Icariin attenuates hypoxia-induced oxidative stress and apoptosis in osteoblasts and preserves their osteogenic differentiation potential in vitro

Promoting osteogenesis and bone regeneration employing icariin-loaded nanoplatforms

There is an increasing demand for innovative strategies that effectively promote osteogenesis and enhance bone regeneration. The critical process of bone regeneration involves the transformation of mesenchymal stromal cells into osteoblasts and the subsequent mineralization of the extracellular matrix, making up the complex mechanism of osteogenesis. Icariin's diverse pharmacological properties, such as anti-inflammatory, anti-oxidant, and osteogenic effects, have attracted considerable attention in biomedical research. Icariin, known for its ability to stimulate bone formation, has been found to encourage the transformation of mesenchymal stromal cells into osteoblasts and improve the subsequent process of mineralization. Several studies have demonstrated the osteogenic effects of icariin, which can be attributed to its hormone-like function. It has been found to induce the expression of BMP-2 and BMP-4 mRNAs in osteoblasts and significantly upregulate Osx at low doses. Additionally, icariin promotes bone formation by stimulating the expression of pre-osteoblastic genes like Osx, RUNX2, and collagen type I. However, icariin needs to be effectively delivered to bone to perform such promising functions.Encapsulating icariin within nanoplatforms holds significant promise for promoting osteogenesis and bone regeneration through a range of intricate biological effects. When encapsulated in nanofibers or nanoparticles, icariin exerts its effects directly at the cellular level. Recalling that inflammation is a critical factor influencing bone regeneration, icariin's anti-inflammatory effects can be harnessed and amplified when encapsulated in nanoplatforms. Also, while cell adhesion and cell migration are pivotal stages of tissue regeneration, icariin-loaded nanoplatforms contribute to these processes by providing a supportive matrix for cellular attachment and movement. This review comprehensively discusses icariin-loaded nanoplatforms used for bone regeneration and osteogenesis, further presenting where the field needs to go before icariin can be used clinically.

Effects of the combination of Epimedii Folium and Ligustri Lucidi Fructus on apoptosis and autophagy in SOP rats and osteoblasts via PI3K/AKT/mTOR pathway

BACKGROUND

This study aimed to investigate the effects of the combination of Epimedii Folium (EF) and Ligustri Lucidi Fructus (LLF) on regulating apoptosis and autophagy in senile osteoporosis (SOP) rats.

METHODS

Firstly, we identified the components in the decoction and drug-containing serum of EL (EF&LLF) by Ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS). Secondly, SOP rats were treated with EF, LLF, EL and caltrate to evaluate the advantages of EL. Finally, H2O2-, chloroquine-, and MHY1485-induced osteoblasts were treated with different doses of EL to reveal the molecular mechanism of EL. We detected bone microstructure, oxidative stress levels, ALP activity and the expressions of Bax, Bcl-2, caspase3, P53, Beclin-1, p-PI3K, PI3K, p-Akt, Akt, p-mTOR, mTOR, and LC3 in vivo and in vitro.

RESULTS

36 compounds in EL decoction and 23 in EL-containing serum were identified, including flavonoids, iridoid terpenoids, phenylethanoid glycosides, polyols and triterpenoids. EL could inhibit apoptosis activity and increase ALP activity. In SOP rats and chloroquine-inhibited osteoblasts, EL could improve bone tissue microstructure and osteoblasts functions by upregulating Bcl-2, Beclin1, and LC3-II/LC3-I, while downregulating p53 in all treatment groups. In H2O2-induced osteoblasts, EL could upregulate the protein and mRNA expressions of Bcl-2 while downregulate LC3-II/LC3-I, p53 and Beclin1. Besides, EL was able to down-regulate PI3K/AKT/mTOR pathway which activated in SOP rats and MHY1485-induced osteoblasts.

CONCLUSIONS

These findings demonstrate that EL with bone protective effects on SOP rats by regulating autophagy and apoptosis via PI3K/Akt/mTOR signaling pathway, which might be an alternative medicine for the treatment of SOP.

Anti-aging effects of icariin and the underlying mechanisms: A mini-review

Aging is an extremely intricate and progressive phenomenon that is implicated in many physiological and pathological conditions. Icariin (ICA) is the main active ingredient of Epimedium and has exhibited multiple bioactivities, such as anti-tumor, neuroprotective, antioxidant, anti-inflammatory, and anti-aging properties. ICA could extend healthspan in both invertebrate and vertebrate models. In this review, the roles of ICA in protection from declined reproductive function, neurodegeneration, osteoporosis, aging intestinal microecology, and senescence of cardiovascular system will be summarized. Furthermore, the underlying mechanisms of ICA-mediated anti-aging effects will be introduced. Finally, we will discuss some key aspects that constrain the usage of ICA in clinical practice and the corresponding strategies to solve these issues.

Fibroblast growth factor 23 regulates hypoxia‑induced osteoblast apoptosis through the autophagy‑signaling pathway

Hypoxia can lead to programmed osteoblast death. Prevention of osteoblast apoptosis caused by hypoxia is of great significance in the study of the occurrence and development of bone necrosis. The present study aimed to investigate the effects and mechanism of fibroblast growth factor 23 (FGF23) on hypoxia‑induced apoptosis in primary osteoblasts and MC3T3‑E1 cells osteoblasts. Cells were transfected with a plasmid carrying the FGF23 gene and a cell model of hypoxia‑induced apoptosis was established. FGF23 mRNA levels were measured using reverse transcription‑quantitative (RT‑q) PCR and western blotting was used to assess protein levels. Apoptosis was analyzed by MTT assay, fluorescein diacetate and ethidium bromide staining, flow cytometry and RT‑qPCR and western blotting were used to verify the mRNA and protein levels of apoptosis‑ and autophagy‑related gene mRNA. The targeted relationship between miR‑17‑5p and FGF23 was confirmed using the StarBase database, TargetScan database and a luciferase reporter assay. FGF23 decreased cell survival and increased the rate of apoptosis. The mRNA and protein expression of the pro‑apoptotic genes Bax and caspases 3 and 9 increased, whereas that of the anti‑apoptotic Bcl‑2 decreased. The expressions of the autophagy‑associated proteins beclin‑1, light chain 3‑II (LC3‑II) and the LC3‑II/LC3‑I ratio were significantly increased. In addition, a luciferase reporter assay confirmed that FGF23 directly regulated micro RNA (miR)‑17‑5p. The effects of FGF23 silencing were reversed by miR‑17‑5p inhibition. FGF23 may regulate hypoxia‑induced osteoblast apoptosis by targeting miR‑17‑5p through the autophagy‑signaling pathway. This provides a rationale for FGF23 as a potential therapeutic target for osteonecrosis of the femoral head.

Exercise performance reduction and preventive measures in highland sports

The plateau is a special environment with low pressure, low oxygen, low temperature, and high ultraviolet radiation. The exercise performance of people on the plateau is generally reduced, which seriously affects the life and health of people living in the plateau and entering the plateau. In recent years, the prevention and treatment of injury caused by high altitude hypoxia has attracted wide attention. It has shown that the higher the altitude with the longer the duration of exercise, the faster the stationing, the greater the impact on people's sports performance. Rapid entry into the plateau and long-term stay in the plateau have an impact on people's explosive power, endurance and fine operation. Advances in medical technology enable various prevention methods to be used to acclimate to high altitude environments. However, in vitro intervention methods are costly, easy to rebound and possess limited effects. Therefore, drug prevention and treatment is obviously a more economical choice. Chemical drugs increase the efficiency of high altitude exercise by improving the ischemic and hypoxic symptoms of the heart and brain, increasing lung ventilation and arterial oxygenation capacity, and accelerating the elimination of adverse product accumulation after exercise. Single Chinese medicine, Chinese patent medicine, and compound preparations can improve exercise performance by promoting body metabolism, improving muscle endurance, enhancing immunity, and other mechanisms. Traditional Chinese medicine has unique advantage and application prospect in improving plateau sports performance damage.

