Steroid-associated Osteonecrosis Research Articles

Chinese herbal Huo-Gu formula for the treatment of steroid-associated osteonecrosis of femoral head: A 14-year follow-up of convalescent SARS patients

SummaryPurposeThe coronavirus disease 2019 (COVID-19) reminds us of the severe acute respiratory syndrome (SARS) outbreak in 2003, and up to date, corticosteroid is commonly administrated to severe patients with COVID-19. Osteonecrosis of the femoral head (ONFH) is a common disabling complication among convalescent SARS patients who received corticosteroid therapy. In China, a considerable number of convalescent SARS patients with steroid-associated ONFH had undergone conservative treatment by traditional Chinese medicine, and this study aims to evaluate the long-term results of a spleen-invigorating Huo-Gu formula (HGF) therapy in these patients.Participants and methodsA total of 33 convalescent SARS patients (9 males and 24 females) with bilateral steroid-associated ONFH (66 hips) were enrolled in this study. All patients received oral HGF therapy for 6 months when they were confirmed the diagnosis of steroid-associated ONFH. They had been regularly followed up at an interval of 1 year. Harris hip score and medical imaging modalities, including plain radiography, computed tomography and magnetic resonance imaging, were performed to evaluate the outcomes.ResultsBased on average 14 years of follow-up of HGF therapy (ranging from 6 to 16 years), 38 hips (57%) among the 66 hips developed definite osteoarthritis, and 14 hips (26%) in 53 precollapse hips (Association Research Circulation Osseous [ARCO] Stage I or II) progressed to femoral head collapse (ARCO Stage III or IV). Only five patients (also 5 hips) underwent total hip arthroplasty, and the mean hip survival time was over 15 years by the Kaplan–Meier analysis. We observed a mean Harris hip score of 63 points, which represented the reserve of 55% in pain score and 70% in physical function score. The severity of groin pain was not correlated to the severity of osteoarthritis.ConclusionChinese herbal HGF therapy demonstrates beneficial effects on preventing femoral head collapse, delaying total hip arthroplasty, and maintaining physical function in the treatment of steroid-associated ONFH. HGF therapy might be therefore a good alternative for the treatment of steroid-associated ONFH secondary to rheumatologic and infection diseases.Translational potential of the articleHGF therapy might be a good alternative for the treatment of steroid-associated ONFH secondary to rheumatologic and infectious diseases.

Gastrin for prevention of steroid-associated osteonecrosis in rats

Summary Background/Objective Steroid-associated osteonecrosis (SAON) mostly occurs in large joints such as hip that finally results in joint collapse and replacement. An effective strategy for preventing SAON is inhibition of bone resorption and lipid formation, whereas promoting bone formation at osteonecrotic-sensitive skeletal sites. The objective of this study was to investigate whether gastrin administration could effectively prevent SAON in vivo and had a significant effect on osteogenesis, osteoclast differentiation and/or adipogenesis in vitro. Methods SAON was induced in rats by injection of both lipopolysaccharide and methylprednisolone. SAON rats were divided into three groups (untreated, low- ​and high-dose gastrin) and treated for two weeks. Lesions in SAON were identified, and efficacy of gastrin was evaluated in osteoclast activity, osteogenesis ​and adipogenesis. In vitro experiments evaluated the osteogenic and adipogenic potential of induced bone marrow stem cells, as well as osteoclast differentiation of stimulated bone marrow cells. Results Gastrin administration effectively prevented the development of SAON in vivo and significantly downregulated osteoclastogenesis, and upregulated osteogenesis in vitro. The underlying mechanism was potentially involved in the inhibited nuclear factor kappa-B (NF-κB) pathway leading to not only suppressed osteoclastogenesis but also facilitated osteoblastogenesis. Conclusion The present study demonstrated for the first time that gastrin could effectively prevent SAON in vivo and had a significant effect on osteogenesis, osteoclast differentiation and/or adipogenesis in vitro that should be an important link between gastrointestinal hormone and metabolic bone diseases. Translational potential of this article Gastrin prevents steroid-associated osteonecrosis with decreasing bone resorption and apoptosis, also enhancing bone formation. These findings provide in vivo evidence to support the use of gastrin to treat osteonecrosis.

