Vitamin K2 Ameliorates Damage of Blood Vessels by Glucocorticoid: a Potential Mechanism for Its Protective Effects in Glucocorticoid-induced Osteonecrosis of the Femoral Head in a Rat Model

[α2-macroglobulin alleviates glucocorticoid-induced avascular necrosis of the femoral head in mice by promoting proliferation, migration and angiogenesis of vascular endothelial cells]

OBJECTIVE

To explore the mechanism underlying the protective effect of α2-macroglobulin (A2M) against glucocorticoid-induced femoral head necrosis.

METHODS

In a human umbilical vein endothelial cell (HUVEC) model with injuries induced by gradient concentrations of dexamethasone (DEX; 10-8-10-5 mol/L), the protective effects of A2M at 0.05 and 0.1 mg/mL were assessed by examining the changes in cell viability, migration, and capacity of angiogenesis using CCK-8 assay, Transwell and scratch healing assays and angiogenesis assay. The expressions of CD31 and VEGF-A proteins in the treated cells were detected using Western blotting. In BALB/c mouse models of avascular necrosis of the femoral head induced by intramuscular injections of methylprednisolone, the effects of intervention with A2M on femoral trabecular structure, histopathological characteristics, and CD31 expression were examined with Micro-CT, HE staining and immunohistochemical staining.

RESULTS

In cultured HUVECs, DEX treatment significantly reduced cell viability, migration and angiogenic ability in a concentration- and time-dependent manner (P<0.05), and these changes were obviously reversed by treatment with A2M in positive correlation with A2M concentration (P<0.05). DEX significantly reduced the expression of CD31 and VEGF-A proteins in HUVECs, while treatment with A2M restored CD31 and VEGF-A expressions in the cells (P<0.05). The mouse models of femoral head necrosis showed obvious trabecular damages in the femoral head, where a large number of empty lacunae and hypertrophic fat cells could be seen and CD31 expression was significantly decreased (P<0.05). A2M treatment of the mouse models significantly improved trabecular damages, maintained normal bone tissue structures, and increased CD31 expression in the femoral head (P<0.05).

CONCLUSION

A2M promotes proliferation, migration, and angiogenesis of DEX-treated HUVECs and alleviates methylprednisolone-induced femoral head necrosis by improving microcirculation damages and maintaining microcirculation stability in the femoral head.

Glucocorticoid-induced activation of NOX/ROS/NF-κB signaling in MSCs contributes to the development of GONFH

BACKGROUND

This study aimed to investigate the pathogenic factors of glucocorticoids (GCs)-induced osteonecrosis of the femoral head (GONFH) and its underlying pathogenesis in vivo and in vitro.

METHODS

Radiographical (µCT) scanning, histopathological, immunohistochemical, reactive oxygen species (ROS) and tunel staining were conducted on GONFH patients and rats. ROS, tunel, flow cytometry, alkaline phosphatase, Oil red O staining, reverse transcription‑quantitative PCR and western blotting were applied to elucidate the exact pathogenesis mechanism.

RESULTS

Clinical and animal studies demonstrated increased levels of ROS, aggravated oxidative stress (OS) microenvironment, augmented apoptosis and imbalance in osteogenic/lipogenic in the GONFH group compared to the control group. The fate of mesenchymal stem cells (MSCs) directed by GCs is a crucial factor in determining GONFH. In vitro studies further revealed that GCs promote excessive ROS production through the expression of NOX family proteins, leading to a deterioration of the OS microenvironment in MSCs, ultimately resulting in apoptosis and imbalance in osteogenic/lipogenic differentiation. Furthermore, our results confirmed that the NOX inhibitor-diphenyleneiodonium chloride and the NF-κB inhibitor-BAY 11-7082 ameliorated apoptosis and osteogenic/lipogenic differentiation imbalance of MSCs induced by an excess of GCs.

CONCLUSION

We demonstrated for the first time that the aggravation of the OS microenvironment in MSCs caused by high doses of GCs leading to apoptosis and differentiation imbalance is a crucial factor in the pathogenesis of GONFH, mediated through activating the NOX/ROS/NF-κB signaling pathway.

Tanshinone I alleviates steroid-induced osteonecrosis of femoral heads and promotes angiogenesis: in vivo and in vitro studies

BACKGROUND

The impaired blood supply to the bones is an important pathological feature of steroid-induced osteonecrosis of the femoral head (SIONFH). Danshen is a Chinese herb that shows therapeutic effects on SIONFH, but the effects of one of its major bioactive constituents, Tanshinone I (TsI), on SIONFH remain unknown. Here, we evaluated the effects of TsI on SIONFH, particularly focusing on its effects on angiogenesis, in in vivo and in vitro research.

METHODS

SIONFH was induced in Sprague-Dawley rats by an intramuscular injection of methylprednisolone (40 mg/kg) in combination with an intraperitoneal injection of lipopolysaccharide (20 μg/kg). Morphological alterations of the femoral head were observed by dual-energy X-ray absorptiometry and HE staining. Western blot, qRT-PCR, and immunohistochemical/immunofluorescence staining were used to determine gene expression.

RESULTS

TsI (10 mg/kg) alleviated bone loss and rescued the expression of angiogenesis-related molecules (CD31, VWF, VEGF, and VEGFR2) in the femoral heads of SIONFH rats. Notably, TsI rescued the down-regulated expression of SRY-box transcription factor 11 (SOX11) in CD31⁺ endothelial cells in the femoral heads of SIONFH rats. In vitro studies showed that TsI preserved the dexamethasone-harmed angiogenic property (migration and tube formation) of human umbilical vein cells (EA.hy926), suppressed dexamethasone-induced cell apoptosis, reduced pro-apoptotic proteins (cytosolic cytochrome C, Bax, and caspase 3/9) and increased anti-apoptotic protein Bcl-2, whereas silencing of SOX11 reversed these beneficial effects.

CONCLUSIONS

This study demonstrates that TsI alleviates SIONFH and promotes angiogenesis by regulating SOX11 expression. Our work would provide new evidence for the application of TsI to treat SIONFH.

FAR591 promotes the pathogenesis and progression of SONFH by regulating Fos expression to mediate the apoptosis of bone microvascular endothelial cells

The specific pathogenesis of steroid-induced osteonecrosis of the femoral head (SONFH) is still not fully understood, and there is currently no effective early cure. Understanding the role and mechanism of long noncoding RNAs (lncRNAs) in the pathogenesis of SONFH will help reveal the pathogenesis of SONFH and provide new targets for its early prevention and treatment. In this study, we first confirmed that glucocorticoid (GC)-induced apoptosis of bone microvascular endothelial cells (BMECs) is a pre-event in the pathogenesis and progression of SONFH. Then, we identified a new lncRNA in BMECs via lncRNA/mRNA microarray, termed Fos-associated lincRNA ENSRNOT00000088059.1 (FAR591). FAR591 is highly expressed during GC-induced BMEC apoptosis and femoral head necrosis. Knockout of FAR591 effectively blocked the GC-induced apoptosis of BMECs, which then alleviated the damage of GCs to the femoral head microcirculation and inhibited the pathogenesis and progression of SONFH. In contrast, overexpression of FAR591 significantly promoted the GC-induced apoptosis of BMECs, which then aggravated the damage of GCs to the femoral head microcirculation and promoted the pathogenesis and progression of SONFH. Mechanistically, GCs activate the glucocorticoid receptor, which translocates to the nucleus and directly acts on the FAR591 gene promoter to induce FAR591 gene overexpression. Subsequently, FAR591 binds to the Fos gene promoter (-245∼-51) to form a stable RNA:DNA triplet structure and then recruits TATA-box binding protein associated factor 15 and RNA polymerase II to promote Fos expression through transcriptional activation. Fos activates the mitochondrial apoptotic pathway by regulating the expression of Bcl-2 interacting mediator of cell death (Bim) and P53 upregulated modulator of apoptosis (Puma) to mediate GC-induced apoptosis of BMECs, which leads to femoral head microcirculation dysfunction and femoral head necrosis. In conclusion, these results confirm the mechanistic link between lncRNAs and the pathogenesis of SONFH, which helps reveal the pathogenesis of SONFH and provides a new target for the early prevention and treatment of SONFH.

