A novel semisynthetic molecule icaritin stimulates osteogenic differentiation and inhibits adipogenesis of mesenchymal stem cells

Therapeutic potential of Chinese medicinal herbs stimulating osteogenic differentiation of bone marrow-derived mesenchymal stem cells in osteoporosis

Osteoporosis (OP) is a common and complex chronic metabolic disease with an increasing incidence rate, which has markedly increased the human health burden worldwide. The predominant cause of OP is an imbalance between osteoblasts (OB) and osteoclasts (OC). Studies on the correlation between bone marrow-derived mesenchymal stem cells (BMSCs) and OP have indicated that BMSCs-induced OB differentiation is an important pathway for bone tissue renewal. Chinese medicinal herbs have been used for centuries to treat various types of OPs because they are safer and more effective. The in vivo and in vitro experiments have confirmed that these herbs or their primary phytochemicals may exert therapeutic effects by stimulating BMSCs differentiation, which restores OB and OP balance, inhibits adipocyte differentiation, exerts anti-inflammatory and antioxidant effects, regulates the immune system, etc. This review summarizes the research on how Chinese medicinal herbs or their primary phytochemicals treat OP by stimulating BMSC differentiation and provides a scientifically reliable basis and perspective for their future clinical application.

A literature review on Epimedium, a medicinal plant with promising slow aging properties

Ethnopharmacological relevance

Aging is related to many factors, such as genes, oxidative damage, metabolic abnormalities, immune regulation and sex hormones. This article reviews the pharmacological mechanism of Epimedium on slow aging from six aspects: gene regulation, antioxidant, the regulation of metabolism, the modulation of the immune system, the regulation of sex hormone, and clinical efficacy.Aim of the studyThrough literature review, to discover the potential pharmacological mechanism of Epimedium for slow aging.

Materials and methods

We reviewed the literature on the applications of Epimedium in multiple systems and the potential underlying mechanisms with systematic and comprehensive illustrations. The review includes the following aspects: gene regulation, antioxidant, the regulation of metabolism, the modulation of the immune system, the regulation of sex hormone, clinical efficacy and safety.

Results

The slow aging active components of Epimedium may be flavonoids, such as Epimedins A, B, C and icariin The slow aging effect of Epimedium may be related to gene regulation, antioxidant, the regulation of metabolism, the modulation of the immune system, and the regulation of sex hormone. No severe adverse reaction has been reported.

Conclusions

Epimedium has potential slow aging effect and been widely used in the clinic for aging-related diseases in the real world in China; however, large-scale studies are still needed.

Role of Traditional Chinese Medicine in Bone Regeneration and Osteoporosis

According to World Health Organization (WHO), osteoporosis is a systematic bone disability marked by reduced bone mass and microarchitectural degeneration of osseous cells, which leads to increased bones feebleness and fractures vulnerability. It is a polygenetic, physiological bone deformity that frequently leads to osteoporotic fractures and raises the risk of fractures in minimal trauma. Additionally, the molecular changes that cause osteoporosis are linked to decreased fracture repair and delayed bone regeneration. Bones have the ability to regenerate as part of the healing mechanism after an accident or trauma, including musculoskeletal growth and ongoing remodeling throughout adulthood. The principal treatment approaches for bone loss illnesses, such as osteoporosis, are hormone replacement therapy (HRT) and bisphosphonates. In this review, we searched literature regarding the Traditional Chinese medicines (TCM) in osteoporosis and bone regeneration. The literature results are summarized in this review for osteoporosis and bone regeneration. Traditional Chinese medicines (TCM) have grown in popularity as a result of its success in curing ailments while causing minimal adverse effects. Natural Chinese medicine has already been utilized to cure various types of orthopedic illnesses, notably osteoporosis, bone fractures and rheumatism with great success. TCM is a discipline of conventional remedy that encompasses herbal medication, massage (tui na), acupuncture, food, and exercise (qigong) therapy. It is based on more than 2,500 years of Chinese healthcare profession. This article serves as a comprehensive review summarizing the osteoporosis, bone regeneration and the traditional Chinese medicines used since ancient times for the management of osteoporosis and bone regeneration.

Icaritin attenuates 6-OHDA-induced MN9D cell damage by inhibiting oxidative stress

Background

We assessed whether ICT can alleviate 6-OHDA-induced cell damage via inhibition of oxidative stress by evaluating the protective effect of icaritin (ICT) against 6-hydroxydopamine (6-OHDA)-induced MN9D cell damage and further determined the mechanism by which ICT reduces oxidative stress.

Methods

MN9D cells were treated with 6-OHDA, to study the mechanism underlying the neuroprotective effect of ICT. MN9D cell damage was assessed by the CCK-8 assay, flow cytometry was performed to measure the content of reactive oxygen species (ROS) in cells, a superoxide dismutase (SOD) kit was used to evaluate SOD activity, and Western blotting was used to measure the expression of α-synuclein (α-Syn), Tyrosine hydroxylase (TH), nuclear factor erythroid-2 related factor 2 (Nrf2), and heme oxygenase-1 (HO-1).

Results

ICT reduced damage to MN9D cells induced by 6-OHDA. ICT increased SOD activity and TH expression and reduced ROS production and α-Syn expression. ICT promoted the translocation of Nrf2 from the cytoplasm to the nucleus and further increased the protein expression of HO-1.