Microarray profiling of circular RNAs in steroid-associated osteonecrosis of the femoral head: Observational study.

The aim of this study was to elucidate the molecular mechanisms and to identify the differential expression of circular RNAs (circRNAs) for steroid-associated osteonecrosis of the femoral head (SONFH) using bioinformatics analysis.circRNA microarray was performed with 3 SONFH tissues and the adjacent normal tissues, and differentially expressed circRNA were identified by limma package in R. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using the Database for Annotation, Visualization and Integrated Discovery database. In addition, a differentially expressed genes (DEG)-associated circRNA/microRNA (miRNA) interaction was predicted by combination of TargetScan and miRanda, and the circRNA/miRNA interaction network generated by the cytoscape software.A total of 647 differentially expressed circRNAs, including 433 upregulated and 214 downregulated circRNA were identified. The most enriched GO terms for upregulated and downregulated circRNA were extracellular matrix organization and leukocyte activation in biological process; extracellular matrix and spindle pole in cellular component; integrin binding and ATP binding in molecular function, and KEGG pathway enrichment analyses showed that the upregulated and downregulated circRNA were strongly associated with Protein digestion and absorption and Cell cycle. Moreover, a total of 212 differentially expressed messenger RNAs (mRNAs), including 113 upregulated and 99 downregulated genes were identified. In addition, from the analysis of miRNA, long noncoding RNAs, mRNA, and circRNA networks, we found that hsa_circ_0008136 and hsa_circ_0074758 were respectively the upregulated and downregulated circRNA with highest degrees.The identified circRNA and mRNA could be implicated in the progression of human SONFH. The findings could lead to a better understanding of SONFH pathogenesis.

Magnesium and vitamin C supplementation attenuates steroid-associated osteonecrosis in a rat model

Magnesium (Mg)-based biometal attracts clinical applications due to its biodegradability and beneficial biological effects on tissue regeneration, especially in orthopaedics, yet the underlying anabolic mechanisms in relevant clinical disorders are lacking. The present study investigated the effect of magnesium (Mg) and vitamin C (VC) supplementation for preventing steroid-associated osteonecrosis (SAON) in a rat experimental model. In SAON rats, 50 mg/kg Mg, or 100 mg/kg VC, or combination, or water control was orally supplemented daily for 2 or 6 weeks respectively. Osteonecrosis was evaluated by histology. Serum Mg, VC, and bone turnover markers were measured. Microfil-perfused samples prepared for angiography and trabecular architecture were evaluated by micro-CT. Primary bone marrow cells were isolated from each group to evaluate their potentials in osteoblastogenesis and osteoclastogenesis. The mechanisms were tested in vitro. Histological evaluation showed SAON lesions in steroid treated groups. Mg and VC supplementation synergistically reduced the apoptosis of osteocytes and osteoclast number, and increased osteoblast surface. VC supplementation significantly increased the bone formation marker PINP, and the combination significantly decreased the bone resorption marker CTX. TNFα expression and oxidative injury were decreased in bone marrow in Mg/VC/combination group. Mg significantly increased the blood perfusion in proximal tibia and decreased the leakage particles in distal tibia 2 weeks after SAON induction. VC significantly elevated the osteoblast differentiation potential of marrow cells and improved the trabecular architecture. The combination supplementation significantly inhibited osteoclast differentiation potential of marrow cells. In vitro study showed promoting osteoblast differentiation effect of VC, and anti-inflammation and promoting angiogenesis effect of Mg with underlying mechanisms. Mg and VC supplementation could synergistically alleviate SAON in rats, indicating great translational potentials of metallic minerals for preventing SAON.

MiR-144-3p Inhibits BMSC Proliferation and Osteogenic Differentiation Via Targeting FZD4 in Steroid-Associated Osteonecrosis.

