Icariin Promotes the Migration of BMSCs In Vitro and In Vivo via the MAPK Signaling Pathway

Natural bioactive compounds modified with mesenchymal stem cells: new hope for regenerative medicine

Mesenchymal stem cells (MSCs) have the potential to differentiate into various cell types, providing important sources of cells for the development of regenerative medicine. Although MSCs have various advantages, there are also various problems, such as the low survival rate of transplanted cells and poor migration and homing; therefore, determining how to reform MSCs to improve their utilization is particularly important. Although many natural bioactive compounds have shown great potential for improving MSCs, many mechanisms and pathways are involved; however, in the final analysis, natural bioactive compounds promoted MSC proliferation, migration and homing and promoted differentiation and antiaging. This article reviews the regulatory effects of natural bioactive compounds on MSCs to provide new ideas for the therapeutic effects of modified MSCs on diseases.

Effects of icariin on dental pulp stem cells and its potential applications in dentin repair

OBJECTIVES

As dental pulp therapy evolves towards regenerative approaches, biomolecules such as icariin, derived from Epimedium flowers, are being evaluated for their therapeutic potential. This study investigates icariin's effectiveness in promoting odontogenic differentiation in human dental pulp stem cells (hDPSCs) in vitro and as a pulp-capping agent in vivo.

DESIGN

The study explored the effects of icariin on hDPSCs at concentrations of 10, 20, and 40 µM. Cell viability and migration assays were conducted to evaluate cytotoxicity and chemotaxis. Odontogenic differentiation was assessed using alkaline phosphatase staining and alizarin red S (ARS) staining, complemented by real-time PCR and Western blot analyses of key markers such as RUNX family transcription factor 2 (RUNX2), collagen type I alpha 1 chain (COL1A1), alkaline phosphatase (ALPL), and dentin sialophosphoprotein (DSPP). Additionally, the in vivo effects of icariin were tested in a rat maxillary molar model, where icariin-treated collagen sponges were used for direct pulp capping to evaluate its potential to induce reparative dentin formation.

RESULTS

Icariin showed no cytotoxic effects on hDPSCs at any tested concentration, enhanced migratory activity in a dose-dependent manner, and significantly increased alkaline phosphatase activity and calcium deposition. Gene and protein expression analyses revealed a dose-dependent increase in odontogenic differentiation markers in icariin-treated hDPSCs. In vivo, icariin effectively promoted reparative dentin formation in exposed rat pulp.

CONCLUSIONS

Icariin enhances odontogenic differentiation of hDPSCs and has promising potential as a pulp-capping agent for vital pulp therapy.

Effect of icariin on ovarian cancer: a combined network pharmacology and meta-analysis of in vitro studies approach

Introduction

An abundance of experimental evidence indicates that icariin (ICA) could potentially exert an anti-tumor effect on ovarian cancer (OC). Nevertheless, the reliability of this evidence remains ambiguous. This study aimed to explore the impact of ICA on OC and the underlying mechanisms.

Methods

Bioinformatics analysis was employed to pinpoint ICA-targeted genes and signaling pathways implicated in OC, utilizing network pharmacology. Subsequently, PubMed, EMBASE, and Web of Science databases were systematically searched from 2001 through June 2023 for in vitro trials evaluating the anti-tumor efficacy of conventional ICA versus placebo in OC. The pathways and genes identified in the literature were recorded, and the therapeutic targets were statistically analyzed and compared with the predicted targets from network pharmacology to confirm the precision of the targets.

Results and Discussion

Fourteen target genes were validated with success. The pathways corresponding to the remaining genes-excluding these 14-were analyzed and found to be primarily associated with cell apoptosis, anti-tumor, and other related pathways. Out of the 76 studies retrieved, eight fulfilled the inclusion criteria. The subsequent meta-analysis suggested that ICA treatment was significantly correlated with reduced cell growth and induced apoptosis. This study demonstrated a certain efficacy of ICA compared to placebo in enhancing anti-tumor outcomes, characterized by increased abilities in reducing cell growth and inducing apoptosis. The pathways involved in the therapeutic effect may be linked to cell apoptosis and anti-tumor mechanisms.