Conclusions

ICT protects against 6-OHDA-induced dopaminergic neuronal cell injury by attenuating oxidative stress, and the mechanism is related to modulate the activities of Nrf2, HO-1 protein, and SOD.

Antiosteoporosis Effects, Pharmacokinetics, and Drug Delivery Systems of Icaritin: Advances and Prospects

Osteoporosis is a systemic skeletal disorder affecting over 200 million people worldwide and contributes dramatically to global healthcare costs. Available anti-osteoporotic drug treatments including hormone replacement therapy, anabolic agents, and bisphosphonates often cause adverse events which limit their long-term use. Therefore, the application of natural products has been proposed as an alternative therapy strategy. Icaritin (ICT) is not only an enzyme-hydrolyzed product of icariin but also an intestinal metabolite of eight major flavonoids of the traditional Chinese medicinal plant Epimedium with extensive pharmacological activities, such as strengthening the kidney and reinforcing the bone. ICT displays several therapeutic effects, including osteoporosis prevention, neuroprotection, antitumor, cardiovascular protection, anti-inflammation, and immune-protective effect. ICT inhibits bone resorption activity of osteoclasts and stimulates osteogenic differentiation and maturation of bone marrow stromal progenitor cells and osteoblasts. As for the mechanisms of effect, ICT regulates relative activities of two transcription factors Runx2 and PPARγ, determines the differentiation of MSCs into osteoblasts, increases mRNA expression of OPG, and inhibits mRNA expression of RANKL. Poor water solubility, high lipophilicity, and unfavorable pharmacokinetic properties of ICT restrict its anti-osteoporotic effects, and novel drug delivery systems are explored to overcome intrinsic limitations of ICT. The paper focuses on osteogenic effects and mechanisms, pharmacokinetics and delivery systems of ICT, and highlights bone-targeting strategies to concentrate ICT on the ideal specific site of bone. ICT is a promising potential novel therapeutic agent for osteoporosis.

Combination of Stem Cells with Chinese Herbs for Secondary Depression in Neurodegenerative Diseases Based on Traditional Chinese Medicine Theories

Depression is a common secondary symptom in neurodegenerative diseases (NDs) caused by the loss of neurons and glial cells. Recent research focuses on stem cell therapy to replace dead nerve cells, but the low efficiency of stem cell differentiation and short survival time are obstacles limiting the therapy's effectiveness. Clinically, patients with different diseases cannot obtain the same effect by using the same cell therapy. However, traditional Chinese medicine (TCM) often uses syndrome differentiation to determine the treatment plan for NDs. Based on TCM syndrome differentiation and treatment, this article summarizes the advantages of Chinese herbal medicine combined with stem cell therapy, mainly for the effects of various herbs on diseases and stem cells, including prolonging the survival time of stem cells, resisting inflammation, and antidepressant-like effects. In particular, it analyzes the unique pathways of the influence of drugs and acupuncture on different therapies, seeking to clarify the scientific TCM system. This review mainly elaborates on the treatment of secondary depression in TCM and the advantages of a herbal combined stem cell therapy in various methods. We believe it can provide a new clinical concept for secondary depression to obtain good clinical effects and reduce the risks borne by patients.

Icaritin inhibits lung cancer-induced osteoclastogenesis by suppressing the expression of IL-6 and TNF-a and through AMPK/mTOR signaling pathway

Bone metastasis is one of the common phenomena in the late stage of lung cancer. Inhibition of bone metastasis can improve the survival of lung cancer patients. However, the current drugs for the treatment of bone metastasis have shown little effect on overall survival. Therefore, there is an urgent necessity to identify novel drugs capable of preventing and treating bone metastasis of lung cancer. Our study determined that icaritin (ICT) can inhibit lung cancer-mediated osteoclastogenesis and induce the apoptosis of osteoclasts. Exposure to ICT increased the activation of adenosine 5'-monophosphate-activated protein kinase (AMPK), reduced the activation of mammalian target of rapamycin (mTOR) and decreased the expression of bcl-2. The bioactivity of ICT on osteoclastogenesis was associated with the regulation of the AMPK/mTOR signaling pathway. Blocking AMPK significantly increased osteoclast differentiation, decreased osteoclast apoptosis and canceled the effects of ICT on the phosphorylation of AMPK as well as the inhibition of mTOR and bcl-2. Furthermore, ICT decreased the levels of IL-6 and TNF-α in osteoclasts, while the AMPK inhibitor compound C significantly abolished the inhibitory effects of ICT on IL-6 and TNF-α. Thus, the present study demonstrated that ICT may be a potential natural agent for the treatment of bone metastasis in patients with lung cancer.

