apoptosis of intervertebral disc endogenous stem cells. The purpose of this study was to explore the possible mechanism of the protective effect of melatonin on oxidative stress injury in NPMSCs induced by H2O2.

METHODS

The Cell Counting Kit-8 assay was used to evaluate the cytotoxicity of hydrogen peroxide and the protective effects of melatonin. ROS content was detected by 2'7'-dichlorofluorescin diacetate (DCFH-DA). Mitochondrial membrane potential (MMP) was detected by the JC-1assay. Transferase mediated d-UTP Nick end labeling (TUNEL) and Annexin V/PI double staining were used to determine the apoptosis rate. Additionally, apoptosis-associated proteins and PI3K/Akt signaling pathway-related proteins were evaluated by immunofluorescence, immunoblotting and PCR. ECMs were evaluated by RT‒PCR and immunofluorescence. In vivo, X-ray, Magnetic resonance imaging (MRI) and Histological analyses were used to evaluate the protective effect of melatonin.

RESULTS

Melatonin had an obvious protective effect on NPMSCs treated with 0-10 μM melatonin for 24 h. In addition, melatonin also had obvious protective effects on mitochondrial dysfunction, decreased membrane potential and cell senescence induced by H2O2. More importantly, melatonin could significantly reduce the apoptosis of nucleus pulposus mesenchymal stem cells induced by H2O2 by regulating the expression of apoptosis-related proteins and decreasing the rate of apoptosis. After treatment with melatonin, the PI3K/Akt pathway was significantly activated in nucleus pulposus mesenchymal stem cells, while the protective effect was significantly weakened after PI3K-IN-1 treatment. In vivo, the results of X-ray, MRI and histological analyses showed that therapy with melatonin could partially reduce the degree of intervertebral disc degeneration.

CONCLUSION

Our research demonstrated that melatonin can effectively alleviate the excessive apoptosis and mitochondrial dysfunction of nucleus pulposus mesenchymal stem cells induced by oxidative stress via the PI3K/Akt pathway, which provides a novel idea for the therapy of intervertebral disc degeneration.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

This study indicates that melatonin can effectively alleviate the excessive apoptosis and mitochondrial dysfunction of NPMSCs through activating the PI3K/Akt pathway. Melatonin might serve as a promising candidate for the prevention and treatment of Intervertebral disc degeneration disease (IVDD) in the future.

Research progress in the molecular mechanism of ferroptosis in Parkinson's disease and regulation by natural plant products

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder of the central nervous system after Alzheimer's disease. The current understanding of PD focuses mainly on the loss of dopamine neurons in the substantia nigra region of the midbrain, which is attributed to factors such as oxidative stress, alpha-synuclein aggregation, neuroinflammation, and mitochondrial dysfunction. These factors together contribute to the PD phenotype. Recent studies on PD pathology have introduced a new form of cell death known as ferroptosis. Pathological changes closely linked with ferroptosis have been seen in the brain tissues of PD patients, including alterations in iron metabolism, lipid peroxidation, and increased levels of reactive oxygen species. Preclinical research has demonstrated the neuroprotective qualities of certain iron chelators, antioxidants, Fer-1, and conditioners in Parkinson's disease. Natural plant products have shown significant potential in balancing ferroptosis-related factors and adjusting their expression levels. Therefore, it is vital to understand the mechanisms by which natural plant products inhibit ferroptosis and relieve PD symptoms. This review provides a comprehensive look at ferroptosis, its role in PD pathology, and the mechanisms underlying the therapeutic effects of natural plant products focused on ferroptosis. The insights from this review can serve as useful references for future research on novel ferroptosis inhibitors and lead compounds for PD treatment.

Effects of Puerarin-Loaded Tetrahedral Framework Nucleic Acids on Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head (ONFH) is recognized as a common refractory orthopedic disease that causes severe pain and poor quality of life in patients. Puerarin (Pue), a natural isoflavone glycoside, can promote osteogenesis and inhibit apoptosis of bone mesenchymal stem cells (BMSCs), demonstrating its great potential in the treatment of osteonecrosis. However, its low aqueous solubility, fast degradation in vivo, and inadequate bioavailability, limit its clinical application and therapeutic efficacy. Tetrahedral framework nucleic acids (tFNAs) are promising novel DNA nanomaterials in drug delivery. In this study, tFNAs as Pue carriers is used and synthesized a tFNA/Pue complex (TPC) that exhibited better stability, biocompatibility, and tissue utilization than free Pue. A dexamethasone (DEX)-treated BMSC model in vitro and a methylprednisolone (MPS)-induced ONFH model in vivo is also established, to explore the regulatory effects of TPC on osteogenesis and apoptosis of BMSCs. This findings showed that TPC can restore osteogenesis dysfunction and attenuated BMSC apoptosis induced by high-dose glucocorticoids (GCs) through the hedgehog and Akt/Bcl-2 pathways, contributing to the prevention of GC-induced ONFH in rats. Thus, TPC is a promising drug for the treatment of ONFH and other osteogenesis-related diseases.

