icaritin and Osteonecrosis

One of the effective strategies for prevention of steroid-associated osteonecrosis (SAON) is to inhibit bone resorption and fat formation and promote bone formation at osteonecrotic sensitive skeletal sites. We identified a novel phytomolecule that showed positive effects on osteogenesis, anti-bone resorption and anti-adipogenesis in vitro and also developed a bone-targeting delivery system (BTDS) for in vivo experimental study. The study investigated if our innovative synthesized BTDS carrying this phytomolecule would be able to effectively prevent SAON in a rat model. SAON was induced by combined injections of lipopolysaccharide and methylprednisolone. SAON rats were divided into four groups, one SAON untreated control group and three SAON treatment groups with different types of delivery systems (Asp

Topics: Adipogenesis; Animals; Bioengineering; Flavonoids; In Situ Nick-End Labeling; Male; Osteogenesis; Osteonecrosis; Rats; Rats, Sprague-Dawley; Steroids

Steroid-associated osteonecrosis (SAON) may lead to joint collapse and subsequent joint replacement. Poly lactic-co-glycolic acid/tricalcium phosphate (P/T) scaffold providing sustained release of icaritin (a metabolite of Epimedium-derived flavonoids) was investigated as a bone defect filler after surgical core-decompression (CD) to prevent femoral head collapse in a bipedal SAON animal model using emu (a large flightless bird). The underlying mechanism on SAON was evaluated using a well-established quadrupedal rabbit model. Fifteen emus were established with SAON, and CD was performed along the femoral neck for the efficacy study. In this CD bone defect, a P/T scaffold with icaritin (P/T/I group) or without icaritin (P/T group) was implanted while no scaffold implantation was used as a control. For the mechanistic study in rabbits, the effects of icaritin and composite scaffolds on bone mesenchymal stem cells (BMSCs) recruitment, osteogenesis, and anti-adipogenesis were evaluated. Our efficacy study showed that P/T/I group had the significantly lowest incidence of femoral head collapse, better preserved cartilage and mechanical properties supported by more new bone formation within the bone tunnel. For the mechanistic study, our in vitro tests suggested that icaritin enhanced the expression of osteogenesis related genes COL1α, osteocalcin, RUNX2, and BMP-2 while inhibited adipogenesis related genes C/EBP-ß, PPAR-γ, and aP2 of rabbit BMSCs. Both P/T and P/T/I scaffolds were demonstrated to recruit BMSCs both in vitro and in vivo but a higher expression of migration related gene VCAM1 was only found in P/T/I group in vitro. In conclusion, both efficacy and mechanistic studies show the potential of a bioactive composite porous P/T scaffold incorporating icaritin to enhance bone defect repair after surgical CD and prevent femoral head collapse in a bipedal SAON emu model.

Topics: 3T3-L1 Cells; Adipogenesis; Animals; Dromaiidae; Finite Element Analysis; Flavonoids; Gait; Hip Joint; Lactic Acid; Magnetic Resonance Imaging; Male; Mice; Osteonecrosis; Plants; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Rabbits; Steroids; Tissue Scaffolds

This study was designed to develop a bioactive scaffold to enhance bone defect repair in steroid-associated osteonecrosis (SAON). Icaritin, a metabolite of the herb Epimedium, has been identified as an angiogenic and osteogenic phytomolecule. Icaritin was homogenized into poly lactic-co-glycolic acid/tricalcium phosphate (PLGA/TCP) to form an icaritin-releasing porous composite scaffold (PLGA/TCP/icaritin) by fine-spinning technology. In vitro, high performance liquid chromatography was used to determine the release of icaritin during degradation of PLGA/TCP/icaritin. The osteogenic effects of PLGA/TCP/icaritin were evaluated using rat bone marrow mesenchymal stem cells (BMSCs). In vivo, the osteogenic effect of PLGA/TCP/icaritin was determined within a bone tunnel after core decompression in SAON rabbits and angiography within scaffolds was examined in rabbit muscle pouch model. In vitro study confirmed the sustainable release of icaritin from PLGA/TCP/icaritin with the bioactive scaffold promoting the proliferation and osteoblastic differentiation of rat BMSCs. In vivo study showed that PLGA/TCP/icaritin significantly promoted new bone formation within the bone defect after core decompression in SAON rabbits and enhanced neovascularization in the rabbit muscle pouch experiment. In conclusion, PLGA/TCP/icaritin is an innovative local delivery system that demonstrates sustainable release of osteogenic phytomolecule icaritin enhancing bone repair in an SAON rabbit model. The supplement of scaffold materials with bioactive phytomolecule(s) might improve treatment efficiency in challenging orthopedic conditions.