Icaritin and icariin reduce p-Tau levels in a cell model of Alzheimer's disease by downregulating glycogen synthase kinase 3β

This study aimed to explore the neuroprotective effect of icariin/icaritin (ICA/ICT) and the role of ICA/ICT in the treatment of Alzheimer's disease (AD). ICA and ICT were used to treat okadaic acid (OA)-induced Tau hyperphosphorylation in SH-SY5Y cells. We detected the relative changes in Tau, p-Tau, protein phosphatase 2A (PP2A), and glycogen synthase kinase 3β (GSK-3β) by Western blotting and enzyme-linked immunosorbent assay. At 40 nmol/L OA, the cell viability of the SH-SY5Y cells was significantly changed. We used different concentrations of ICA and IC to treat AD model cells and found that the effect of 2.5 μmol/L ICA and 1 μmol/L ICT was best after 48 H of treatment. After SH-SY5Y cell induction, the p-Tau levels were increased (P < 0.05); after the ICA/ICT treatment, the p-Tau and GSK-3β levels were decreased (P < 0.05), although PP2A expression did not change (P > 0.05). We found that ICA and ICT exert an effect on AD model cells by decreasing the levels of GSK-3β and p-Tau. The therapeutic effect of ICT is slightly better than that of ICA. Although these drugs were effective in the cell model, more studies are required to determine whether they are promising for the treatment and prevention of AD.

Icariin Promotes the Osteogenesis of Bone Marrow Mesenchymal Stem Cells through Regulating Sclerostin and Activating the Wnt/β-Catenin Signaling Pathway

Osteoporosis (OP) is a metabolic disease characterized by decreased bone mass and increased risk of fragility fractures, which significantly reduces the quality of life. Stem cell-based therapies, especially using bone marrow mesenchymal stem cells (BMSCs), are a promising strategy for treating OP. Nevertheless, the survival and differentiation rates of the transplanted BMSCs are low, which limits their therapeutic efficiency. Icariin (ICA) is a traditional Chinese medicine formulation that is prescribed for tonifying the kidneys. It also promotes the proliferation and osteogenic differentiation of BMSCs, although the specific mechanism remains unclear. Based on our previous research, we hypothesized that ICA promotes bone formation via the sclerostin/Wnt/β-catenin signaling pathway. We isolated rat BMSCs and transfected them with sclerostin gene (SOST) overexpressing or knockdown constructs and assessed osteogenic induction in the presence or absence of ICA. Sclerostin significantly inhibited BMSC proliferation and osteogenic differentiation, whereas the presence of ICA not only increased the number of viable BMSCs but also enhanced ALP activity and formation of calcium nodules during osteogenic induction. In addition, the osteogenic genes including Runx2, β-catenin, and c-myc as well as antioxidant factors (Prdx1, Cata, and Nqo1) were downregulated by sclerostin and restored by ICA treatment. Mechanistically, ICA exerted these effects by activating the Wnt/β-catenin pathway. In conclusion, ICA can promote the proliferation and osteogenic differentiation of BMSCs in situ and therefore may enhance the therapeutic efficiency of BMSC transplantation in OP.

Phytochemicals impact on osteogenic differentiation of mesenchymal stem cells

Medicinal plants have always been utilized for the prevention and treatment of the spread of different diseases all around the world. To name some traditional medicine that has been used over centuries, we can refer to phytochemicals such as naringin, icariin, genistein, and resveratrol gained from plants. Osteogenic differentiation and mineralization of stem cells can be the result of specific bioactive compounds from plants. One of the most appealing choices for therapy can be mesenchymal stem cells (MSCs) because it has a great capability of self-renewal and differentiation into three descendants, namely, endoderm, mesoderm, and ectoderm. Stem cell gives us the glad tidings of great advances in tissue regeneration and transplantation field for treatment of diseases. Using plant bioactive phytochemicals also holds tremendous promises in treating diseases such as osteoporosis. The purpose of the present review article thus is to investigate what are the roles and consequences of phytochemicals on osteogenic differentiation of MSCs.

Icaritin promotes the osteogenesis of bone marrow mesenchymal stem cells via the regulation of sclerostin expression

Icaritin, a metabolite of icariin, is a potent promoter of bone marrow-derived mesenchymal stem cells (BMSCs) osteogenesis, but the underlying mechanisms remain unclear. To examine the effects of icaritin on osteogenic differentiation, BMSCs were exposed to osteogenic induction medium with or without icaritin pretreatment in the present study. It was identified that icaritin (0.01-1 µM) exhibited no cytotoxicity on the proliferative abilities of the BMSCs. Icaritin at 1 µM increased alkaline phosphatase activity, mineral deposition and osteoblast-specific gene expression. Treatment with 1 µM Icaritin upregulated osteocalcin, RUNX family transcription factor 2, tissue-nonspecific alkaline phosphatase and β-catenin, and suppressed sclerostin (SOST) gene expression in different stages of osteogenic differentiation. It was also demonstrated that SOST over-expression inhibited icaritin-induced osteogenesis. The western blot analysis data suggested that ICI 182780, which causes estrogen receptor α (ERα) degradation, reversed the icaritin-induced decrease in SOST expression, which was inconsistent with the results of immunofluorescence analysis. In conclusion, icaritin was demonstrated to promote the osteogenesis of hBMSCs by downregulating SOST expression, and icaritin-induced suppression of SOST was regulated in part via the Wnt/β-catenin/ERα axis.