Extracellular Vesicle-Conjugated Functional Matrix Hydrogels Prevent Senescence by Exosomal miR-3594-5p-Targeted HIPK2/p53 Pathway for Disc Regeneration

Nucleus pulposus stem cells (NPSCs) senescence plays a critical role in the progression of intervertebral disc degeneration (IDD). Stem cell-derived extracellular vesicles (EV) alleviate cellular senescence. Whereas, the underlying mechanism remains unclear. Low stability largely limited the administration of EV in vivo. RGD, an arginine-glycine-aspartic acid tripeptide, strongly binds integrins expressed on the EV membranes, allowing RGD to anchor EV and prolong their bioavailability. An RGD-complexed nucleus pulposus matrix hydrogel (RGD-DNP) is developed to enhance the therapeutic effects of small EV (sEV). RGD-DNP prolonged sEV retention in vitro and ex vivo. sEV-RGD-DNP promoted NPSCs migration, decreased the number of SA-β-gal-positive cells, alleviated cell cycle arrest, and reduced p16, p21, and p53 activation. Small RNA-seq showed that miR-3594-5p is enriched in sEV, and targets the homeodomain-interacting protein kinase 2 (HIPK2)/p53 pathway. The HIPK2 knockdown rescues the impaired therapeutic effects of sEV with downregulated miR-3594-5p. RGD-DNP conjugate with lower amounts of sEV achieved similar disc regeneration with free sEV of higher concentrations in DNP. In conclusion, sEV-RGD-DNP increases sEV bioavailability and relieves NPSCs senescence by targeting the HIPK2/p53 pathway, thereby alleviating IDD. This work achieves better regenerative effects with fewer sEV and consolidates the theoretical basis for sEV application for IDD treatment.

GDF11, a target of miR-32-5p, suppresses high-glucose-induced mitochondrial dysfunction and apoptosis in HK-2 cells through PI3K/AKT signaling activation

PURPOSE

To investigate the role and underlying mechanism of GDF11 on diabetic nephropathy (DN)-related mitochondrial dysfunction and apoptosis.

METHODS

A DN model of rats was established in this study. Human Kidney-2 (HK-2) cells were cultured under high-glucose (HG) condition with or without recombinant GDF11 (rGDF11). Mitochondrial morphology of HK-2 cells was analyzed by transmission electron microscope and MitoTracker Red CMXRos staining. Mitochondrial membrane potential (MMP) and ROS production were monitored using JC-1 assay kit and MitoSOX staining, respectively. Cell apoptosis was detected by TUNEL or flow cytometry assays.

RESULTS

Herein, we observed that GDF11 was down-regulated in renal cortex and serum of DN rats, which was accompanied by renal mitochondrial morphological abnormalities. In line with the findings in vivo, HK-2 cells exposed to HG presented with mitochondrial morphological alterations and further apoptosis accompanied by GDF11 reduction. In addition, HG promoted a decrease in MMP while an increase in mitochondrial ROS production. Conversely, rGDF11 treatment significantly alleviated these HG-induced mitochondrial defects in HK-2 cells. Meanwhile, HK-2 cell apoptosis induced by HG was simultaneously suppressed by rGDF11. Mechanistically, the decreased levels of p-AKT induced by HG were attenuated after rGDF11 administration. Inhibition of the PI3K/AKT pathway resisted the effects of rGDF11 on the MMP and apoptosis of HK-2 cells. In addition, we identified that GDF11 is a target of miR-32-5p. Up-regulation of miR-32-5p could inhibit the expression of GDF11.

CONCLUSION

rGDF11 treatment rescued HG-induced HK-2 cell mitochondrial dysfunction and apoptosis, which may be dependent on the activation of the PI3K/AKT pathway.

