Inhibitory effects of vitamin E on osteocyte apoptosis and DNA oxidative damage in bone marrow hemopoietic cells at early stage of steroid-induced femoral head necrosis

Role of vitamins beyond vitamin D3 in bone health and osteoporosis (Review)

The objective of the present review was to summarize the molecular mechanisms associated with the effects of the vitamins A, C, E and K, and group B vitamins on bone and their potential roles in the development of osteoporosis. Epidemiological findings have demonstrated an association between vitamin deficiency and a higher risk of developing osteoporosis; vitamins are positively related to bone health upon their intake at the physiological range. Excessive vitamin intake can also adversely affect bone formation, as clearly demonstrated for vitamin A. Vitamins E (tocopherols and tocotrienols), K2 (menaquinones 4 and 7) and C have also been shown to promote osteoblast development through bone morphogenetic protein (BMP)/Smad and Wnt/β‑catenin signaling, as well as the TGFβ/Smad pathway (α‑tocopherol). Vitamin A metabolite (all‑trans retinoic acid) exerts both inhibitory and stimulatory effects on BMP‑ and Wnt/β‑catenin‑mediated osteogenesis at the nanomolar and micromolar range, respectively. Certain vitamins significantly reduce receptor activator of nuclear factor kappa‑B ligand (RANKL) production and RANKL/RANK signaling, while increasing the level of osteoprotegerin (OPG), thus reducing the RANKL/OPG ratio and exerting anti‑osteoclastogenic effects. Ascorbic acid can both promote and inhibit RANKL signaling, being essential for osteoclastogenesis. Vitamin K2 has also been shown to prevent vascular calcification by activating matrix Gla protein through its carboxylation. Therefore, the maintenance of a physiological intake of vitamins should be considered as a nutritional strategy for the prevention of osteoporosis.

Preclinical models for studying corticosteroid-induced osteonecrosis of the femoral head

Nontraumatic osteonecrosis of the femoral head (ONFH) is a refractory condition that commonly results in femoral head collapse and degenerative arthritis of the hip. In the early stages, surgical procedures for hip preservation, including core decompression (CD), have been developed to prevent progressive collapse of the femoral head. Optimization of bone regeneration and biological augmentation may further enhance the therapeutic efficacy of CD for ONFH. Thus, combining CD with cell-based therapy has recently been proposed. In fact, patients treated with cell-based therapy using autologous bone marrow concentrate demonstrate improved survivorship of the femoral head, compared with conventional CD alone. Preclinical research studies to investigate adjunctive therapies for CD often utilize the rabbit model of corticosteroid-induced ONFH. Mesenchymal stem cells (MSCs) are known to promote osteogenesis and angiogenesis, and decrease inflammation in bone. Local drug delivery systems have the potential to achieve targeted therapeutic effects by precisely controlling the drug release rate. Scaffolds can provide an osteoconductive structural framework to facilitate the repair of osteonecrotic bone tissue. We focused on the combination of both cell-based and scaffold-based therapies for bone tissue regeneration in ONFH. We hypothesized that combining CD and osteoconductive scaffolds would provide mechanical strength and structural cell guidance; and that combining CD and genetically modified (GM) MSCs to express relevant cytokines, chemokines, and growth factors would promote bone tissue repair. We developed GM MSCs that overexpress the anti-inflammatory, pro-reconstructive cytokines platelet-derived growth factor-BB to provide MSCs with additional benefits and investigated the efficacy of combinations of these GM MSCs and scaffolds for treatment of ONFH in skeletally mature male New Zealand white rabbits. In the future, the long-term safety, efficacy, durability, and cost-effectiveness of these and other biological and mechanical treatments must be demonstrated for the patients affected by ONFH.

Plasma 8-OHdG act as a biomarker for steroid-induced osteonecrosis of the femoral head

BACKGROUND

Oxidative stress was closely related to the occurrence and development of Steroid-induced osteonecrosis of the femoral head (SIONFH). 8-hydroxy-2'-deoxyguanosine (8-OHdG) is a important index of oxidative stress. The aim of this study is to investigate the role of 8-OHdG in the development of SIONFH.

METHODS

From May 2021 and November 2021, 33 patients diagnosed with SIONFH and 26 healthy controls were recruited in this study. Assessment included the radiography and pathology evaluation of clinical bone tissue, expression position and level of 8-OHdG, level of plasma 8-OHdG, as well as the receiver operating characteristic (ROC) curve.