Repair of Osteoporotic Bone Defects in Rats via the Sirtuin 1-Wnt/β-catenin Signaling Pathway by Novel Icariin/Porous Magnesium Alloy Scaffolds

The slow rate of bone regeneration and repair in osteoporotic defects is one of the difficulties of clinical work. To prepare a novel icariin (ICA)/porous magnesium alloy scaffold and to investigate its effectiveness and possible mechanism in repairing osteoporotic bone defects, bilateral ovariectomy was performed on Sprague-Dawley rats. Then, a cylindrical bone defect was created in the model, and a novel ICA/porous magnesium alloy scaffold was prepared and implanted into the defect. Eight or 12 weeks after repairing, specimens and micro-computed tomography (CT) data were collected. Microscopic observation was fulfilled through hematoxylin and eosin, Goldner, Masson, periodic acid-Schiff, and Sirius red staining. The expression of proteins was detected by immunohistochemical staining. The novel ICA/porous magnesium alloy scaffold was noncytotoxic and biologically safe. After it was implanted into the defect for 8 or 12 weeks, the surface color and smoothness, depth, and area of the defect were better than those in the control group. Besides, there was sufficient osteoid tissue, more mineralized bones, more collagen fibers, and more polysaccharide components in the defect repaired with the ICA/porous magnesium alloy scaffold. These conditions are closer to those of real bones. Moreover, the repair effect improved with the repair time. Compared with those in the control group, the expression levels of Sirtuin 1(SIRT1), Wnt5a, β-catenin, glycogen synthase kinase 3β, alkaline phosphatase, runt-related transcription factor 2, bone morphogenetic protein-2, and osteocalcin proteins were elevated in bone tissue after the scaffold was implanted into the defect for 8 weeks (all P < 0.05). The novel ICA/porous magnesium alloy scaffold promotes the repair of osteoporotic bone defects in rats, a process that may be achieved through activation of the SIRT1-Wnt/β-catenin signaling pathway.

Icariin promotes cell adhesion for osteogenesis in bone marrow stromal cells via binding to integrin α5β1

BACKGROUND AND PURPOSE

Icariin, an 8-prenylated flavonoid glycoside, is an anabolic agent that could exert rapid estrogenic actions via ligand-independent activation of estrogen receptor alpha (ERα) in osteoblastic cells to promote osteogenesis. However, relatively little is known about its direct cellular target, its protective effects, and cell adhesion activities in bone marrow stromal cells (BMSCs) against microgravity. In the present study, the effects of icariin on osteogenesis and cell adhesion under microgravity were examined with the involvement of integrin receptor α5β1, connexin 43, and CAMs.

STUDY DESIGN AND METHODS

Icariin was orally administered to 6-month-old ovariectomized (OVX) Sprague-Dawley (SD) rats for 3 months through daily intake of phytoestrogen-free rodent diets containing icariin at 2 different dosages (50 and 500 ppm). BMSCs were harvested for experiments and RNA-sequencing analysis to examine the mechanism of action of icariin and its direct cellular target in stimulating osteogenesis.

RESULTS

The results revealed that icariin induced the expression of cell adhesion molecules (CAMs) and protected against microgravity-induced disruption of actin cytoskeleton and the loss of osteogenic activities in BMSCs through the activation of connexin-43 (Cx43) and Ras homolog family member A (RhoA) and Rac family small GTPase 1 (Rac1)-mediated signaling pathways. Computerized molecular docking techniques and the competitive solid-phase binding ELISA assay confirmed that icariin could be a direct ligand of integrin alpha 5 beta 1 (α5β1), and it could also increase the protein expression of integrin α5β1 for mechanosensing.

CONCLUSION

Our findings suggest that icariin could directly activate cell adhesion signaling by binding to integrin α5β1, which opens up new avenues for the development of integrin α5β1 ligand as an agent to protect against unloading-induced bone loss.

Astragalus polysaccharides augment BMSC homing via SDF-1/CXCR4 modulation: a novel approach to counteract peritoneal mesenchymal transformation and fibrosis

PURPOSE

This study aimed to evaluate the potential of astragalus polysaccharide (APS) pretreatment in enhancing the homing and anti-peritoneal fibrosis capabilities of bone marrow mesenchymal stromal cells (BMSCs) and to elucidate the underlying mechanisms.

