Enhanced cartilage repair using gelatin methacryloyl hydrogels combined with icariin and magnesium-doped bioactive glass

Cartilage repair remains challenging due to limited self-healing, poor biocompatibility, and insufficient mechanical properties of current materials. To overcome these issues, we developed a multifunctional composite hydrogel by integrating gelatine methacrylate (GelMA) with magnesium-doped bioactive glass (Mg-BG) and icariin (ICA). SEM analysis revealed that pure GelMA exhibited a highly porous yet loosely organized structure, whereas the addition of Mg-BG and ICA produced a denser, more interconnected porous network that enhances cell adhesion and nutrient diffusion. In vitro, the ICA/Mg-BG/GelMA hydrogel achieved a swelling ratio up to 430% and maintained cell viability above 80% over 5 days. Moreover, qRT-PCR and immunohistochemical analyses demonstrated that the composite hydrogel upregulated chondrogenic markers (SOX9, ACAN, and COL2A1) compared with GelMA alone. Specifically, it downregulates M1 pro-inflammatory markers (CCR7, iNOS, CD86) and upregulates M2 anti-inflammatory markers (ARG1, CD163, CD206), thereby creating a regenerative microenvironment. These results indicate that the synergistic combination of GelMA, Mg-BG, and ICA not only improves the scaffold's mechanical support but also enhances its biological functionality, offering a promising strategy for cartilage repair. Future studies will focus on in vivo validation to further assess its clinical potential.

HBP-A Attenuates Knee Osteoarthritis Progression via MLK3/P38/HDAC4 Axis-Mediated Dual Protection of Articular Cartilage and Quadriceps

Knee osteoarthritis (KOA), a degenerative joint disease driven by biomechanical instability, involves cartilage degradation, muscle dysfunction, and MLK3/P38 MAPK pathway activation. Histone deacetylase 4 (HDAC4), a regulator of chondrocyte and muscle homeostasis, interacts with this pathway during disease progression. While Hyriopsis Bioactive Polysaccharide-Anodonta (HBP-A) exhibits P38 MAPK inhibitory properties in vitro, its in vivo therapeutic effects on musculoskeletal tissues remain uncharacterised. A destabilisation of the medial meniscus (DMM) mouse model was established to investigate HBP-A's therapeutic potential. Animals were randomly divided into sham-operated, DMM-induced, and HBP-A-treated groups. Following surgical induction, HBP-A (0.26 g/kg) was administered daily via oral gavage for 4 weeks. Comprehensive assessments included behavioural tests for pain sensitivity, micro-CT scanning, histological evaluation, and transmission electron microscope. Molecular mechanisms were investigated via immunohistochemical or immunofluorescence staining of MLK3, P38 MAPK, Caspase-3, and HDAC4, complemented by RT-qPCR analysis of myokine expression. HBP-A treatment significantly alleviated pain sensitivity compared to the DMM group. Structural evaluations revealed preserved subchondral bone integrity and attenuated cartilage degeneration, with histological scoring confirming reduced pathological changes. Quadriceps exhibited mitigated atrophy and restored ultrastructural organisation. Molecular profiling demonstrated suppressed MLK3/P38 MAPK pathway activation, diminished apoptotic activity, and elevated HDAC4 expression in both cartilage and quadriceps. HBP-A additionally normalised dysregulated expression of muscle-derived osteogenic factors linked to bone-cartilage crosstalk. These findings establish HBP-A as a dual-target therapeutic agent for KOA, concurrently mitigating cartilage and muscle degeneration through MLK3/P38 MAPK/HDAC4 axis modulation.

Control and interplay of scaffold-biomolecule interactions applied to cartilage tissue engineering

Cartilage tissue engineering based on the combination of biomaterials, adult or stem cells and bioactive factors is a challenging approach for regenerative medicine with the aim of achieving the formation of a functional neotissue stable in the long term. Various 3D scaffolds have been developed to mimic the extracellular matrix environment and promote cartilage repair. In addition, bioactive factors have been extensively employed to induce and maintain the cartilage phenotype. However, the spatiotemporal control of bioactive factor release remains critical for maximizing the regenerative potential of multipotent cells, such as mesenchymal stromal cells (MSCs), and achieving efficient chondrogenesis and sustained tissue homeostasis, which are essential for the repair of hyaline cartilage. Despite advances, the effective delivery of bioactive factors is limited by challenges such as insufficient retention at the site of injury and the loss of therapeutic efficacy due to uncontrolled drug release. These limitations have prompted research on biomolecule-scaffold interactions to develop advanced delivery systems that provide sustained release and controlled bioavailability of biological factors, thereby improving therapeutic outcomes. This review focuses specifically on biomaterials (natural, hybrid and synthetic) and biomolecules (molecules, proteins, nucleic acids) of interest for cartilage engineering. Herein, we review in detail the approaches developed to maintain the biomolecules in scaffolds and control their release, based on their chemical nature and structure, through steric, non-covalent and/or covalent interactions, with a view to their application in cartilage repair.

A Novel Scaffold of Icariin/Porous Magnesium Alloy-Repaired Knee Cartilage Defect in Rat by Wnt/β-Catenin Signaling Pathway

Cartilage defects caused by joint diseases are difficult to treat clinically. Tissue engineering materials provide a new means to promote the repair of cartilage defects. The purpose of this study is to design a novel scaffold of porous magnesium alloy loaded with icariin and sustained release in order to explore the effect and possible mechanism of this scaffold in repairing SD rat knee articular cartilage defect. We constructed a novel type of icariin/porous magnesium alloy scaffold, observed the structure of the scaffold by electron microscope, detected the drug release of icariin in the scaffold and the biological safety, and established an animal model of cartilage defect in the femoral intercondylar fossa of the knee joint in rats; the scaffold was placed in the defect. After 12 weeks of repair, the rat knee articular cartilage repair was evaluated by gross specimens and micro-CT, HE, safranin O-fast green, and toluidine blue staining combined with the modified Mankin's score. The protein expressions of the Wnt/β-catenin signaling pathway-related factors (β-catenin, Wnt5a, Wnt1, sFRP1) and chondrogenic differentiation-related factors (Sox9, Aggrecan, Col2α1) were detected by immunohistochemical staining. We found that the novel scaffold of icariin/porous magnesium alloy can release icariin slowly and has biosafety in rats. Compared with other groups, icariin/porous magnesium alloy can significantly promote the repair of cartilage defects and the expressions of β-catenin, Wnt5a, Wnt1, Sox9, Aggrecan, and Col2α1 (P < 0.05). This novel scaffold can promote the repair of rat knee cartilage defects, and this process may be achieved by activating the Wnt/β-catenin signaling pathway.

Empowering Cartilage Restructuring with Biodegradable Magnesium Doped-Silicon Based-Nanoplatforms: Sustained Delivery and Enhanced Differentiation Potential

Background

Cartilage-related diseases, such as hypoplastic chondrodysplasia a rare genetic disorder that affects newborns, causing abnormal cartilage development and restricted skeletal growth. However, the development of effective treatment strategies for chondrodysplasia still faces significant challenges due to limitations in the controlled drug delivery, biocompatibility, and biodegradability of nanomedicines.

Methods

A biodegradable magnesium doped-silicon based-nanoplatforms based on silicon nanoparticles (MON) was constructed. Briefly, the MON was modified with sulfhydryl groups using MPTMS to form MOS. Further engineering of MOS was achieved by incorporating Mg2+ ions through the "dissolution-regrowth" method, resulting in MMOS. Ica was effectively loaded into the MMOS channels, and HA was anchored on the surface of MOS to obtain MMOS-Ica@HA nanoplatforms. Additionally, in vitro cell experiments and in vivo zebrafish embryo models were used to evaluate the effect of the nanoplatforms on cartilage differentiation or formation and the efficiency of treating chondrodysplasia.

Results

A series of characterization tests including TEM, SEM, DLS, XPS, EDX, and BET analysis validate the successful preparation of MOS-Ica@HA nanoplatforms. The prepared nanoplatforms show excellent dispersion and controllable drug release behavior. The cytotoxicity evaluation reveals the good biocompatibility of MOS-Ica@HA due to the sustained and controllable release of Ica. Importantly, the presence of Ica and Mg component in MOS-Ica@HA significantly promote chondrogenic differentiation of BMSCs via the Smad5/HIF-1α signaling pathway. In vitro and in vivo experiments confirmed that the nanoplatforms improved chondrodysplasia by promoting cartilage differentiation and formation.

Conclusion

The findings suggest the potential application of the developed biodegradable MMOS-Ica@HA nanoplatforms with acceptable drug loading capacity and controlled drug release in chondrodysplasia treatment, which indicates a promising approach for the treatment of chondrodysplasia.