Mechanism of Action of Icariin in Bone Marrow Mesenchymal Stem Cells

Osteoporosis, femoral head necrosis, and congenital bone defects are orthopedic disorders characterized by reduced bone generation and insufficient bone mass. Bone regenerative therapy primarily relies on the bone marrow mesenchymal stem cells (BMSCs) and their ability to differentiate osteogenically. Icariin (ICA) is the active ingredient of Herba epimedii, a common herb used in traditional Chinese medicine (TCM) formulations, and can effectively enhance BMSC proliferation and osteogenesis. However, the underlying mechanism of ICA action in BMSCs is not completely clear. In this review, we provide an overview of the studies on the role and mechanism of action of ICA in BMSCs, to provide greater insights into its potential clinical use in bone regeneration.

Isomeric flavonoid aglycones derived from Epimedii Folium exerted different intensities in anti-osteoporosis through OPG/RANKL protein targets

Two Epimedium-derived isomeric flavonoids, CIT and IT, had the therapeutic effect in osteopenic rats. However, it is difficult to expound their activity differences in anti-osteoporosis. This paper contrasted their anti-osteoporosis activity from the perspective of their affinity to OPG/RANKL protein targets. Molecular docking indicated that both of CIT and IT could interact with the hydrophobic pockets of OPG/RANKL, while CIT was easier and more stable to combine with RANKL. On the contrary, compared with CIT, IT was more inclined to combine with OPG and stay away from combining with RANKL. Subsequently, whether the interaction between isomeric flavonoids and OPG/RANKL targets promoted or suppressed bone resorption was undefined and which was validated by zebrafish embryo and ovariectomized rats in this paper. Compared with IT, the staining area and cumulative optical density of zebrafish skeleton were significantly increased after the treatment of CIT (0.1 μM, p < 0.05). Furthermore, CIT mainly reflected a more significant role in upregulating OPG (p < 0.05), downregulating RANKL (p < 0.05), reducing serum AKP and TRACP level (p < 0.05), enhancing bone biomechanical properties (p < 0.05), increasing bone mineral density (p < 0.05) and improving trabecular bone microarchitecture (p < 0.05) in osteoporotic rats. In conclusion, the combination of isomeric flavonoids (CIT/IT) and OPG/RANKL targets attenuated the excitation effects of OPG or RANKL on RANKL. Because CIT was more firmly combined with RANKL than IT, CIT had stronger anti-osteoporosis effect by inhibiting bone resorption.

STAT-3 regulation of CXCR4 is necessary for the prenylflavonoid Icaritin to enhance mesenchymal stem cell proliferation, migration and osteogenic differentiation

Mesenchymal stem cell (MSC) dysfunction has been implicated in the pathogenesis of osteoporosis. MSCs derived from osteoporotic subjects demonstrate significant impairment in proliferation, adhesion and chemotaxis, and osteogenic differentiation, leading to reduced functional bone-forming osteoblasts and ultimately nett bone loss and osteoporosis. Epimedium herbs and its active compound Icaritin (ICT) have been used in Chinese ethnopharmacology for the treatment of metabolic bone diseases. Using an in-vitro cell culture model, we investigated the benefits of ICT treatment in enhancing MSC proliferation, migration and osteogenic differentiation, and provide novel data to describe its mechanism of action. ICT enhances MSC proliferation, chemotaxis to stromal cell-derived factor-1 (SDF-1) and osteogenic differentiation through the activation of signal transduction activator transcription factor 3 (STAT-3), with a consequential up-regulation in the expression and activity of cysteine (C)-X-C motif chemokine receptor 4 (CXCR4). These findings provide a strong basis for future clinical studies to confirm the therapeutic potential of ICT for the prevention and treatment of osteoporosis and fragility fractures.

Prevention and Treatment of Osteoporosis Using Chinese Medicinal Plants: Special Emphasis on Mechanisms of Immune Modulation

Numerous studies have examined the pathogenesis of osteoporosis. The causes of osteoporosis include endocrine factors, nutritional status, genetic factors, physical factors, and immune factors. Recent osteoimmunology studies demonstrated that the immune system and immune factors play important regulatory roles in the occurrence of osteoporosis, and people should pay more attention to the relationship between immunity and osteoporosis. Immune and bone cells are located in the bone marrow and share numerous regulatory molecules, signaling molecules, and transcription factors. Abnormal activation of the immune system alters the balance between osteoblasts and osteoclasts, which results in an imbalance of bone remodeling and osteoporosis. The incidence of osteoporosis is also increasing with the aging of China's population, and traditional Chinese medicine has played a vital role in the prevention and treatment of osteoporosis for centuries. Chinese medicinal plants possess unique advantages in the regulation of the immune system and the relationships between osteoporosis and the immune system. In this review, we provide a general overview of Chinese medicinal plants in the prevention and treatment of osteoporosis, focusing on immunological aspects.

Bone mass improved effect of icariin for postmenopausal osteoporosis in ovariectomy-induced rats: a meta-analysis and systematic review

OBJECTIVE

Ovariectomy (OVX)-induced rats are the most frequently used animal model to research postmenopausal osteoporosis. Our objective was to summarize and critically assess the bone mass improved effect of icariin (ICA) for treatment of postmenopausal osteoporosis in an OVX-induced rat model.

METHODS

The PUBMED, EMBASE, and Chinese databases were searched from their inception date to February 2015. Two reviewers independently selected animal studies that evaluated the bone mass improved effect of ICA compared with control in OVX-induced rats. Extracted data were analyzed by RevMan statistical software, and the methodological quality of each study was assessed.