RESULTS

We observed that expression levels of 8-OHdG in bone samples decreased with Association Research Circulation Osseous (ARCO) stages. Plasma 8-OHdG levels were significantly increased in the SIONFH group compared to the healthy control group. Plasma 8-OHdG level of pre-collapse patients was higher than that of post-collapse patients, the decreased plasma 8-OHdG level was related to higher ARCO stages.

CONCLUSION

Plasma 8-OHdG may represent potential biomarkers during SIONFH at different stages. Higher plasma 8-OHdG levels indicated early stage of SIONFH. The current study provided new clues for early diagnosis and treatment for SIONFH.

Dragon blood resin ameliorates steroid-induced osteonecrosis of femoral head through osteoclastic pathways

Objective: Dragon's Blood resin (DBR) is a traditional medicinal substance renowned for its diverse pharmacological effects, which consists of potent anti-inflammatory, antioxidant and angiogenic properties. This study aimed to elucidate its therapeutic mechanism in alleviating steroid-induced osteonecrosis of the femoral head (SIONFH). Methods: Techniques such as SPR and LC-MS were employed to identify and analyze the target proteins of DBR in bone marrow macrophages (BMMs). In vitro, BMMs were treated with RANKL and DBR, and TRAcP staining and actin belt staining were utilized to assess osteoclast activity. The inhibitory effects and underlying mechanisms of DBR on osteoclastogenesis and reactive oxygen species (ROS) generation were determined using real-time PCR, western blotting and immunofluorescence staining. An in vivo SIONFH rat model was set up to assess the curative impacts of DBR using micro-CT scanning and pathological staining. Results: Bioinformatic tools revealed a pivotal role of osteoclast differentiation in SIONFH. Proteomic analysis identified 164 proteins binding in BMMs. In vitro assessments demonstrated that DBR hindered osteoclastogenesis by modulating the expression of specific genes and proteins, along with antioxidant proteins including TRX1 and Glutathione Reductase. Notably, the resin effectively inhibited the expression of crucial proteins, such as the phosphorylation of JNK and the nuclear localization of p65 within the TRAF6/JNK and NFκB signaling pathways. In vivo experiments further confirmed that DBR mitigated the onset of SIONFH in rats by curbing osteoclast and ROS activities. Conclusion: These findings underscore the potential of Dragon's Blood as an effective administration for early-stage SIONFH, shedding light on its therapeutic influence on ROS-mediated osteoclastic signaling pathways.

Vitamin E Enhances Cell Viability and the Osteogenic Differentiation of Cell Spheroids Made of Gingiva-Derived Stem Cells

Background and Objectives: Vitamin E is reported to expedite new bone formation in animal models, and this has led to a decrease in the time needed for treatment. In this study, human gingiva-derived stem cell-derived spheroids were examined to determine the effects of vitamin E on cell survival, osteogenic differentiation, and mineralization. Materials and Methods: Human gingiva-derived stem cells were used to create spheroids, which were then cultivated with vitamin E at doses of 0, 0.1, 1, 10, and 100 ng/mL. The morphological examination and the qualitative and quantitative vitality of the cells were assessed. Alizarin Red S staining and alkaline phosphatase activity assays were performed on days 7 and 14 to evaluate the osteogenic differentiation. The expression levels of RUNX2 and COL1A1 were assessed using a real-time polymerase chain reaction. Results: The addition of vitamin E did not appear to alter the spheroid's shape at the measured quantities without altering the diameter. During the culture time, the majority of the cells in the spheroids fluoresced green. Regardless of concentration, there were substantial increases in cell viability in the vitamin E-loaded groups on day 7 (p < 0.05). On day 14, the Alizarin Red S staining was statistically higher in the 1 ng/mL group compared to the unloaded control (p < 0.05). The addition of vitamin E to the culture enhanced the mRNA expression levels of RUNX2, OCN, and COL1A1 based on the real-time polymerase chain reaction data. Conclusions: We draw the conclusion that vitamin E may be used to promote the osteogenic differentiation of stem cell spheroids in light of these data.

Suppression of apoptosis in osteocytes, the potential way of natural medicine in the treatment of osteonecrosis of the femoral head

OBJECTIVES

In the field of orthopedics, osteonecrosis of the femoral head (ONFH) is a common and refractory condition sometimes known as "immortal cancer" due to its complicated etiology, difficult treatment, and high disability rate. This paper's main goal is to examine the most recent literature on the pro-apoptotic effects of traditional Chinese medicine TCM monomers or compounds on osteocytes and to provide a summary of the potential signal routes.

METHODS

The last ten years' worth of literature on ONFH as well as the anti-ONFH effects of aqueous extracts and monomers from traditional Chinese medicine were compiled.