MicroRNAs have recently been recognized to be engaged in the development of bone diseases. This study was performed to elucidate the effects of miR-144-3p on proliferation and osteogenesis of mesenchymal stem cells (MSCs) from the patients with steroid-associated osteonecrosis (ONFH) and its related mechanism. The expression level of miR-144-3p in the MSCs from the proximal femur of the patients was examined by Real-time PCR. The cell proliferation ability was assayed by MTT. The differentiation ability of MSCs was assayed by Alizarin Red S (ARS) staining. The interaction between miR-144-3p and frizzled4 (FZD4) was investigated by Real-time PCR, western blot and luciferase reporter assay. ONFH samples had the obviously high expression of miR-144-3p compared to the control. MiR-144-3p had a negative effect on the proliferation and osteogenesis of MSCs. Via targeting FZD4, miR-144-3p decreased β-catenin nuclear translocation, the transcription of RUNX2 and COL1A1. Over-expression of FZD4 partially reversed miR-144-3p-induced decrease in the proliferation and osteogenesis of MSCs. MiR-144-3p might play an important role in the development of ONFH and might be used as a novel class of therapeutic targets for this disease.

A tree shrew model for steroid-associated osteonecrosis

Osteonecrosis is a common human disease in orthopedics. It is difficult to treat, and half of patients may need artificial joint replacement, resulting in a considerable economic burden and a reduction in quality of life. Hormones are one of the major causes of osteonecrosis and high doses of corticosteroids are considered the most dangerous factor. Because of the complexity of treatment, we still need a better animal model that can be widely used in drug development and testing. Tree shrews are more closely related to primates than rodents. As such, we constructed a successful tree shrew model to establish and evaluate steroid-associated osteonecrosis (SAON). We found that low-dose lipopolysaccharide (LPS) combined with high-dose methylprednisolone (MPS) over 12 weeks could be used to establish a tree shrew model with femoral head necrosis. Serum biochemical and histological analyses showed that an ideal model was obtained. Thus, this work provides a useful animal model for the study of SAON and for the optimization of treatment methods.

Animal models and research on preventions and treatments of steroid-associated osteonecrosis of the femoral head

Steroid associated-osteonecrosis (SAON) is non-trauma induced osteonecrosis, which is induced by long-term or high dose of corticosteroid indicated for inflammatory or immune diseases, etc. Subchondral collapse at late stage of SAON usually needs to be treated with joint replacement, while the costs and the prognosis of the surgery are challenge. It is important to perform the fundamental researches on the hip preservation treatments of SAON at early stage, and it is necessary to establish suitable animal models for studying the mechanisms of SAON and evaluating the potential treatments for the SAON. Rabbit SAON model is the most frequently used animal model. It is extensively used in studies on etiology and pathology of SAON. Furthermore, it is possible to evaluate potential drugs for preventing SAON and improving osteogenic repair of mid-stage SAON to prevent joint collapse. Because of bi-pedal, emu has the similar mechanical properties with human. Thus, it can be a suitable animal model for studying preventions and treatments of subchondral collapse of SAON, such as core-decompression with biodegradable materials for bone regeneration. In conclusion, this review updates the current animal SAON models with similar pathology to clinical SAON. These typical models could be used as clinical references for investigating drugs in prevention of early-stage of SAON and biomaterials in hip-preservation surgery for mid-stage of SAON.

Dynamic and Cell-Infiltratable Hydrogels as Injectable Carrier of Therapeutic Cells and Drugs for Treating Challenging Bone Defects.

Biopolymeric hydrogels have been widely used as carriers of therapeutic cells and drugs for biomedical applications. However, most conventional hydrogels cannot be injected after gelation and do not support the infiltration of cells because of the static nature of their network structure. Here, we develop unique cell-infiltratable and injectable (Ci-I) gelatin hydrogels, which are physically cross-linked by weak and highly dynamic host–guest complexations and are further reinforced by limited chemical cross-linking for enhanced stability, and then demonstrate the outstanding properties of these Ci-I gelatin hydrogels. The highly dynamic network of Ci-I hydrogels allows injection of prefabricated hydrogels with encapsulated cells and drugs, thereby simplifying administration during surgery. Furthermore, the reversible nature of the weak host–guest cross-links enables infiltration and migration of external cells into Ci-I gelatin hydrogels, thereby promoting the participation of endogenous cells in the healing process. Our findings show that Ci-I hydrogels can mediate sustained delivery of small hydrophobic molecular drugs (e.g., icaritin) to boost differentiation of stem cells while avoiding the adverse effects (e.g., in treatment of bone necrosis) associated with high drug dosage. The injection of Ci-I hydrogels encapsulating mesenchymal stem cells (MSCs) and drug (icaritin) efficiently prevented the decrease in bone mineral density (BMD) and promoted in situ bone regeneration in an animal model of steroid-associated osteonecrosis (SAON) of the hip by creating the microenvironment favoring the osteogenic differentiation of MSCs, including the recruited endogenous cells. We believe that this is the first demonstration on applying injectable hydrogels as effective carriers of therapeutic cargo for treating dysfunctions in deep and enclosed anatomical sites via a minimally invasive procedure.