Application of Biomaterials in Treating Early Osteonecrosis of the Femoral Head: Research Progress and Future Perspectives

Osteonecrosis of the femoral head (ONFH), a progressive pathological process of femoral head ischemia and osteocyte necrosis, is a refractory orthopedic disease caused by multiple etiologies and there is no complete cure at present. With the extension of ONFH duration, osteocyte apoptosis and trabecular bone loss can decrease the load-bearing capacity of the femoral head, which leads to the collapse of the articular cartilage and subchondral bone. Therefore, an urgent clinical need exists to develop effective treatment strategies of early-stage ONFH for maintaining the hip joint function and preventing femoral head collapse. In recent years, extensive attention has been paid to the application of diverse biomaterials in treating early ONFH for sustaining the normal morphology and function of the autologous femoral head, and slowing disease progression. Herein, we review the research progress of bone grafts, metallic materials, bioceramics, bioglasses and polymer materials for early ONFH treatment, and discuss the biological mechanisms of bone repair and regeneration in the femoral-head necrotic area. We propose suggestions for future research directions, from a special perspective of improving the local microenvironment in femoral head by facilitating vessel-associated osteoclasts (VAOs) generation and coupling of bone-specific angiogenesis and osteogenesis, as well as inhibiting bone-associated osteoclasts (BAOs) and BAO-mediated bone resorption. This review can provide ideas for the research, development, and clinical application of biomaterials for treating early ONFH. STATEMENT OF SIGNIFICANCE: We believe that at least three aspects of this manuscript make it interesting to readers of the Acta Biomaterialia. First, we briefly summarize the incidence, pathogenesis, risk factors, classification criteria and treatment of early osteonecrosis of the femoral head (ONFH). Second, we review the research progress in biomaterials for early ONFH treatment and the biological mechanisms of bone repair and regeneration in femoral-head necrotic area. Third, we propose future research progress on improving the local microenvironment in femoral head by facilitating vessel-associated osteoclasts generation and coupling of bone-specific angiogenesis and osteogenesis, as well as inhibiting bone-associated osteoclasts and bone resorption. We hope this review can provide ideas for the research, development, and clinical application of biomaterials for treating early ONFH.

Advances in experimental models of osteonecrosis of the femoral head

Background

Osteonecrosis of the femoral head (ONFH) is a devastating disease affecting young adults, resulting in significant pain, articular surface collapse, and disabling dysfunction. ONFH can be divided into two broad categories: traumatic and non-traumatic. It has been established that ONFH results from an inadequate blood supply that causes the death of osteocytes and bone marrow cells. Nonetheless, the precise mechanism of ONFH remains to be elucidated. In this regard, preclinical animal and cell models to study ONFH have been established to assess the efficacy of various modalities for preventing and treating ONFH. Nevertheless, it should be borne in mind that many models do not share the same physiologic and metabolic characteristics as humans. Therefore, it is necessary to establish a reproducible model that better mimics human disease.

Methods

We systematically reviewed the literatures in regard to ONFH experimental models over the past 30 years. The search was performed in PubMed and Web of Science. Original animal, cell studies with available full-text were included. This review summarizes different methods for developing animal and cell experimental models of ONFH. The advantages, disadvantages and success rates of ONFH models are also discussed. Finally, we provide experimental ONFH model schemes as a reference.

Results

According to the recent literatures, animal models of ONFH include traumatic, non-traumatic and traumatic combined with non-traumatic models. Most researchers prefer to use small animals to establish non-traumatic ONFH models. Indeed, small animal-based non-traumatic ONFH modeling can more easily meet ethical requirements with large samples. Otherwise, gradient concentration or a particular concentration of steroids to induce MSCs or EPCs, through which researchers can develop cell models to study ONFH.

Conclusions

Glucocorticoids in combination with LPS to induce ONFH animal models, which can guarantee a success rate of more than 60% in large samples. Traumatic vascular deprivation combines with non-traumatic steroids to induce ONFH, obtaining success rates ranging from 80% to 100%. However, animals that undergo vascular deprivation surgery may not survive the glucocorticoid induction process. As for cell models, 10-6mol/L Dexamethasone (Dex) to treat bone marrow stem cells, which is optimal for establishing cell models to study ONFH.

The translational potential of this article

This review aims to summarize recent development in experimental models of ONFH and recommended the modeling schemes to verify new models, mechanisms, drugs, surgeries, and biomaterials of ONFH to contribute to the prevention and treatment of ONFH.

Ginkgo biloba L. extract prevents steroid-induced necrosis of the femoral head by rescuing apoptosis and dysfunction in vascular endothelial cells via the PI3K/AKT/eNOS pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Ginkgo biloba L. extract (EGb) is one of the world's most extensively used herbal medicines. Due to the diverse pharmacological properties of EGb, it has been used in the treatment of neurological illnesses, as well as cardiovascular and cerebrovascular ailments. However, the effect and pharmacological mechanism of EGb on steroid-induced necrosis of the femoral head (SINFH) are still unclear.

AIM OF THE STUDY

SINFH remains a challenging problem in orthopedics. Previous investigations have shown that EGb has the potential to reduce the occurrence of SINFH. The goal was to determine the effect and mechanism of EGb in preventing SINFH by inhibiting apoptosis and improving vascular endothelial cells (VECs) functions.

MATERIALS AND METHODS

CCK-8, nitric oxide (NO) production and flow cytometry were used to determine the cell apoptosis and function. The scratch and angiogenesis tests assessed migration and tube formation. Western blot analysis detected the expressions of apoptosis-related proteins and PI3K/AKT/eNOS pathway-related proteins. Apoptosis and angiogenesis were also detected treated with the inhibitors. A mouse model of SINFH was established. Paraffin section was used to determine the necrotic pathology and apoptosis. Vessels in the femoral heads were assessed by immunofluorescence staining.

RESULTS

When stimulated by methylprednisolone (MPS), cell viability, NO generation and tube formation were decreased, the apoptotic rate increased. Simultaneously, MPS decreased the expression levels of p-PI3K, p-AKT, and p-eNOS. EGb increased the expression levels of these proteins, restrained apoptosis, and restored cell functions. The addition of the inhibitors decreased anti-apoptotic effect and angiogenesis. In addition, when compared to the model mice, there were fewer empty lacunae and normal trabecular arrangement after taking different doses of EGb. The protective effect was also confirmed by the vascular quantitative analysis in vivo.

CONCLUSION

This study established that EGb increased endothelial cell activity and inhibited apoptosis and function loss induced by MPS, elucidating the effect and molecular mechanism of EGb on early SINFH.

Effects of angiotensin II combined with asparaginase and dexamethasone on the femoral head in mice: A model of steroid-induced femoral head osteonecrosis

Background: To study the pathogenesis of steroid-induced femoral head osteonecrosis, an ideal animal model is very important. As experimental animals, mice are beneficial for studying the pathogenesis of disease. However, there are currently few mouse models of steroid-induced femoral head osteonecrosis, and there are many questions that require further exploration and research.

Purposes: The purpose of this study was to establish a new model of osteonecrosis in mice using angiotensin II (Ang II) combined with asparaginase (ASP) and dexamethasone (DEX) and to study the effects of this drug combination on femoral head osteonecrosis in mice.

Methods: Male BALB/c mice (n = 60) were randomly divided into three groups. Group A (normal control, NC) was treated with physiological saline and given a normal diet. Group B (DEX + ASP, DA) was given free access to food and water (containing 2 mg/L DEX) and subjected to intraperitoneal injection of ASP (1200 IU/kg twice/week for 8 weeks). Group C (DEX + ASP + Ang II, DAA) was treated the same as group B, it was also given free access to food and water (containing 2 mg/L DEX) and subjected to intraperitoneal injection of ASP (1200 IU/kg twice/week for 8 weeks), but in the 4th and 8th weeks, subcutaneous implantation of a capsule osmotic pump (0.28 mg/kg/day Ang II) was performed. The mice were sacrificed in the 4th and 8th weeks, and the model success rate, mouse mortality rate, body weight, blood lipids, coagulation factors, histopathology, and number of local vessels in the femoral head were evaluated.

Results: DAA increased the model success rate [4th week, 30% (DA) vs. 40% (DAA) vs. 0% (NC); 8th week, 40% (DA) vs. 70% (DAA) vs. 0% (NC)]. There was no significant difference in mortality rate between the groups [4th week, 0% (DA) vs. 0% (DAA) vs. 0% (NC); 8th week, 5% (DA) vs. 10% (DAA) vs. 0% (NC)]. DAA affected mouse body weight and significantly affected blood lipids and blood coagulation factors. DAA reduces the number of blood vessels in the femoral head and destroys the local blood supply.

Conclusion: Angiotensin II combined with asparaginase and dexamethasone can obviously promote the necrosis of femoral head and provide a new idea for the model and treatment of osteonecrosis.

Exosomal miR-150 derived from BMSCs inhibits TNF-α-mediated osteoblast apoptosis in osteonecrosis of the femoral head by GREM1/NF-κB signaling

Aim: The purpose of this study was to investigate the functions of exosomal miR-150 derived from bone marrow mesenchymal stem cells in osteonecrosis of the femoral head (ONFH). Materials & methods: Cell viability and apoptosis were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and flow cytometry. Alizarin red staining was performed to detect calcium deposits. A rat model was established to assess the effects of exosomal miR-150 on ONFH in vivo. Results: Exosomes or exosomal miR-150 derived from bone marrow mesenchymal stem cells inhibited TNF-α-induced osteoblast apoptosis and promoted osteogenic differentiation and autophagy. Exosomal miR-150 suppressed apoptosis and induced autophagy in TNF-α-treated osteoblasts by regulating the GREM1/NF-κB axis. Exosomal miR-150 also improved the pathological features of ONFH in vivo. Conclusion: Exosomal miR-150 alleviates ONFH by mediating the GREM1/NF-κB axis. This study provides a potential therapeutic strategy for ONFH.