Icariin Promotes Osteogenic Differentiation in a Cell Model with NF1 Gene Knockout by Activating the cAMP/PKA/CREB Pathway

Neurofibromatosis type 1 is a rare autosomal dominant genetic disorder, with up to 50% of patients clinically displaying skeletal defects. Currently, the pathogenesis of bone disorders in NF1 patients is unclear, and there are no effective preventive and treatment measures. In this study, we found that knockout of the NF1 gene reduced cAMP levels and osteogenic differentiation in an osteoblast model, and icariin activated the cAMP/PKA/CREB pathway to promote osteoblast differentiation of the NF1 gene knockout cell model by increasing intracellular cAMP levels. The PKA selective inhibitor H89 significantly impaired the stimulatory effect of icariin on osteogenesis in the NF1 cell model. In this study, an osteoblast model of NF1 was successfully constructed, and icariin was applied to the cell model for the first time. The results will help to elucidate the molecular mechanism of NF1 bone disease and provide new ideas for the clinical prevention and treatment of NF1 bone disease and drug development in the future.

Osteoporosis remission via an anti-inflammaging effect by icariin activated autophagy

The pace of bone formation slows down with aging, which leads to the development of osteoporosis. In addition to senescent bone marrow mesenchymal stem cells (S-BMSCs), senescent macrophages (S-MΦs) present in the bone marrow produce numerous inflammatory cytokines that contribute to the inflammaged microenvironment and are involved in the development of osteoporosis. Although autophagy activation has shown a significant anti-aging effect, its influence on inflammaging and its role in osteoporosis treatment remain unclear. Traditional Chinese herbal medicine contains bioactive components that exhibit remarkable advantages in bone regeneration. We have demonstrated that icariin (ICA), a bioactive component of traditional Chinese herbal medicine, activates autophagy, exerts a significant anti-inflammaging effect on S-MΦs, and rejuvenates osteogenesis of S-BMSCs, thereby alleviating bone loss in osteoporotic mice. The transcriptomic analysis further reveals that the TNF-α signaling pathway, which is significantly associated with the level of autophagy, regulates this effect. Moreover, the expression of senescence-associated secretory phenotype (SASP) is significantly reduced after ICA treatment. In summary, our findings suggest that bioactive components/materials targeting autophagy can effectively modulate the inflammaging of S-MΦs, offering an innovative treatment strategy for osteoporosis remission and various age-related comorbidities.

Potential of Icariin–Glucosamine Combination in the Treatment of Osteoarthritis by Topical Application: Development of Topical Formulation and In Vitro Permeation Study

The aim of this study was to develop a topically applied formulation with the potential to alleviate arthritis ailments. A combination of two active ingredients, icariin from Epimedium L. (Species: Epimedium Koreanum) extract as a potential promoter of chondrogenesis and glucosamine sulfate as a precursor of cartilage tissues, was tested. In permeation studies, the potential for skin permeation of both substances was confirmed; however, the in vitro release test did not accurately reflect the degree of skin permeation. The in vitro release of icariin was at a level of 15.0–19.0% for the plant-extract-derived icariin and 29.0–35.0% for the pure substance. The level of glucosamine sulfate release was 38.4% (on average). For icariin of both origins, the release results were higher than those obtained via oral administration (about 12.0%), which shows the potential superiority of topical application. In addition, the physicochemical parameters that affect the in vitro release and performance of topical formulations were addressed. This preliminary research and permeation analysis of the formulation produced a promising picture of its prospects regarding arthritis treatment, although further investigation is needed.

Nanoengineered hydrogels as 3D biomimetic extracellular matrix with injectable and sustained delivery capability for cartilage regeneration

The regeneration of articular cartilage remains a great challenge due to the difficulty in effectively enhancing spontaneous healing. Recently, the combination of implanted stem cells, suitable biomaterials and bioactive molecules has attracted attention for tissue regeneration. In this study, a novel injectable nanocomposite was rationally designed as a sustained release platform for enhanced cartilage regeneration through integration of a chitosan-based hydrogel, articular cartilage stem cells (ACSCs) and mesoporous SiO₂ nanoparticles loaded with anhydroicaritin (AHI). The biocompatible engineered nanocomposite acting as a novel 3D biomimetic extracellular matrix exhibited a remarkable sustained release effect due to the synergistic regulation of the organic hydrogel framework and mesopore channels of inorganic mSiO₂ nanoparticles (mSiO₂ NPs). Histological assessment and biomechanical tests showed that the nanocomposites exhibited superior performance in inducing ACSCs proliferation and differentiation in vitro and promoting extracellular matrix (ECM) production and cartilage regeneration in vivo. Such a novel multifunctional biocompatible platform was demonstrated to significantly enhance cartilage regeneration based on the sustained release of AHI, an efficient bioactive natural small molecule for ACSCs chondrogenesis, within the hybrid matrix of hydrogel and mSiO₂ NPs. Hence, the injectable nanocomposite holds great promise for use as a 3D biomimetic extracellular matrix for tissue regeneration in clinical diagnostics.

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The anhydroicaritin (AHI) was identified as a bioactive factor for promoting cartilage repair.

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The hydrogel was designed to achieve sustained AHI release and optimize the microenvironment of cartilage defect sites.

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The hydrogel exhibited superior advantages for chondrogenic differentiation and cartilage regeneration.

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The hydrogel holds a great promise for use as functional scaffold for tissue and organ regeneration in the future.

Icariin-loaded hydrogel with concurrent chondrogenesis and anti-inflammatory properties for promoting cartilage regeneration in a large animal model

Currently, an effective repair method that can promote satisfactory cartilage regeneration is unavailable for cartilage damages owing to inevitable inflammatory erosion. Cartilage tissue engineering has revealed considerable treatment options for cartilage damages. Icariin (ICA) is a flavonoid component of Epimedii folium with both chondrogenic and anti-inflammatory properties. In this study, we prepared an ICA/CTS hydrogel by loading ICA into chitosan (CTS) hydrogel to impart chondrogenesis and anti-inflammatory properties to the ICA/CTS hydrogel. In vitro results revealed that ICA showed sustained release kinetics from the ICA/CTS hydrogel. In addition, compared to the CTS hydrogel, the ICA/CTS hydrogel exhibited a favorable in vitro anti-inflammatory effect upon incubation with lipopolysaccharide pre-induced RAW264.7 macrophages, as indicated by the suppression of inflammatory-related cytokines (IL-6 and TNF-α). Additionally, when co-cultured with chondrocytes in vitro, the ICA/CTS hydrogel showed good cytocompatibility, accelerated chondrocyte proliferation, and enhanced chondrogenesis compared to the CTS hydrogel. Moreover, the in vitro engineered cartilage from the chondrocyte-loaded ICA/CTS hydrogel achieved stable cartilage regeneration when subcutaneously implanted in a goat model. Finally, the addition of ICA endowed the ICA/CTS hydrogel with a potent anti-inflammatory effect compared to what was observed in the CTS hydrogel, as confirmed by the attenuated IL-1β, IL-6, TNF-α, and TUNEL expression. The prepared ICA/CTS hydrogel offered an effective method of delivery for chondrogenic and anti-inflammatory agents and served as a useful platform for cartilage regeneration in an immunocompetent large animal model.

Progress in Composite Hydrogels and Scaffolds Enriched with Icariin for Osteochondral Defect Healing

Osteochondral structure reconstruction by tissue engineering, a challenge in regenerative medicine, requires a scaffold that ensures both articular cartilage and subchondral bone remodeling. Functional hydrogels and scaffolds present a strategy for the controlled delivery of signaling molecules (growth factors and therapeutic drugs) and are considered a promising therapeutic approach. Icariin is a pharmacologically-active small molecule of prenylated flavonol glycoside and the main bioactive flavonoid isolated from Epimedium spp. The in vitro and in vivo testing of icariin showed chondrogenic and ostseoinductive effects, comparable to bone morphogenetic proteins, and suggested its use as an alternative to growth factors, representing a low-cost, promising approach for osteochondral regeneration. This paper reviews the complex structure of the osteochondral tissue, underlining the main aspects of osteochondral defects and those specifically occurring in osteoarthritis. The significance of icariin's structure and the extraction methods were emphasized. Studies revealing the valuable chondrogenic and osteogenic effects of icariin for osteochondral restoration were also reviewed. The review highlighted th recent state-of-the-art related to hydrogels and scaffolds enriched with icariin developed as biocompatible materials for osteochondral regeneration strategies.