Topics: Animals; Bone Marrow Cells; Calcium Phosphates; Cells, Cultured; Disease Models, Animal; Femoral Fractures; Flavonoids; Fracture Healing; Lactic Acid; Male; Neovascularization, Physiologic; Osteogenesis; Osteonecrosis; Phytoestrogens; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Rabbits; Rats; Tissue Engineering; Tissue Scaffolds

Intravascular-thrombosis and extravascular-lipid-deposition are the two key pathogenic events considered to interrupt intraosseous blood supply during steroid-associated osteonecrosis (ON) development. However, there are no reported candidate agents capable of simultaneously targeting these two key pathogenic events. The authors' published experimental studies have shown that Epimedium-derived flavonoids possess an anti-ON effect. Further, the authors have recently identified a small molecule Icaritin as an intestinal metabolite of Epimedium-derived flavonoids.. The present study was to evaluate the prevention effect of the available semisynthesized small molecule Icaritin on steroid-associated ON development in a rabbit model.. After receiving an established inductive protocol for inducing steroid-associated ON, eighty-four male 28-week-old New-Zealand white rabbits were divided into the following three daily oral administration groups, including low dose Icaritin group (L-ICT; n=28; 5 mg x kg(-1) x day(-1)), high dose Icaritin group (H-ICT; n=28; 10 mg x kg(-1) x day(-1)), and control vehicle group (CON; n=28). Before and after induction, dynamic contrast-enhanced MRI was performed on proximal femur for intra-osseous perfusion function index. Meanwhile, blood samples were examined for coagulation, fibrinolysis, lipid-transportation, endothelium injury, oxidative stress, and hepatocyte injury index, while marrow samples were quantified for adipogenic potential index of mesenchymal stem cell by in vitro culture and proliferator-activated receptor-gamma (PPARgamma) protein expression by western blot. At baseline, week 1 and 2 post-induction, 4, 8 and 16 rabbits in each group were sacrificed, respectively. After sacrifice, femora were dissected for micro-CT-based micro-angiography, followed by histological examination of ON lesion, intravascular thrombosis, extravascular fat-cell and vascular endothelial growth factor (VEGF) localized expression.. The ON incidence in the L-ICT and H-ICT groups was both significantly lower than that in the CON group (p<0.05 for both). The ON incidence in the H-ICT group was significantly lower than that in the L-ICT group (p<0.05). A significant decrease in the vascularization index and a significant increase in the permeability index seen in the CON group was attenuated in the L-ICT group and almost prevented in the H-ICT group at week 1 post-induction. Reduced perfusion to vessel-like structural units was more rarely found in the H-ICT group than in the L-ICT group. Regarding intravascular thrombosis, a significant increase in the thrombotic vessel count, endothelium injury index, coagulation index, and a significant decrease in both the fibrinolysis and oxidative stress index in the CON group were attenuated in the L-ICT group and prevented in the H-ICT group. For extravascular lipid-deposition, a significant increase in the fat cell area fraction, adipogenic potential index, PPARgamma expression and lipid-transportation index in the CON group was attenuated in the L-ICT group and prevented in the H-ICT group. Increased immunoreactivity of VEGF in the CON group was attenuated in the L-ICT group and prevented in the H-ICT group. Regarding safety, the hepatocyte injury index did not show significant change from baseline in any group.. Icaritin, a novel semisynthesized small molecule with osteoprotective potential, exerts dose-dependent effect on reducing incidence of steroid-associated ON with inhibition of both intravascular thrombosis and extravascular lipid-deposition. Suppression of the up-regulated PPARgamma expression for extravascular adipogenesis of mesenchymal stem cells and protection from activated oxidative stress for intravascular endothelium injury were found to be involved in the underlying mechanisms.

Topics: Angiography; Animals; Blood Vessels; Dose-Response Relationship, Drug; Flavonoids; Lipid Metabolism; Magnetic Resonance Imaging; Male; Osteonecrosis; Particle Size; Perfusion; Rabbits; Steroids; Thrombosis; Treatment Outcome; Vascular Endothelial Growth Factor A; X-Ray Microtomography