C/EBPα regulates the fate of bone marrow mesenchymal stem cells and steroid-induced avascular necrosis of the femoral head by targeting the PPARγ signalling pathway

BACKGROUND

The imbalance of osteogenic/adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is closely related to steroid-induced avascular necrosis of the femoral head (SANFH). We aimed to investigate the epigenetic mechanism of intramedullary fat accumulation and continuous osteonecrosis after glucocorticoid (GC) withdrawal in SANFH.

METHODS

An SANFH model was established in SD rats, which received an intermittent high GC dose for the first 4 weeks followed by an additional 4 weeks without GC. We explored the synergistic effects and mechanisms of C/EBPα and PPARγ on the differentiation of BMSCs by lentivirus-mediated gene knockdown and overexpression assays. A chromatin immunoprecipitation assay was performed to identify epigenetic modification sites on PPARγ in vivo and in vitro.

RESULTS

In the SANFH model, intramedullary fat was significantly increased, and the transcription factors C/EBPα and PPARγ were upregulated simultaneously in the femoral head. In vitro, C/EBPα promoted adipogenic differentiation of BMSCs by targeting the PPARγ signalling pathway, while overexpression of C/EBPα significantly impaired osteogenic differentiation. Further studies demonstrated that histone H3K27 acetylation of PPARγ played an important role in the epigenetic mechanism underlying SANFH. C/EBPα upregulates the histone H3K27 acetylation level in the PPARγ promoter region by inhibiting HDAC1. Additionally, inhibiting the histone acetylation level of PPARγ effectively prevented adipogenic differentiation, thus slowing the progression of SANFH.

CONCLUSIONS

Our results demonstrate the molecular mechanism by which C/EBPα regulates PPARγ expression by acetylating histones and revealed the epigenetic phenomenon in SANFH for the first time.

Peripheral Blood-Derived Stem Cells for the Treatment of Cartilage Injuries: A Systematic Review

Background: The treatment of cartilage damage is a hot topic at present, and cell therapy is an emerging alternative therapy. Stem cells derived from peripheral blood have become the focus of current research due to the ease of obtaining materials and a wide range of sources.

Methods: We used a text search strategy using the [“mesenchymal stem cells” (MeSH term) OR “MSC” OR “BMMSC” OR “PBMSC” OR” PBMNC” OR “peripheral blood stem cells”] AND (cartilage injury [MeSH term] OR “cartilage” OR “chondral lesion”). After searching the literature, through the inclusion and exclusion criteria, the last included articles were systematically reviewed.

Result: We found that peripheral blood-derived stem cells have chondrogenic differentiation ability and can induce chondrogenic differentiation and repair in vivo and have statistical significance in clinical and imaging prognosis. It is an improvement of academic differences. Compared with the bone marrow, peripheral blood is easier to obtain, widely sourced, and simple to obtain. In the future, peripheral blood will be a more potential cell source for cell therapy in the treatment of cartilage damage.

Conclusion: Stem cells derived from peripheral blood can repair cartilage and are an important resource for the treatment of cartilage damage in the future. The specific mechanism and way of repairing cartilage need further study.

Animal Models of Femur Head Necrosis for Tissue Engineering and Biomaterials Research

Femur head necrosis, also known as osteonecrosis of the femoral head (ONFH), is a widespread disabling pathology mostly affecting young and middle-aged population and one of the major causes of total hip arthroplasty in the elderly. Currently, there are limited number of different clinical or medication options for the treatment or the reversal of progressive ONFH, but their clinical outcomes are neither satisfactory nor consistent. In pursuit of more reliable therapeutic strategies for ONFH, including recently emerged tissue engineering and biomaterials approaches, in vivo animal models are extremely important for therapeutic efficacy evaluation and mechanistic exploration. Based on the better understanding of pathogenesis of ONFH, animal modeling method has evolved into three major routes, including steroid-, alcohol-, and injury/trauma-induced osteonecrosis, respectively. There is no consensus yet on a standardized ONFH animal model for tissue engineering and biomaterial research; therefore, appropriate animal modeling method should be carefully selected depending on research purposes and scientific hypotheses. In this work, mainstream types of ONFH animal model and their modeling techniques are summarized, showing both merits and demerits for each. In addition, current studies and experimental techniques of evaluating therapeutic efficacy on the treatment of ONFH using animal models are also summarized, along with discussions on future directions related to tissue engineering and biomaterial research. Impact statement Exploration of tissue engineering and biomaterial-based therapeutic strategy for the treatment of femur head necrosis is important since there are limited options available with satisfactory clinical outcomes. To promote the translation of these technologies from benchwork to bedside, animal model should be carefully selected to provide reliable results and clinical outcome prediction. Therefore, osteonecrosis of the femoral head animal modeling methods as well as associated tissue engineering and biomaterial research are overviewed and discussed in this work, as an attempt to provide guidance for model selection and optimization in tissue engineering and biomaterial translational studies.

Evolutionary course of the femoral head osteonecrosis: Histopathological - radiologic characteristics and clinical staging systems

Osteonecrosis of the femoral head (ONFH) is a recalcitrant ischemic disorder, which could be classified into two major categories: traumatic and nontraumatic. Regardless of different risk factors, it has been testified that ONFH results from primitive vascular problems, leading to temporary or permanent loss of blood supply to bone tissue. Histopathological and microarchitectural alterations ensues, which is a gradual evolutionary process involving bone marrow and osteocyte necrosis, progressive destruction of subchondral bone, unsuccessful reparative process, and eventual articular collapse and degenerative arthritis. Based on the imaging features of ONFH, different classification systems have been developed to evaluate the severity and prognosis of the disease, which is pivotal for implementation of treatment strategy, especially the joint-preserving surgery. However, patients classified with the same severity stage, especially in the peri-collapse stage, sometimes responded differently after similar joint-preserving surgery. The unusual phenomenon may be attributed to the limitation of the current imaging classification systems, which might underestimate the disease severity, especially when referring to the early stages. In this review, we briefly summarize the etiology and pathogenesis of ONFH. The imaging features and staging classification systems of ONFH are also described. More importantly, we focus on histopathological and microstructural alterations of the femoral head, and provide an overview of their essential contribution to ONFH progression. Given the observation of discordance between imaging characteristics and histopathological alterations, a substantial amount of research on the relationship between imaging and histopathological features is required to further modify and revise the current wide-accepted classification systems.

Overexpression of HIF-1α enhances the protective effect of mitophagy on steroid-induced osteocytes apoptosis

Glucocorticoid (GC; dexamethasone, DEX) -induced osteonecrosis of the femoral head (GIOFH) is a challenging orthopedic disease, and its underlying mechanism remains not clear. This study exposed murine long bone osteocyte-Y4 (MLO-Y4) cells to DEX below normoxic or hypoxic circumstances and found that cell autophagy have been reduced. At the same time, flow cytometry analysis showed increased apoptosis, which was more pronounced in hypoxic environments. Recent research also claimed that GC induces osteoporosis after osteocyte apoptosis, and subsequent microfractures lead to ischemia and hypoxia of the femoral head, resulted in GIOFH. Presently, we found that both mitophagy-related protein hypoxia-inducible factor-1α (HIF-1α) and BNIP3 were up-regulated in the hypoxic environment, and their expression was down-regulated when exposed to DEX. Besides, we demonstrated that overexpressing HIF-1α resisted DEX-induced apoptosis in a hypoxic environment. Here, we demonstrated that overexpression of HIF-1α, through its downstream marker BNIP3, reduced the suppression of DEX on mitophagy induced by hypoxia and protected bone cells from apoptosis. Also, these findings may provide a direction of the promising application for better GIOFH treatment shortly.