Exploration of the Effect of Icariin on Nude Mice with Lung Cancer Bone Metastasis via the OPG/RANKL/RANK System

Epimedium is a traditional Chinese medicine that is most commonly prescribed by practitioners of Chinese medicine for the clinical treatment of malignant tumor bone metastasis. The main component of Epimedium is icariin (ICA). Studies have shown that ICA inhibits bone resorption of osteoclasts through the OPG/RANKL/RANK signaling pathway. Osteoclasts are the only cells in the body that have a bone-destroying capability. The OPG/RANKL/RANK system consists of cytokines that play major roles in osteoclast formation. Therefore, our study selected the OPG/RANKL/RANK system as the research target to investigate the effect of ICA on nude mice with lung cancer bone metastasis. We established the model of bone metastasis in nude mice, intervened the model with icariin and zoledronic acid, and detected the levels of OPG and RANKL by ELISA and western blot. The results showed that ICA had a significant inhibitory effect on bone metastases in nude mice. ICA achieved its antibone metastasis effect in nude mice with lung cancer via inhibiting RANKL expression and simultaneously increasing OPG expression. ICA not only alleviated osteolytic bone destruction caused by bone metastases, but it also reduced weight loss in tumor-bearing nude mice at the late stage of the experiment. The role of ICA in preventing bone metastasis of lung cancer merits further investigation.

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.

Natural Polymeric Scaffolds for Tissue Engineering Applications

Natural polymeric scaffolds can be used for tissue engineering applications such as cell delivery and cell-free supporting of native tissues. This is because of their desirable properties such as; high biocompatibility, tunable mechanical strength and conductivity, large surface area, porous- and extracellular matrix (ECM)-mimicked structures. Specifically, their less toxicity and biocompatibility makes them suitable for several tissue engineering applications. For these reasons, several biopolymeric scaffolds are currently being explored for numerous tissue engineering applications. To date, research on the nature, chemistry, and properties of nanocomposite biopolymers are been reported, while the need for a comprehensive research note on more tissue engineering application of these biopolymers remains. As a result, this present study comprehensively reviews the development of common natural biopolymers as scaffolds for tissue engineering applications such as cartilage tissue engineering, cornea repairs, osteochondral defect repairs, and nerve regeneration. More so, the implications of research findings for further studies are presented, while the impact of research advances on future research and other specific recommendations are added as well.

Effect of quercetin on chondrocyte phenotype and extracellular matrix expression

Due to the poor repair ability of cartilage tissue, regenerative medicine still faces great challenges in the repair of large articular cartilage defects. Quercetin is widely applied as a traditional Chinese medicine in tissue regeneration including liver, bone and skin tissues. However, the evidence for its effects and internal mechanisms for cartilage regeneration are limited. In the present study, the effects of quercetin on chondrocyte function were systematically evaluated by CCK8 assay, PCR assay, cartilaginous matrix staining assays, immunofluorescence assay, and western blotting. The results showed that quercetin significantly up-regulated the expression of chondrogenesis genes and stimulated the secretion of GAG (glycosaminoglycan) through activating the ERK, P38 and AKT signalling pathways in a dose-dependent manner. Furthermore, in vivo experiments revealed that quercetin-loaded silk protein scaffolds dramatically stimulated the formation of new cartilage-like tissue with higher histological scores in rat femoral cartilage defects. These data suggest that quercetin can effectively stimulate chondrogenesis in vitro and in vivo, demonstrating the potential application of quercetin in the regeneration of cartilage defects.

Small molecule compounds promote the proliferation of chondrocytes and chondrogenic differentiation of stem cells in cartilage tissue engineering

The application of tissue engineering to generate cartilage is limited because of low proliferative ability and unstable phenotype of chondrocytes. The sources of cartilage seed cells are mainly chondrocytes and stem cells. A variety of methods have been used to obtain large numbers of chondrocytes, including increasing chondrocyte proliferation and stem cell chondrogenic differentiation via cytokines, genes, and proteins. Natural or synthetic small molecule compounds can provide a simple and effective method to promote chondrocyte proliferation, maintain a stable chondrocyte phenotype, and promote stem cell chondrogenic differentiation. Therefore, the study of small molecule compounds is of great importance for cartilage tissue engineering. Herein, we review a series of small molecule compounds and their mechanisms that can promote chondrocyte proliferation, maintain chondrocyte phenotype, or induce stem cell chondrogenesis. The studies in this field represent significant contributions to the research in cartilage tissue engineering and regenerative medicine.

Herbal Remedies as Potential in Cartilage Tissue Engineering: An Overview of New Therapeutic Approaches and Strategies

It is estimated that by 2023, approximately 20% of the population of Western Europe and North America will suffer from a degenerative joint disease commonly known as osteoarthritis (OA). During the development of OA, pro-inflammatory cytokines are one of the major causes that drive the production of inflammatory mediators and thus of matrix-degrading enzymes. OA is a challenging disease for doctors due to the limitation of the joint cartilage's capacity to repair itself. Though new treatment approaches, in particular with mesenchymal stem cells (MSCs) that integrate the tissue engineering (TE) of cartilage tissue, are promising, they are not only expensive but more often do not lead to the regeneration of joint cartilage. Therefore, there is an increasing need for novel, safe, and more effective alternatives to promote cartilage joint regeneration and TE. Indeed, naturally occurring phytochemical compounds (herbal remedies) have a great anti-inflammatory, anti-oxidant, and anabolic potential, and they have received much attention for the development of new therapeutic strategies for the treatment of inflammatory diseases, including the prevention of age-related OA and cartilage TE. This paper summarizes recent research on herbal remedies and their chondroinductive and chondroprotective effects on cartilage and progenitor cells, and it also emphasizes the possibilities that exist in this research area, especially with regard to the nutritional support of cartilage regeneration and TE, which may not benefit from non-steroidal anti-inflammatory drugs (NSAIDs).

Electrospun Icariin-Loaded Core-Shell Collagen, Polycaprolactone, Hydroxyapatite Composite Scaffolds for the Repair of Rabbit Tibia Bone Defects

Background

Electrospinning is a widely used technology that can produce scaffolds with high porosity and surface area for bone regeneration. However, the small pore sizes in electrospun scaffolds constrain cell growth and tissue-ingrowth. In this study, novel drug-loading core-shell scaffolds were fabricated via electrospinning and freeze drying to facilitate the repair of tibia bone defects in rabbit models.

Materials and Methods

The collagen core scaffolds were freeze-dried containing icariin (ICA)-loaded chitosan microspheres. The shell scaffolds were electrospun using collagen, polycaprolactone and hydroxyapatite materials to form CPH composite scaffolds with the ones containing ICA microspheres named CPHI. The core-shell scaffolds were then cross-linked by genipin. The morphology, microstructure, physical and mechanical properties of the scaffolds were assessed. Rat marrow mesenchymal stem cells from the wistar rat were cultured with the scaffolds. The cell adhesion and proliferation were analysed. Adult rabbit models with tibial plateau defects were used to evaluate the performance of these scaffolds in repairing the bone defects over 4 to 12 weeks.

Results

The results reveal that the novel drug-loading core-shell scaffolds were successfully fabricated, which showed good physical and chemical properties and appropriate mechanical properties. Furthermore, excellent cells attachment was observed on the CPHI scaffolds. The results from radiography, micro-computed tomography, histological and immunohistochemical analysis demonstrated that abundant new bones were formed on the CPHI scaffolds.

Conclusion

These new core-shell composite scaffolds have great potential for bone tissue engineering applications and may lead to effective bone regeneration and repair.

The Effects of Fibrin-icariin Nanoparticle Loaded in Poly (lactic-co-glycolic) Acid Scaffold as a Localized Delivery System on Chondrogenesis of Human Adipose-derived Stem Cells

Background:

Nowadays, cartilage tissue engineering is the best candidate for regeneration of cartilage defects. This study evaluates the effect of fibrin/icariin (ICA) nanoparticles (F/I NPs) on chondrogenesis of stem cells.

Materials and Methods:

F/I NPs were characterized by Dynamic Light Scattering DLS. Poly (lactic-co-glycolic) acid (PLGA)-F/I NP scaffold was fabricated and assessed by scanning electron microscope. Human adipose-derived stem cells (hADSCs) were seeded on scaffold and induced for chondrogenesis. After 14 days, cell viability and gene expression were analyzed by the 3-(4, 5- dimethylthiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. MTT assay and real-time polymerase chain reaction (RT-PCR).

Results:

The size and surface charge of F/I NP were about 28–30 nm and − 17, respectively. The average of pore size of PLGA and PLGA–fibrin/ICA was 230 and 340 μm, respectively. Cell viability of differentiated cells in P/F group was higher than others significantly (P ≤ 0.05). Furthermore, quantitative RT-PCR analysis demonstrated that ICA upregulated cartilaginous-specific gene expression. Furthermore, the results of the expression of type I collagen revealed that ICA downregulated this gene significantly (P < 0.01).