Hypermethylation of Frizzled1 is associated with Wnt/\u03b2-catenin signaling inactivation in mesenchymal stem cells of patients with steroid-associated osteonecrosis

The Wnt/β-catenin signaling pathway is associated with the pathogenesis of steroid-induced osteonecrosis. Our investigation studied whether aberrant CpG island hypermethylation of the FZD1 gene was present in patients with osteonecrosis of the femoral head (ONFH), which results in Wnt/β-catenin signaling inactivation and subsequent cell dysfunction. Bone marrow was collected from the proximal femurs of patients with steroid-associated ONFH (n = 21) and patients with new femoral neck fractures (n = 22), and then mesenchymal stem cells (MSCs) were isolated. We investigated cell viability, the transcription and translation levels of Wnt/β-catenin signaling-related genes, the extent of methylation at CpG islands of the FZD1 promoter, and the osteogenic and adipogenic differentiation abilities of MSCs from the control group and from the ONFH group treated with or without 5′-Aza-dC. According to the results, MSCs from the ONFH group showed a reduced proliferation ability, low transcription and translation levels of FZD1, inhibition of the Wnt/β-catenin signaling pathway, weakened osteogenesis and enhanced adipogenesis ability. Aberrant CpG island hypermethylation of FZD1 was observed in the ONFH group. Treatment with 5’-Aza-dC resulted in de novo FZD1 expression, reactivation of the Wnt/β-catenin signaling pathway and promotion of osteogenesis. Taken together, our study not only provides novel insights into the regulation of the Wnt/β-catenin signaling pathway in this disease but also reveals potential for the use of demethylating agents for the treatment of GC-associated ONFH.

Osteogenic magnesium incorporated into PLGA/TCP porous scaffold by 3D printing for repairing challenging bone defect

Bone defect repair is a challenging clinical problem in musculoskeletal system, especially in orthopaedic disorders such as steroid associated osteonecrosis (SAON). Magnesium (Mg) as a biodegradable metal with properly mechanical properties has been investigating for a long history. In this study, Mg powder, poly (lactide-co-glycolide) (PLGA), β-tricalcium phosphate (β-TCP) were the elements to formulate a novel porous PLGA/TCP/Mg (PTM) scaffolds using low temperature rapid prototyping (LT-RP) technology. The physical characterization of PTM scaffold and Mg ions release were analyzed in vitro. The osteogenic and angiogenic properties of PTM scaffolds, as well as the biosafety after implantation were assessed in an established SAON rabbit model. Our results showed that the PTM scaffold possessed well-designed bio-mimic structure and improved mechanical properties. Findings of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and micro-computed tomography (micro CT)-based angiography indicated that PTM scaffold could increase blood perfusion and promote new vessel ingrowth at 4 weeks after surgery, meanwhile, a plenty of newly formed vessels with well-architective structure were observed at 8 weeks. Correspondingly, at 12 weeks after surgery, micro-CT, histological and mechanical properties analysis showed that PTM could significant enhance new bone formation and strengthen newly formed bone mechanical properties. The mean bone volume in PTM group was 56.3% greater than that in PT group. Biosafety assessments from 0 to 12 weeks after implantation did not induce increase in serum Mg ions concentration, and immune response, liver and kidney function parameters were all at normal level. These findings suggested that the PTM scaffold had both osteogenic and angiogenic abilities which were synergistic effect in enhancing new bone formation and strengthen newly formed bone quality in SAON. In summary, PTM scaffolds are promising composite biomaterials for repairing challenging bone defect that would have great potential for its clinical translation.