Extracellular Vesicles Derived from Osteogenic-Differentiated Human Bone Marrow-Derived Mesenchymal Cells Rescue Osteogenic Ability of Bone Marrow-Derived Mesenchymal Cells Impaired by Hypoxia

In orthopedics, musculoskeletal disorders, i.e., non-union of bone fractures or osteoporosis, can have common histories and symptoms related to pathological hypoxic conditions induced by aging, trauma or metabolic disorders. Here, we observed that hypoxic conditions (2% O2) suppressed the osteogenic differentiation of human bone marrow-derived mesenchymal cells (hBMSC) in vitro and simultaneously increased reactive oxygen species (ROS) production. We assumed that cellular origin and cargo of extracellular vesicles (EVs) affect the osteogenic differentiation capacity of hBMSCs cultured under different oxygen pressures. Proteomic analysis revealed that EVs isolated from osteogenic differentiated hBMSC cultured under hypoxia (hypo-osteo EVs) or under normoxia (norm-osteo EVs) contained distinct protein profiles. Extracellular matrix (ECM) components, antioxidants and pro-osteogenic proteins were decreased in hypo-osteo EVs. The proteomic analysis in our previous study revealed that under normoxic culture conditions, pro-osteogenic proteins and ECM components have higher concentrations in norm-osteo EVs than in EVs derived from naïve hBMSCs (norm-naïve EVs). When selected for further analysis, five anti-hypoxic proteins were significantly upregulated (response to hypoxia) in norm-osteo EVs. Three of them are characterized as antioxidant proteins. We performed qRT-PCR to verify the corresponding gene expression levels in the norm-osteo EVs' and norm-naïve EVs' parent cells cultured under normoxia. Moreover, we observed that norm-osteo EVs rescued the osteogenic ability of naïve hBMSCs cultured under hypoxia and reduced hypoxia-induced elevation of ROS production in osteogenic differentiated hBMSCs, presumably by inducing expression of anti-hypoxic/ antioxidant and pro-osteogenic genes.

A comprehensive review of natural products with anti-hypoxic activity

Natural products exhibit substantial impacts in the field of anti-hypoxic traetment. Hypoxia can cause altitude sickness and other negative effect on the body. Headache, coma, exhaustion, vomiting and, in severe cases, death are some of the clinical signs. Currently, hypoxia is no longer just a concern in plateau regions; it is also one of the issues that can not be ignored by urban residents. This review covered polysaccharides, alkaloids, saponins, flavonoids, peptides and traditional Chinese compound prescriptions as natural products to protect against hypoxia. The active ingredients, effectiveness and mechanisms were discussed. The related anti-hypoxic mechanisms involve increasing the hemoglobin (HB) content, glycogen content and adenosine triphosphate (ATP) content, removing excessive reactive oxygen species (ROS), reducing lipid peroxidation, regulating the levels of related enzymes in cells, protecting the structural and functional integrity of the mitochondria and regulating the expression of apoptosis-related genes. These comprehensive summaries are beneficial to anti-hypoxic research and provide useful information for the development of anti-hypoxic products.

Epimedii Folium and Ligustri Lucidi Fructus Promote Osteoblastogenesis and Inhibit Osteoclastogenesis against Osteoporosis via Acting on Osteoblast-Osteoclast Communication

Osteoblast (OB) and osteoclast (OC) play important roles in bone formation and bone resorption, which can communicate with each other through cytokine paracrine. Previous studies have confirmed that Epimedii Folium (EF) and Ligustri Lucidi Fructus (LLF) used alone or in combination can treat osteoporosis (OP) through regulating bone remodeling, but the effects of EF and LLF on osteoblastogenesis, osteoclastogenesis, and OB-OC communication are unclear. In this study, we investigated the direct and indirect effects of EF and LLF on OBs and OCs via monoculture and coculture (transwell) models of OBs and OCs. We found that the combination of EF and LLF (EF&LLF) could promote osteoblastogenesis and inhibit osteoclastogenesis directly and indirectly. In order to study the mechanisms of EF&LLF on indirectly regulating osteoblastogenesis and osteoclastogenesis, we detected the expression of cytokines by which OBs and OCs could communicate with each other. We found that EF&LLF could downregulate the expression of RANKL and M-CSF and the protein ratio of RANKL/OPG of OBs and Atp6v0d2 expression of OCs and upregulate the expression of OPG and TGF-β1 of OBs and the expression of TGF-β1, BMP-2, and IGF-1 of OCs, indicating that EF&LLF could regulate cytokine expressions of OBs/OCs to affect OB-OC communication. In addition, EF&LLF had a better effect on regulating cytokines of OBs and OCs than EF or LLF in single use. This study suggested that EF&LLF exhibited the effects of promoting osteoblastogenesis and inhibiting osteoclastogenesis via acting on OB-OC communication and provided some scientific evidences for EF&LLF against OP.

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.

Enzymatic synthesis of anhydroicaritin, baohuoside and icariin

Anhydroicaritin (1a), baohuoside (1b) and icariin (1c) were recognized as major pharmacologically active ingredients of Epimedium plants. Their primary means of acquisition were chemical isolation from plants. However, it suffers from low yield, environmental pollution and shortage of plants. Herein, to remedy these problems, biosynthesis was explored to obtain the three active ingredients. Fortunately, with SfFPT as 8-prenyltransferase, EpPF3RT and Ep7GT as glycosyltransferases, kaempferide (1) was transferred to 1a, 1b and 1c enzymatically. Thus, we report the details of this method. This approach represents a promising environmental friendly alternative for the production of these compounds from an abundant analogue.

Roles of Altered Macrophages and Cytokines: Implications for Pathological Mechanisms of Postmenopausal Osteoporosis, Rheumatoid Arthritis, and Alzheimer's Disease

Postmenopausal osteoporosis (PMOP) is characterized by the uncoupling of bone resorption and bone formation induced by estrogen deficiency, which is a complex outcome related to estrogen and the immune system. The interaction between bone and immune cells is regarded as the context of PMOP. Macrophages act differently on bone cells, depending on their polarization profile and secreted paracrine factors, which may have implications for the development of PMOP. PMOP, rheumatoid arthritis (RA), and Alzheimer's disease (AD) might have pathophysiological links, and the similarity of their pathological mechanisms is partially visible in altered macrophages and cytokines in the immune system. This review focuses on exploring the pathological mechanisms of PMOP, RA, and AD through the roles of altered macrophages and cytokines secretion. First, the multiple effects on cytokines secretion by bone-bone marrow (BM) macrophages in the pathological mechanism of PMOP are reviewed. Then, based on the thought of "different tissue-same cell type-common pathological molecules-disease pathological links-drug targets" and the methodologies of "molecular network" in bioinformatics, highlight that multiple cytokines overlap in the pathological molecules associated with PMOP vs. RA and PMOP vs. AD, and propose that these overlaps may lead to a pathological synergy in PMOP, RA, and AD. It provides a novel strategy for understanding the pathogenesis of PMOP and potential drug targets for the treatment of PMOP.