Conclusions:

The results indicated that F/I NP could be a potential factor for chondrogenesis of stem cells and downregulation of fibrocartilage marker.

Icariin-conditioned serum engineered with hyaluronic acid promote repair of articular cartilage defects in rabbit knees

BACKGROUND

Osteochondral defects mostly occur as a result of trauma or articular degeneration. The poor regenerative ability of articular cartilage remains osteochondral defects are a tricky problem to deal with. The modern treatment strategies mainly focus on cartilage tissue engineering with bioactive materials. In this study, we aimed to develop icariin conditioned serum (ICS) together with hyaluronic acid (HA) and determine their ability in reparing osteochondral tissue in a critical-sized defect in rabbit knees.

METHODS

Primary chondrocytes were incubated with serum conditioned with icariin at different concentrations, then cell proliferation rates and glycosaminoglycan (GAG) secretion were detected. Rabbits were treated with intra-articular injection of 0.5 mL normal saline (NS), ICS, HA and ICS + HA in the right knee joint, respectively. ICRS scores were used to assess the macroscopic cartilage regeneration. Histological and immunohistochemical analysis including H&E, Safranin O, toluidine blue and collagen II staining were used to determine the repair of cartilage and the regeneration of chondrocytes.

RESULTS

Icariin at a low dose of 0.94 g/kg was identified to have significantly promoted the proliferation of chondrocytes and enhance the secretion of GAG. Femoral condyle from rabbits treated by ICS together with HA was observed to be integrated with native cartilage and more subchondral bone regeneration. ICS together with HA could promote repair of the cartilage defect and increase the neoformation of cartilage.

CONCLUSIONS

These results demonstrated the potential of ICS combined with HA to promote reparative response in cartilage defects and the possible application in bioactive material based cartilage regeneration therapies.

Autologous Freeze-Dried, Platelet-Rich Plasma Carrying Icariin Enhances Bone-Tendon Healing in a Rabbit Model

BACKGROUND

Tendon-bone interface (TBI) injuries are common in sports activities. Owing to the limited regenerative ability of the TBI, its functional healing remains a difficulty in clinical practice. Icariin (ICA) provides strong stimulation for osteogenesis. Platelet-rich plasma (PRP) can be used as a carrier for bioactive molecules, although its ability to provide sustained release for such molecules needs improvement.

HYPOTHESIS

Freeze-dried PRP (FD-PRP) as a carrier for ICA can provide sustained release of ICA into the tendon-bone (T-B) healing site, thus accelerating T-B healing.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 84 New Zealand rabbits with partial patellectomy in the hindlimb were randomly allocated into 3 different treatments: ICA incorporated with FD-PRP (ICA/FD-PRP), FD-PRP alone (FD-PRP), or saline control (CTL). The rabbit patella-patellar tendon (PP) interfaces were postoperatively harvested at postoperative week 8 or 16 for gross, radiological, histological, and mechanical evaluations.

RESULTS

Our results showed that FD-PRP can act as a carrier for sustained release of ICA into the T-B healing site. Macroscopically, no signs of infection or osteoarthritis were shown in the regenerated PP interfaces, and the area of cartilaginous metaplasia in the FD-PRP and ICA/FD-PRP groups at postoperative week 16 was significantly larger than that of the CTL group (P < .05 for all). Radiologically, micro-computed tomography showed that new bone which formed at the healing site in the ICA/FD-PRP group was significantly increased, remodeled, and mineralized in comparison with the CTL group (P < .05 for all). Histologically, the ICA/FD-PRP group exhibited a significant native PP interface, as shown by the enlargement and remodeling of new bone, well-organized collagen fibers, and robust production of proteoglycans in the regenerated fibrocartilage. The mechanical strength of the regenerated PP interface was significantly improved in the ICA/FD-PRP group. Significantly higher failure load and stiffness were shown in the ICA/FD-PRP group compared with the CTL and FD-PRP groups, respectively (P < .05 for all).

CONCLUSION

FD-PRP is a suitable sustained-release carrier for ICA, and ICA/FD-PRP can provide sustained release of ICA into the T-B healing site, thus effectively accelerating T-B healing.

CLINICAL RELEVANCE

Findings of this study demonstrate the feasibility of using FD-PRP as a carrier for ICA to improve T-B healing and provide a foundation for future clinical application.

mPEG-icariin nanoparticles for treating myocardial ischaemia

Icariin (ICA), a major active ingredient from Chinese medicine, has unique pharmacological effects on ischaemic heart disease. However, its hydrophobic property limits its administration and leads to poor efficacy. This work aimed to change its hydrophobic property and improve the treatment efficacy. We designed a new nano-drug to increase the ICA delivery. ICA was modified with hydrophilic polyethylene glycol monomethyl ether (mPEG) by a succinic anhydride linker to form a polyethylene glycol-icariin (mPEG-ICA) polymer. The structure of this polymer was identified by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The content of ICA in the polymer was 32% as detected by ultraviolet spectrophotometry. mPEG-ICA nanoparticles, of 143.3 nm, were prepared by the dialysis method, and zeta potential was 0.439 mV by dynamic light scattering. The nanoparticles had a spherical shape on transmission electron microscopy. In media with pH 7.4 and 6.8, ICA release from mPEG-ICA nanoparticles after 72 h was about 0.78% and 64.05%, respectively, so the ICA release depended on the release media pH. On MTT and lactate dehydrogenase activity assay, mPEG-ICA nanoparticles could reduce cell damage induced by oxgen-glucose deprivation. Hoechst 33258 staining and TUNEL and AnnexinV-FITC/PI double staining showed that ICA nanoparticles could increase the activity of H9c2 cardiomyocytes under oxgen-glucose deprivation conditions by decreasing apoptosis. ICA modified by hydrophilic mPEG could improve its efficacy.

Development of an injectable thiolated icariin functionalized collagen/hyaluronic hydrogel to promote cartilage formation in vitro and in vivo

Development of an in situ injectable hydrogel with controlled-release of bioactive molecules is an effective strategy to maintain chondrocyte phenotype and promote cartilage formation for clinical applications. In this study, we developed an injectable thiolated icariin functionalized hyaluronic acid/collagen hydrogel (HIC) under physiological conditions. In order to covalently introduce icariin (Ica) into an injectable hydrogel and increase its loading, thiolated icariin (Ica-SH) was successfully synthesized. Ica-SH could not only decrease the cytotoxicity of Ica, but also increase the Ica loading in hydrogels. Compared to hyaluronic acid/collagen hydrogels, HICs facilitated chondrocyte proliferation, maintained chondrocyte phenotype and promoted the secretion of the cartilage extracellular matrix. Overall, this study suggests that HIC has great potential to be developed as an effective and less invasive candidate for clinical application in articular cartilage repair.

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 Reduces Cartilage Degeneration in a Mouse Model of Osteoarthritis and is Associated with the Changes in Expression of Indian Hedgehog and Parathyroid Hormone-Related Protein

Background

The aim of this study was to determine the role of icariin, a Chinese traditional herbal medicine extracted from Epimedium, in osteoarthritis (OA), using the murine anterior cruciate ligament transection (ACLT)-induced model of OA and micromass culture of murine chondrocytes.

Material/Methods

Twenty-four three-month-old C57/6J mice were randomly divided into three groups: the sham group (no surgery and joint injection with normal saline) (N=8); the ACLT + ICA group (ACLT surgery and icariin treatment) (N=8); and the ACLT group (ACLT surgery and joint injection with normal saline) (N=8). At 12 weeks after ACLT surgery, murine articular cartilage was harvested from all mice for histological evaluation of any differences in cartilage degeneration. In vitro micromass culture of mouse chondrocytes was used to study the effects of icariin on chondrocyte differentiation and growth from the three mouse groups.

Results

Icariin treatment (mice in the ACLT + ICA group) significantly reduced degeneration of cartilage in OA with increased cartilage thickness, associated with increased expression of collagen type II alpha 1 (COL2A1), decreased chondrocyte hypertrophy, and decreased expression of collagen type X (ColX) and matrix metalloproteinase 13 (MMP13). In vitro, icariin promoted chondrocyte differentiation by upregulating the expression of agrrecan, Sox9 and parathyroid hormone-related protein (PHrP) and down-regulation of Indian hedgehog (Ihh) and genes regulated by Ihh.

Conclusions

In a mouse model of OA icariin treatment reduced destruction of cartilage, promoted chondrocyte differentiation, upregulated expression of PHrP and down-regulated the expression of Ihh.