METHODS

Forty male Sprague-Dawley rats were allocated into four groups: control, peritoneal dialysis fluid (PDF), PDF + BMSCs, and PDF + APSBMSCs (APS-pre-treated BMSCs). A peritoneal fibrosis model was induced using PDF. Dil-labeled BMSCs were administered intravenously. Post-transplantation, BMSC homing to the peritoneum and pathological alterations were assessed. Stromal cell-derived factor-1 (SDF-1) levels were quantified via enzyme-linked immunosorbent assay (ELISA), while CXCR4 expression in BMSCs was determined using PCR and immunofluorescence. Additionally, a co-culture system involving BMSCs and peritoneal mesothelial cells (PMCs) was established using a Transwell setup to examine the in vitro effects of APS on BMSC migration and therapeutic efficacy, with the CXCR4 inhibitor AMD3100 deployed to dissect the role of the SDF-1/CXCR4 axis and its downstream impacts.

RESULTS

In vivo and in vitro experiments confirmed that APS pre-treatment notably facilitated the targeted homing of BMSCs to the peritoneal tissue of PDF-treated rats, thereby amplifying their therapeutic impact. PDF exposure markedly increased SDF-1 levels in peritoneal and serum samples, which encouraged the migration of CXCR4-positive BMSCs. Inhibition of the SDF-1/CXCR4 axis through AMD3100 application diminished BMSC migration, consequently attenuating their therapeutic response to peritoneal mesenchyme-to-mesothelial transition (MMT). Furthermore, APS upregulated CXCR4 expression in BMSCs, intensified the activation of the SDF-1/CXCR4 axis's downstream pathways, and partially reversed the AMD3100-induced effects.

CONCLUSION

APS augments the SDF-1/CXCR4 axis's downstream pathway activation by increasing CXCR4 expression in BMSCs. This action bolsters the targeted homing of BMSCs to the peritoneal tissue and amplifies their suppressive influence on MMT, thereby improving peritoneal fibrosis.

Macrophage membrane (MMs) camouflaged near-infrared (NIR) responsive bone defect area targeting nanocarrier delivery system (BTNDS) for rapid repair: promoting osteogenesis via phototherapy and modulating immunity

Bone defects remain a significant challenge in clinical orthopedics, but no targeted medication can solve these problems. Inspired by inflammatory targeting properties of macrophages, inflammatory microenvironment of bone defects was exploited to develop a multifunctional nanocarrier capable of targeting bone defects and promoting bone regeneration. The avidin-modified black phosphorus nanosheets (BP-Avidin, BPAvi) were combined with biotin-modified Icaritin (ICT-Biotin, ICTBio) to synthesize Icaritin (ICT)-loaded black phosphorus nanosheets (BPICT). BPICT was then coated with macrophage membranes (MMs) to obtain MMs-camouflaged BPICT (M@BPICT). Herein, MMs allowed BPICT to target bone defects area, and BPICT accelerated the release of phosphate ions (PO43-) and ICT when exposed to NIR irradiation. PO43- recruited calcium ions (Ca2+) from the microenvironment to produce Ca3(PO4)2, and ICT increased the expression of osteogenesis-related proteins. Additionally, M@BPICT can decrease M1 polarization of macrophage and expression of pro-inflammatory factors to promote osteogenesis. According to the results, M@BPICT provided bone growth factor and bone repair material, modulated inflammatory microenvironment, and activated osteogenesis-related signaling pathways to promote bone regeneration. PTT could significantly enhance these effects. This strategy not only offers a solution to the challenging problem of drug-targeted delivery in bone defects but also expands the biomedical applications of MMs-camouflaged nanocarriers.