Flavonoids: Classification, Function, and Molecular Mechanisms Involved in Bone Remodelling

Flavonoids are polyphenolic compounds spotted in various fruits, vegetables, barks, tea plants, and stems and many more natural commodities. They have a multitude of applications through their anti-inflammatory, anti-oxidative, anti-carcinogenic properties, along with the ability to assist in the stimulation of bone formation. Bone, a rigid connective body tissue made up of cells embedded in a mineralised matrix is maintained by an assemblage of pathways assisting osteoblastogenesis and osteoclastogenesis. These have a significant impact on a plethora of bone diseases. The homeostasis between osteoblast and osteoclast formation decides the integrity and structure of the bone. The flavonoids discussed here are quercetin, kaempferol, icariin, myricetin, naringin, daidzein, luteolin, genistein, hesperidin, apigenin and several other flavonoids. The effects these flavonoids have on the mitogen activated protein kinase (MAPK), nuclear factor kappa β (NF-kβ), Wnt/β-catenin and bone morphogenetic protein 2/SMAD (BMP2/SMAD) signalling pathways, and apoptotic pathways lead to impacts on bone remodelling. In addition, these polyphenols regulate angiogenesis, decrease the levels of inflammatory cytokines and play a crucial role in scavenging reactive oxygen species (ROS). Considering these important effects of flavonoids, they may be regarded as a promising agent in treating bone-related ailments in the future.

Pretreatment with mechano growth factor E peptide attenuates osteoarthritis through improving cell proliferation and extracellular matrix synthesis in chondrocytes under severe hypoxia

Osteoarthritis (OA) is characterized by pain and declining gait function associated with degeneration of cartilage. A severe hypoxic environment occurs due to tissue injury in the joint cavity and may aggravate the development of OA. In this study, the effects of severe hypoxia and treatment with mechano growth factor (MGF) E peptide on metabolism of the extracellular matrix (ECM) during the progression of OA were determined. The results showed that cell viability, cell proliferation, and type II collagen expression in chondrocytes were significantly inhibited by cobalt chloride (CoCl₂)-simulated severe hypoxia, whereas cell apoptosis and expression levels of hypoxia inducible factor 1 alpha, type I collagen, and matrix metalloproteinases 1/13 were clearly induced. Pretreatment with MGF E peptide reduced the abovementioned adverse effects induced by CoCl₂-simulated severe hypoxia in chondrocytes. Pretreatment also upregulated the proliferation of chondrocytes under severe hypoxia through the PI3K-Akt and MEK-ERK1/2 signaling pathways. In a rat model of monosodium iodoacetate (MIA)-induced OA. MIA treatment induced tissue necrosis and cartilage degeneration, and histological score was significantly decreased. The levels of type II collagen and aggrecan were reduced after MIA treatment for 4 or 6 weeks, and abnormal distribution of ECM occurred in the inner epicondyle after 6 weeks. MGF E peptide also reduced the progression of MIA-induced OA by retarding cartilage degeneration, upregulating type II collagen synthesis, and improving ECM distribution after 4 or 6 weeks. Our findings suggest that MGF attenuates the progression of OA, and thus may be applied for the treatment of OA in the clinic.

Emerging Natural-Product-Based Treatments for the Management of Osteoarthritis

Osteoarthritis (OA) is a complex degenerative disease in which joint homeostasis is disrupted, leading to synovial inflammation, cartilage degradation, subchondral bone remodeling, and resulting in pain and joint disability. Yet, the development of new treatment strategies to restore the equilibrium of the osteoarthritic joint remains a challenge. Numerous studies have revealed that dietary components and/or natural products have anti-inflammatory, antioxidant, anti-bone-resorption, and anabolic potential and have received much attention toward the development of new therapeutic strategies for OA treatment. In the present review, we provide an overview of current and emerging natural-product-based research treatments for OA management by drawing attention to experimental, pre-clinical, and clinical models. Herein, we review current and emerging natural-product-based research treatments for OA management.

The Use of Herbal Medicines for the Prevention of Glucocorticoid-Induced Osteoporosis

Glucocorticoids are drugs that are widely used to suppress inflammation and the activation of the immune system. However, the prolonged use or at high doses of glucocorticoid can result in adverse side effects including osteoporosis, bone loss, and an increased risk of fracture. A number of compounds derived from natural plant sources have been reported to exert anti-inflammatory activity by interacting with the glucocorticoid receptor (GR), likely owing to their chemical similarity to glucocorticoids, or by regulating GR, without a concomitant risk of treatment-related side effects such as osteoporosis. Other herbal compounds can counteract the pathogenic processes underlying glucocorticoid-induced osteoporosis (GIOP) by regulating homeostatic bone metabolic processes. Herein, we systematically searched the PubMed, Embase, and Cochrane library databases to identify articles discussing such compounds published as of May 01, 2021. Compounds reported to exert anti-inflammatory glucocorticoid-like activity without inducing GIOP include escin, ginsenosides, and glycyrrhizic acid, while compounds reported to alleviate GIOP by improving osteoblast function or modulating steroid hormone synthesis include tanshinol and icariin.

PIM1 Promotes Survival of Cardiomyocytes by Upregulating c-Kit Protein Expression

Enhancing cardiomyocyte survival is crucial to blunt deterioration of myocardial structure and function following pathological damage. PIM1 (Proviral Insertion site in Murine leukemia virus (PIM) kinase 1) is a cardioprotective serine threonine kinase that promotes cardiomyocyte survival and antagonizes senescence through multiple concurrent molecular signaling cascades. In hematopoietic stem cells, PIM1 interacts with the receptor tyrosine kinase c-Kit upstream of the ERK (Extracellular signal-Regulated Kinase) and Akt signaling pathways involved in cell proliferation and survival. The relationship between PIM1 and c-Kit activity has not been explored in the myocardial context. This study delineates the interaction between PIM1 and c-Kit leading to enhanced protection of cardiomyocytes from stress. Elevated c-Kit expression is induced in isolated cardiomyocytes from mice with cardiac-specific overexpression of PIM1. Co-immunoprecipitation and proximity ligation assay reveal protein–protein interaction between PIM1 and c-Kit. Following treatment with Stem Cell Factor, PIM1-overexpressing cardiomyocytes display elevated ERK activity consistent with c-Kit receptor activation. Functionally, elevated c-Kit expression confers enhanced protection against oxidative stress in vitro. This study identifies the mechanistic relationship between PIM1 and c-Kit in cardiomyocytes, demonstrating another facet of cardioprotection regulated by PIM1 kinase.

"Take My Bone Away?" Hypoxia and bone: A narrative review

To maintain normal cellular and physiological function, sufficient oxygen is required. Recently, evidence has suggested that hypoxia, either pathological or environmental, may influence bone health. It appears that bone cells are distinctly responsive to hypoxic stimuli; for better or worse, this is still yet to be elucidated. Hypoxia has been shown to offer potentially therapeutic effects for bone by inducing an osteogenic-angiogenic response, although, others have noted excessive osteoclastic bone resorption instead. Much evidence suggests that the hypoxic-inducible pathway is integral in mediating the changes in bone metabolism. Furthermore, many factors associated with hypoxia including changes in energy metabolism, acid-base balance and the increased generation of reactive oxygen species, are known to influence bone metabolism. This review aims to examine some of the putative mechanisms responsible for hypoxic-induced alterations of bone metabolism, with regard to osteoclasts and osteoblasts, both positive and negative.