CONCLUSIONS

When all the relevant signal pathways are considered, the key apoptotic routes include those mediated by the mitochondrial pathway, the MAPK signaling pathway, the PI3K/Akt signaling pathway, the Wnt/-catenin signaling pathway, the HIF-1 signaling network, etc. As a result, we anticipate that this study will shed light on the value of TCM and its constituent parts for treating ONFH by inducing apoptosis in osteocytes and offer some guidance for the future development of innovative medications as anti-ONFH medications in clinical settings.

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.

Improving the valence self-reversible conversion of cerium nanoparticles on titanium implants by lanthanum doping to enhance ROS elimination and osteogenesis

Equipped with anti-oxidative properties, cerium oxide nanoparticles (CNPs) are gradually being adopted over the years in the field of oxidative stress research. However, the effects of CNPs may be diminished when under the influence of prolonged and substantially elevated levels of oxidative stress. Therefore, it is imperative to enhance the efficacy of CNPs to resist oxidative stress. In this study, our approach involves the fabrication of titanium surface CNPs coatings doped with different concentrations of lanthanum ions (La³⁺) and the investigation of their local anti-oxidative stress potential. The physicochemical characterization showed that the La-CNPs groups had a substantial increase in the generation of oxygen vacancies within the CNPs structure with the increase of La doping concentration. In vitro findings proofed that the cytocompatibility of different La-CNPs coatings showed a trend of increasing first and then decreasing with the increase of La doping concentration under oxidative stress microenvironment. Among these groups, the 30 % La-CNPs group presented the best cell proliferation and osteogenic differentiation which could activate the FoxO1 pathway, then upregulated the expression of SOD1 and CAT, and finally resulted in the inhibition of ROS production. In vivo results further confirmed that the 30 % La-CNPs group showed significant osteogenic effects in two rat models (osteoporosis and diabetes models). In conclusion, we believe that the 30 % La-CNPs coating holds promising potential for its implant applications in patients with oxidative stress-related diseases.

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.

Adverse Effects of Oxidative Stress on Bone and Vasculature in Corticosteroid-Associated Osteonecrosis: Potential Role of Nuclear Factor Erythroid 2-Related Factor 2 in Cytoprotection

Significance: Osteonecrosis (ON) is characterized by bone tissue death due to disturbance of the nutrient artery. The detailed process leading to the necrotic changes has not been fully elucidated. Clinically, high-dose corticosteroid therapy is one of the main culprits behind osteonecrosis of the femoral head (ONFH). Recent Advances: Numerous studies have proposed that such ischemia concerns various intravascular mechanisms. Of all reported risk factors, the involvement of oxidative stress in the irreversible damage suffered by bone-related and vascular endothelial cells during ischemia simply cannot be overlooked. Several articles also have sought to elucidate oxidative stress in relation to ON using animal models or in vitro cell cultures. Critical Issues: However, as far as we know, antioxidant monotherapy has still not succeeded in preventing ONFH in humans. To provide this desideratum, we herein summarize the current knowledge about the influence of oxidative stress on ON, together with data about the preventive effects of administering antioxidants in corticosteroid-induced ON animal models. Moreover, oxidative stress is counteracted by nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent cytoprotective network through regulating antioxidant expressions. Therefore, we also describe Nrf2 regulation and highlight its role in the pathology of ON. Future Directions: This is a review of all available literature to date aimed at developing a deeper understanding of the pathological mechanism behind ON from the perspective of oxidative stress. It may be hoped that this synthesis will spark the development of a prophylactic strategy to benefit corticosteroid-associated ONFH patients. Antioxid. Redox Signal. 35, 357-376.

Osteocyte apoptosis: the roles and key molecular mechanisms in resorption-related bone diseases

Vital osteocytes have been well known to function as an important orchestrator in the preservation of robustness and fidelity of the bone remodeling process. Nevertheless, some key pathological factors, such as sex steroid deficiency and excess glucocorticoids, and so on, are implicated in inducing a bulk of apoptotic osteocytes, subsequently resulting in resorption-related bone loss. As much, osteocyte apoptosis, under homeostatic conditions, is in an optimal state of balance tightly controlled by pro- and anti-apoptotic mechanism pathways. Importantly, there exist many essential signaling proteins in the process of osteocyte apoptosis, which has a crucial role in maintaining a homeostatic environment. While increasing in vitro and in vivo studies have established, in part, key signaling pathways and cross-talk mechanism on osteocyte apoptosis, intrinsic and complex mechanism underlying osteocyte apoptosis occurs in various states of pathologies remains ill-defined. In this review, we discuss not only essential pro- and anti-apoptotic signaling pathways and key biomarkers involved in these key mechanisms under different pathological agents, but also the pivotal role of apoptotic osteocytes in osteoclastogenesis-triggered bone loss, hopefully shedding new light on the attractive and proper actions of pharmacotherapeutics of targeting apoptosis and ensuing resorption-related bone diseases such as osteoporosis and fragility fractures.