Involvement of tumor necrosis factor alpha in steroid-associated osteonecrosis of the femoral head: friend or foe?

BackgroundThe etiology and pathology osteonecrosis of the femoral head (ONFH) are not completely clarified. As a cytokine participating in systemic inflammation, tumor necrosis factor alpha (TNFα) has been shown to be involved in the pathogenesis of ONFH. However, the role of TNFα in ONFH is not clearly clarified. In the present study, we investigated the effects of TNFα on proliferation, angiogenesis, and osteogenic differentiation of rat bone mesenchymal stem cells (rMSCs) and the underlying mechanisms.MethodsAll femoral bone tissues were separated in surgeries. After extracting total RNA and protein, we evaluated TNFα content by ELISA and the relative expression levels of genes by quantitative real-time PCR and western blot. Also, immunohistochemistry staining was performed to observe the expression of Runx2 in the bone samples. Chick embryo chorioallantoic membrane (CAM) assay was performed to observe the effect of TNFα on angiogenesis. The genomic DNAs were treated by bisulfite modification, and methylation status of CpG sites in the CpG islands of human and rat Runx2 gene promoter was determined by DNA sequencing. The binding of H3K4me3 and H3K27me3 in Runx2 promoter was checked by ChIP assay. RNA-seq analysis was used to find out the genes and pathways changed by TNFα in rMSCs.ResultsThe results demonstrate TNFα promotes cell proliferation and angiogenesis whereas inhibits osteogenesis. Epigenetic regulations including DNA methylation and histone modifications play important roles in mediating the effect of TNFα on osteogenic differentiation. We find an increased rate of CpG methylation in rat Runx2 promoter in TNFα-treated rMSCs, as well as significantly increased occupancy of H3K27me3 in Runx2 gene promoter. The content of TNFα in necrotic tissue is much lower than that of normal tissue. And relevantly, human Runx2 promoter is demethylated in necrotic tissue using bone samples from patient with ONFH. In addition, we have observed that Wnt signaling pathway is inhibited by TNFα as multiple Wnts are markedly decreased in TNFα-treated rMSCs by RNA-seq analysis.ConclusionTaken together, our study shows that TNFα plays complicated roles in the pathogenesis of ONFH, including proliferation, angiogenesis, and osteogenesis. Targeting TNFα should not be considered as an applicable strategy to inhibit the progression of ONFH.

MiR-217 promotes cell proliferation and osteogenic differentiation of BMSCs by targeting DKK1 in steroid-associated osteonecrosis

MicroRNAs (miRNAs) have recently been recognized to play an important role in bone-associated diseases. This study aims to explore the expression profile and biological function of miR-217, which is known to be related to tumor cell proliferation and migration, to the proliferation and osteogenic differentiation of MSCs from the patients with steroid-associated osteonecrosis (ONFH). Bone marrow was obtained from the proximal femur of 10 patients with ONFH and 10 patients with femoral neck fractures. Bone marrow-derived mesenchymal stem cells (MSCs) were isolated and cultured. The expression profile, biological function of miR-217 and the interaction between miR-217 and DKK1 were assayed using cell viability measurement, western blot, Real-time PCR, luciferase reporter assay, Alizarin Red S (ARS) staining. We noted that the expression level of miR-217 was significantly decreased in the ONFH samples compared to the control samples (P < 0.0001). By targeting DKK1, miR-217 promoted nuclear translocation of β-catenin, increased expression of RUNX2, COL1A1 and obviously promoted the proliferation and differentiation of MSCs. Restoring the expression of DKK1 in the MSCs partially reversed the role of miR-217. These findings suggest that miR-217 promotes cell proliferation and osteogenic differentiation by inhibiting DKK1 during the development of steroid-associated osteonecrosis.

Microbubble-Mediated Ultrasound Outweighs Low-Intensity Pulsed Ultrasound on Osteogenesis and Neovascularization in a Rabbit Model of Steroid-Associated Osteonecrosis.