Icariin alleviates hypoxia-induced damage in MC3T3-E1 cells by downregulating TALNEC2

Osteonecrosis is a harmful musculoskeletal disease. We aim to detect the effects of icariin (ICA) in MC3T3-E1 cell. MC3T3-E1 cell was pretreated with ICA and was subjected to hypoxia stimuli. The tumor-associated long noncoding RNA expressed on chromosome 2 (TALNEC2) overexpression or silencing vectors (pTALNEC2 or si-TALNEC2) was utilized for MC3T3-E1 cell transfection. Viability and apoptosis rate were individually tested by cell counting kit-8 and Annexin V-fluorescein isothiocyanate/propidium iodide kit untied with flow cytometry. The alkaline phosphatase activity (ALP) activity was tested through ALP assay. The quantitative reverse transcription PCR or Western blot was performed for elements detection at the RNA or protein level. Hypoxia treatment induced viability inhibition and CyclinD1 reduction, but elevation of p53 and p16. It also promoted apoptosis by increasing apoptotic cells, Bax, and cleaved-poly ADP-ribose polymerase but decreasing Bcl-2. Also, hypoxia stimuli restrained ALP activity, and osteopontin, osteocalcin, and Runt-related transcription factor 2 expression. Those effects caused by hypoxia stimuli were all reversed by ICA. TALNEC2 was downregulated by ICA, whose impacts were subsequently abolished by pTALNEC2. Silencing TALNEC2 displayed similar effects with ICA. But the apoptosis was not affected by si-TALNEC2. ICA blocked ste20-related proline/alanine-rich kinase/c-Jun N-terminal kinase (SPAK/JNK) but triggered phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway in MC3T3-E1 cell by suppressing TALNEC2. ICA relieved hypoxia-stimulated damage by restraining TALNEC2 through blocking SPAK/JNK and triggering PI3K/AKT/mTOR in the MC3T3-E1 cell.

Icariin protects human nucleus pulposus cells from hydrogen peroxide-induced mitochondria-mediated apoptosis by activating nuclear factor erythroid 2-related factor 2

Intervertebral disc degeneration (IVDD) is a well-known cause of lower back pain. Icariin has been shown to exert a protective effect on human nucleus pulposus (NP) cells and accordingly has implications for the prevention and treatment of IVDD; however, the molecular mechanisms underlying its action are not fully established. In this study, the mechanisms underlying its protection against hydrogen peroxide (H₂O₂)-induced oxidative stress injury were investigated. In vitro, we demonstrated that icariin inhibits H₂O₂-induced mitochondria-mediated apoptosis. It upregulates oxidative stress mediators, i.e., reactive oxygen species, and downregulates mitochondrial membrane potential. Nuclear factor erythroid 2-related factor 2 (Nrf-2) is a key factor involved in the regulation of the endogenous defense system. It was proved that icariin could activate the Nrf-2 signaling pathway, upregulate the protein expression of nuclear respiratory factor-1 and the mitochondrial transcription factor, promoting mitochondrial biogenesis in human NP cells. An Nrf-2 agonist and inhibitor promoted or partly abolished the protective effects of icariin on mitochondrial homeostasis. Moreover, it was demonstrated that the Nrf-2 signaling pathway could be inhibited by the phosphatidylinositol 3-Kinase/AKT pathway. In vivo, icariin ameliorated IVDD in a rat model by promoting Nrf-2 activity, and preserving extracellular matrix in NP cells. These data suggest that icariin could ameliorate IVDD in rat models in vivo. In summary, the protective effects of icariin on human NP cells may suppress the pathogenesis of IVDD via the Nrf-2 signaling pathway. Our findings suggest that the Nrf-2 signaling pathway is a novel therapeutic target for the treatment of IVDD.

The cardioprotective effects of icariin on the isoprenaline-induced takotsubo-like rat model: Involvement of reactive oxygen species and the TLR4/NF-κB signaling pathway

INTRODUCTION

Takotsubo syndrome (TS) is an acute cardiac syndrome that mimics acute coronary syndrome (ACS) but lacks coronary obstruction and is associated with sudden physical or psychiatric episodes. Several hypotheses have been proposed for the TS mechanism, but the precise cause of this syndrome remains poorly known. Recent studies noted TS patients with acute endogenous catecholamine discharge, which could trigger an oxidative stress response and inflammatory action.

METHODS

A single dose of the selective β-adrenergic agonist isoprenaline (ISO) was used to induce a takotsubo-like (TS-like) model. Different icariin or metoprolol doses were supplied as cardioprotective agents by intragastric administration (IG), and lipopolysaccharides (LPS) were assessed to investigate the possible mechanism of action of icariin. Transthoracic echocardiography was used to study cardiac function and morphology. The amounts of intracellular lipids and myocardial fibrosis, which represent the degree of cardiac impairment, were assessed by histological analysis. Real-time polymerase chain reaction (RT-PCR) was performed to analyze a variety of anti-oxidant elements and inflammatory factors, and Western blotting was conducted to analyze the expression of signaling pathway proteins involved in the development of TS.

RESULTS

The TS-like incidence in rats was lowest with icariin precondition at 2-h post-ISO administration, and both the left ventricular ejection fraction (LVEF) and ejection volume per minute were higher than those of the other groups. However, LPS administration increased the incidence of TS and aggravated cardiac impairment. Moreover, ISO significantly increased the levels of both reactive oxygen species (ROS) and TLR4/NF-κB signaling pathway proteins compared to those of the Sha-group, whereas icariin remarkably decreased the ROS levels and increased anti-oxidant element expression while reducing pro-inflammatory factor secretion and suppressing TLR4/NF-κB signaling pathway protein expression. However, the cardioprotective effect of icariin was significantly weakened by combining treatment with LPS.

CONCLUSION

Icariin prevented ISO-induced TS-like cardiac dysfunction in rats. The effects were induced mainly through maintenance of the dynamic balance of the ROS system, promotion of anti-oxidant element activity, and suppression of TLR4/NF-κB signaling pathway protein expression. Furthermore, the ability of icariin to increase anti-inflammatory and reduce pro-inflammatory factor secretion may be involved in the protective process.

Mimicking growth factors: role of small molecule scaffold additives in promoting tissue regeneration and repair

The primary aim of tissue engineering scaffolds is to mimic the in vivo environment and promote tissue growth. In this quest, a number of strategies have been developed such as enhancing cell-material interactions through modulation of scaffold physico-chemical parameters. However, more is required for scaffolds to relate to the cell natural environment. Growth factors (GFs) secreted by cells and extracellular matrix (ECM) are involved in both normal repair and abnormal remodeling. The direct use of GFs on their own or when incorporated within scaffolds represent a number of challenges such as release rate, stability and shelf-life. Small molecules have been proposed as promising alternatives to GFs as they are able to minimize or overcome many shortcomings of GFs, in particular immune response and instability. Despite the promise of small molecules in various TE applications, their direct use is limited by nonspecific adverse effects on non-target tissues and organs. Hence, they have been incorporated within scaffolds to localize their actions and control their release to target sites. However, scanty rationale is available which links the chemical structure of these molecules with their mode of action. We herewith review various small molecules either when used on their own or when incorporated within polymeric carriers/scaffolds for bone, cartilage, neural, adipose and skin tissue regeneration.

Can Hypoxic Conditioning Improve Bone Metabolism? A Systematic Review

Among other functions, hypoxia-inducible factor plays a critical role in bone–vascular coupling and bone formation. Studies have suggested that hypoxic conditioning could be a potential nonpharmacological strategy for treating skeletal diseases. However, there is no clear consensus regarding the bone metabolism response to hypoxia. Therefore, this review aims to examine the impact of different modes of hypoxia conditioning on bone metabolism. The PubMed and Web of Science databases were searched for experimental studies written in English that investigated the effects of modification of ambient oxygen on bone remodelling parameters of healthy organisms. Thirty-nine studies analysed the effect of sustained or cyclic hypoxia exposure on genetic and protein expression and mineralisation capacity of different cell models; three studies carried out in animal models implemented sustained or cyclic hypoxia; ten studies examined the effect of sustained, intermittent or cyclic hypoxia on bone health and hormonal responses in humans. Different modes of hypoxic conditioning may have different impacts on bone metabolism both in vivo and in vitro. Additional research is necessary to establish the optimal cyclical dose of oxygen concentration and exposure time.