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

Bone marrow-derived mesenchymal stem cells (BMSCs) are widely used in tissue engineering for regenerative medicine due to their multipotent differentiation potential. However, their poor migration ability limits repair effects. Icariin (ICA), a major component of the Chinese medical herb Herba Epimedii, has been reported to accelerate the proliferation, osteogenic, and chondrogenic differentiation of BMSCs. However, it remains unknown whether ICA can enhance BMSC migration, and the possible underlying mechanisms need to be elucidated. In this study, we found that ICA significantly increased the migration capacity of BMSCs, with an optimal concentration of 1 μmol/L. Moreover, we found that ICA stimulated actin stress fiber formation in BMSCs. Our work revealed that activation of the MAPK signaling pathway was required for ICA-induced migration and actin stress fiber formation. In vivo, ICA promoted the recruitment of BMSCs to the cartilage defect region. Taken together, these results show that ICA promotes BMSC migration in vivo and in vitro by inducing actin stress fiber formation via the MAPK signaling pathway. Thus, combined administration of ICA with BMSCs has great potential in cartilage defect therapy.

[Effect of icariin on serum bone turnover markers expressions and histology changes in mouse osteoarthritis model]

Objective

To investigate the effects of icariin (ICA) on serum bone turnover markers expressions and histological changes of cartilage and subchondral bone in mouse osteoarthritis (OA) model.

Methods

Eighty 8-week-old male C57BL/6J mouse were randomly divided into 8 groups ( n=10). The OA model was established by anterior cruciate ligament transaction (ACLT). Group A: sham operation/early-stage normal saline administration; group B: sham operation/early-stage ICA administration; group C: ACLT/early-stage normal saline administration; group D: ACLT/early-stage ICA administration; group E: sham operation/late-stage normal saline administration; group F: sham operation/late-stage ICA administration; group G: ACLT/late-stage normal saline administration; group H: ACLT/late-stage ICA administration. Each animal received either ACLT or simply opening joint capsule, respectively. For groups B and D, ICA was given by gavage [10 mg/(kg·day)] on the first day after ACLT. For groups F and H, ICA was given with the same volume at 4 weeks after operation. The blood serum of the mouse was collected and prepared at 8 weeks after operation. Serum bone turnover markers and cytokines, including C-telopeptide of type I collagen (CTX), osteocalcin (OC), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and IL-1β, were measured by ELISA. Tissue samples from the knee were stained by alcian blue/hematoxylin & orange G (AB/H&OG). Histological changes of cartilage and subchondral bone were observed and evaluated by Osteoarthritis Research Society International (OARSI) scoring system.

Results

Comparison between each group with early-stage administration (groups A, B, C, and D): Compared with groups A and B, the levels of CTX and OC in group C were significantly reduced ( P<0.05); the levels of IL-6, TNF-α, and IL-1β and OARSI score was significantly increased ( P<0.05). Compared with group C, the levels of CTX and OC in group D were significantly increased ( P<0.05); the level of IL-6 was significantly reduced ( P<0.05); the levels of TNF-α and IL-1β were not changed ( P>0.05), and OARSI score was significantly reduced ( P<0.05). Histological observation showed that the tibial cartilage loss was significantly improved. Comparison between each group with late-stage administration (groups E, F, G, and H): Compared with groups E and F, the levels of CTX and OC in group G were significantly reduced ( P<0.05); the levels of IL-6, TNF-α, and IL-1β and OARSI score were significantly increased ( P<0.05). Compared with group G, the level of CTX in group H were increased ( P<0.05); the levels of OC, IL-6, TNF-α, and IL-1β and OARSI score were not changed ( P>0.05). Histological observation showed that the tibial cartilage loss had no changes after late-stage ICA administration.

Conclusion

ICA plays protective effects on subchondral bone, hyaline, and calcified cartilage. Meanwhile, ICA can improve bone remodeling in subchondral bone of OA to some extent. The consistent changes of serum bone markers and pathological morphology suggest that early intervention of ICA on OA is more effective.

Icariin: a Potential Compound for the Recovery of Tibial Dyschondroplasia Affected Chicken Via Up-Regulating BMP-2 Expression

BACKGROUND

Tibial dyschondroplasia (TD) is a skeletal disease of fast growing chicken and other avian species. It is characterized by an avascular and non-mineralized growth plate, which leads to a deformed tibial bone and lameness. Unfortunately, this disease is not only responsible for causing huge economic losses but also raises animal welfare concerns. Icariin is a flavonoid, which is isolated from Epimedium pubescens herb, and it has been used to cure different diseases including bone fractures and osteoporosis.

RESULTS

We designed this experiment to use icariin for the treatment of TD affect chickens; for this purpose, a total of 180 chicks were equally divided into three groups: control, TD and icariin. All the three groups were offered ad libitum same normal standard diet with an addition of thiram (50 mg/kg) from 3rd day to 7th day in TD and icariin group in order to induce TD in chickens. After the induction of TD, the chickens in icariin groups were fed standard diet with an addition of icariin at the rate of 10 mg/kg in drinking water to check the therapeutic effect of this flavonoid on TD. Our results showed that the icariin helped in restoring the TD lesion into a normal structure with significantly (P < 0.05) up-regulating the bone morphogenetic protein-2 (BMP-2) expression in the tibial growth plates (GP).

CONCLUSIONS

Icariin increased the vascular area in the growth plate and decreased the average TD score. In conclusion, this study shows that icariin is a potential compound for the recovery of TD affected chickens via up-regulating the BMP-2 expression without posing a threat of ingestion of toxic veterinary drug residues to human beings upon the consumption of treated chickens.

Icariin conjugated hyaluronic acid/collagen hydrogel for osteochondral interface restoration

Over the past decades, numerous tissue-engineered constructs have been investigated for the osteochondral repair. However, it still remains a challenge to regenerate the functionalized calcified layer. In this study, the potential of icariin (Ica) conjugated hyaluronic acid/collagen (Ica-HA/Col) hydrogel to promote the osteochondral interface restoration was investigated. Compared with HA/Col hydrogel, Ica-HA/Col hydrogel simultaneously facilitated chondrogenesis and osteogenesis in vitro. The cells encapsulated in Ica-HA/Col hydrogel tended to aggregate into bigger clusters. The chondrogenic genes' expression level was remarkably up-regulated, and the matrix synthesis of sGAG and type II collagen was significantly enhanced. Similarly, the osteogenic genes, including RUNX2, ALP, and OCN were also up-regulated at early stage. Consequently, more calcium deposition was observed in the Ica-HA/Col hydrogel construct. Moreover, the gene expression and matrix synthesis of type X collagen, an important marker for the formation of calcified layer; were significantly higher in the Ica-HA/Col hydrogel. Furthermore, the in vivo study showed that Ica-HA/Col constructs facilitated the reconstruction of osteochondral interface in rabbit subchondral defects. In the Ica-HA/Col group, the neo-cartilage layer contained more type II collagen and the newly formed subchondral bone deposited more abundant type I collagen. Overall, the results indicated that Ica-HA/Col hydrogel might be a promising scaffold to reconstruct an osteochondral interface, therefore promoting restoring of osteochondral defect.

STATEMENT OF SIGNIFICANCE

The osteochondral defect restoration not only involves the repair of damaged cartilage and the subchondral bone, but also the reconstruction of osteochondral interface (the functional calcified layer). The calcified layer regeneration is essential for integrative and functional osteochondral repair. Over the past decade, numerous tissue engineered constructs have been investigated for the osteochondral repair. However, it still remains a challenge to regenerate a functionalized calcified layer. The present study demonstrates that Ica-HA/Col hydrogel facilitates deposition of matrix related to calcified layer in mixed chondrogenic/osteogenic inductive media and restoration of osteochondral defect in vivo. Since, Ica-HA/Col hydrogel as is cheaper, easier and more efficient, it might be a desired scaffold for the osteochondral defects restoration.