Microbubbles magnify the acoustic pressure of low-intensity pulsed ultrasound (LIPUS) and may enhance its bioeffect for diagnostic and therapeutic purposes. This study compared the effect of this novel microbubble-mediated ultrasound (MUS) with that of the traditional LIPUS on osteogenesis and neovascularization in a rabbit model of steroid-associated osteonecrosis. We hypothesized that MUS might outweigh LIPUS on promoting osteogenesis and neovascularization in steroid-associated osteonecrosis. The bilateral femoral head necrosis was induced by lipopolysaccharide and methylprednisolone in the rabbits. The indices of bone mineral density (BMD), trabecular number, maximal loading strength, and mineral apposition rate were analyzed, demonstrating that the animal model of steroid-associated osteonecrosis was successfully established. Both the MUS group (GM) and the LIPUS group (GL) were insonated 20 min daily for six weeks. GM received an extra intracapsular injection of microbubbles before insonation every other day. Fluorescence bone labeling, Micro-CT Analysis, biomechanical test, quantitative real-time PCR, Western blot analysis, and histological evaluation were performed for comparing GM with GL. The results demonstrated a 39% higher mineral apposition rate in GM compared with GL. The BMD and the maximal loading strength of femoral head of GM increased by 4.3% and 27.8% compared to those of GL, respectively. The mRNA and protein expression of BMP-2 and VEGF were also significantly higher in GM. The number of blood vessels of GM was 65% greater than that of GL. MUS is more potent than LIPUS in enhancing osteogenesis, neovascularization, and biomechanical strength of femoral head in the animal model of steroid-associated osteonecrosis. Without increasing the intensity of insonation or the risk of tissue damage, MUS is better for inhibiting the process of steroid-associated osteonecrosis.

Correction to: Raman spectroscopy reveals differences in molecular structure between human femoral heads affected by steroid-associated and alcohol-associated osteonecrosis.

The original publication of this paper contain an error for the first name and last name of the second author have been mixed up as "Wenliang, Z.".

Raman spectroscopy reveals differences in molecular structure between human femoral heads affected by steroid-associated and alcohol-associated osteonecrosis.

The purposes of this study were to document novel Raman spectroscopic findings in femoral heads affected by osteonecrosis and to identify molecular structure differences based on aetiology. We obtained 13 femoral heads with osteonecrosis from 13 different patients who underwent total hip arthroplasty. Comparisons were made between the viable zones of each femoral head examined. The samples were scanned with X-ray micro-CT for structural mapping and a central coronal section slab was prepared for Raman spectroscopy and histological analyses. Raman spectra were collected at different locations, including the viable and necrotic zones of the femoral head, using a highly spectrally resolved Raman microprobe. Significant alterations in the spectral morphology in the high wavenumber region were found, with a pronounced inhibition of peculiar lipid signals in the frequency interval 2851 ~ 2890cm-1 and at ~ 1750cm-1. The necrotic zone in steroid-associated osteonecrosis showed an increase in the ratio of lipid-related bands to protein-related bands, while alcohol-associated osteonecrosis exhibited a decrease in this ratio. We systematically found a decrease in Raman intensity for sphingomyelin and phenylalanine fingerprint bands in the necrotic zones, and these differences may be related to the etiology of osteonecrosis.