Prohexadione-calcium alleviates saline-alkali stress in soybean seedlings by improving the photosynthesis and up-regulating antioxidant defense

Soil salinization seriously restricts the growth and yield of soybeans. However, little information is available on the early growth stages of soybeans which are subjected to the gibberellin biosynthesis inhibitor, prohexadione-calcium (Pro-Ca). This study aimed to investigate the effects of exogenous Pro-Ca on saline-alkali stress-induced damages to photosynthesis and antioxidant defenses in soybean (Glycine max L.) seedlings. At the V3 growth stage, salt-tolerant genotype Hefeng 50 (HF50) and salt-sensitive genotype Kenfeng 16 (KF16) were subjected to 110 mmol L-1 mixed saline-alkali stress respectively, and then 100 mg L-1 Pro-Ca was sprayed on the leaves. Our results showed that saline-alkali stress accelerated the degradation of thylakoids, inhibited chlorophyll synthesis, reduced shoot dry weight, electron transfer rate (ETR), and peroxidase (POD) activity, the concentration of ascorbic acid (AsA) and soluble sugar, but enhanced the concentration of proline, hydrogen peroxide (H2O2) and the rate of superoxide radical (O2∙-) generation. Additionally, saline-alkali stress induced a lower decrease of the net photosynthetic rate (Pn), potential activity of PSII (Fv/F0), and maximum quantum yield of PSII (Fv/Fm) in salt-tolerant HF50 than in salt-sensitive KF16. Nevertheless, foliar spraying of exogenous Pro-Ca increased the chlorophyll content, Pn, Fv/F0, and Fv/Fm. These results were more prominent when Pro-Ca was applied to KF16 under saline-alkali conditions. Furthermore, exogenous application of Pro-Ca retarded the degradation of thylakoids, increased the ETR and the accumulation of AsA, soluble sugar, and proline, activated the activities of superoxide dismutase (SOD), catalase (CAT), and POD, and decreased the concentration of malondialdehyde (MDA), electrolyte leakage (EL), O2∙-, and H2O2. These results indicated that Pro-Ca could effectively protect soybean seedlings against damage from saline-alkali stress by regulating seedling phenotype, photosynthetic apparatus, antioxidant defense, and osmoregulation.

Non-arteritic anterior ischaemic optic neuropathy sequential to SARS-CoV-2 virus pneumonia: preventable by endothelial protection?

We present a case of non-arteritic anterior ischaemic optic neuropathy (NAION) with no ocular or systemic risk factors in a patient who recovered from a recent SARS-CoV-2 pneumonia. NAION is the most common acute optic neuropathy among individuals over 50 years of age. It results from a transient hypoperfusion of the optic nerve head circulation, especially in patients with low vascular compliance due to ocular or systemic risk factors. We attribute the ophthalmological condition to a SARS-CoV-2 virus-associated endotheliopathy that can be prevented with timely protection of endothelial function with vitamins D and K₂.

Lithium chloride prevents glucocorticoid-induced osteonecrosis of femoral heads and strengthens mesenchymal stem cell activity in rats

Background:

Accumulating evidence suggests that lithium influences mesenchymal stem cell (MSC) proliferation and osteogenic differentiation. As decreased bone formation in femoral heads is induced by glucocorticoids (GCs), we hypothesized that lithium has a protective effect on GC-induced osteonecrosis of femoral heads (ONFH).

Methods:

A rat ONFH model was induced by methylprednisolone (MP) and the effect of lithium chloride on the models was evaluated. Micro-computed tomography (CT)-based angiography and bone scanning were performed to analyze the vessels and bone structure in the femoral heads. Hematoxylin and eosin and immunohistochemical staining were performed to evaluate the trabecular structure and osteocalcin (OCN) expression, respectively. Bone marrow-derived MSCs were isolated from the models, and their proliferative and osteogenic ability was evaluated. Western blotting and quantitative real-time polymerase chain reaction were performed to detect osteogenic-related proteins including Runx2, alkaline phosphatase, and Collagen I.

Results:

Micro-CT analysis showed a high degree of osteonecrotic changes in the rats that received only MP injection. Treatment with lithium reduced this significantly in rats that received lithium (MP + Li group); while 18/20 of the femoral heads in the MP showed severe osteonecrosis, only 5/20 in the MP + Li showed mild osteonecrotic changes. The MP + Li group also displayed a higher vessel volume than the MP group (0.2193 mm³vs. 0.0811 mm³, P < 0.05), shown by micro-CT-based angiography. Furthermore, histological analysis showed better trabecular structures and more OCN expression in the femoral heads of the MP + Li group compared with the MP group. The ex vivo investigation indicated higher proliferative and osteogenic ability and upregulated osteogenic-related proteins in MSCs extracted from rats in the MP + Li group than that in the MP group.

Conclusions:

We concluded that lithium chloride has a significant protective effect on GC-induced ONFH in rats and that lithium also enhances MSC proliferation and osteogenic differentiation in rats after GC administration.

Gradient radiation breeding and culture domestication of menaquinone producing strains

By comparing the survival rate and positive mutation rate of the primary mutagenic strain and progeny mutagenic strain under different radiation doses, the results showed that the tolerance of the mutagenic strain to radiation dose increased with the increase of the mutagenic generations. We adopted an improved gradient radiation breeding strategy to improve the breeding efficiency. The strains were treated with radiation in four stages. The first stage was low energy N⁺ ion implantation (ion energy 15 keV, dose 80 × 2.6 × 10¹³ cm^-2). In the second stage, the energy and dose of N⁺ ion reached to 20 keV, 90 × 2.6 × 10¹³ cm^-2. In the third stage, ⁶⁰Co-γ radiation (dose of 1.56 kGy) was used. In the fourth stage, the radiation dose of ⁶⁰Co-γ increased to 1.82 kGy. After each stage of radiation, the MK (Menaquinone) precursor 1, 4-dihydroxy-2-naphthalate (DHNA) was used as the stress factor to domesticate the mutant strains. By gradually increasing the concentration of DHNA in the culture medium, the substrate tolerance of Flavobacterium sp. was effectively improved. By measuring SOD (superoxide dismutase) activity and malondialdehyde, it showed that the cell damage caused by radiation mutagenesis to the offspring mutant was less than that of the primary mutant. Changes in membrane permeability and membrane potential of the mutant strains were reflected in changes in fluorescence intensity of luciferin diacetate and rhodamine 123, which could explain the enhanced substrate tolerance of strain F-2. After gradient radiation breeding and culture acclimation, the biomass of mutant Strain F-2 was 6.59 g/L, and the MK yield was 9.59 mg/L.

CircCDR1as Suppresses Bone Microvascular Endothelial Cell Activity and Angiogenesis Through Targeting miR-135b/ FIH-1 Axis

Objective

The current study investigated the role of CircCDR1as on angiogenesis of bone microvascular endothelial cells (BMECs) isolated from non‐traumatic ONFH.

Methods

Forty corticosteroid‐induced ONFH patients received THA were enrolled in our study. Expressions of CircCDR1as, miR‐135b, and FIH‐1 were detected by qRT‐PCR in affected necrosis tissue and non‐affected normal tissue. Bone microvascular endothelial cells (BMEC) were isolated from six patients and treated with 0.1 mg/mL hydrocortisone to establish a GC‐damaged model of BMECs. Circ CDR1as plasmid and miR‐135b mimic were transfected into BMECs. BMEC proliferation was assessed using MTT assays. The migration ability of cells was detected by scratch‐wound assays. Matrigel assay was performed to detect angiogenesis in vitro. Western blot assay was used to detect HIF‐1α, VEGF, and FIH‐1 expressions. FISH, RNA pull down, RIP, and luciferase assay were carried out to determine the interaction of CircCDR1as, miR‐135b, and FIH‐1.

Results

CircCDR1as was upregulated(2.02 ± 0.30 vs. 1.00 ± 0.10,P < 0.001) whereas miR‐135b was downregulated (0.55 ± 0.12 vs. 1.00 ± 0.10,P < 0.001) in affected tissues than in non‐affected tissues. Expression of CircCDR1as and FIH‐1 were negatively associated with miR‐135b in affected tissues (CircCDR1as with miR‐135b: r = −0.506, P < 0.001; FIH‐1 with miR‐135b r = −0.510, P < 0.001). Total blood tubule density was increased when CircCDR1as was silenced compared with NC (P < 0.01 vs. NC). The number of migrated BMECs were significantly increased in CircCDR1as silencing group compared with NC group (P < 0.05 vs. NC). In addition, CircCDR1as plasmids transfection increased the protein expressions of FIH‐1 (P < 0.05 vs. NC) and reduced the HIF‐1α as well as VEGF expression compared with NC group (P < 0.05 vs. NC). FISH, RNA pull down, RIP, and luciferase assay identified that FIH‐1 was a target of miR‐135b and could be modulated by CircCDR1as.

Conclusion

CircCDR1as decreases angiogenesis and proliferation of BMECs by sponging miR‐135b and upregulate FIH‐1.

Juvenile-onset multifocal osteonecrosis in systemic lupus erythematosus: A case report

RATIONALE

Osteonecrosis (ON) is a devastating illness that leads to bone ischemia and potential joint destruction. Systemic lupus erythematosus (SLE) is a chronic, autoimmune disease, with multi-system involvement which is closely associated with occurrence of ON. Multifocal ON, with an estimated morbidity of 3% in SLE patients, is extremely rare in juvenile subjects.

PATIENT CONCERNS

A 13.3-year-old female SLE patient was admitted to hospital 20 months following the SLE diagnosis because of a sudden aggravation of sore knees. She suffered from double knee joint pain and her left knee joint showed typical signs of inflammation including redness, swelling, heat, and pain.

DIAGNOSES

The SLE patient was diagnosed with multifocal ON of her knee joint based on magnetic resonance imaging findings of bone destruction and osteoproliferation at the bilateral distal femur and proximal tibia.