Icariin promotes stable chondrogenic differentiation of bone marrow mesenchymal stem cells in self‑assembling peptide nanofiber hydrogel scaffolds

Icariin, a traditional Chinese medicine, has previously been demonstrated to promote chondrogenesis of bone marrow mesenchymal stem cells (BMSCs) in traditional 2D cell culture. The present study investigated whether icariin has the potential to promote stable chondrogenic differentiation of BMSCs without hypertrophy in a 3D microenvironment. BMSCs were cultivated in a self-assembling peptide nanofiber hydrogel scaffold in chondrogenic medium for 3 weeks. Icariin was added to the medium throughout the culture period at concentrations of 1×10⁻⁶ M. Chondrogenic differentiation markers, including collagen II and SRY-type high mobility group box 9 (SOX9) were detected by immunofluorescence, reverse transcription-quantitative polymerase chain reaction and toluidine blue staining. Hypertrophic differentiation was further assessed by detecting collagen X and collagen I gene expression levels and alkaline phosphatase activity. The results demonstrated that icariin significantly enhanced cartilage extracellular matrix synthesis and gene expression levels of collagen II and SOX9, and additionally promoted more chondrocyte-like rounded morphology in BMSCs. Furthermore, chondrogenic medium led to hypertrophic differentiation via upregulation of collagen X and collagen I gene expression levels and alkaline phosphatase activity, which was not potentiated by icariin. In conclusion, these results suggested that icariin treatment may promote chondrogenic differentiation of BMSCs, and inhibit the side effect of growth factor activity, thus preventing further hypertrophic differentiation. Therefore, icariin may be a potential compound for cartilage tissue engineering.

Effect of Icariin on Tibial Dyschondroplasia Incidence and Tibial Characteristics by Regulating P2RX7 in Chickens

Tibial dyschondroplasia (TD) is a disease of rapid growing chickens that occurs in many avian species; it is characterized by nonvascular and nonmineralized growth plates, along with tibia bone deformation and lameness. Icariin is widely used to treat bone diseases in humans, but no report is available regarding the effectiveness of icariin against avian TD. Therefore, this study was designed to determine its effect against TD. For this purpose, a total of 180 broiler chicks were distributed into three groups including control, TD, and icariin group. Control group was given a standard normal diet, while TD and icariin groups received normal standard diet containing 50 mg/kg thiram to induce TD from days 3 to 7 after hatch. After the induction of TD, the chicks of icariin group were fed with standard normal diet by adding 10 mg/kg icariin in water. Then morphological and production parameters analysis of tibial bone indicators, physiological index changes, and gene expression were examined. The results showed that icariin administration not only decreased the mortality but also mitigated the lameness and promoted the angiogenesis, which diminished the TD lesion and significantly increased the expression of P2RX7 (P < 0.05) in TD affected thiram induced chicks. In conclusion, present findings suggest that icariin has a significant role in promoting the recovery of chicken growth plates affected by TD via regulating the P2RX7. Our findings reveal a new target for clinical treatment and prevention of TD in broiler chickens.

Icariin Ameliorate Thiram-Induced Tibial Dyschondroplasia via Regulation of WNT4 and VEGF Expression in Broiler Chickens

Tibial dyschondroplasia (TD) is main bone problem in fast growing poultry birds that effect proximal growth plate (GP) of tibia bone. TD is broadly defined as non-vascularized and non-mineralized, and enlarged GP with tibia bone deformation and lameness. Icariin (Epimedium sagittatum) is a traditional Chinese medicine, which is commonly practiced in the treatment of various bone diseases. Recently, many researcher reports about the beneficial effects of icariin in relation to various types of bone conditions but no report is available about promoting effect of icariin against TD. Therefore, current study was conducted to explore the ameliorating effect of icariin in thiram-induced TD chickens. A total of 180 broiler chicks were equally distributed in three groups; control, TD induced by thiram (50 mg/kg), and icariin group (treated with icariin @10 mg/kg). All groups were administered with normal standard diet ad libitum regularly until the end of experiment. The wingless-type member 4 (WNT4) and vascular endothelial growth factor (VEGF) genes and proteins expression were analyzed by quantitative real-time polymerase chain reaction and western blot analysis respectively. Tibial bone parameters, physiological changes in serum, antioxidant enzymes, and chicken growth performance were determined to assess advantage and protective effect of the medicine in broiler chicken. The expression of WNT4 was decreased while VEGF increased significantly (P < 0.05) in TD affected chicks. TD enhanced the GP, lameness, and irregular chondrocytes, while reduced the liver function, antioxidant enzymes in liver, and performance of chickens. Icariin treatment up-regulated WNT4 and down-regulated VEGF gene and protein expressions significantly (P < 0.05), restored the GP width, increased growth performance, corrected liver functions and antioxidant enzymes levels in liver, and mitigated the lameness in broiler chickens. In conclusion, icariin administration recovered GP size, normalized performance and prevented lameness significantly. Therefore, icariin treatments are encouraged to reduce the incidence of TD in broiler chickens.

Cartilage Tissue Engineering Via Icariin and Adipose-derived Stem Cells in Fibrin Scaffold

Background:

Nowadays, cartilage tissue engineering is the best candidate for regeneration of cartilage defects. This study evaluates the function of herbal extracts icariin (ICA), the major pharmacological constituent of herba Epimedium, compared with transforming growth factor β3 (TGFβ3) to prove its potential effect for cartilage tissue engineering.

Materials and Methods:

ICA, TGFβ3, and TGFβ3 + ICA were added fibrin-cell constructions derived from adipose tissue stem cells. After 14 days, cell viability analyzed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H- tetrazolium bromide assay and the expression of cartilage genes was evaluated with real-time polymerase chain reaction (RT-PCR).

Results:

The results showed ICA, TGFβ3, and TGFβ3 + ICA increased the rate of proliferation and viability of cells; but there were no significant differences between them (P > 0.05). Furthermore, quantitative RT-PCR analysis demonstrated that cooperation of ICA with TGFβ3 showed a better effect in expression of cartilaginous specific genes and increased Sox9, type II collagen, and aggrecan expression significantly. Furthermore, the results of the expression of type I and X collagens revealed that TGFβ3 increased the expression of them (P < 0.01); However, treatment with ICA + TGFβ3 down regulated the expression of these genes significantly.

Conclusion:

The results indicated ICA could be a potential factor for chondrogenesis and in cooperation with TGFβ3 could reduce its hypertrophic effects and it is a promising factor for cartilage tissue engineering.

Role of IFT88 in icariin‑regulated maintenance of the chondrocyte phenotype

Maintenance of the chondrocyte phenotype is crucial for cartilage repair during tissue engineering. Intraflagellar transport protein 88 (IFT88) is an essential component of primary cilia, shuttling signals along the axoneme. The hypothesis of the present study was that IFT88 could exert an important role in icariin‑regulated maintenance of the chondrocyte phenotype. To this end, the effects of icariin on proliferation and differentiation of the chondrogenic cell line, ATDC5, were explored. Icariin‑treated ATDC5 cells and primary chondrocytes expressed IFT88. Icariin has been demonstrated to aid in the maintenance of the articular cartilage phenotype in a rat model of post‑traumatic osteoarthritis (PTOA). Icariin promoted chondrocyte proliferation and expression of the chondrogenesis marker genes, COL II and SOX9, increased ciliary assembly, and upregulated IFT88 expression in a concentration‑ and time‑dependent manner. Icariin‑treated PTOA rats secreted more cartilage matrix compared with the controls. Knockdown of IFT88 expression with siRNA reduced extracellular signal‑regulated kinase (ERK) phosphorylation, and icariin upregulated IFT88 expression by promoting ERK phosphorylation. Thus, IFT88 serves a major role in icariin‑mediated maintenance of the chondrocyte phenotype, promoting ciliogenesis and IFT88 expression by increasing ERK phosphorylation. Icariin may therefore be useful for maintenance of the cartilage phenotype during tissue engineering.

Icariin Regulates Cellular Functions and Gene Expression of Osteoarthritis Patient-Derived Human Fibroblast-Like Synoviocytes

Synovial inflammation plays an important role in the pathogenesis and progress of osteoarthritis (OA). There is an urgent need to find safe and effective drugs that can reduce the inflammation and regulate the pathogenesis of cytokines of the OA disease. Here, we investigated the effect of icariin, the major pharmacological active component of herb Epimedium on human osteoarthritis fibroblast-like synoviocytes (OA–FLSs). The OA–FLSs were isolated from patients with osteoarthritis and cultured in vitro with different concentrations of icariin. Then, cell viability, proliferation, and migration were investigated; MMP14, GRP78, and IL-1β gene expression levels were detected via qRT-PCR. Icariin showed low cytotoxicity to OA–FLSs at a concentration of under 10 μM and decreased the proliferation of the cells at concentrations of 1 and 10 μM. Icariin inhibited cell migration with concentrations ranging from 0.1 to 1 μM. Also, the expression of three cytokines for the pathogenesis of OA which include IL-1β, MMP14 and GRP78 was decreased by the various concentrations of icariin. These preliminary results imply that icariin might be an effective compound for the treatment of OA disease.