RESULTS

Seven studies with adequate randomization were included in the systematic review. Overall, ICA seemed to significantly improve bone mass as assessed using the bone mineral density (seven studies, n = 169; weighted mean difference, 0.02; 95% CI, 0.01-0.02, I = 77%, P < 0.00001) using a random-effects model. There is no significant difference between ICA and estrogen (E) (six studies, n = 128; weighted mean difference, 0.00; 95% CI, -0.00 to 0.01, I = 54%, P = 0.01).

CONCLUSIONS

Bone mass improved effect of ICA for postmenopausal osteoporosis was observed in OVX-induced rats. Assessment of the methodological quality of studies involving OVX-induced animal models is required, and good methodological quality should be valued in systematic reviews of animal studies.

The prenylflavonoid Icaritin enhances osteoblast proliferation and function by signal transducer and activator of transcription factor 3 (STAT-3) regulation of C-X-C chemokine receptor type 4 (CXCR4) expression

In this study, we examined the effects of a natural prenylflavonoid Icaritin (ICT), on human osteoblast proliferation and osteogenic function. We observed that ICT dose-dependently enhanced osteoblast proliferation by ~15% over a 7day period. This increase in cell proliferation was associated with corresponding increases in osteoblast functions as measured by ALP secretion, intracellular calcium ions influx and calcium deposition. These anabolic effects were associated with a 4-fold increase in CXCR4 mRNA and protein expression. Silencing of CXCR4 protein expression using small interfering RNA reversed ICT-induced increase in cell proliferation, ALP activity and calcium deposition. Interestingly, we observed that ICT dose-dependently increased STAT-3 phosphorylation; and this resulted in increased binding of phosphorylated STAT-3 to the promoter region of the CXCR4 gene, to increase CXCR4 protein expression. Furthermore, we found that inhibition of STAT-3 phosphorylation resulted in a decrease in CXCR4 protein expression; whilst increasing phosphorylation of STAT-3 using a constitutive active STAT-3 vector significantly increased CXCR4 levels. Moreover, the chemical inhibition of STAT-3 phosphorylation annulled our previously observed ICT-induced increases of osteoblast proliferation and function. Finally, in a rat model of estrogen-deficient osteoporosis, ICT restored both osteoblasts numbers and CXCR4 expression. Taken together, both cellular and animal models support the novel findings that ICT; through the phosphorylation of STAT-3, up-regulated CXCR4, to increase osteoblast proliferation and function.

Icaritin induces MC3T3-E1 subclone14 cell differentiation through estrogen receptor-mediated ERK1/2 and p38 signaling activation

Icaritin (ICT), a hydrolytic product of icariin from the genus Epimedium, has many indicated pharmacological and biological activities. Several studies have shown that ICT has potential osteoprotective effects, including stimulation of osteoblast differentiation and inhibition of osteoclast differentiation. However, the molecular mechanism for this anabolic action of ICT remains largely unknown. Here, we found that ICT could enhance MC3T3-E1 subclone 14 preosteoblastic cell differentiation associated with increased mRNA levels and protein expression of the differentiation markers alkaline phosphatase (ALP), type 1 collagen (COL1), osteocalcin (OC), osteoponin (OPN) and runt-related transcription factor 2 (RUNX2), and improved mineralization, confirmed by bone nodule formation and collagen synthesis. To characterize the underlying mechanisms, we examined the effect of ICT on estrogen receptor (ER) and mitogen-activated protein kinase (MAPK) signaling. ICT treatment induced p38 kinase and extracellular signal-regulated kinase 1/2 (ERK1/2) activation, but it demonstrated at the same time point no effect on activation of c-Jun N-terminal kinase (JNK). ER antagonist ICI182780, p38 antagonist SB203580 and ERK1/2 antagonist PD98059 markedly inhibited the ICT-induced the mRNA expression of ALP, COL1, OC and OPN. ICI182780 attenuated the ICT-induced phosphorylation of p38 and ERK1/2. These observations indicate a potential mechanism of osteogenic effects of ICT involving the ERK1/2 and p38 pathway activation through the ER.

Primary cilium is required for the stimulating effect of icaritin on osteogenic differentiation and mineralization of osteoblasts in vitro

OBJECTIVE

Icaritin, one effective metabolite of Herba Epimedii-derived flavonoid icariin, has a strong osteogenic activity. However, its action mechanism remains unclear. Since primary cilia have been shown to play a pivotal role in regulating the osteogenesis, we hypothesized primary cilia are indispensable in mediating icaritin osteogenic effect.

MATERIALS AND METHODS

Primary rat calvarial osteoblasts were transfected with siRNA1 targeting intraflagellar transport protein 88 (IFT88), a protein required for ciliogenesis, to prevent formation of primary cilium and were treated with 10^-6 M icaritin.