INTERVENTIONS

The patient received high-dose methylprednisolone and intravenous cyclophosphamide pulse therapies for controlling active lupus and nephritis. Oral calcitriol and dipyridamole were administered to alleviate knee pain and inhibit thrombi formation, thereby suppressing ON progress.

OUTCOMES

Three weeks following the treatment, the swelling in patient's left knee subsided. Her self-reporting pain score decreased from 9 to 4 and walking time increased from 45minutes to 90minutes per day. Nearly 5 weeks later, the pain in bilateral knee joints disappeared and the patient could walk without difficulties.

LESSONS

This patient is the youngest SLE patient who developed multifocal ON based on the reported literature. It suggests that ON can occur in young SLE patients. A combination of internal and external risk factors can promote the development of ON. The balanced approach to the application of corticosteroids and immunosuppressors in the treatment of SLE and prevention of ON is a challenging problem that deserves further exploration.

Dexamethasone Does Not Inhibit Treadmill Training-Induced Angiogenesis in Myocardium: Role of MicroRNA-126 Pathway

Dexamethasone (DEX) has important anti-inflammatory activities; however, it induces hypertension and skeletal muscle microcirculation rarefaction. Nevertheless, nothing is known about DEX outcomes on cardiac microcirculation. By contrast, exercise training prevents skeletal and cardiac microvessel loss because of microRNA expression and a better balance between their related angiogenic and apoptotic proteins in spontaneously hypertensive rats. The purpose of this study was to investigate whether DEX and/or exercise training could induce microRNA alterations leading to cardiac angiogenesis or microvascular rarefaction. Animals performed 8 weeks of exercise training and were treated with DEX (50 μg/kg per day, subcutaneously) for 14 days. Cardiovascular parameters were measured, and the left ventricle muscle was collected for analyses. DEX treatment increased arterial pressure and did not cause cardiac microcirculation rarefaction. Treadmill training prevented the DEX-induced increase in arterial pressure. In addition, training, regardless of DEX treatment, increased microRNA-126 expression, phospho-protein kinase B/protein kinase B, and endothelial nitric oxide synthase levels associated with cardiac angiogenesis. In conclusion, this study suggests, for the first time, that treadmill training induces myocardial angiogenesis because of angiogenic pathway improvement associated with an increase in microRNA-126. Furthermore, DEX, per se, did not cause capillary density alterations and did not attenuate cardiac angiogenesis induced by training.

Hypoxia alleviates dexamethasone-induced inhibition of angiogenesis in cocultures of HUVECs and rBMSCs via HIF-1α

BACKGROUND AND AIM

Inadequate vascularization is a challenge in bone tissue engineering because internal cells are prone to necrosis due to a lack of nutrient supply. Rat bone marrow-derived mesenchymal stem cells (rBMSCs) and human umbilical vein endothelial cells (HUVECs) were cocultured to construct prevascularized bone tissue in osteogenic induction medium (OIM) in vitro. The angiogenic capacity of HUVECs was limited in the coculture system. In this study, the effects of the components in the medium on HUVEC angiogenesis were analyzed.

METHODS

The coculture system was established in OIM. Alizarin red staining and alkaline phosphatase staining were used to assess the osteogenic ability of MSCs. A Matrigel tube assay was used to assess the angiogenic ability of HUVECs in vitro. The proliferation of HUVECs was evaluated by cell counting and CCK-8 assays, and migration was evaluated by the streaked plate assay. The expression levels of angiogenesis-associated genes and proteins in HUVECs were measured by qRT-PCR and Western blotting, respectively.

RESULTS

Dexamethasone in the OIM suppressed the proliferation and migration of HUVECs, inhibiting the formation of capillary-like structures. Our research showed that dexamethasone stimulated HUVECs to secrete tissue inhibitor of metalloproteinase (TIMP-3), which competed with vascular endothelial growth factor (VEGF-A) to bind to vascular endothelial growth factor receptor 2 (VEGFR2, KDR). This effect was related to inhibiting the phosphorylation of ERK and AKT, which are two downstream targets of KDR. However, under hypoxia, the enhanced expression of hypoxia-inducible factor-1α (HIF-1α) decreased the expression of TIMP-3 and promoted the phosphorylation of KDR, improving HUVEC angiogenesis in the coculture system.

CONCLUSION

Coculture of hypoxia-preconditioned HUVECs and MSCs showed robust angiogenesis and osteogenesis in OIM, which has important implications for prevascularization in bone tissue engineering in the future.

Desferoxamine protects against glucocorticoid-induced osteonecrosis of the femoral head via activating HIF-1α expression

Glucocorticoid-induced osteonecrosis of the femoral head (GIOFH) is one of the most common complications of glucocorticoid administration. By chelating Fe²⁺ , desferoxamine (DFO) was reported to be able to activate the HIF-1α/VEGF pathway and promote angiogenesis. In the present study, we examined whether DFO administration could promote angiogenesis and bone repair in GIOFH. GIOFH was induced in rats by methylprednisolone in combination with lipopolysaccharide. Bone repair was assessed by histologic analysis and microcomputed tomography (micro-CT). Vascularization was assessed by Microfil perfusion and micro-CT analysis. Immunohistochemical staining was performed to analyze the expression of HIF-1α, VEGF, and CD31. Our in vivo study revealed that DFO increased HIF-1α/VEGF expression and promoted angiogenesis and osteogenesis in GIOFH. Moreover, our in vitro study revealed that DFO restored dexamethone-induced HIF-1α downregulation and angiogenesis inhibition. Besides, our in vitro study also demonstrated that DFO could protect bone marrow-derived stem cells from dexamethone-induced apoptosis and mitochondrial dysfunction by promoting mitophagy and mitochondrial fission. In summary, our data provided useful information for the development of novel therapeutics for management of GIOFH.

In vivo vascular rarefaction and hypertension induced by dexamethasone are related to phosphatase PTP1B activation not endothelial metabolic changes

Glucocorticoids have important anti-inflammatory and immunomodulatory activities. Dexamethasone (Dex), a synthetic glucocorticoid, induces insulin resistance, hyperglycemia, and hypertension. The hypertensive mechanisms of Dex are not well understood. Previously, we showed that exercise training prior to Dex treatment significantly decreases blood vessel loss and hypertension in rats. In this study, we examined whether the salutary effects of exercise are associated with an enhanced metabolic profile. Analysis of the NAD and ATP content in the tibialis anterior muscle of trained and non-trained animals indicated that exercise increases both NAD and ATP; however, Dex treatment had no effect on any of the experimental groups. Likewise, Dex did not change NAD and ATP in cultured endothelial cells following 24 h and 48 h of incubation with high concentrations. Reduced VEGF-stimulated NO production, however, was verified in endothelial cultured cells. Reduced NO was not associated with changes in survival or the BH4 to BH2 ratio. Moreover, Dex had no effect on bradykinin- or shear-stress-stimulated NO production, indicating that VEGF-stimulated eNOS phosphorylation is a target of Dex's effects. The PTP1B inhibitor increased NO in Dex-treated cells in a dose-dependent fashion, an effect that was replicated by the glucocorticoid receptor inhibitor, RU486. In combination, these results indicate that Dex-induced endothelial dysfunction is mediated by glucocorticoid receptor and PTP1B activation. Moreover, since exercise reduces the expression of PTP1B and normalized insulin resistance in aging rats, our findings indicate that exercise training by reducing PTP1B activity counteracts Dex-induced hypertension in vivo.

Decreased angiogenic and increased apoptotic activities of bone microvascular endothelial cells in patients with glucocorticoid-induced osteonecrosis of the femoral head

Background

Glucocorticoid-induced osteonecrosis of the femoral head (ONFH) is closely associated with the dysfunction of the bone microvascular endothelial cells (BMECs). The present study investigated the angiogenic and apoptotic activity of the BMECs in glucocorticoid-induced ONFH.

Methods

This study enrolled a total of 12 patients, six of whom were assigned to the ONFH group whereas the other six served as the control group. The ONFH group was composed of patients with glucocorticoid-induced ONFH while the control group had femoral neck fractures. BMECs were isolated from the subchondral region of the femoral head. Cell proliferation, cell viability, tube formation assay, Transwell assay, TUNEL assay, and Western blot analysis were performed.

Results

BMECs of the two groups were successfully isolated and identified. No significant differences were noticed in BMECs proliferation between the two groups. However, compared to the control, cell viability, tube formation, and migration of BMECs were significantly decreased and the number of TUNEL positive cells was markedly increased in the ONFH group. In the ONFH group, it was also noted that the amount of Bax and cleaved-caspase3 was elevated while that of Bcl-2 was reduced.

Conclusion

The findings of our study revealed that BMECs obtained from the glucocorticoid-induced ONFH patients had decreased angiogenic and increased apoptotic activities, which could explain the pathogenesis and progression of glucocorticoid-induced ONFH.