Proanthocyanidins inhibit the apoptosis and aging of nucleus pulposus cells through the PI3K/Akt pathway delaying intervertebral disc degeneration

BACKGROUND

Low back pain is a common symptom of intervertebral disc degeneration (IDD), which seriously affects the quality of life of patients. The abnormal apoptosis and senescence of nucleus pulposus (NP) cells play important roles in the pathogenesis of IDD. Proanthocyanidins (PACs) are polyphenolic compounds with anti-apoptosis and anti-aging effects. However, their functions in NP cells are not yet clear. Therefore, this study was performed to explore the effects of PACs on NP cell apoptosis and aging and the underlying mechanisms of action.

METHODS

Cell viability was evaluated by cell counting kit-8 (CCK-8) assay. The apoptosis rate was determined TUNEL assays. Levels of apoptosis-associated molecules (Bcl-2, Bax, C-caspase-3 and Caspase-9) were evaluated via western blot. The senescence was observed through SA-β-gal staining and western blotting analysis was performed to observe the expression of senescence-related molecules (p-P53, P53, P21 and P16).

RESULTS

Pretreatment with PACs exhibited protective effects against IL-1β-induced NP cell apoptosis including apoptosis rate, expressions of proapoptosis and antiapoptosis related genes and protein. PACs could also alleviate the increase of p-p53, P21, and P16 in IL-1β-treated NP cells. SA-β-gal staining showed that IL-1β-induced senescence of NP cells was prevented by PACs pertreatment. In addition, PACs activated PI3K/Akt pathway in IL-1β-stimulated NP cells. However, these protected effects were inhibited after LY294002 treatment.

CONCLUSION

The results of the present study showed that PACs inhibit IL-1β-induced apoptosis and aging of NP cells by activating the PI3K/Akt pathway, and suggested that PACs have therapeutic potential for IDD.

Targeting Autophagy for Developing New Therapeutic Strategy in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is a prevalent cause of low back pain. IVDD is characterized by abnormal expression of extracellular matrix components such as collagen and aggrecan. In addition, it results in dysfunctional growth, senescence, and death of intervertebral cells. The biological pathways involved in the development and progression of IVDD are not fully understood. Therefore, a better understanding of the molecular mechanisms underlying IVDD could aid in the development of strategies for prevention and treatment. Autophagy is a cellular process that removes damaged proteins and dysfunctional organelles, and its dysfunction is linked to a variety of diseases, including IVDD and osteoarthritis. In this review, we describe recent research findings on the role of autophagy in IVDD pathogenesis and highlight autophagy-targeting molecules which can be exploited to treat IVDD. Many studies exhibit that autophagy protects against and postpones disc degeneration. Further research is needed to determine whether autophagy is required for cell integrity in intervertebral discs and to establish autophagy as a viable therapeutic target for IVDD.

Intervertebral Disc Degeneration and Low Back Pain Depends on Duration and Magnitude of Axial Compression

Purpose

The pathological role of axial stress in intervertebral disc degeneration (IDD) is controversial, and there was no quantified study until now. Here, we tried to clarify the correlation between IDD or low back pain (LBP) and axial stress at different duration and magnitude in vitro and in vivo.

Method

In vitro, the gene expression of aggrecan, matrix metalloproteinase-3 (MMP3), calcitonin gene-related peptide (CGRP), and substance P (SP) was measured when nucleus pulposus cells (NPCs) were compressed under gradual severity. In vivo, a measurable Ilizarov-type compression apparatus was established for single coccygeal (Co) intervertebral disc (IVD) compression of Co7-8 in mouse. Gradient stress was placed at 0.4 Mpa (mild), 0.8 Mpa (moderate), and 1.2 Mpa (severe) for three days to investigate the effect of the magnitude of axial stress. Additionally, mild compression with 3, 7, and 14 days was used to determine the effect of the duration of axial stress. Subsequently, we evaluated the severity of IDD and LBP by radiological X-ray film; histological examination with H&E staining; immunohistochemical analysis with collagen II, aggrecan, and CGRP staining; and western blot analysis with collagen II, aggrecan, MMP-3, and interleukin-1β (IL-1β).