RESULTS

Alkaline phosphatase (ALP) activity was significantly increased after 3 days in cells transfected with scrambled siRNA control and treated by icaritin (SC+I group) compared to cells transfected with scrambled siRNA control only (SC group). ALP activity after IFT88 siRNA1 transfection and icaritin treatment (siRNA1+I group) was significantly lower than that of SC+I group. Formation of ALP positively stained colonies after 6 days, osteocalcin secretion after 9 days and formation of calcified nodules after 12 days displayed a similar tendency among the three groups. mRNA expression of osteogenesis-related genes ALP, BMP-2, COL1α, RUNX-2 and OSX after 24 h was significantly increased in SC+I group, but was not different with SC group in siRNA1+I group. Protein levels of BMP-2, COL1α, RUNX-2 and OSX after 48 h showed the similar tendency with gene expression.

CONCLUSION

Primary cilia are important in mediating icaritin-stimulated osteogenic differentiation and may be a novel target for pharmacological therapies for bone loss.

Icaritin, a novel plant-derived osteoinductive agent, enhances the osteogenic differentiation of human bone marrow- and human adipose tissue-derived mesenchymal stem cells

For the treatment of diseases affecting bones using bone regenerative medicine, there is an urgent need to develop safe, inexpensive drugs that can strongly induce bone formation. In the present study, we systematically investigated the effects of icaritin, a metabolic product of icariin, on the osteogenic differentiation of human bone marrow‑derived mesenchymal stem cells (hBMSCs) and human adipose tissue‑derived stem cells (hADSCs) in vitro. After treatment with icaritin at concentrations of 10‑8-10‑5 M, hBMSCs and hADSCs were examined for alkaline phosphatase activity, osteocalcin (OC) secretion, matrix mineralization and expression levels of bone‑related mRNA and proteins. Data showed that icaritin at concentrations 10‑7-10‑5 M significantly increased alkaline phosphatase activity, OC secretion at different time points, and calcium deposition at day 21. In addition, icaritin upregulated the mRNA expression of genes for bone morphogenetic proteins (BMP‑2, ‑4 and ‑7), bone transcription factors (Runx2 and Dlx5) and bone matrix proteins (ALP, OC and Col‑1). Moreover, icaritin increased the protein levels of BMPs, Runx2 and OC, as detected by western blot analysis. These findings suggest that icaritin enhances the osteogenic differentiation of hBMSCS and hADSCs. Icaritin exerts its potent osteogenic effect possibly by directly stimulating the production of BMPs. Although the osteogenic activity of icaritin in vitro was inferior to that of rhBMP‑2, icaritin displayed better results than icariin. Moreover, the low cost, simple extraction procedure, and an abundance of icaritin make it appealing as a bone regenerative medicine.

Icaritin enhances mESC self-renewal through upregulating core pluripotency transcription factors mediated by ERα

Utilization of small molecules in modulation of stem cell self-renewal is a promising approach to expand stem cells for regenerative therapy. Here, we identify Icaritin, a phytoestrogen molecule enhances self-renewal of mouse embryonic stem cells (mESCs). Icaritin increases mESCs proliferation while maintains their self-renewal capacity in vitro and pluripotency in vivo. This coincides with upregulation of key pluripotency transcription factors OCT4, NANOG, KLF4 and SOX2. The enhancement of mESCs self-renewal is characterized by increased population in S-phase of cell cycle, elevation of Cylin E and Cyclin-dependent kinase 2 (CDK2) and downregulation of p21, p27 and p57. PCR array screening reveals that caudal-related homeobox 2 (Cdx2) and Rbl2/p130 are remarkably suppressed in mESCs treated with Icaritin. siRNA knockdown of Cdx2 or Rbl2/p130 upregulates the expression of Cyclin E, OCT4 and SOX2, and subsequently increases cell proliferation and colony forming efficiency of mESCs. We then demonstrate that Icaritin co-localizes with estrogen receptor alpha (ERα) and activates its nuclear translocation in mESCs. The promotive effect of Icaritin on cell cycle and pluripotency regulators are eliminated by siRNA knockdown of ERα in mESCs. The results suggest that Icaritin enhances mESCs self-renewal by regulating cell cycle machinery and core pluripotency transcription factors mediated by ERα.

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.

FOXO1 Is Involved in the Effects of Cigarette Smoke Extract on Osteoblastic Differentiation of Cultured Human Periosteum-derived Cells

Cigarette smoke is associated with delayed fracture healing, alterations in mineral content, and osteoporosis, however, its effects on osteoblastic differentiation of osteoprogenitor cells are not fully understood. In the present study, we examined the effects of cigarette smoke extract (CSE) on osteoblastic differentiation of cultured human periosteum-derived cells. We found that CSE inhibited alkaline phosphatase (ALP) activity, mineralization and Runx2 transactivation of the periosteum-derived cells. Nucleofection of RUNX2 into the periosteum-derived cells increased expression of endogenous osteocalcin (OC) and ALP genes in osteogenic induction medium and increased OC expression in non-osteogenic medium. Treatment of the periosteum-derived cells with CSE resulted in decreased phosphorylation of AKT and forkhead box protein O1 (FOXO1). The AKT phosphorylation-resistant mutant, FOXO1-A3, inhibited transcriptional activity of RUNX2 in the periosteum-derived cells. The current study suggests one mechanism by which CSE exposure leads to inhibition of osteoblastic differentiation of cultured human periosteum-derived cells.