PLGA scaffold carrying icariin to inhibit the progression of osteoarthritis in rabbits

Icariin, the main effective component extracted from epimedium, has been shown to stimulate osteogenic differentiation and bone formation and to increase synthesis of the cartilage extracellular matrix. However, there has been little study on the effects of icariin on osteoarthritis. In this study, we loaded icariin onto poly(lactic-co-glycolic acid) (PLGA) electrospinning. The aim of this study was to explore a composite scaffold and to inhibit the progression of osteoarthritis. Our main experimental results demonstrated that the PLGA/icariin composite spinning scaffold had higher hydrophilicity, and icariin was released slowly and steadily from the scaffold. According to the results of an MTT test, immunofluorescence staining, an alkaline phosphate activating assay and a real-time polymerase chain reaction (RT-PCR) assay, the PLGA/icariin composite scaffold had good biocompatibility. In models of osteoarthritis, the results of a RT-PCR assay indicated that the PLGA/icariin scaffold promoted the synthesis of the extracellular matrix. The results of X-ray microtomography and histological evaluation demonstrated that the PLGA/icariin scaffold maintained the functional morphology of articular cartilage and inhibited the resorption of subchondral bone trabeculae. These findings indicated that the PLGA and icariin composite scaffold has therapeutic potential for use in the treatment of osteoarthritis.

Icariin Protects Bone Marrow Mesenchymal Stem Cells Against Iron Overload Induced Dysfunction Through Mitochondrial Fusion and Fission, PI3K/AKT/mTOR and MAPK Pathways

Iron overload has been reported to contribute to bone marrow mesenchymal stem cells (BMSCs) damage, but the precise mechanism still remains elusive. Icariin, a major bioactive monomer belonging to flavonoid glucosides isolated from Herba Epimedii, has been shown to protect cells from oxidative stress induced apoptosis. The aim of this study was to investigate whether icariin protected against iron overload induced dysfunction of BMSCs and its underlying mechanism. In this study, we found that iron overload induced by 100 μM ferric ammonium citrate (FAC) caused apoptosis of BMSCs, promoted cleaved caspase-3 and BAX protein expressions while inhibited Bcl-2 protein expression, which effects were significantly attenuated by icariin treatment. In addition, iron overload induced significant depolarization of mitochondrial membrane potential (MMP), reactive oxygen species (ROS) generation and inhibition of mitochondrial fusion/fission, which effects were also attenuated by icariin treatment. Meanwhile, we found that iron overload induced by 100 μM FAC significantly inhibited mitochondrial fission protein FIS1 and fusion protein MFN2 expressions, inhibited DRP1 and Cytochrome C protein translocation from the cytoplasm to mitochondria. Icariin at concentration of 1 μM was able to promote mitochondrial fission protein FIS1 and fusion protein MFN2 expressions, and increase DRP1 and cytochrome C protein translocation from the cytoplasm to mitochondria. Further, osteogenic differentiation and proliferation of BMSCs was significantly inhibited by iron overload, but icariin treatment rescued both osteogenic differentiation and proliferation of BMSCs. Further studies showed that icariin attenuated iron overload induced inactivation of the PI3K/AKT/mTOR pathway and activation of the ERK1/2 and JNK pathways. In summary, our study indicated that icariin was able to protect against iron overload induced dysfunction of BMSCs. These effects were potentially related to the modulation of mitochondrial fusion and fission, activation of the PI3K/AKT/mTOR pathway and inhibition of ERK1/2 and JNK pathways.

Abyssinone V, a prenylated flavonoid isolated from the stem bark of Erythrina melanacantha increases oxidative stress and decreases stress resistance in Caenorhabditis elegans

OBJECTIVES

Recent studies showed that distinct extracts of Erythrina species used in the traditional medicine of sub-Saharan Africa are protective against stress conditions. However, the underlying molecular mechanisms as well as relevant compounds remain unclear.

METHODS

We used the model organism Caenorhabditis elegans to investigate compounds isolated from the stem bark of Erythrina melanacantha (abyssinone V (1), abyssinon-4'O-methylether (2), sigmoidin B-4'O-methylether (3), glabranin (4), 8-prenylnaringenin (5), citflavanone (6), exiguaflavanone (7) and homoeriodictyol (8)). Antioxidative capacity in vitro (trolox equivalent antioxidative capacity assay) and modulation of oxidative stress in vivo (2', 7'-dichlorofluorescein assay) were investigated; stress resistance was analysed using the nucleic acid stain SYTOX green.

KEY FINDINGS

None of the prenylated flavonoids caused protection against thermal stress; in contrast, most of the compounds (1, 4, 5, 8) decreased stress resistance. None of the compounds decreased the accumulation of reactive oxygen species, but abyssinone V (1) caused an increase in oxidative stress. In line with these results, none of these compounds showed radical-scavenging effects in vitro.

CONCLUSIONS

The stem bark of E. melanacantha contains various prenylated flavonoids, but no compound protected C. elegans against stress conditions. In contrast, abyssinone V increases oxidative stress and reduces stress resistance in this model organism.

Ep7GT, a glycosyltransferase with sugar donor flexibility from Epimedium pseudowushanense, catalyzes the 7-O-glycosylation of baohuoside

A novel glycosyltransferase from Epimedium pseudowushanense, Ep7GT, regiospecifically catalyzes the 7-O-glucosylation of baohuoside to form icariin and shows sugar donor/acceptor promiscuity to yield different flavonoid glycosides.

Icariin protects against iron overload-induced bone loss via suppressing oxidative stress

Iron overload is common in patients with diseases such as hemoglobinopathies, hereditary hemochromatosis or elderly men and postmenopausal women. This disorder is frequently associated with bone loss and recently has been considered as an independent risk factor for osteoporosis. By excess reactive oxygen species (ROS) production through Fenton reaction, iron could induce osteoblast apoptosis, inhibit osteoblast osteogenic differentiation. Moreover, Iron could also promote osteoclasts differentiation and bone absorption. The goal of the study is to investigate whether icariin could reverse iron overload-induced bone loss in vitro and in vivo. Icariin is the major active ingredient of Herba Epimedii and has antioxidant, antiosteoporosis functions. In the current study, we demonstrated that oral administration of icariin significantly prevented bone loss in iron overloaded mice. Icariin could protect against iron overload-induced mitochondrial membrane potential dysfunction and ROS production, promote osteoblast survival and reverse the reduction of Runx2, alkaline phosphatase, and osteopontin expression induced by iron overload. Icariin also inhibited osteoclasts differentiation and function. Moreover, we also found that icariin remarkably reduced iron accumulation in bone marrow, suggesting that icariin has the ability to regulate systemic iron metabolism in vivo. These results indicated that icariin could be a potential natural resource for developing medicines to prevent or treat iron overload-induced osteoporosis.

Chinese single herbs and active ingredients for postmenopausal osteoporosis: From preclinical evidence to action mechanism

Postmenopausal osteoporosis is a systemic metabolic skeletal disease generally ascribable to a dearth of estrogen. Whether traditional Chinese medicine is effective in management of postmenopausal osteoporosis remains unclear. This article reviews the experimental evidence of both in vitro and in vivo preclinical studies with the theme of the application of Chinese single herbs and active ingredients in postmenopausal osteoporosis. It includes three single herbs (Herba Epimedium, Rhizoma Drynariae, and Salvia miltiorrhiza) and eight active ingredients (saikosaponins, linarin, echinacoside, sweroside, psoralen, poncirin, vanillic acid, and osthole). The experimental studies indicated their potential use as treatment for postmenopausal osteoporosis and investigated the underlying mechanisms including osteoprotegerin/receptor activator of nuclear factor κB ligand (OPG/RANKL), extracellular-signal-regulated kinase/c-Jun N terminal kinase/mitogen-activated protein kinase (ERK/JNK/MAPK), estrogen receptor (ER), bone morphogenetic protein (BMP), transforming growth factor (TGF)-β, Wnt/β-catenin, and Notch signaling pathways. This review contributes to a better understanding of traditional Chinese medicine and provides useful information for the development of more effective anti-osteoporosis drugs.