The Role of Herbal Medicine in Modulating Bone Homeostasis

Osteoporosis and other bone diseases are a major public health concern worldwide. Current pharmaceutical treatments for bone disorders have limitations, driving interest in complementary herbal medicines that can help maintain bone health. This review summarizes the scientific evidence for medicinal herbs that modulate bone cell activity and improve bone mass, quality and strength. Herbs with osteogenic, anti-osteoporotic, and anti-osteoclastic effects are discussed, including compounds and mechanisms of action. Additionally, this review examines the challenges and future directions for translational research on herbal medicines for osteoporosis and bone health. While preliminary research indicates beneficial bone bioactivities for various herbs, rigorous clinical trials are still needed to verify therapeutic efficacy and safety. Further studies should also elucidate synergistic combinations, bioavailability of active phytochemicals, and precision approaches to match optimal herbs with specific etiologies of bone disease. Advancing evidence- based herbal medicines may provide novel alternatives for promoting bone homeostasis and treating skeletal disorders.

Icariin: A Potential Alternative Against Osteoporosis

Osteoporosis is a metabolic skeletal disorder characterized by increased fragility and fracture risk as s result of reduced bone mineral density and microstructural destruction and caused a heavy burden on families and society. Current medicines, on the other hand, have some limitations, with side effects and doubts regarding long-term efficacy being highlighted. Studies seeking for natural constituents as potential treatment options therefore come into focus. Icariin is a phytochemical derived from a traditional Chinese medicine, Herba epimedium, that has been used to treat orthopedic disorders in ancient China for thousands of years, including osteoporosis, osteoarthritis, and fracture. Icariin belongs to a category of prenylated flavonoids and has been shown to help reduce osteoporosis bone loss while having relatively low side effects. Icariin's anti-osteoporosis properties manifest in a variety of ways, like promoting osteogenesis, suppressing osteoclastogenesis and bone resorption, regulating migration, proliferation, and differentiation of mesenchymal stem cells, enhancing angiogenesis, anti-inflammation, and antioxidation. These procedures entail a slew of critical signaling pathways, such as PPARγ, ERα/AKT/β-catenin, and MAPK. Therefore, icariin can be an applicable alternative to improve osteoporosis although the underlying mechanisms have yet to be fully understood. In this study, we searched using the terms “icariin” and “osteoporosis,” and included 64 articles meeting the inclusion criteria and reviewed the research of icariin in anti-osteoporosis over the last 10 years, and discussed new prospects for future study. Therefore, this review may provide some references for further studies.

A mechanistic review of chinese medicine polyphenols on bone formation and resorption

Bone reconstruction includes a steady state system of bone formation and bone absorption. This tight coupling requires subtle coordination between osteoblasts and osteoclasts. If this balance is broken, it will lead to bone mass loss, bone density reduction, and bone metabolic diseases, such as osteoporosis. Polyphenols in Chinese herbal medicines are active ingredients in plant extracts with high safety and few side effects, and they can play a role in affecting bone formation and bone resorption. Some of these have estrogen-like effects and can better target bone health in postmenopausal women. The purpose of this review is to provide comprehensive information on the mechanisms underlying the relationship between traditional Chinese medicine polyphenols and bone formation or bone resorption.

Bushen Jianpi Quyu Formula Alleviates Myelosuppression of an Immune-Mediated Aplastic Anemia Mouse Model via Inhibiting Expression of the PI3K/AKT/NF-κB Signaling Pathway

Bushen Jianpi Quyu Formula (BSJPQYF), an experienced formula, has been used to treat aplastic anemia (AA) more than three decades. To determinate the effect of BSJPQYF on AA, we constructed an immune-mediated AA mouse model. All mice were divided into four groups: control, model, low dose (0.85 g/mL), and high dose (1.7 g/mL BSJPQYF) group. They were administered with different concentrations of BSJPQYF or normal saline for 14 days. Besides, components of BSJPQYF were analyzed by electrospray ionization and mass spectrometry (ESI-MS). Subsequently, mouse peripheral blood and femurs were collected, and bone marrow mesenchymal stem cells (BMSCs) were isolated by fluorescence-activated cell sorting (FACS). Among them, tumor necrosis factor-α (TNF-α), transforming growth factor-β (TGF-β), and interferon-γ (IFN-γ) were measured by ELISA assay, PI3K, AKT, p-AKT, NF-κB, p-NF-κB, TNF-α, and cleaved caspase-3 proteins were detected by western blot. Compared with standard compounds, we identified three compounds of BSJPQYF, namely, icariin, kaempferol and tanshinone iia, as potentially effective compounds for the treatment of AA. Through an in vivo study, we found the administration of BSJPQYF in high dose for 14 days could significantly increase peripheral blood count and bone marrow (BM) cells, meanwhile decrease TNF-α, TGF-β, and IFN-γ levels. Besides, it could suppress the protein expression of PI3K and the phosphorylation of AKT and NF-κB to restrict the protein expression of TNF-α, eventually reduce the protein expression of cleaved caspase-3. This study demonstrated the therapeutic effects of BSJPQYF in AA, which could alleviate myelosuppression through inhibiting the expression of the PI3K/AKT/NF-κB signaling pathway.