Steroid-associated osteonecrosis animal model in rats

SummaryObjectiveEstablished preclinical disease models are essential for not only studying aetiology and/or pathophysiology of the relevant diseases but more importantly also for testing prevention and/or treatment concept(s). The present study proposed and established a detailed induction and assessment protocol for a unique and cost-effective preclinical steroid-associated osteonecrosis (SAON) in rats with pulsed injections of lipopolysaccharide (LPS) and methylprednisolone (MPS).MethodsSixteen 24-week-old male Sprague–Dawley rats were used to induce SAON by one intravenous injection of LPS (0.2 mg/kg) and three intraperitoneal injections of MPS (100 mg/kg) with a time interval of 24 hour, and then, MPS (40 mg/kg) was intraperitoneally injected three times a week from week 2 until sacrifice. Additional 12 rats were used as normal controls. Two and six weeks after induction, animals were scanned by metabolic dual energy X-ray absorptiometry for evaluation of tissue composition; serum was collected for bone turnover markers, Microfil perfusion was performed for angiography, the liver was collected for histopathology and bilateral femora and bilateral tibiae were collected for histological examination.ResultsThree rats died after LPS injection, i.e., with 15.8% (3/19) mortality. Histological evaluation showed 100% incidence of SAON at week 2. Dual energy X-ray absorptiometry showed significantly higher fat percent and lower lean mass in SAON group at week 6. Micro-computed tomography (Micro-CT) showed significant bone degradation at proximal tibia 6 weeks after SAON induction. Angiography illustrated significantly less blood vessels in the proximal tibia and significantly more leakage particles in the distal tibia 2 weeks after SAON induction. Serum amino-terminal propeptide of type I collagen and osteocalcin were significantly lower at both 2 and 6 weeks after SAON induction, and serum carboxy-terminal telopeptide was significantly lower at 6 weeks after SAON induction. Histomorphometry revealed significantly lower osteoblast surface and higher marrow fat fraction and oedema area in SAON group. Hepatic oedema appeared 2 weeks after SAON induction, and lipid accumulation appeared in the liver of SAON rats 6 weeks after SAON induction.ConclusionThe present study successfully induced SAON in rats with pulsed injection of LPS and MPS, which was well simulating the clinical feature and pathology. Apart from available large animal models, such as bipedal emus or quadrupedal rabbits, our current SAON small model in rats could be a cost-effective preclinical experimental model to study body metabolism, molecular mechanism of SAON and potential drugs developed for prevention or treatment of SAON.The translational potential of this articleThe present study successfully induced SAON in a small animal model in rats with pulsed injection of LPS and MPS. The evaluation protocols with typical histopathologic ON features and advanced evaluation approaches to identify the metabolic disorders of SAON could be used in future rat SAON studies. The SAON rat model is a suitable and cost-effective animal model to study molecular mechanism of SAON and potential drugs developed for prevention and treatment of SAON.

Mitochondrial stress and redox failure in steroid-associated osteonecrosis.

The purpose of the role of antioxidant enzymes and mitochondria in the developmental mechanism of steroid-associated osteonecrosis in the femur. In the present study Japanese white rabbits (mean weight 3.5kg) were injected into the gluteus with methylprednisolone (MP) 20mg/kg, and killed after 3 days (MP3 group), 5 days (MP5 group), and 14 days (MP14 group) (n=3 each). As a Control group (C group) Japanese white rabbits not administered MP were used. In experiment 1, the expression of the antioxidant enzymes Superoxide dismutade (SOD) and catalase was compared in liver, kidney, heart, humerus, and femur in C group, and the presence/absence of mitochondria transcription factor A (TFAM) expression was determined by Western blotting (WB) and used to evaluate the number of mitochondria and their function. In experiment 2, the presence/absence of necrosis was determined by immunohistochemistry, while changes in the expression of SOD, catalase, and TFAM in the femur after steroid administration were determined by Western blotting (WB). In experiment 1, intense expression of all of SOD, catalase, and TFAM was found in the liver, kidney, and heart as compared to the humerus and femur. In experiment 2, the expression of all of SOD, catalase, and TFAM in MP3 and MP5 groups was decreased on WB as compared with C group, while in MP14 group a tendency to improvement was seen. Accordingly, steroid-associated mitochondrial injury and redox failure are concluded to be important elements implicated in the pathogenesis of osteonecrosis.

Icariin Protects against Glucocorticoid-Induced Osteonecrosis of the Femoral Head in Rats