Icariin, but Not Genistein, Exerts Osteogenic and Anti-apoptotic Effects in Osteoblastic Cells by Selective Activation of Non-genomic ERα Signaling

Genistein and icariin are flavonoid compounds that exhibit estrogen-like properties in inducing bone formation and reducing bone loss associated with estrogen deficiency in both preclinical and clinical studies. However, the mechanisms that are involved in mediating their estrogenic actions in bone cells are far from clear. The present study aimed to study the signaling pathways that mediate the estrogenic actions of genistein and icariin in osteoblastic cells. The effects of genistein and icariin on the activation of estrogen receptor (ER) and the downstream mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway in murine osteoblastic MC3T3-E1 cells and rat osteoblastic UMR-106 cells were studied. As expected, genistein displayed higher binding affinity toward ERβ than ERα and significantly induced estrogen response element (ERE)-dependent transcription in UMR-106 cells in a dose-dependent manner. In contrast, icariin failed to bind to ERα or ERβ and did not induce ERE-dependent transcription in UMR-106 cells at 10^-10 to 10^-7 M. The effects of genistein (10 nM) and icariin (0.1 μM) on cell proliferation and differentiation in osteoblastic UMR-106 cells were abolished in the presence of ER antagonist ICI 182,780 (1 μM), MAPK inhibitor U0126 (10 μM), and PI3K inhibitor LY294002 (10 μM). Genistein at 10 nM rapidly induced ERK1/2 phosphorylation at 5–10 min in UMR-106 cells and the phosphorylation of ERα at both Ser118 and Ser167 in both MC3T3-E1 and transfected UMR-106 cells whereas icariin at 0.1 μM rapidly activated both ERK1/2 and Akt phosphorylation in UMR-106 cells and subsequent ERα phosphorylation at both Ser118 and Ser167 in MC3T3-E1 and transfected UMR-106 cells. Confocal imaging studies confirmed that the phosphorylation of ERα at Ser 118 and Ser 167 by genistein and icariin in MC3T3-E1 cells was mediated via MAPK- and PI3K-dependent pathway, respectively. Furthermore, our studies showed that icariin exerted stronger anti-apoptotic effects than genistein and 17β-estradiol (E2) and inhibited the cleavage of downstream caspase-3 in MC3T3-E1 cells induced by a potent PI3K inhibitor, PI828 (at 2 μM). These results indicated that the mechanisms that mediate the estrogenic actions of icariin in osteoblastic cells are different from those of genistein.

Irbesartan attenuates advanced glycation end products-mediated damage in diabetes-associated osteoporosis through the AGEs/RAGE pathway

AIMS

Diabetes-associated osteoporosis is mainly caused by the formation and accumulation of advanced glycation end products (AGEs). Angiotensin II type 1 receptor blocker (ARB) has anabolic bone effects on the physicochemical properties of the bone in diabetes. We hypothesized that ARB could inhibit AGEs-induced deleterious effects.

MAIN METHODS

In this study, we chose seven-week-old Leprdb/Lepr+ (db/+) and Leprdb/Leprdb (db/db) mice. After 12 week intervention by irbesartan, the microarchitecture and mechanical strength of the bone of seven-week-old db/db mice were investigated systematically. Meanwhile, the molecular mechanisms of the osteoblasts were analyzed, after AGEs or irbesartan were added to the culture. Also, intracellular formation of reactive oxygen species (ROS) was measured with DCF fluorescence.

KEY FOUNDINGS

Results showed that 12-week irbesartan treatment could dramatically improve trabecular bone microarchitecture through increasing BV/TV (p = 0.003, +46.7%), Tb.N (p = 0.020, +52.0%), and decreasing that of Tb.Sp (p = 0.005, -21.2%) and SMI (p = 0.007, -26.4%), comparing with the db/db group. Irbesartan could also substantially raise biomechanical parameters including max load (p = 0.013, +20.7%), fracture load (p = 0.014, +70.5%), energy absorption (p = 0.019, +99.4%). Besides, it could inhibit AGEs-induced damage of cell proliferation and osteogenic differentiation of osteoblasts, as well as suppressing the activation of apoptosis caused by AGEs. Moreover, co-incubation with irbesartan could prevent the AGEs-induced increase of intracellular oxidative stress and RAGE expression in osteoblasts.

SIGNIFICANCE

In conclusion, this study suggested that irbesartan might play a protective role in diabetes-related bone damages by blocking the deleterious effects of AGEs/RAGE-mediated oxidative stress. This may provide a revolutionary benefits to therapy with irbesartan on diabetic osteoporosis.

The effect of icariin on bone metabolism and its potential clinical application

Osteoporosis is a bone disease characterized by reduced bone mass, which leads to increased risk of bone fractures, and poses a significant risk to public health, especially in the elderly population. The traditional Chinese medicinal herb Epimedii has been utilized for centuries to treat bone fracture and bone loss. Icariin is a prenylated flavonol glycoside isolated from Epimedium herb, and has been shown to be the main bioactive component. This review provides a comprehensive survey of previous studies on icariin, including its structure and function, effect on bone metabolism, and potential for clinical application. These studies show that icariin promotes bone formation by stimulating osteogenic differentiation of BMSCs (bone marrow-derived mesenchymal stem cells), while inhibiting osteoclastogenic differentiation and the bone resorption activity of osteoclasts. Furthermore, icariin has been shown to be more potent than other flavonoid compounds in promoting osteogenic differentiation and maturation of osteoblasts. A 24-month randomized double-blind placebo-controlled clinical trial reported that icariin was effective in preventing postmenopausal osteoporosis with relatively low side effects. In conclusion, icariin may represent a class of flavonoids with bone-promoting activity, which could be used as potential treatment of postmenopausal osteoporosis.

Icariin and icaritin recover UVB-induced photoaging by stimulating Nrf2/ARE and reducing AP-1 and NF-κB signaling pathways: a comparative study on UVB-irradiated human keratinocytes

Icariin (ICA) and icaritin (ICT) have potential to treat UVB-induced skin oxidative stress, inflammation and photoaging.

Antidepressant Flavonoids and Their Relationship with Oxidative Stress

Depression is a serious disorder that affects hundreds of millions of people around the world and causes poor quality of life, problem behaviors, and limitations in activities of daily living. Therefore, the search for new therapeutic options is of high interest and growth. Research on the relationship between depression and oxidative stress has shown important biochemical aspects in the development of this disease. Flavonoids are a class of natural products that exhibit several pharmacological properties, including antidepressant-like activity, and affects various physiological and biochemical functions in the body. Studies show the clinical potential of antioxidant flavonoids in treating depressive disorders and strongly suggest that these natural products are interesting prototype compounds in the study of new antidepressant drugs. So, this review will summarize the chemical and pharmacological perspectives related to the discovery of flavonoids with antidepressant activity. The mechanisms of action of these compounds are also discussed, including their actions on oxidative stress relating to depression.