Results

When NPCs suffered gradual increased mechanical stress, the cells exhibited gradual downregulated expression of extracellular matrix (ECM)-related gene of aggrecan, upregulated expression of IDD-related gene of MMP3, and LBP-related gene of CGRP and SP. In the meantime, with different magnitudes of axial stress, the IVD showed progressively severe IDD and LBP, with gradual narrowing intervertebral height, destruction of IVD anatomy, decreased ECM, and increased catabolic factors and proalgesic peptides.

Conclusion

Axial compression is one of the critical pathological factors to cause IDD and LBP, and there was a strong positive correlation depended on the duration and magnitude of compression.

Puerarin alleviates cadmium-induced oxidative damage to bone by reducing autophagy in rats

Autophagy is a regulatory mechanism involved in cadmium (Cd)-induced bone toxicity and is suppressed by various stimuli, including oxidative stress. Puerarin is an isoflavonoid compound isolated from Pueraria, a plant used in traditional Chinese medicine. The underlying mechanisms of action of puerarin remain unclear. The objective of this study was to explore the mitigating effects of puerarin on cadmium-induced oxidative damage in the bones of rats. Cadmium exposure increased oxidative damage in rat bones; this was markedly decreased by puerarin treatment, as demonstrated by changes in the activity of antioxidative enzymes. Cadmium-induced blockage of the expression of key bone regulatory proteins, autophagy-related markers, and signaling molecules was also alleviated by puerarin treatment. Additionally, cadmium reduced expression of the autophagic protein Rab7 and of late endosomal/lysosomal adaptor and MAPK and mTOR activator 1 (LAMTOR1); the decrease in these proteins was not restored by puerarin treatment. We speculate that puerarin relieves the inhibition of fusion of autophagosomes with lysosomes that is induced by cadmium; however, this specific effect of puerarin and downstream effects on bone regulatory mechanisms require further investigation. In conclusion, puerarin alleviates cadmium-induced oxidative damage in the bones of rats by attenuating autophagy, which is likely associated with the antioxidant activity of puerarin.

1,25(OH)2D3 Mitigates Oxidative Stress-Induced Damage to Nucleus Pulposus-Derived Mesenchymal Stem Cells through PI3K/Akt Pathway

Intervertebral disc degeneration (IVDD) is one of the main causes of low back pain. The local environment of the degenerated intervertebral disc (IVD) increases oxidative stress and apoptosis of endogenous nucleus pulposus-derived mesenchymal stem cells (NPMSCs) and weakens its ability of endogenous repair ability in degenerated IVDs. A suitable concentration of 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) has been certified to reduce oxidative stress and cell apoptosis. The current study investigated the protective effect and potential mechanism of 1,25(OH)₂D₃ against oxidative stress-induced damage to NPMSCs. The present results showed that 1,25(OH)₂D₃ showed a significant protective effect on NPMSCs at a concentration of 10⁻¹⁰ M for 24 h. Protective effects of 1,25(OH)₂D₃ were also exhibited against H₂O₂-induced NPMSC senescence, mitochondrial dysfunction, and reduced mitochondrial membrane potential. The Annexin V/PI apoptosis detection assay, TUNEL assay, immunofluorescence, western blot, and real-time quantitative polymerase chain reaction assay showed that pretreatment with 1,25(OH)₂D₃ could alleviate H₂O₂-induced NPMSC apoptosis, including the apoptosis rate and the expression of proapoptotic-related (Caspase-3 and Bax) and antiapoptotic-related (Bcl-2) proteins. The intracellular expression of p-Akt increased after pretreatment with 1,25(OH)₂D₃. However, these protective effects of 1,25(OH)₂D₃ were significantly decreased after the PI3K/Akt pathway was inhibited by the LY294002 treatment. In vivo, X-ray, MRI, and histological analyses showed that 1,25(OH)₂D₃ treatment relieved the degree of IVDD in Sprague–Dawley rat disc puncture models. In summary, 1,25(OH)₂D₃ efficiently attenuated oxidative stress-induced NPMSC apoptosis and mitochondrial dysfunction via PI3K/Akt pathway and is a promising candidate treatment for the repair of IVDD.

Puerarin action on stem cell proliferation, differentiation and apoptosis: Therapeutic implications for geriatric diseases

BACKGROUND

Aging is associated with a decline in cognitive and physical functions and various geriatric diseases, such as cardiovascular and neurodegenerative diseases. Puerarin (Pue), one of the main active flavonoids of Radix Puerariae (R. pueraria), is reportedly effective in treating geriatric diseases, including cardiovascular disease and hypertension.