Background/Aims: Glucocorticoid (GC)-related osteonecrosis of the femoral head (ONFH) is a common complication following administration of steroids to treat many diseases. Our previous study demonstrated that icariin (ICA) might have a beneficial effect on the bone marrow mesenchymal stem cells (BMSCs) of patients with steroid-associated osteonecrosis. In this study, we investigated the underlying mechanisms of ICA associated with the potential enhancement of osteogenesis and anti-adipogenesis in GC-related ONFH. Methods: In vitro cell proliferation was evaluated by CCK-8 assay. Alizarin red S and alkaline phosphatase (ALP) activity were used to measure osteogenic differentiation, while adipogenic differentiation was revealed by oil red O staining and TG content assay. The expression level of osteogenesis-associated genes and PPARγ was evaluated by RT-qPCR, western blotting and immunofluorescence. A total of 30 female SD rats were randomly separated into three groups: a control group, a methylprednisolone (MPS) group and a MPS + ICA group. Serum ALP and TG (triglyceride), micro-CT scanning, histological and immunohistochemical analyses were performed in the animal model. Results: In the in vitro study, ICA promoted proliferation, improved osteogenic differentiation and suppressed adipogenic differentiation of BMSCs treated with MPS. The group treated with MPS and 10^-6 M ICA expressed higher levels of Runx2, ALP, bone morphogenetic protein (BMP) 2, and OC and lower expression of PPARγ than the MPS group. In the in vivo study, ICA prevented bone loss in a rat model of GC-related ONFH as shown by micro-CT scanning, histological and immunohistochemical analyses. Conclusions: ICA is an effective compound for promoting bone repair and preventing or delaying the progression of GC-associated ONFH in rats. This effect can be explained by its ability to improve the balance between adipogenesis and osteogenesis, indicating that ICA is an effective candidate for management of GC-associated ONFH.

Porous composite scaffold incorporating osteogenic phytomolecule icariin for promoting skeletal regeneration in challenging osteonecrotic bone in rabbits

Steroid-associated osteonecrosis (SAON) often requires surgical core decompression (CD) in the early stage for removal of necrotic bone to facilitate repair where bone grafts are needed for filling bone defect and avoiding subsequent joint collapse. In this study, we developed a bioactive composite scaffold incorporated with icariin, a unique phytomolecule that can provide structural and mechanical support and facilitate bone regeneration to fill into bone defects after surgical CD in established SAON rabbit model. An innovative low-temperature 3D printing technology was used to fabricate the poly (lactic-co-glycolic acid)/β-calcium phosphate/icariin (PLGA/TCP/Icariin, PTI) scaffold. The cytocompatibility of the PTI scaffold was tested in vitro, and the osteogenesis properties of PTI scaffolds were assessed in vivo in the SAON rabbit models. Our results showed that the fabricated PTI scaffold had a well-designed biomimic structure that was precisely printed to provide increased mechanical support and stable icariin release from the scaffold for bone regeneration. Furthermore, our in vivo study indicated that the PTI scaffold could enhanced the mechanical properties of new bone tissues and improved angiogenesis within the implanted region in SAON rabbit model than those of PLGA/TCP (PT) scaffold. The underlying osteoblastic mechanism was investigated using MC3T3-E1 cells in vitro and revealed that icariin could facilitate MC3T3-E1 cells ingrowth into the PTI scaffold and regulate osteoblastic differentiation. The PTI scaffold exhibited superior biodegradability, biocompatibility, and osteogenic capability compared with those of PT scaffold. In summary, the PTI composite scaffold which incorporated bioactive phyto-compounds is a promising potential strategy for bone tissue engineering and regeneration in patients with challenging SAON.

A novel bone targeting delivery system carrying phytomolecule icaritin for prevention of steroid-associated osteonecrosis in rats

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 (Asp8-liposome-icaritin, liposome-icaritin and Asp8-liposome) for two weeks. SAON lesions were identified and osteoclasts activity, osteogenesis and adipogenesis at these sites were evaluated by immunohistochemistry. Ex vitro study was also designed to evaluate the osteogenic and adipogenic potential of the isolated bone marrow stromal cells (BMSCs) via real-time PCR and histochemical staining. Our results showed that as a bone surface-specific BTDS, Asp8-liposome-icaritin effectively prevented steroids-treated rats from SAON with significantly decreased osteocytes apoptosis, down-regulated osteoclatsogenesis and up-regulated osteogenesis. However, both liposome-icaritin and Asp8-liposome treatment did not show significant efficacy for SAON prevention. In summary, this proof-concept-study showed for the first time that the innovative Asp8-liposome-icaritin BTDS was effective for prevention of SAON in terms of bone resorption prevention, adipogenesis suppression, and bone-formation enhancement.