Synergistically Promoting Bone Regeneration by Icariin-Incorporated Porous Microcarriers and Decellularized Extracellular Matrix Derived From Bone Marrow Mesenchymal Stem Cells

Multifunctionality has becoming essential for bone tissue engineering materials, such as drug release. In this study, icariin (ICA)-incorporated poly(glycolide-co-caprolactone) (PGCL) porous microcarriers were fabricated and then coated with decellularized extracellular matrix (dECM) which was derived from bone marrow mesenchymal stem cells (BMSC). The porous structure was generated due to the soluble gelatin within the microcarriers. The initial released ICA in microcarriers regulated osteogenic ECM production by BMSCs during ECM formation. The dECM could further synergistically enhance the migration and osteogenic differentiation of BMSCs together with ICA as indicated by the transwell migration assay, ALP and ARS staining, as well as gene and protein expression. Furthermore, in vivo results also showed that dECM and ICA exhibited excellent synergistic effects in repairing rat calvarial defects. These findings suggest that the porous microcarriers loaded with ICA and dECM coatings have great potential in the field of bone tissue engineering.

Odontogenic Effect of Icariin on the Human Dental Pulp Cells

Background and Objectives: Human dental pulp cells (HDPCs) can be used for dentin regeneration due to its odontogenic differentiation property. Icariin can induce osteogenic differentiation of stem cells. However, its potential to induce odontogenic differentiation of HDPCs remains unclear. Thus, the aim of this study was to evaluate the capacity of icariin to induce odontogenic differentiation of HDPCs and investigate the underlying molecular mechanism. Materials and Methods: Cell viability assay was used to detect the cytotoxicity of icariin to HDPCs. Effect of icariin on HDPCs chemotaxis was measured by scratch migration assay. The mineralized and odontogenic differentiation of HDPCs was assessed by alkaline phosphatase (ALP) staining, alizarin red S (ARS) staining, real-time PCR, and Western blot of dentin matrix protein 1 (DMP 1) and dentin sialophosphoprotein (DSPP). In addition, Mitogen-activated protein kinase (MAPK) signaling pathway of icariin-induced biomineralization was investigated by Western blot. Results: Cells treated with icariin at all concentrations tested maintained viability, indicating that icariin was biocompatible. Icariin accelerated HDPCs chemotaxis (p < 0.05). Expression levels of related odontogenic markers were increased in the presence of icariin (p < 0.05). Icariin-induced odontogenic differentiation occurred via activation of the MAPK signaling pathway. Furthermore, MAPK inhibitors suppressed expression levels of DSPP and DMP 1 protein, ALP activity, and mineralization of HDPCs. Conclusions: Icariin can upregulate odontogenic differentiation of HDPCs by triggering the MAPK signaling pathway.