PTEN inhibitor VO-OHpic attenuates GC-associated endothelial progenitor cell dysfunction and osteonecrosis of the femoral head via activating Nrf2 signaling and inhibiting mitochondrial apoptosis pathway

Background

Glucocorticoid (GC)-associated osteonecrosis of the femoral head (ONFH) is the most common in non-traumatic ONFH. Despite a strong relationship between GC and ONFH, the detailed mechanisms have remained elusive. Recent studies have shown that GC could directly injure the blood vessels and reduce blood supply in the femoral head. Endothelial progenitor cells (EPCs), which were inhibited quantitatively and functionally during ONFH, play an important role in maintaining the normal structure and function of vascular endothelium. Phosphatase and tensin homolog (PTEN) is a tumor suppressor gene that promotes cell apoptosis, and its expression was found to be elevated in GC-associated ONFH patients. However, whether direct inhibition of PTEN attenuates GC-associated apoptosis and dysfunction of the EPCs remains largely unknown.

Methods

We investigated the effect of, VO-OHpic, a potent inhibitor of PTEN, in attenuating GC-associated apoptosis and dysfunction of EPCs and the molecular mechanism. SD rats were used to study the effect of VO-OHpic on angiogenesis and osteonecrosis in vivo.

Results

The results revealed that methylprednisolone (MPS) obviously inhibit angiogenesis of EPCs by inducing apoptosis, destroying the normal mitochondrial structure, and disrupting function of mitochondria. VO-OHpic treatment is able to reverse the harmful effects by inhibiting the mitochondrial apoptosis pathway and activating the NF-E2-related factor 2 (Nrf2) signaling. Si-Nrf2 transfection significantly reduced the protective effects of VO-OHpic on EPCs. Our in vivo studies also showed that intraperitoneal injection of VO-OHpic obviously attenuates the osteonecrosis of the femoral head induced by MPS and potently increases the blood supply in the femoral head.

Conclusion

Taken together, the data suggests that inhibition of PTEN with VO-OHpic attenuates apoptosis and promotes angiogenesis of EPCs in vitro via activating Nrf2 signaling pathway and inhibiting the mitochondrial apoptosis pathway. Moreover, VO-OHpic also mitigates GC-associated ONFH and potentiates angiogenesis in the femoral head.

Variants in RETN gene are associated with steroid-induced osteonecrosis of the femoral head risk among Han Chinese people

Background

Gene polymorphism has an important influence on RETN gene expression level, and the increased level of resistin encoded in RETN will lead to metabolic disorder, especially lipid metabolism. Moreover, steroid-induced osteonecrosis of the femoral head (steroid-induced ONFH) is closely related to lipid metabolism level, so this study is intended to explore the relationship of RETN polymorphisms with susceptibility to steroid-induced ONFH in the Chinese Han population.

Methods

In this case-control study, eight single-nucleotide polymorphisms (SNPs) of RETN were genotyped by the Agena MassARRAY system in 199 steroid-induced ONFH patients and 200 healthy controls. The relationship between RETN polymorphisms and steroid-induced ONFH risk was assessed using genetic models and haplotype analyses. Odds ratio (OR) and 95% confidence intervals (CIs) were obtained by logistic regression adjusted for age.

Results

We found significant differences in the distribution of HDL-C, TG/HDL-C, and LDL-C/HDL-C between the patients and the control group (p < 0.05). In allele model and genotype model analysis, rs34861192, rs3219175, rs3745368, and rs1477341 could reduce the risk of steroid-induced ONFH. Further stratified analysis showed that rs3745367 was related to the clinical stage of patients, and rs1477341 was significantly correlated with an increased TG level and a decreased TC/HDL-C level. The linkage analysis showed that two SNPs (rs34861192 and rs3219175) in RETN even significant linkage disequilibrium.

Conclusions

Our results provide the firstly evidence that RETN gene polymorphisms were associated with a reduced risk of steroid-induced ONFH in Chinese Han population.

Endocrine roles of vitamin K-dependent- osteocalcin in the relation between bone metabolism and metabolic disorders

Obesity and diabetes are important metabolic diseases and a major public health problem among the world, they have serious health and economic complications. Overweight and obesity are increased risk for deficiency of vitamin particularly shortage of fat soluble-vitamins. Studies reported that vitamin K supplementation reduces oxidative stress and metabolic risk biomarkers for diabetes, as well as reduces progression of insulin resistance. Vitamin K-dependent-protein osteocalcin (bone derived hormone) plays crucial roles in energy metabolism. There is a clear association between circulating vitamin k and dependent-osteocalcin concentrations with obesity and risk of Type 2 diabetes. Osteocalcin through molecular mechanisms improves insulin resistance, lipid and glucose profile, and mediate vitamin K positive effects. Insulin also signals osteocalcin to regulate bone mineralization. Normal carboxylation of vitamin K-dependent proteins/ hormones is a key step in preventing apoptosis and calcification of vascular endothelial cells. A missing relationship between bone, glucose and fat metabolism could clarify and manage many metabolic mechanisms. This review focuses on the physiological relationship between vitamin K-dependent-osteocalcin, metabolic and cardiovascular diseases through some molecular proteins and hormones including adipokines. A better understanding of the mechanism of action of osteocalcin modulated by vitamin K could help in implementing therapeutic drugs to cure metabolic diseases.

Peripheral Blood Stem Cell Therapy Does Not Improve Outcomes of Femoral Head Osteonecrosis With Cap-Shaped Separated Cartilage Defect

A combination treatment with porous tantalum rod implantation and intra-arterial infusion of peripheral blood stem cells (PBSCs) provides a promise for treating early and intermediate stages of osteonecrosis of the femoral head (ONFH). However, its clinical indications and application restrictions remain unclear. This study aims to determine the clinical, histological, and radiological outcomes of a combination treatment using mechanical support and a targeted intra-arterial infusion of PBSCs for painful ONFH with a cap-shaped separation (CSS) cartilage defect. Compared with the standard pain management (control group), this combination treatment did not improve the Harris Hip Score (HHS) at 36 months. Micro-CT and histologic analyses showed severe focal destruction in all CSS-ONFH femoral heads in both the combination and control groups. Femoral heads showed a higher percentage of bone lesions in the combination treatment group than in the control group. There was no significant difference in osteoclast number in the subchondral bone areas between the two groups. A high level of expression of inflammatory cytokines, including tumor necrosis factor-α and interleukin-1β, was detected in blood vessels around the subchondral bone in both groups. The RANKL/OPG (receptor activator of the nuclear factor-kB ligand/osteoprotegerin) ratio was also similar between the control and combination treatment groups. Our results indicate that this combination treatment is not an effective method for the treatment of patients with painful CSS-ONFH. Moreover, this combination treatment did not inhibit inflammatory osteoclastogenesis in patients with more advanced disease. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:269-276, 2020.

Inhibition of PERK Signaling Prevents Against Glucocorticoid-induced Endotheliocyte Apoptosis and Osteonecrosis of the Femoral Head

Vascular injury is considered an important pathological process during glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH). In this study, we tried to investigate whether the endoplasmic reticulum (ER) stress is triggered in the GC-induced endotheliocyte (EC) apoptosis and ONFH. The results showed that a GC upregulated the expression of ER stress-related proteins, and PERK-CHOP signaling played an important role and induced EC apoptosis. The inhibition of PERK by GSK2656157 significantly decreased the GC-induced EC apoptosis in vitro and in vivo, thus protecting a rat model from vascular injury and significantly preventing GC-induced ONFH.

The potential roles of circular RNAs in osteonecrosis of the femoral head (Review)

Circular RNAs (circRNAs) are categorized as non-coding RNAs that, unlike widely known canonical linear RNAs, form a covalently closed continuous loop without 5′ or 3′ polarities, which enables them to resist digestion by RNA exonucleases. Although the functions of circRNAs remain largely unknown, accumulated evidence has demonstrated that circRNAs can act as microRNA sponges, which allows them to regulate numerous biological processes and disease mechanisms, including apoptosis, angiogenesis, invasion, metastasis and stem cell differentiation. Although research into circRNAs is in its infancy, studies have identified critical roles for circRNAs in the initiation and progression of disease. The present study delineated the characteristics and functions of circRNAs, and focused on the potential relationship between circRNAs and osteonecrosis of the femoral head (ONFH). CircRNAs represent a novel avenue for studying the mechanisms underlying ONFH as well as possible treatments.

Icariin promotes angiogenesis in glucocorticoid-induced osteonecrosis of femoral heads: In vitro and in vivo studies

The injury and dysfunction of the femoral head microvascular endothelial cells are associated with the pathogenesis of glucocorticoid-induced osteonecrosis of the femoral head (ONFH). Reports indicate that icariin (ICA) can enhance vascular roles and also inhibit endothelial cell dysfunction. However, it still remains unclear whether ICA can promote angiogenesis in glucocorticoid-induced ONFH. In this study, we investigate this hypothesis through in vitro and in vivo experiments. Results showed that 0.1 mg/mL hydrocortisone significantly suppressed bone microvascular endothelial cells (BMECs) proliferation while ICA at 10^-5  mol/L reversed this inhibition. ICA significantly promoted BMECs migration, tube formation, the angiogenesis-related cytokines expression and the activation of Akt. Furthermore, ICA enhanced Bcl-2 expression but diminished Bax expression. According to in vivo results, rats with ICA treatment exhibited a lower ratio of empty lacunae, higher volume of blood vessels and more CD31-positive cells. This study revealed that ICA promotes angiogenesis of BMECs in vitro and improves femoral head blood vessel volume of rats treated with glucocorticoid, suggesting the efficacy of ICA in the prevention of glucocorticoid-induced ONFH.