Evaluation of Osteogenesis and Angiogenesis of Icariin in Local Controlled Release and Systemic Delivery for Calvarial Defect in Ovariectomized Rats

Typically, bone regenerative medicine is applied to repair bone defects in patients with osteoporosis. Meanwhile, there is an urgent need to develop safe and cheap drugs that induce bone formation. Icariin, which is reported to promote the osteogenesis of stem cells in vitro, is the main active component of Herba Epimedii. However, whether icariin could repair bone defects caused by osteoporosis remains unknown. In this study, an osteoporosis model in rats was established by an ovariectomy first, and then, the osteogenic and angiogenic differentiation of bone mesenchymal stem cells (BMSCs) treated with icariin was evaluated. Furthermore, calcium phosphate cement (CPC) scaffolds loaded with icariin were constructed and then implanted into nude mice to determine the optimal construction. To evaluate its osteogenic and angiogenic ability in vivo, this construction was applied to calvarial defect of the ovariectomized (OVX) rats accompanied with an icariin gavage. This demonstrated that icariin could up-regulate the expression of osteogenic and angiogenic genes in BMSCs. Meanwhile, osteoclast formation was inhibited. Moreover, CPC could act as a suitable icariin delivery system for repairing bone defects by enhancing osteogenesis and angiogenesis, while the systemic administration of icariin has an antiosteoporotic effect that promotes bone defect repair.

RhoA inhibits the hypoxia-induced apoptosis and mitochondrial dysfunction in chondrocytes via positively regulating the CREB phosphorylation

Chondrocytes that are embedded within the growth plate or the intervertebral disc are sensitive to environmental stresses, such as inflammation and hypoxia. However, little is known about the molecular signalling pathways underlining the hypoxia-induced mitochondrial dysfunction and apoptosis in chondrocytes. In the present study, we firstly examined the hypoxia-induced apoptosis, mitochondrial dysfunction and the activation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) signalling in human chondrocyte cell line, C28/I2 and then investigated the regulatory role of RhoA, a well-recognized apoptosis suppressor, in such process, with gain-of-function strategy. Our results indicated that hypoxia induced apoptosis and inhibited CREB phosphprylation in chondrocytes, meanwhile, the dysfunctional mitochondria with up-regulated mitochondrial superoxide and reactive oxygen species (ROS) levels, whereas with a reduced mitochondrial membrane potential (MMP) and Complex IV activity were observed in the hypoxia-treated C28/I2 cells. However, the overexpressed RhoA blocked the hypoxia-mediated reduction in CREB phosphprylation and inhibited the apoptosis induction, along with an ameliorated mitochondrial function in the hypoxia-treated C28/I2 cells. In conclusion, the present study confirmed the reduced CREB phosphorylation, along with the apoptosis induction and mitochondrial dysfunction in the hypoxia-treated chondrocyte cells. And the overexpression of RhoA ameliorated the hypoxia-induced mitochondrial dysfunction and apoptosis via blocking the hypoxia-mediated reduction in CREB phosphorylation.

Combination of mesenchymal stem cell injection with icariin for the treatment of diabetes-associated erectile dysfunction

The present study was aimed to examine whether icariin, a traditional Chinese medicine, could improve therapeutic effects of adipose derived mesenchymal stem cells (ADSCs) for diabetes-associated erectile dysfunction (DMED). DMED were induced in rats by intraperitoneal injection of streptozotocin and confirmed by erectile function measurement. Then, rats of diabetic ED were randomly divided to receive the treatment of saline, ADSCs, icariin or ADSCs combined with icariin respectively. Compared with the treatment by ADSCs or icariin alone, intracavernosum injection of ADSCs combined with the following daily gastric gavage of icariin significantly augmented the value of ICP and ICP/MAP (p<0.01). Meanwhile, the survival of transplanted ADSCs was much improved due to the application of icariin. Similarly, immunofluorescent staining analysis demonstrated that the improved erectile tissue structure by combination of ADSCs and icariin was significantly associated with the increased expression of endothelial markers (vWF) (p<0.01) and smooth muscle markers (α-SMA) (p<0.01). Furthermore, the structure changes in corpus cavernosum were further confirmed by the Masson’s trichrome staining. To explore the possible mechanism underlying icariin-enhanced therapeutic efficacy of MSCs, we employed an in vitro testing system by introducing H₂O₂ to imitate oxidative stress condition considering the oxidative environment faced by engrafted ADSCs and anti-oxidative capacity of icariin_.In vitro, we found that the addition of icariin considerably reduced the apoptosis of ADSCs, and attenuated the intracellular reactive oxygen species (ROS), the superoxidase dismutase (SOD) activity and the lactate dehydrogenase (LDH). Subsequently, we examined the expression of apoptosis-related proteins and explored the potential signaling pathway through which icariin promoted the survival of ADSCs against oxidative stress. It was demonstrated that icariin significantly inhibited the upregulation of apoptosis-related proteins under oxidative condition, including Bax and cleaved caspase-3, while promoted the expression of anti-apoptotic factor BCL2. These effects were accompanied with the activation of signal molecules, PI3K/Akt and STAT3. The further signal protein inhibition assays exhibited that the suppression of STAT3 abrogated the icariin-mediated anti-apoptotic effects observed above, while did not influence the expression of PI3K/Akt. However, PI3K inhibition could abrogate icariin–mediated STAT3 activation and achieved a similar effect as STAT3 inhibition. Our results suggested that icariin was an effective adjuvant for enhancing ADSC-based therapy of DMEM, which may be ascribed to their protection of ADSCs against oxidative stress via the regulation of PI3K/Akt-STAT3 signal pathway.

Jiawei Erzhiwan improves menopausal metabolic syndrome by enhancing insulin secretion in pancreatic β cells

Menopausal metabolic syndrome (MMS) is a series of syndrome caused by ovarian function decline and hormone insufficiency, and is a high risk factor for cardiovascular diseases (CVD) and type II diabetes mellitus (T2DM). Erzhiwan (EZW), composed of Herba Ecliptae and Fructus Ligustri Lucidi, is a traditional Chinese herbal formula that has been used to treat menopausal syndrome for many years. We added Herba Epimedii, Radix Rehmanniae, and Fructus Corni into EZW, to prepare a new formula, termed Jiawei Erzhiwan (JE). The present study was designed to determine the anti-MMS effects of JE using ovariectomized (OVX) adult female rats that were treated with JE for 4 weeks, and β-tc-6 cells and INS cells were used to detected the protect effectiveness of JE. Our results showed JE could increase insulin sensitivity and ameliorated hyperlipidemia. Metabolomics analysis showed that the serum levels of branched and aromatic amino acids were down-regulated in serum by JE administration. Moreover, JE enhanced the function of islet β cells INS-1 and β-tc-6, through increasing the glucose stimulated insulin secretion (GSIS), which was abolished by estrogen receptor (ER) antagonist, indicating that JE functions were mediated by ER signaling. Additionally, JE did not induce tumorigenesis in rat mammary tissue or promoted proliferation of MCF-7 and Hela cells. In conclusion, our work demonstrated that JE ameliorated OVX-induced glucose and lipid metabolism disorder through activating estrogen receptor pathway and promoting GSIS in islet β cells, thus indicating that JE could be a safe and effective medication for MMS therapy.

The effect of quercetin delivery system on osteogenesis and angiogenesis under osteoporotic conditions

Bone regeneration under osteoporotic conditions with impaired angiogenesis, osteogenesis and remodeling represents a great challenge.

Short-Term Hypoxia Accelerates Bone Loss in Ovariectomized Rats by Suppressing Osteoblastogenesis but Enhancing Osteoclastogenesis

Background

Although it has been reported that hypoxic exposure can attenuate hypertension, heart disease, diabetes, and some other diseases, effects of hypoxia on osteoporosis are still unknown.

Material/Methods

The current study investigated whether short-term hypoxic exposure (in comparison with normoxic conditions) affects bone metabolism in normal or ovariectomized (OVX) adult female rats in an vivo study. Micro-computed tomography bone volume/structural analyses, histological examination, and serum bone turnover biochemical assays were used. In addition, the expressions of some associated major regulatory molecules were measured in osteoblastic cultures.