A regulatory loop containing miR-26a, GSK3β and C/EBPα regulates the osteogenesis of human adipose-derived mesenchymal stem cells

Elucidating the molecular mechanisms responsible for osteogenesis of human adipose-derived mesenchymal stem cells (hADSCs) will provide deeper insights into the regulatory mechanisms of this process and help develop more efficient methods for cell-based therapies. In this study, we analysed the role of miR-26a in the regulation of hADSC osteogenesis. The endogenous expression of miR-26a increased during the osteogenic differentiation. The overexpression of miR-26a promoted hADSC osteogenesis, whereas osteogenesis was repressed by miR-26a knockdown. Additionally, miR-26a directly targeted the 3′UTR of the GSK3β, suppressing the expression of GSK3β protein. Similar to the effect of overexpressing miR-26a, the knockdown of GSK3β promoted osteogenic differentiation, whereas GSK3β overexpression inhibited this process, suggesting that GSK3β acted as a negative regulator of hADSC osteogenesis. Furthermore, GSK3β influences Wnt signalling pathway by regulating β-catenin, and subsequently altered the expression of its downstream target C/EBPα. In turn, C/EBPα transcriptionally regulated the expression of miR-26a by physically binding to the CTDSPL promoter region. Taken together, our data identified a novel feedback regulatory circuitry composed of miR-26a, GSK3β and C/EBPα, the function of which might contribute to the regulation of hADSC osteogenesis. Our findings provided new insights into the function of miR-26a and the mechanisms underlying osteogenesis of hADSCs.

Chemical Constituents, Quality Control, and Bioactivity of Epimedii Folium (Yinyanghuo)

Epimedii Folium (Yinyanghuo in Chinese) is one of the most commonly used traditional Chinese medicines. Its main active components are flavonoids, which exhibit multiple biological activities, such as promotion of bone formation and sexual function, protection of the nervous system, and prevention of cardiovascular diseases. Flavonoids also show anti-inflammatory and anticancer effects. Various effective methods, including genetic and chemical approaches, have been developed for the quality control of Yinyanghuo. In this review, the studies conducted in the last decade about the chemical constituents, quality control, and bioactivity of Yinyanghuo are summarized and discussed.

Icariin prevents ovariectomy-induced bone loss and lowers marrow adipogenesis

OBJECTIVE

Icariin prevents bone loss by stimulating new bone formation and by inhibiting bone resorption. However, less is known about how icariin affects marrow adiposity. This lack of information is a vital problem, as the degree of marrow adipogenesis may be an alternative indicator of the severity of osteoporosis in relation to the degree of osteogenesis and osteoblastogenesis. To explore this question, we tested the effects of icariin on bone mineral density (BMD) and marrow fat content in a rat model of postmenopausal osteoporosis.

METHODS

Thirty-six 3-month-old female Sprague-Dawley rats were randomly assigned to one of the following treatment groups: sham operation, ovariectomized controls, and ovariectomized rats treated orally with either 17β-estradiol or icariin for 12 weeks. BMD and marrow fat fraction were dynamically measured on weeks 0, 6, and 12. After 12 weeks of treatment, serum 17β-estradiol and bone biomarker levels were measured, and marrow adipocytes were quantitatively evaluated by histopathology.

RESULTS

Ovariectomized controls experienced a marked increase in fat fraction over time, with increases of 40% between weeks 0 and 6 and 69.4% between weeks 6 and 12 (P < 0.001). Marrow adiposity in ovariectomized controls was dramatically higher than that in sham rats on week 6; however, a reduction in BMD was detected in ovariectomized rats on week 12 (P < 0.001). Ovariectomized rats had levels of serum alkaline phosphatase and serum C-terminal telopeptide of type I collagen that were 49.4% and 67.2% higher, respectively, than those of sham rats (P < 0.001). The density, size, and volume of marrow adipocytes in ovariectomized controls were 57.3%, 29.5%, and 163% higher, respectively, than those in sham rats. Early icariin treatment decreased bone biomarker levels, inhibited bone degeneration, and restored marrow fat infiltration and adipocyte parameters to the levels observed in sham rats. Overall, the osteoprotective effect of icariin was comparable with that of 17β-estradiol; however, icariin did not produce uterine estrogenicity.

CONCLUSIONS

Early icariin treatment restores marrow adiposity in the estrogen-deficient rat model.

Biodistribution evaluation of icaritin in rats by ultra-performance liquid chromatography-tandem mass spectrometry

ETHNOPHARMACOLOGICAL RELEVANCE

Icaritin (ICT) is a major bioactive prenylflavonoid derivative contained in the Epimedium which is a widely used herbal medicine for the treatment of infertility, impotence, cardiovascular and skeletal diseases listed in the Chinese Pharmacopoeia. The aim of this study is to investigate the tissue distribution of ICT in rats by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) MATERIALS AND METHODS: ICT was intraperitoneally administrated to rats for 7 consecutive days at dose levels of 20, 40 and 60 mg/kg/day, respectively. Various tissue homogenates were pretreated by protein precipitation with acetonitrile. ICT and internal standard coumestrol were separated on a BEH C18 column with a gradient mobile phase and detected using precursor-product ion transitions of m/z 367.1→297.1 for ICT and 267.0→211.1 for coumestrol at the negative ionization mode, respectively.