La-Doped mesoporous calcium silicate/chitosan scaffolds for bone tissue engineering

Trace rare earth elements such as lanthanum (La) regulated effectively bone tissue performances; however, the underlying mechanism remains unknown. In order to accelerate bone defects especially in patients with osteoporosis or other metabolic diseases, we firstly constructed lanthanum-doped mesoporous calcium silicate/chitosan (La-MCS/CTS) scaffolds by freeze-drying technology. During the freeze-drying procedure, three-dimensional macropores were produced within the La-MCS/CTS scaffolds by using ice crystals as templates, and the La-MCS nanoparticles were distributed on the macropore walls. The hierarchically porous structures and biocompatible components contributed to the adhesion, spreading and proliferation of rat bone marrow-derived mesenchymal stem cells (rBMSCs), and accelerated the in-growth of new bone tissues. Particularly, the La3+ ions in the bone scaffolds remarkably induced the osteogenic differentiation of rBMSCs via the activation of the TGF signal pathway. A critical-sized calvarial-defect rat model further revealed that the La-MCS/CTS scaffolds significantly promoted new bone regeneration as compared with pure MCS/CTS scaffolds. In conclusion, the La-MCS/CTS scaffold showed the prominent ability in osteogenesis and bone regeneration, which showed its application potential for bone defect therapy.

Role of Vascular Smooth Muscle Cell Phenotypic Switching and Calcification in Aortic Aneurysm Formation

Aortic aneurysm is a vascular disease whereby the ECM (extracellular matrix) of a blood vessel degenerates, leading to dilation and eventually vessel wall rupture. Recently, it was shown that calcification of the vessel wall is involved in both the initiation and progression of aneurysms. Changes in aortic wall structure that lead to aneurysm formation and vascular calcification are actively mediated by vascular smooth muscle cells. Vascular smooth muscle cells in a healthy vessel wall are termed contractile as they maintain vascular tone and remain quiescent. However, in pathological conditions they can dedifferentiate into a synthetic phenotype, whereby they secrete extracellular vesicles, proliferate, and migrate to repair injury. This process is called phenotypic switching and is often the first step in vascular pathology. Additionally, healthy vascular smooth muscle cells synthesize VKDPs (vitamin K-dependent proteins), which are involved in inhibition of vascular calcification. The metabolism of these proteins is known to be disrupted in vascular pathologies. In this review, we summarize the current literature on vascular smooth muscle cell phenotypic switching and vascular calcification in relation to aneurysm. Moreover, we address the role of vitamin K and VKDPs that are involved in vascular calcification and aneurysm. Visual Overview- An online visual overview is available for this article.

Effects of combined menaquinone-4 and PTH1-34 treatment on osetogenesis and angiogenesis in calvarial defect in osteopenic rats

PURPOSE

The aim of this study was to evaluate the effect of combining human parathyroid hormone (1-34) (PTH_1-34; PTH) and menaquinone-4 (MK-4) on calvarial bone defect repair in osteopenic rats.

METHODS

Fourteen week olds were subject to craniotomy for the establishment of osteopenic animal models fed through a chronically low-protein diet. After that, critical calvarial defect model was established and all rats were randomly divided into four groups: sham, MK-4, PTH, and PTH + MK-4. The animals received MK-4 (30 mg/kg/day), PTH_1-34 (60 μg/kg, three times a week), or PTH_1-34 (60 μg/kg, three times a week) plus MK-4 (30 mg/kg/day) for 8 weeks, respectively. Serum γ-carboxylated osteocalcin (Gla-OC) levels, histological and immunofluorescent labeling were employed to evaluate the bone formation and mineralization in calvarial bone defect. In addition, Microfil perfusion, immunohistochemical, and micro-CT suggested enhanced angiogenesis and bone formation in calvarial bone healing.

RESULTS

In this study, treatment with either PTH_1-34 or MK-4 promoted bone formation and vascular formation in calvarial bone defects compared with the sham group. In addition, combined treatment of PTH_1-34 plus MK-4 increased serum level of Gla-OC, improved vascular number and vascular density, and enhanced bone formation in calvarial bone defect in osteopenic conditions as compared with monotherapy.

CONCLUSIONS

In summary, this study indicated that PTH_1-34 plus MK-4 combination therapy accelerated bone formation and angiogenesis in calvarial bone defects in presence of osteopenia.

Vitamin C Prevents Hydrocortisone-Induced Injury in HMEC-1 through Promoting Bestrophin-3 Expression

OBJECTIVE

To investigate the protective effects and underlying mechanisms of Vitamin C (VC) on hydrocortisone (HC)-induced cell injury in human microvascular endothelial cells (HMEC).

METHODS

Cell viability was measured by CCK-8 assay and the expression of Best-3 was detected by Western blotting assay. The experiment was divided into normal control, HC injury group, VC treatment groups, HC + Best-3 siRNA group, HC + VC + Best-3 siRNA group, HC + pcDNA3.1 Best-3 group, and HC + VC + pcDNA3.1 Best-3 group.

RESULTS

HC inhibited HMEC-1 cell viability was balanced with lower expression of Best-3 in a dose-dependent manner. Conversely, VC promoted HMEC-1 cell viability was paralleled to higher expression of Best-3 in a dose-dependent manner. Silencing Best-3 with Best-3 siRNA inhibited HMEC-1 cell viability, however, over-expression of Best-3 with pcDNA3.1 Best-3 promoted HMEC-1 cell viability. Moreover, VC and over-expression of Best-3 prevented HC-induced HMEC-1 cell apoptosis; however, silencing Best-3 further enhanced HC-induced HMEC-1 cell apoptosis. HC reduced Best-3 expression, which was alleviated by VC treatment. HC treatment decreased Bcl-2 expression, facilitated Bax expression. Both of VC and over-expression of Best-3 promoted Bcl-2 expression and decreased Bax expression. Additionally, VC and Best-3 expression have a synergistic effect.

CONCLUSIONS

VC can efficiently attenuate HC-induced HMEC-1 cell injury, which may be related to promote Best-3 expression.

Combined treatment with vitamin K2 and PTH enhanced bone formation in ovariectomized rats and increased differentiation of osteoblast in vitro

Osteoporosis is accompanied by insufficient osteogenic capacity. Several lines of evidence suggested that solutions to enhance osteoblastogenesis were important strategies for osteoporotic bone defect repair. This study investigated the effect of combined treatment with vitamin K2 and PTH on bone formation in calvarial bone defect in osteoporotic rats and its influence on osteoblast in vitro. Bilateral ovariectomy was used in SPF Sprague Dawley rats to generate an osteoporosis model. Subsequently, a calvarial defect model was established and all osteoporotic rats were randomly assigned to the following groups: control, VK (vitamin K2, 30 mg/kg everyday), PTH (recombinant human PTH (1-34), 60 μg/kg, three times a week) or VK + PTH (vitamin K2, 30 mg/kg everyday plus PTH, 60 μg/kg three times a week) for 8 weeks. In vitro, bone marrow-derived stem cells (BMSCs) were cultured and treated with vitamin K2, PTH or vitamin K2+PTH. ALP staining and western blot were performed to observe the influence of combined treatment on BMSCs. Bone formation within calvarial defect were assessed by serum γ-carboxylated osteocalcin (Gla-OC), micro-CT, histological and immunofluorescent labeling. In this study, combined treatment of PTH and vitamin K2 showed positive effects on preventing bone loss in femurs in OVX rats. Combined treatment increased serum Gla-OC and promoted bone formation in osteoporotic calvarial bone defects. Immunohistochemistry showed that OCN and RUNX2 were more highly expressed in the VK + PTH group than in the control groups. In vitro studies results suggested that combined treatment with PTH and vitamin K2 increased expression of ALP, BMP2 and RUNX2 in BMSCs. Our data suggested that the combination of vitamin K2 and PTH increased differentiation of osteoblast and had a synergistic effect on bone formation in osteoporotic calvarial bone defect.