PURPOSE

This review aims to summarize and discuss the profound physiological impact of Pue on various stem cell populations and provide new insights into the use of Pue for the prevention and treatment of geriatric diseases.

METHODS

The literature was retrieved from the core collection of electronic databases, such as Web of Science, Google Scholar, PubMed, and Science Direct, using the following keywords and terms: Puerarin, Stem Cell, Proliferation, Differentiation, Apoptosis, and Geriatric diseases. These keywords were used in multiple overlapping combinations.

RESULTS

Pue is effective in the treatment and management of age-related diseases, such as cardiovascular disease, diabetes, hypertension, and cerebrovascular disease. Pue exerts significant physiological effects on various stem cell populations, including their self-renewal/proliferation, differentiation and apoptosis. Most importantly, it could improve the efficiency and accuracy of stem cell therapy for treating various geriatric diseases. Further studies are essential to improve our understanding of the underlying mechanisms and elucidate their significance for future clinical applications.

CONCLUSION

The effects of Pue on various stem cell populations and their regulatory mechanisms are discussed in detail to provide new insights into the use of Pue in the prevention and treatment of geriatric diseases.

Endogenous repair theory enriches construction strategies for orthopaedic biomaterials: a narrative review

The development of tissue engineering has led to new strategies for mitigating clinical problems; however, the design of the tissue engineering materials remains a challenge. The limited sources and inadequate function, potential risk of microbial or pathogen contamination, and high cost of cell expansion impair the efficacy and limit the application of exogenous cells in tissue engineering. However, endogenous cells in native tissues have been reported to be capable of spontaneous repair of the damaged tissue. These cells exhibit remarkable plasticity, and thus can differentiate or be reprogrammed to alter their phenotype and function after stimulation. After a comprehensive review, we found that the plasticity of these cells plays a major role in establishing the cell source in the mechanism involved in tissue regeneration. Tissue engineering materials that focus on assisting and promoting the natural self-repair function of endogenous cells may break through the limitations of exogenous seed cells and further expand the applications of tissue engineering materials in tissue repair. This review discusses the effects of endogenous cells, especially stem cells, on injured tissue repairing, and highlights the potential utilisation of endogenous repair in orthopaedic biomaterial constructions for bone, cartilage, and intervertebral disc regeneration.

Antioxidant Effects of Resveratrol in Intervertebral Disk

Intervertebral disk (IVD) degeneration (IVDD) can cause various spinal degenerative diseases. Cumulative evidence has indicated that IVDD can result from inflammation, apoptosis, autophagy, biomechanical changes and other factors. Currently, lack of conservative treatment for degenerative spinal diseases leads to an urgent demand for clinically applicable medication to ameliorate the progression of IVDD. Resveratrol (3,5,4'-trihydroxy-trans-stilbene), a polyphenol compound extracted from red wine or grapes, has shown protective effects on IVD, alleviating the progression of IVDD. Resveratrol has been demonstrated as a scavenger of free radicals both in vivo and in vitro. The antioxidant effects of resveratrol are likely attributed to its regulation on mitochondrial dysfunction or the elimination of reactive oxygen species. This review will summarize the mechanisms of the reactive oxygen species production and elaborate the mechanisms of resveratrol in retarding IVDD progression, providing a comprehensive understanding of the antioxidant effects of resveratrol in IVD.

Proper animal experimental designs for preclinical research of biomaterials for intervertebral disc regeneration

Low back pain is a vital musculoskeletal disease that impairs life quality, leads to disability and imposes heavy economic burden on the society, while it is greatly attributed to intervertebral disc degeneration (IDD). However, the existing treatments, such as medicines, chiropractic adjustments and surgery, cannot achieve ideal disc regeneration. Therefore, advanced bioactive therapies are implemented, including stem cells delivery, bioreagents administration, and implantation of biomaterials etc. Among these researches, few reported unsatisfying regenerative outcomes. However, these advanced therapies have barely achieved successful clinical translation. The main reason for the inconsistency between satisfying preclinical results and poor clinical translation may largely rely on the animal models that cannot actually simulate the human disc degeneration. The inappropriate animal model also leads to difficulties in comparing the efficacies among biomaterials in different reaches. Therefore, animal models that better simulate the clinical charateristics of human IDD should be acknowledged. In addition, in vivo regenerative outcomes should be carefully evaluated to obtain robust results. Nevertheless, many researches neglect certain critical characteristics, such as adhesive properties for biomaterials blocking annulus fibrosus defects and hyperalgesia that is closely related to the clinical manifestations, e.g., low back pain. Herein, in this review, we summarized the animal models established for IDD, and highlighted the proper models and parameters that may result in acknowledged IDD models. Then, we discussed the existing biomaterials for disc regeneration and the characteristics that should be considered for regenerating different parts of discs. Finally, well-established assays and parameters for in vivo disc regeneration are explored.