RESULTS

ICT was widely distributed in rat's various tissues and its concentrations in tissues increased with elevated doses. A sensitive and reliable UPLC-MS/MS method was firstly established to quantify ICT in rat tissues. The lower limit of quantification was 0.5 ng/mL based on 100 μL of tissue homogenates. The intra- and inter-day accuracy at all levels fell in the ranges of 90.8-103.4% and 91.6-100.3%, and the intra- and inter-day precision (RSD) were in the ranges of 2.9-10.5% and 2.6-9.1%, respectively.

CONCLUSIONS

The UPLC-MS/MS showed good accuracy, precision and recovery and was suitable for the quantification of ICT in rat tissues. Wide distribution of ICT could helpfully elucidate systemic effects and various functions of ICT.

Insights from Ayurveda for translational stem cell research

Ayurveda, the traditional Indian system of medicine has given great emphasis to the promotion of health. Ayurveda therapies are based on restoration of body balance and nourishment of dhatus or tissues. Rasayana concept of Ayurveda explains tissue regeneration and cell renewal. The drugs and therapies explained as rasayana provide research opportunities for biology of regeneration. Specific rasayana stimulate and nourish respective dhatus. Interpretation of this description offers clues for specific differentiation of stem cells with appropriate extract. The preliminary experiments on Medhya drugs suggest neuronal stem cells differentiation. Authors highlight the potential of Ayurveda and its possible contributions in regenerative medicine. Authors propose a protocol based on integrative approach derived from Ayurveda concepts and current understanding of regenerative medicine. The advanced understanding about adult and embryonic stem cells along with concepts of regeneration in Ayurveda has immense potential in the development of regenerative medicine.

Icaritin suppresses the proliferation of human osteosarcoma cells in vitro by increasing apoptosis and decreasing MMP expression

AIM

To explore whether icaritin, a prenylflavonoid derivative of the Chinese tonic herb Epimedium, could suppress the proliferation of human osteosarcoma cells in vitro, and to elucidate the mechanisms of the action.

METHODS

Human osteosarcoma SaOS2 cell line was used in the present study. The proliferation of the cells was examined using MTT assay and immunofluorescence DAPI staining. Cell motility was studied with the scratch assay. Cell apoptosis was determined by Annexin V-FITC and PI double staining using flow cytometry. Western blotting and RT-PCR were used to measure the expression of mRNAs and proteins in the cells.

RESULTS

Icaritin (5-15 μmol/L) suppressed the proliferation of SaOS2 cells in vitro in a dose-dependent manner. Furthermore, the cell motility was significantly decreased after exposure to icaritin. Moreover, icaritin (5 μmol/L) time-dependently induced the apoptosis of SaOS2 cells, markedly suppressed MMP-2 and MMP-9 expression, upregulated caspase-3 and caspase-9 expression, and increased the level of cleaved caspase-3 in the cells. Co-exposure to the caspase-3 inhibitor zVAD-fmk (10 μmol/L) compromised the icaritin-induced caspase-3 expression and apoptosis in SaOS2 cells.

CONCLUSION

Icaritin suppresses the proliferation of SaOS2 human osteosarcoma cells by increasing apoptosis and downregulating MMP expression.

Cultured human periosteal-derived cells have inducible adipogenic activity and can also differentiate into osteoblasts in a perioxisome proliferator-activated receptor-mediated fashion

We investigated the adipogenic activity of cultured human periosteal-derived cells and studied perioxisome proliferator-activated receptor (PPAR) ligand-mediated differentiation of cultured human periosteal-derived cells into osteoblasts. Periosteal-derived cells expressed adipogenic markers, including CCAAT/enhancer binding protein α (C/EBP- α), C/EBP-δ, aP2, leptin, LPL, and PPARγ. Lipid vesicles were formed in the cytoplasm of periosteal-derived cells. Thus, periosteal-derived cells have potential adipogenic activity. The PPARα and PPARγ agonists, WY14643 and pioglitazone, respectively, did not modulate alkaline phosphatase (ALP) activity in periosteal-derived cells during induced osteoblastic differentiation, however, the PPARα and PPARγ antagonists, GW6471 and T0070907, respectively, both decreased ALP activity in these cells. WY14643 did not affect, whereas pioglitazone enhanced, alizarin red-positive mineralization and calcium content in the periosteal-derived cells. GW6471 and T0070907 both decreased mineralization and calcium content. By RT-PCR, pioglitazone significantly increased ALP expression in periosteal-derived cells between culture day 3 and 2 weeks. Pioglitazone increased Runx2 expression after 3 days, which declined thereafter, but did not alter osteocalcin expression. Both of GW6471 and T0070907 decreased ALP mRNA expression. These results suggest that pioglitazone enhances osteoblastic differentiation of periosteal-derived cells by increasing Runx2 and ALP mRNA expression, and increasing mineralization. GW6471 and T0070907 inhibit osteoblastic differentiation of the periosteal-derived cells by decreasing ALP expression and mineralization in the periosteal-derived cells. In conclusion, although further study will be needed to clarify the mechanisms of PPAR-regulated osteogenesis, our results suggest that PPARγ agonist stimulates osteoblastic differentiation of cultured human periosteal-derived cells and PPARα and PPARγ antagonists inhibit osteoblastic differentiation in these cells.