Fracture repair by IOX2: Regulation of the hypoxia inducible factor-1α signaling pathway and BMSCs

The treatment of fracture delayed union and nonunion has become a challenging problem. Hypoxia inducible factor-1α (HIF-1α) is reported to be a key factor in fracture healing, and is degraded by hydroxylation of prolyl hydroxylase (PHDs) under normal oxygen. Small molecules could inhibit the activity of PHDs, stabilize HIF-1α protein, regulate the expression of downstream target genes of HIF-1α, and make the body adapt to hypoxia. The migration and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is the most promising candidate for the treatment of fracture nonunion. Here we reported that IOX2, an HIF-1α PHD inhibitor, markedly improved the proliferation and migration of BMSCs by upregulating intracellular Ca²⁺ and concomitant decreasing reactive oxygen species (ROS) in vitro, and facilitated the repair of bone fracture by increasing the number of BMSCs and cartilage formation in vivo. No significant influence of IOX2 on the proliferation and migration of BMSCs after silencing of the HIF-1α. Together, our findings indicated that IOX2 promoted the proliferation and migration of BMSCs via the HIF-1α pathway and further accelerated fracture healing. These results provide a deeper understanding of the mechanism by which HIF promotes fracture healing.

Icariin-Loaded Hydrogel Regulates Bone Marrow Mesenchymal Stem Cell Chondrogenic Differentiation and Promotes Cartilage Repair in Osteoarthritis

Intra-articular injection of mesenchymal stem cells is a potential therapeutic strategy for cartilage protection and symptom relief for osteoarthritis (OA). However, controlling chondrogenesis of the implanted cells in the articular cavity remains a challenge. In this study, hydrogels containing different concentrations of icariin were prepared by in situ crosslinking of hyaluronic acid and Poloxamer 407. This injectable and thermoresponsive hydrogel, as a 3D cell culture system, showed good biocompatibility with chondrocytes and bone marrow mesenchymal stem cells (BMSCs), as well as promoted proliferation and chondrogenesis of BMSCs through the Wnt/β-catenin signaling pathway. Intra-articular injection of this kind of BMSC-loaded composite hydrogel can significantly prevent cartilage destruction by inducing chondrogenic differentiation of BMSCs, and relieve pain through regulating the expression of inflammatory cytokines (e.g., IL-10 and MMP-13) in the OA model. Incorporating BMSCs into this novel icariin-loaded hydrogel indicates a more superior efficacy than the single BMSC injection, which suggests a great potential for its application in OA.

SETD4 in the Proliferation, Migration, Angiogenesis, Myogenic Differentiation and Genomic Methylation of Bone Marrow Mesenchymal Stem Cells

Epigenetic modification is a crucial mechanism affecting the biological function of stem cells. SETD4 is a histone methyltransferase, and its biological role in bone marrow mesenchymal stem cells (BMSCs) is currently unknown. In this study, we employed CRISPR/Cas9 technology edited mouse model and found that SETD4 knockout significantly promoted the proliferation of BMSCs, impaired BMSCs migration and differentiation potentials of lineages of cardiacmyocyte and smooth muscle cell, and even the angiogenesis via paracrine of VEGF. Through Reduced Representation Bisulfite Sequencing (RRBS) method, we verified that the overall genomic methylation of BMSCs in the SETD4 knockout group only was decreased by 0.47 % compared with wild type. However, the changed genomic methylation covers a total of 96,331 differential methylated CpG sites and 8,692 differential methylation regions (DMRs), with part of them settled in promoter regions. Bioinformatic analysis revealed that differential CpG islands and DMRs in promoter impacted 270 GO functions and 34 KEGG signaling pathways, with some closely related to stem cell biology. Mechanismly, SETD4 knockout inhibited sets of monomethylases and dimethylases for histone lysine, along with significant changes in some factors including Nkx2.5, Gata4, Gli2, Grem2, E2f7, Map7, Nr2f2 and Shox2 that associated with stem cell biology. These results are the first to reveal that even though SETD4 changes the genome's overall methylation to a limited extent in BMSCs, it still affects the numerous cellular functions and signaling pathways, implying SETD4-altered genomic methylation serves a crucial molecular role in BMSCs' biological functions.

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.

MicroRNA-23 suppresses osteogenic differentiation of human bone marrow mesenchymal stem cells by targeting the MEF2C-mediated MAPK signaling pathway

BACKGROUND

The present study aimed to determine the role and mechanism of miR-23 with respect to regulating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs).

MATERIALS

The expression of miR-23 and MEF2C was measured in osteoporosis (OP) patients and healthy controls by a quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). The correlation between miR-23 and MEF2C was determined by the Pearson correlation coefficient. Moreover, bioinformatic analysis was performed using public databases. Target gene function and potential pathways were further examined. Then, we used a miR-23 mimic or inhibitor to further explore the potential mechanism of miR-23.