Role of microRNAs in Pressure Ulcer Immune Response, Pathogenesis, and Treatment

Pressure ulcers are preventable, yet highly prevalent, chronic wounds that have significant patient morbidity and high healthcare costs. Like other chronic wounds, they are characterized by impaired wound healing due to dysregulated immune processes. This review will highlight key biochemical pathways in the pathogenesis of pressure injury and how this signaling leads to impaired wound healing. This review is the first to comprehensively describe the current literature on microRNA (miRNA, miR) regulation of pressure ulcer pathophysiology.

MAGOH/MAGOHB Inhibits the Tumorigenesis of Gastric Cancer via Inactivation of b-RAF/MEK/ERK Signaling

Background

Gastric cancer is one of the most malignant tumors all over the world. It has been reported that proteins play key roles during the tumorigenesis of gastric cancer. To identify novel potential targets for gastric cancer, differential expressed proteins between gastric cancer and adjacent normal tissues were analyzed with proteomics and bioinformatics tool.

Methods

The differentially expressed proteins between gastric cancer and adjacent normal tissues were analyzed by Omicsbean (multi-omics data analysis tool). Cell viability was tested by CCK-8 assay. Flow cytometry was used to measure cell apoptosis and cycle. Transwell assay was used to test cell migration and invasion. Gene and protein expressions were detected by RT-qPCR, immunohistochemistry and Western blot, respectively.

Results

MAGOH and MAGOHB were found to be notably upregulated in gastric cancer tissues compared with that in normal tissues. Knockdown of MAGOH significantly inhibited the proliferation of gastric cancer cells via inducing the cell apoptosis. In addition, MAGOH knockdown induced G2 phase arrest in gastric cancer cells. Moreover, MAGOH knockdown notably inhibited migration and invasion of gastric cancer cells. Importantly, double knockdown of MAGOH and MAGOHB exhibited much better anti-tumor effects on gastric cancer compared with alone treatment. Finally, double knockdown of MAGOH and MAGOHB mediated the tumorigenesis of gastric cancer via regulation of RAF/MEK/ERK signaling.

Conclusion

MAGOH knockdown inhibited the tumorigenesis of gastric cancer via mediation of b-RAF/MEK/ERK signaling, and double knockdown of MAGOH and MAGOHB exhibited much better anti-tumor effects. This finding might provide us a new strategy for the treatment of gastric cancer.

CircCOG8 Downregulation Contributes to the Compression-Induced Intervertebral Disk Degeneration by Targeting miR-182-5p and FOXO3

Circular RNAs (circRNAs) have been increasingly demonstrated to play critical roles in the pathogenesis of various human diseases. Intervertebral disk degeneration (IDD) is recognized as the major contributor to lower back pain, and mechanical stress is a predominant trigger for IDD. However, little is known about the part that circRNAs play in the involvement of mechanical stress during IDD development. In the present study, we identified a novel circRNA and examined the role of this circRNA in a compression loading-induced IDD process. We detected the expression pattern of circCOG8 and observed its function in disk NP cells under mechanical stress. We conducted bioinformatics analysis, RNA immunoprecipitation experiment, and reporter gene assay to unveil the mechanism of the circCOG8 downregulation mediated IVD degeneration. Results showed that the circCOG8 expression was obviously down-regulated by the mechanical stress in disk NP cells. CircCOG8 attenuated NP cells apoptosis, intracellular ROS accumulation, and ECM degradation in vitro and ex vivo. CircCOG8 directly interacted with miR-182-5p and, thus, modulated the FOXO3 expression to affect the compression-induced IDD progression. Altogether, the present study revealed that the circCOG8/miR-182-5p/FOXO3 pathway was an important underlying mechanism in the involvement of compression during the IDD progression. Intervention of circCOG8 is a new therapeutic strategy for IDD treatment.