Results

While the 14-day hypoxic exposure did not change the bone-remodeling process in normal adult female rats, it decreased bone volume, osteoclast density, and serum bone formation marker (alkaline phosphatase) level, but increased osteoclast density and serum bone resorption marker (C-telopeptide of collagen) level in OVX rats. The bone marrow adipocyte number and serum fatty acid binding protein-4 level were increased in OVX-hypoxic rats compared with OVX-normoxic rats. Consistently, in human MG-63 osteoblastic cultures, the hypoxic condition suppressed protein expression of osteogenic transcriptional factors Runx2 and osterix, elevated protein expression of osteoclastogenic cytokine receptor activator of nuclear factor kappa-B ligand, but reduced that of osteoclastogenic inhibitor osteoprotegerin.

Conclusions

Our results suggest that, although no change occurred in the bone-remodeling process in normal adult female rats after hypoxic exposure, under the estrogen-deficient osteoporotic condition, the hypoxic condition can alter the bone microenvironment so that it may further impair osteoblastic differentiation and enhance osteoclastic formation, and thus reduce bone formation, enhance bone resorption, and accelerate bone loss.

Epimedium Polysaccharide Alleviates Polyglutamine-Induced Neurotoxicity in Caenorhabditis elegans by Reducing Oxidative Stress

Epimedium has been traditionally used to treat a variety of medical conditions, including neurological disorders. In this study, an acidic polysaccharide EbPS-A1 is isolated from Epimedium brevicornum and found to contain mainly galacturonic acid, galactose, and rhamnose but also arabinose and glucuronic acid. Using Caenorhabditis elegans models, we show that EbPS-A1 is capable of inhibiting behavioral dysfunction mediated by polyglutamine (polyQ), which is implicated in several neurodegenerative disorders such as Huntington's disease. Interestingly, EbPS-A1 does not inhibit polyQ aggregation or extend lifespan in the nematodes; it does, however, improve the survival under increased oxidative stress of both polyQ and wild-type nematodes intoxicated by paraquat. Further studies reveal that EbPS-A1 is capable of not only scavenging free radicals in vitro but also reducing reactive oxygen species levels, enhancing antioxidant enzyme activities, and decreasing lipid peroxidation product in C. elegans models. Together, these results suggest that the protective effect of Epimedium polysaccharide against polyQ-mediated neurotoxicity is likely due to its antioxidant function.

Natural Products from Chinese Medicines with Potential Benefits to Bone Health

Osteoporosis is a progressive, systemic bone disorder characterized by loss of bone mass and microstructure, leading to reduced bone strength and increased risk of fracture. It is often associated with reduced quality of life and other medical complications. The disease is common in the aging population, particularly among postmenopausal women and patients who receive long-term steroidal therapy. Given the rapid growth of the aging population, increasing life expectancy, the prevalence of bone loss, and financial burden to the healthcare system and individuals, demand for new therapeutic agents and nutritional supplements for the management and promotion of bone health is pressing. With the advent of global interest in complementary and alternative medicine and natural products, Chinese medicine serves as a viable source to offer benefits for the improvement and maintenance of bone health. This review summarizes the scientific information obtained from recent literatures on the chemical ingredients of Chinese medicinal plants that have been reported to possess osteoprotective and related properties in cell-based and/or animal models. Some of these natural products (or their derivatives) may become promising leads for development into dietary supplements or therapeutic drugs.

Physiological oxygen tension modulates soluble growth factor profile after crosstalk between chondrocytes and osteoblasts

OBJECTIVES

Physiological oxygen tension plays a critical role in homoeostatic maintenance and development of endochondral bone. Based on the proximity between uncalcified cartilage and subchondral bone, and microchannels that serve as a message delivery network between them, we aimed to explore the influence of low oxygen tension on soluble factor secretion in both chondrocytes and osteoblasts, after co-culture.

MATERIALS AND METHODS

Contact co-culture was achieved for morphological observation using red fluorescent protein (RFP)-labelled chondrocytes and green fluorescent protein (GFP)-labelled osteoblasts, and non-contact co-culture achieved by transwell chambers. This was used to screen genetic variation of growth factors in hypoxia, including respective phenotypic markers, factors involving hypoxia and angiogenesis relationships, bone morphogenetic family proteins, and other general factors.

RESULTS

We observed a significant increase in chondrocyte size following co-culture, in both normoxia and hypoxia, but not of osteoblasts. Expression of Aggrecan in chondrocytes and alkaline phosphatase in osteoblasts was down-regulated under hypoxia following co-culture. Under hypoxia, we found that expression of hypoxia-inducible factor-1α, vascular endothelial growth factor-A/B, VE-cadherin, bone morphogenetic protein-2, and insulin-like growth factor-1 in chondrocytes, increased, but HIF-1α, platelet-derived growth factor, BMP-5/-6 and fibroblast growth factor-1 in osteoblasts, decreased.

CONCLUSIONS

These results not only indicate the importance of crosstalk between chondrocytes and osteoblasts but also improve our understanding of the mechanisms underlying homoeostatic maintenance of endochondral bone.

Protective effects of icariin on cisplatin-induced acute renal injury in mice

Cisplatin chemotherapy often causes acute kidney injury in cancer patients. Icariin is a bioactive flavonoid, which has renal protection and anti-inflammation effects. This study investigated the mechanism underlying the attenuation of cisplatin-induced renal injury by icariin. BALB/c mice were treated with cisplatin (15 mg/kg) with or without treatment with icariin (30 or 60 mg/kg for 5 days). Renal function, histological changes, degree of oxidative stress and tubular apoptosis were examined. The effects of icariin on cisplatin-induced expression of renal TNF-α, NF-κB, cleaved caspase-3 and Bcl-2 family proteins were evaluated. Treatment of mice with cisplatin resulted in renal damage, showing an increase in blood urea nitrogen and creatinine levels, tubular damage, oxidative stress and apoptosis. These renal changes could be significantly improved by icariin treatment, especially in high dose of icariin group. Examination of molecules involving inflammation and apoptosis of the kidney revealed that treatment of icariin reduced expression of TNF-α, NF-κB, cleaved caspase-3, and Bax, increased the expression of BCL-2. These results indicate that icariin ameliorates the cisplatin-mediated nephrotoxicity via improving renal oxidant status, consequent NF-κB activation and inflammation cascade and apoptosis, and the following disturbed expression of apoptosis related proteins.

FFA-ROS-P53-mediated mitochondrial apoptosis contributes to reduction of osteoblastogenesis and bone mass in type 2 diabetes mellitus

This study evaluated the association between free fatty acid (FFA), ROS generation, mitochondrial dysfunction and bone mineral density (BMD) in type 2 diabetic patients and investigated the molecular mechanism. db/db and high fat (HF)-fed mice were treated by Etomoxir, an inhibitor of CPT1, MitoQ, and PFT-α, an inhibitor of P53. Bone metabolic factors were assessed and BMSCs were isolated and induced to osteogenic differentiation. FFA, lipid peroxidation and mtDNA copy number were correlated with BMD in T2DM patients. Etomoxir, MitoQ and PFT-α significantly inhibited the decrease of BMD and bone breaking strength in db/db and HF-fed mice and suppressed the reduction of BMSCs-differentiated osteoblasts. Etomoxir and MitoQ, but not PFT-α, inhibited the increase of mitochondrial ROS generation in db/db and HF-fed mice and osteoblasts. In addition, Etomoxir, MitoQ and PFT-α significantly inhibited mitochondrial dysfunction in osteoblasts. Moreover, mitochondrial apoptosis was activated in osteoblasts derived from db/db and HF-fed mice, which was inhibited by Etomoxir, MitoQ and PFT-α. Furthermore, mitochondrial accumulation of P53 recruited Bax and initiated molecular events of apoptotic events. These results demonstrated that fatty acid oxidation resulted in ROS generation, activating P53/Bax-mediated mitochondrial apoptosis, leading to reduction of osteogenic differentiation and bone loss in T2DM.