Icariin possesses chondroprotective efficacy in a rat model of dexamethasone-induced cartilage injury through the activation of miR-206 targeting of cathepsin K

The present study aimed to investigate the articular cartilage and chondrocytes of dexamethasone (DXM)-induced cartilage injuries in rats in response to treatment with icariin, as well as the implicated molecular mechanism. Effects of icariin on bone metabolism and articular cartilage in experimental rats were investigated. Subsequently, the present study assessed dysregulated microRNA (miRNA) in the articular cartilage of experimental rats, and validated the significant miRNA and their targets. Finally, the effects of icariin on chondrocytes in experimental rats and the implicated molecular mechanism were explored. Quantitative polymerase chain reaction demonstrated that icariin significantly reversed DXM-induced bone degradation and stimulated bone regeneration. In addition, some notable changes in articular cartilage were also observed following continuous administration of icariin to DXM-treated rats, including enhanced cartilage area (revealed by safranin-O staining), substantial decrements in serum concentrations of deoxypyridinoline and C-terminal telopeptide of type II collagen, reduced expression of collagen type I and matrix metalloproteinase-13, as well as elevated expression of transforming growth factor-β. Furthermore, miR-206 was determined to be significantly upregulated in the icariin group compared with the DXM-treated group. A luciferase assay further validated cathepsin K as the target RNA of miR-206. Additionally, icariin (100 µM) facilitated the viability of chondrocytes and reduced apoptotic chondrocytes. More importantly, icariin (100 µM) not only abolished the inhibition effect of DXM on miR-206 expression in chondrocytes, but also eliminated the enhancing effect of DXM on cathepsin K expression. Overall, the present study identified icariin as a novel therapeutic agent in DXM-induced cartilage injury in rats, and revealed that the activation of miR-206 targeting of cathepsin K may be responsible for the chondroprotective efficacy of icariin.

Flavonoid Compound Icariin Activates Hypoxia Inducible Factor-1α in Chondrocytes and Promotes Articular Cartilage Repair

Articular cartilage has poor capability for repair following trauma or degenerative pathology due to avascular property, low cell density and migratory ability. Discovery of novel therapeutic approaches for articular cartilage repair remains a significant clinical need. Hypoxia is a hallmark for cartilage development and pathology. Hypoxia inducible factor-1alpha (HIF-1α) has been identified as a key mediator for chondrocytes to response to fluctuations of oxygen availability during cartilage development or repair. This suggests that HIF-1α may serve as a target for modulating chondrocyte functions. In this study, using phenotypic cellular screen assays, we identify that Icariin, an active flavonoid component from Herba Epimedii, activates HIF-1α expression in chondrocytes. We performed systemic in vitro and in vivo analysis to determine the roles of Icariin in regulation of chondrogenesis. Our results show that Icariin significantly increases hypoxia responsive element luciferase reporter activity, which is accompanied by increased accumulation and nuclear translocation of HIF-1α in murine chondrocytes. The phenotype is associated with inhibiting PHD activity through interaction between Icariin and iron ions. The upregulation of HIF-1α mRNA levels in chondrocytes persists during chondrogenic differentiation for 7 and 14 days. Icariin (10⁻⁶ M) increases the proliferation of chondrocytes or chondroprogenitors examined by MTT, BrdU incorporation or colony formation assays. Icariin enhances chondrogenic marker expression in a micromass culture including Sox9, collagen type 2 (Col2α1) and aggrecan as determined by real-time PCR and promotes extracellular matrix (ECM) synthesis indicated by Alcian blue staining. ELISA assays show dramatically increased production of aggrecan and hydroxyproline in Icariin-treated cultures at day 14 of chondrogenic differentiation as compared with the controls. Meanwhile, the expression of chondrocyte catabolic marker genes including Mmp2, Mmp9, Mmp13, Adamts4 and Adamts5 was downregulated following Icariin treatment for 14 days. In a differentiation assay using bone marrow mesenchymal stem cells (MSCs) carrying HIF-1α floxed allele, the promotive effect of Icariin on chondrogenic differentiation is largely decreased following Cre recombinase-mediated deletion of HIF-1α in MSCs as indicated by Alcian blue staining for proteoglycan synthesis. In an alginate hydrogel 3D culture system, Icariin increases Safranin O positive (SO+) cartilage area. This phenotype is accompanied by upregulation of HIF-1α, increased proliferating cell nuclear antigen positive (PCNA+) cell numbers, SOX9+ chondrogenic cell numbers, and Col2 expression in the newly formed cartilage. Coincide with the micromass culture, Icariin treatment upregulates mRNA levels of Sox9, Col2α1, aggrecan and Col10α1 in the 3D cultures. We then generated alginate hydrogel 3D complexes incorporated with Icariin. The 3D complexes were transplanted in a mouse osteochondral defect model. ICRS II histological scoring at 6 and 12 weeks post-transplantation shows that 3D complexes incorporated with Icariin significantly enhance articular cartilage repair with higher scores particularly in selected parameters including SO+ cartilage area, subchondral bone and overall assessment than that of the controls. The results suggest that Icariin may inhibit PHD activity likely through competition for cellular iron ions and therefore it may serve as an HIF-1α activator to promote articular cartilage repair through regulating chondrocyte proliferation, differentiation and integration with subchondral bone formation.

Icariin: A promising osteoinductive compound for repairing bone defect and osteonecrosis

Icariin (Ica), the main active component of Herba Epimedii, has been identified as an osteogenic and angiogenic phytomolecule. To develop a bioactive scaffold for enhancing bone repair, Ica was loaded into porous tricalcium phosphate (TCP) scaffolds, and the obtained porous Ica/TCP composites were investigated for treating osteonecrosis of the femoral head (ONFH) in a rabbit model. ONFH was histopathologically confirmed at two weeks after methylprednisolone acetate injection, and the rabbits were treated with porous Ica/TCP scaffolds (group A), porous TCP scaffolds (group B), and autogenous cancellous bone graft (group C). At 12 weeks, the amount of newly formed bone in group A increased significantly compared with that in group B (P = 0.003). The mean histological and radiological scores for repaired defects in group A were significantly higher than those in group B (P = 0.007, P = 0.029, respectively), but were lower than those in group C (P = 0.032, P = 0.046, respectively). In addition, the expression of vascular endothelial growth factor by immunohistochemical testing and real-time polymerase chain reaction in group A was significantly higher than that in group B (P = 0.002, P = 0.001, respectively), but was lower than that in group C (P = 0.034, P = 0.005, respectively). Therefore, Ica can be a promising osteogenic and angiogenic compound for repairing bone defects and preventing the collapse of the femoral head in ONFH.

Pharmacological effects and pharmacokinetic properties of icariin, the major bioactive component in Herba Epimedii

Herba Epimedii is an important medicinal plant which has been used in various traditional Chinese formulations for thousands of years as well as in modern proprietary traditional Chinese medicine products. It has extensive clinical indications, especially for the treatment of sexual dysfunction and osteoporosis. There have been more than 260 chemical moieties identified in the genus Epimedium most of which belong to flavonoids. Icariin is the most abundant constituent in Herba Epimedii. Icariin is pharmacologically bioactive and demonstrates extensive therapeutic capacities such as osteoprotective effect, neuroprotective effect, cardiovascular protective effect, anti-cancer effect, anti-inflammation effect, immunoprotective effect and reproductive function. Particularly, the significant osteogenic effect of icariin made it a promising drug candidate in bone tissue engineering. The current review paper aims to summarize the literatures reporting the pharmacological effects of icariin. The pharmacokinetic properties of bioactive ingredients in Herba Epimedii have also been discussed.

Effects of icariin on the regulation of the OPG-RANKL-RANK system are mediated through the MAPK pathways in IL-1β-stimulated human SW1353 chondrosarcoma cells

Arthrodial cartilage degradation and subchondral bone remodeling comprise the most predominant pathological changes in osteoarthritis (OA). Moreover, accumulating evidence indicates that the abnormal expression of osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL) and receptor activator of nuclear factor kappa-B (RANK) plays a vital role in the collapse of cartilage and subchondral bone. In the present study, the effects of icariin on the expression levels of these 3 factors in interleukin (IL)-1β-stimulated SW1353 chondrosarcoma cells were investigated. The SW1353 chondrosarcoma cells were cultured in the presence or absence of icariin and mitogen-activated protein kinase signaling pathway inhibitors, and were then stimulated with IL-1β. Cell viability was assessed by MTT assay. The mRNA and protein expression of OPG, RANKL and RANK was analyzed by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and ELISA, respectively. In addition, the levels of phosphorylated p38 (p-p38) and phosphorylated extracellular signal-regulated kinase (p-ERK)1/2 were detected by western blot analysis. The results from western blot analysis revealed that treatment with icariin decreased the levels of p-p38 and increased the levels of p-ERK1/2 in the IL-1β-stimulated SW1353 cells. In addition, treatment with icariin decreased the levels of RANK and RANKL. Furthermore, the suppressive effects of icariin on OPG and OPG/RANKL were greater than those exhibited by the p38 signaling pathway inhibitor (SB203580). The findings of the the present study suggest that icariin has therapeutic potential for use in the treatment of OA.