RESULTS

miR-23 is found to be up-regulated and MEF2C is down-regulated in OP patients compared to healthy controls. miR-23 had a negative correlation with MEF2C (r = -0.937, p = 0.001). Bioinformatic analysis revealed that a total of 664 overlapping target genes were found in the TargetScan (http://www.targetscan.org), miRDB (http://mirdb.org) and miRanda (http://www.microrna.org/microrna/home.do) databases. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that miR-23 may regulate the mitogan-activated protein kinase (MAPK) signaling pathway. miR-23 is down-regulated and MEF2C is significantly up-regulated in the osteogenic differentiation of hBMSCs. MEF2C was significantly up-regulated in the osteogenic differentiation of hBMSCs. Overexpression of miR-23 significantly down-regulated alkaline phosphatase (ALP) activity and calcium deposition, whereas the miR-23 inhibitor had the opposite effects. Moreover, overexpression of miR-23 significantly decreased osteoblast-related markers (Runx2, Osx, ALP and OCN). Further experiments confirmed that MEF2C is a direct target of miR-23. Moreover, the miR-23 mimic enhanced the expression of p-p38 but had no effect on p-JNK.

CONCLUSIONS

miR-23 decreases the osteogenic differentiation of hBMSCs through the MEF2C/MAPK signaling pathway.

Recruitment of Mesenchymal Stem Cells to Damaged Sites by Plant-Derived Components

Mesenchymal stem cells (MSCs) are capable of differentiating into a limited number of diverse cells and secrete regenerative factors that contribute to the repair of damaged tissue. In response to signals emitted by tissue damage, MSCs migrate from the bone marrow and area surrounding blood vessels within tissues into the circulating blood, and accumulate at the site of damage. Hence, MSC transplantation therapy is beginning to be applied to the treatment of various intractable human diseases. Recent medicinal plants studies have shown that plant-derived components can activate cell functions. For example, several plant-derived components activate cell signaling pathways, such as phosphatidylinositol 3-kinase and mitogen-activated protein kinase (MAPK), enhance expression of the CXCL12/CXCR4 axis, stimulate extracellular matrix remodeling, and consequently, promote cell migration of MSCs. Moreover, plant-derived components have been shown to promote recruitment of MSCs to damaged tissues and enhance healing in disease models, potentially advancing their therapeutic use. This article provides a comprehensive review of several plant-derived components that activate MSC migration and homing to damaged sites to promote tissue repair.

Prenylflavonoid Icariin Induces Estrogen Response Element-Independent Estrogenic Responses in a Tissue-Selective Manner

Icariin, a flavonoid phytoestrogen derived from Herba epimedii, has been reported to exert estrogenic effects in bone and activate phosphorylation of estrogen receptor (ER) α in osteoblastic cells. However, it is unclear whether icariin selectively exerts estrogenic activities in bone without inducing undesirable effects in other estrogen-sensitive tissues. The present study aimed to investigate the tissue-selective estrogenic activities of icariin in estrogen-sensitive tissues in vivo and in vitro. Long-term treatment with icariin effectively prevented bone of ovariectomized (OVX) rats from estrogen deficiency–induced osteoporotic changes in bone structure, bone mineral density, and trabecular properties. Moreover, icariin regulated the transcriptional events of estrogen-responsive genes related to bone remodeling and prevented dopaminergic neurons against OVX-induced changes by rescuing expression of estrogen-regulated tyrosine hydroxylase and dopamine transporter in the striatum. Unlike estrogen, icariin did not induce estrogenic effects in the uterus and breast in mature OVX rats or immature CD-1 mice. In vitro studies demonstrated that icariin exerted estrogen-like activities and regulated the expression of estrogen-responsive genes but did not induce estrogen response element–dependent luciferase activities in ER-positive cells. Our results support the hypothesis that icariin, through its distinct mechanism of actions in activating ER, selectively exerts estrogenic activities in different tissues and cell types.

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.

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.