Collagen type V a2 (COL5A2) is decreased in steroid-induced necrosis of the femoral head

Collagen is essential for bone adhesion and formation. In the present study, proteomic analysis suggested that collagen type V a2 (COL5A2) was significantly decreased in the necrotic area of patients with steroid-induced necrosis of the femoral head (ONFH). In vitro, the effects of methylprednisolone (MP) on the proliferation and differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs) were investigated. The expression of the osteogenic-related proteins, Runx2, alkaline phosphatase (ALP), osteocalcin (OC) and COL5A2 was significantly downregulated post-MP treatment. In vivo analyses revealed that post-MP treatment, rats showed typical signs of ONFH by micro-CT scanning and hematoxylin and eosin (H&E) staining. Immunohistochemical staining demonstrated that the expression of COL5A2 and vascular endothelial growth factor (VEGF) was significantly decreased post-MP treatment. In conclusion, the expression COL5A2 was lower in patients with steroid-induced ONFH, hence COL5A2 may be a promising therapeutic target for steroid induced ONFH treatment.

Glucocorticoid-activated IRE1α/XBP-1s signaling: an autophagy-associated protective pathway against endotheliocyte damage

Glucocorticoid-induced endothelial injury has been reported in several diseases. Although there are several theories, the exact mechanism underlying the role of glucocorticoids in this process remains unclear. Autophagy has been reported to occur as a response to different stimuli and can affect cell survival and function. In this study, we found that glucocorticoids induced apoptosis and endoplasmic reticulum (ER) stress in endotheliocytes. Furthermore, we discovered that glucocorticoids induced autophagy in these cells and the inositol requiring protein 1 (IRE1α)/X-box binding protein 1s (XBP-1s) axis, one of the downstream signaling pathways of ER stress, was associated with the glucocorticoid-induced autophagy. The autophagy partly protected endotheliocytes from glucocorticoid-induced apoptosis and inhibition of proliferation. In conclusion, glucocorticoid-induced endoplasmic reticulum stress activated the IRE1α/XBP-1s signaling and induced autophagy, which, in turn, played a protective role in endotheliocyte survival and proliferation, avoiding further cellular damage caused by glucocorticoids.

Magnetic Mesoporous Calcium Sillicate/Chitosan Porous Scaffolds for Enhanced Bone Regeneration and Photothermal-Chemotherapy of Osteosarcoma

The development of multifunctional biomaterials to repair bone defects after neoplasm removal and inhibit tumor recurrence remained huge clinical challenges. Here, we demonstrate a kind of innovative and multifunctional magnetic mesoporous calcium sillicate/chitosan (MCSC) porous scaffolds, made of M-type ferrite particles (SrFe₁₂O₁₉), mesoporous calcium silicate (CaSiO₃) and chitosan (CS), which exert robust anti-tumor and bone regeneration properties. The mesopores in the CaSiO₃ microspheres contributed to the drug delivery property, and the SrFe₁₂O₁₉ particles improved photothermal therapy (PTT) conversion efficacy. With the irradiation of NIR laser, doxorubicin (DOX) was rapidly released from the MCSC/DOX scaffolds. In vitro and in vivo tests demonstrated that the MCSC scaffolds possessed the excellent anti-tumor efficacy via the synergetic effect of DOX drug release and hyperthermia ablation. Moreover, BMP-2/Smad/Runx2 pathway was involved in the MCSC scaffolds promoted proliferation and osteogenic differentiation of human bone marrow stromal cells (hBMSCs). Taken together, the MCSC scaffolds have the ability to promote osteogenesis and enhance synergetic photothermal-chemotherapy against osteosarcoma, indicating MCSC scaffolds may have great application potential for bone tumor-related defects.

Animal models of steroid-induced osteonecrosis of the femoral head-a comprehensive research review up to 2018

Osteonecrosis of the femoral head (ONFH) is a significant cause of both pain and disability that often affects young adults during what ought to be their most productive age. Two broad categories of ONFH exist: traumatic and non-traumatic. Traumatic ONFH results from acute mechanical disruption of the femoral head's blood supply. Many factors that increase the risk of non-traumatic osteonecrosis have been identified. Steroid-induced osteonecrosis of the femoral head (SONFH) is the most common form of non-traumatic ONFH. Many hypotheses as to the pathogenesis of SONFH have been proposed, including intravascular thrombosis, abnormal fat metabolism, intramedullary adipocyte hypertrophy, and osteoporosis; however, the exact mechanism of SONFH is still not clearly understood. Animal models using rats, mice, rabbits, chickens, pigs, and emus have been used to study SONFH. Unfortunately, these models each have limitations. Therefore, it is necessary to establish a reproducible model that better simulates human disease. The present review is intended to summarize the currently available models, evaluative indicators, and application of current understanding to both the prevention and treatment of SONFH.

Analysis of early stage osteonecrosis of the human femoral head and the mechanism of femoral head collapse

We explored the mechanism of early stage osteonecrotic femoral head collapse by analyzing and comparing different regions in human osteonecrotic femoral head samples. Eight osteonecrotic femoral heads (ARCO II-III) were obtained from patients undergoing total hip arthroplasty. Bone structure was observed and evaluated by micro-computed tomography (CT) scans and pathology. Osteoblast and osteoclast activities were detected by tartrate-resistant acid phosphatase, alkaline phosphatase, and immunofluorescent staining. Some trabeculae had microfractures in the subchondral bone and necrotic region, which had lower bone mineral density, as well as trabecular thickness and number, but greater osteoclast activity. A sclerotic band had already appeared in certain samples which had greater trabecular thickness and number, bone mineral density, and osteoblast activity. The appearance of the femoral head did not change significantly in the early stage of osteonecrosis of the femoral head. However, osteoblast and osteoclast activities had already changed in different regions of the osteonecrotic femoral head, which may lead to eventual collapse of the femoral head. Therefore, osteonecrosis of the femoral head must be treated during the early stage. In addition, osteoblast activity should be promoted and osteoclast activity inhibited as early as possible to prevent collapse of an osteonecrotic femoral head.

Circulating microRNA signature of steroid-induced osteonecrosis of the femoral head

OBJECTIVES

Steroid-induced osteonecrosis of the femoral head (ONFH) is a common orthopaedic disease of which early detection remains clinically challenging. Accumulating evidences indicated that circulating microRNAs (miRNAs) plays vital roles in the development of several bone diseases. However, the association between circulating miRNAs and steroid-induced ONFH remains elusive.

MATERIALS AND METHODS

miRNA microarray was performed to identify the differentially abundant miRNAs in the serums of systemic lupus erythematosus (SLE) patients with steroid-induced ONFH as compared with SLE control and healthy control group. We predicted the potential functions of these differentially abundant miRNAs using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses and reconstructed the regulatory networks of miRNA-mRNA interactions.

RESULTS

Our data indicated that there were 11 differentially abundant miRNAs (2 upregulated and 9 downregulated) between SLE-ONFH group and healthy control group and 42 differentially abundant miRNAs (14 upregulated and 28 downregulated) between SLE-ONFH group and SLE control group. We also predicted the potential functions of these differentially abundant miRNAs using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses and reconstructed the regulatory networks of miRNA-mRNA interactions.

CONCLUSIONS

These findings corroborated the idea that circulating miRNAs play significant roles in the development of ONFH and may serve as diagnostic markers and therapeutic targets.

Exosomes derived from human platelet-rich plasma prevent apoptosis induced by glucocorticoid-associated endoplasmic reticulum stress in rat osteonecrosis of the femoral head via the Akt/Bad/Bcl-2 signal pathway

An excess of glucocorticoids (GCs) is reported to be one of the most common causes of osteonecrosis of the femoral head (ONFH). In addition, GCs can induce bone cell apoptosis through modulating endoplasmic reticulum (ER) stress. Among the three main signal pathways in ER stress, the PERK (protein kinase RNA-like ER kinase)/CHOP (CCAAT-enhancer-binding protein homologous protein) pathway has been considered to be closely associated with apoptosis. Platelet-rich plasma (PRP) has been referred to as a concentration of growth factors and the exosomes derived from PRP (PRP-Exos) have a similar effect to their parent material. The enriched growth factors can be encapsulated into PRP-Exos and activate Akt and Erk pathways to promote angiogenesis. Activation of the Akt pathway may promote the expression of anti-apoptotic proteins like Bcl-2, while CHOP can inhibit B-cell lymphoma 2 (Bcl-2) expression to increase the level of cleaved caspase-3 and lead to cell death. Consequently, we hypothesized that PRP-Exos prevent apoptosis induced by glucocorticoid-associated ER stress in rat ONFH via the Akt/Bad/Bcl-2 signal pathway. To verify this hypothesis, a dexamethasone (DEX)-treated in vitro cell model and methylprednisolone (MPS)-treated in vivo rat model were adopted. Characterization of PRP-Exos, and effects of PRP-Exos on proliferation, apoptosis, angiogenesis, and osteogenesis of cells treated with GCs in vitro and in vivo were examined. Furthermore, the mechanism by which PRP-Exos rescue the GC-induced apoptosis through the Akt/Bad/Bcl-2 pathway was also investigated. The results indicate that PRP-Exos have the capability to prevent GC-induced apoptosis in a rat model of ONFH by promoting Bcl-2 expression via the Akt/Bad/Bcl-2 signal pathway under ER stress.