A novel therapeutic approach with Caviunin-based isoflavonoid that en routes bone marrow cells to bone formation via BMP2/Wnt-β-catenin signaling

Recently, we reported that extract of Dalbergia sissoo made from leaves and pods have antiresorptive and bone-forming effects. The positive skeletal effect attributed because of active molecules present in the extract of Dalbergia sissoo. Caviunin 7-O-[β-D-apiofuranosyl-(1-6)-β-D-glucopyranoside] (CAFG), a novel isoflavonoid show higher percentage present in the extract. Here, we show the osteogenic potential of CAFG as an alternative for anabolic therapy for the treatment of osteoporosis by stimulating bone morphogenetic protein 2 (BMP2) and Wnt/β-catenin mechanism. CAFG supplementation improved trabecular micro-architecture of the long bones, increased biomechanical strength parameters of the vertebra and femur and decreased bone turnover markers better than genistein. Oral administration of CAFG to osteopenic ovariectomized mice increased osteoprogenitor cells in the bone marrow and increased the expression of osteogenic genes in femur and show new bone formation without uterine hyperplasia. CAFG increased mRNA expression of osteoprotegerin in bone and inhibited osteoclast activation by inhibiting the expression of skeletal osteoclastogenic genes. CAFG is also an effective accelerant for chondrogenesis and has stimulatory effect on the repair of cortical bone after drill-hole injury at the tissue, cell and gene level in mouse femur. At cellular levels, CAFG stimulated osteoblast proliferation, survival and differentiation. Signal transduction inhibitors in osteoblast demonstrated involvement of p-38 mitogen-activated protein kinase pathway stimulated by BMP2 to initiate Wnt/β-catenin signaling to reduce phosphorylation of GSK3-β and subsequent nuclear accumulation of β-catenin. Osteogenic effects were abrogated by Dkk1, Wnt-receptor blocker and FH535, inhibitor of TCF-complex by reduction in β-catenin levels. CAFG modulated MSC responsiveness to BMP2, which promoted osteoblast differentiation via Wnt/β-catenin mechanism. CAFG at 1 mg/kg^/day dose in ovariectomy mice (human dose ∼0.081 mg/kg) led to enhanced bone formation, reduced bone resorption and bone turnover better than well-known phytoestrogen genistein. Owing to CAFG's inherent properties for bone, it could be positioned as a potential drug, food supplement, for postmenopausal osteoporosis and fracture repair.

Icariin promotes directed chondrogenic differentiation of bone marrow mesenchymal stem cells but not hypertrophy in vitro

Icariin (ICA), a Traditional Chinese Medicine, has been demonstrated to be a promoting compound for extracellular matrix synthesis and gene expression of chondrocytes. However, whether ICA can act as a substitute for or cooperate with growth factors to directly promote stable chondrogenesis of bone marrow mesenchymal stem cells (BMSCs) remains unknown. In the present study, rat BMSCs were cultivated in monolayer cultures with a chondrogenic medium containing transforming growth factor-β3 for 14 days; ICA was added to the same chondrogenic medium throughout the culture period at a concentration of 1×10⁻⁶ M. Cell morphology was observed using an inverted microscope, and chondrogenic differentiation markers, including collagen II, aggrecan and SRY (sex determining region Y)-box 9 (SOX9), were detected by immunofluorescence, reverse transcription-quantitative polymerase chain reaction and western blot analysis. Hypertrophic differentiation was also analyzed using collagen I gene expression and alkaline phosphatase (ALP) activity. The results revealed that ICA was effective at forming an increased number of and larger aggregates, and significantly upregulated the mRNA expression levels and protein synthesis of collagen II, aggrecan and SOX9. Furthermore, the chondrogenic medium alone caused hypertrophic differentiation through the upregulation of collagen I gene expression and ALP activity, which was not potentiated by the presence of ICA. Thus, ICA promoted directed chondrogenic differentiation of BMSCs, but had no effect on hypertrophic differentiation. The present results also suggested that ICA may be an effective accelerant of growth factors for cartilage tissue engineering by promoting their chondrogenic differentiating effects but reducing the effect of hypertrophic differentiation.

Extracellular matrix production in vitro in cartilage tissue engineering

Cartilage tissue engineering is arising as a technique for the repair of cartilage lesions in clinical applications. However, fibrocartilage formation weakened the mechanical functions of the articular, which compromises the clinical outcomes. Due to the low proliferation ability, dedifferentiation property and low production of cartilage-specific extracellular matrix (ECM) of the chondrocytes, the cartilage synthesis in vitro has been one of the major limitations for obtaining high-quality engineered cartilage constructs. This review discusses cells, biomaterial scaffolds and stimulating factors that can facilitate the cartilage-specific ECM production and accumulation in the in vitro culture system. Special emphasis has been put on the factors that affect the production of ECM macromolecules such as collagen type II and proteoglycans in the review, aiming at providing new strategies to improve the quality of tissue-engineered cartilage.

Icariin and icaritin stimulate the proliferation of SKBr3 cells through the GPER1-mediated modulation of the EGFR-MAPK signaling pathway

Icariin (ICA) and icaritin (ICT), with a similar structure to genistein, are the important bioactive components of the genus Epimedium, and regulate many cellular processes. In the present study, using the estrogen receptor (ER)-negative breast cancer cell line, SKBr3, as a model, we examined the hypothesis that ICA and ICT at low concentrations stimulate SKBr3 cell proliferation in vitro through the functional membrane, G protein‑coupled estrogen receptor 1 (GPER1), mediated by the epithelial growth factor receptor (EGFR)‑mitogen-activated protein kinase (MAPK) signaling pathway. MTT assay revealed that ICA and ICT at doses of 1 nM to 1 µM markedly stimulated SKBr3 cell proliferation in a dose-dependent manner. The ICA- and ICT-stimulated cell growth was completely suppressed by the GPER1 antagonist, G-15, indicating that the ICA‑ and ICT-stimulated cell proliferation was mediated by GPER1 activation. Semi-quantitative RT-PCR analysis revealed that treatment with ICA and ICT enhanced the transcription of c-fos, a proliferation-related early gene. The ICA- and ICT-stimulated mRNA expression was markedly attenuated by G-15, AG-1478 (an EGFR antagonist) or PD98059 (a MAPK inhibitor). Our data also demonstrated that ICA and ICT increased the phosphorylation of ERK1/2. The ICA- and ICT-stimulated ERK1/2 phosphorylation was blocked by pre-treatment of the cells with G-15 and AG-1478 or PD 98059. Flow cytometric analysis confirmed that the ICA- and ICT-stimulated SKBr3 cell proliferation involved the GPER1-mediated modulation of the EGFR‑MAPK signaling pathway. To the best of our knowledge, our current findings demonstrate for the first time that ICA and ICT promote the progression of ER-negative breast cancer through the activation of membrane GPER1.

Anti-angiogenic activity of Herba Epimedii on zebrafish embryos in vivo and HUVECs in vitro

Herba Epimedii, an herb commonly used in East Asian medicine, is commonly used for treatment of impotence, osteoporosis and many inflammatory conditions in traditional Chinese medicine. Recent studies revealed that Herba Epimedii also has anti-tumor or anti-cancer activities, which may possibly be mediated through anti-angiogenesis. This study aims to examine and confirm the anti-angiogenic activity in the herb using both in vivo and in vitro approaches. The 95% ethanol extract and four subsequent fractions (n-hexane, ethyl acetate (EA), n-butanol and aqueous fractions) of Herba Epimedii were tested on the zebrafish model by the quantitative assay for endogenous alkaline phosphatase; then, the active fraction was further tested on Tg(fli1a:EGFP)y1 zebrafish embryos and human umbilical vein endothelial cells (HUVECs) for the anti-angiogenic effects. In addition, the action mechanism of Herba Epimedii was further investigated on wild-type zebrafish embryos and HUVECs. The EA fraction showed anti-angiogenic effects in both in vivo and in vitro models. Further experiments demonstrated that it might affect angiogenesis by acting on multiple molecular targets in zebrafish embryos and ERK signaling pathway in HUVECs. In conclusion, Herba Epimedii can inhibit angiogenesis, which may be the mechanism for its anti-inflammatory, anti-tumor and anti-cancer actions.