Effects of maternal dietary vitamin E on the egg characteristics, hatchability and offspring quality of prolonged storage eggs of broiler breeder hens

This research aims to evaluate the effects of maternal vitamin E (VE) dietary supplementation on the egg characteristics, hatchability and antioxidant status of the embryo and newly hatched chicks of prolonged storage eggs. A total of 576 75-week-old Ross 308 breeder hens were randomly allocated into three dietary VE treatments (100, 200 and 400 mg/kg) with 6 replicates of 32 hens, for a 12-week feeding trial. At week 12, a total of 710 eggs were collected over a 5-day period, and eggs per treatment were attributed into 5 replicates and stored for 14 days until incubation. The egg yolk, trunk and head of 7-day-old embryo and the serum, liver, brain and yolk sac of newly hatched chicks were sampled for the evaluation of antioxidant status. Results showed that as maternal dietary VE levels increased, yolk α-tocopherol concentration increased (p < .05). Compared with 100 mg/kg VE, the use of 200 and 400 mg/kg VE increased the hatchability of set/fertile eggs and total antioxidant capacity (T-AOC) of liver and serum in chicks (p < .05), and decreased both the early embryonic mortality and the malondialdehyde (MDA) content of trunk and head in 7-day-old embryos (p < .05); moreover, 400 mg/kg VE increased the yolk T-AOC (p < .05) and decreased yolk and brain MDA content of chicks (p < .05). Brain T-AOC of chicks in 200 mg/kg VE group was improved compared to that of chicks in 100 mg/kg VE group (p < .05). In conclusion, maternal dietary VE at 200 or 400 mg/kg could increase hatchability by decreasing early embryonic mortality and increasing the antioxidant status of egg yolk, embryo and newly hatched chicks as breeder egg storage was prolonged to 14-18 days. The suitable VE level for the broiler breeder diet was 200 mg/kg as breeder egg storage was prolonged.

Steroid-induced osteonecrosis of the femoral head reveals enhanced reactive oxygen species and hyperactive osteoclasts

Steroid-induced osteonecrosis of the femoral head (ONFH) is a progressive bone disorder which typically results in femoral head collapse and hip joint dysfunction. It is well-accepted that abnormal osteoclast activity contributes to loss of bone structural integrity and subchondral fracture in ONFH. However, the pathophysiologic mechanisms underlying the recruitment and hyperactivation of osteoclasts in ONFH remain incompletely understood. We assessed the changes of reactive oxygen species (ROS) level and subsequent osteoclast alterations in steroid-induced osteonecrotic femoral heads from both patients and rat ONFH models. When compared with healthy neighboring bone, the necrotic region of human femoral head was characterized by robust up-regulated expression of osteoclast-related proteins [cathepsin K and tartrate-resistant acid phosphatase(TRAP)] but pronounced down-regulation of antioxidant enzymes (catalase, γ-glutamylcysteine synthetase [γ-GCSc], and superoxide dismutase 1 [SOD1]). In addition, the ratio of TNFSF11 (encoding RANKL)/TNFRSF11B (encoding OPG) was increased within the necrotic bone. Consistently, in rat ONFH models induced by methylprednisolone (MPSL) and imiquimod (IMI), significant bone loss in the femoral head was observed, attributable to increased numbers of TRAP positive osteoclasts. Furthermore, the decreased expression of antioxidant enzymes observed by immunoblotting was accompanied by increased ex-vivo ROS fluorescence signals of dihydroethidium (DHE) in rat ONFH models. Therefore, this study lends support to the rationale that antioxidant agents may be a promising therapeutic avenue to prevent or mitigate the progression of steroid-induced ONFH by inhibiting ROS level and hyperactive osteoclasts.

A Mini Review: Stem Cell Therapy for Osteonecrosis of the Femoral Head and Pharmacological Aspects

Osteonecrosis of the femoral head (ONFH) is a common disease that occurs frequently. Due to various etiologies, the blood supply directed to the femoral head is interrupted in patients with ONFH. This disease can result in degeneration and necrosis of the subchondral bone of the femoral head, which ultimately cause a collapse of the femoral head. Of note, ONFH can extremely affect the quality of living of patients with a high disability rate. Also, this disease often includes middle-aged and younger people. However, effective treatments of ONFH are still challenging in clinics. In recent years, stem cells have been profoundly studied and a relevant new technology has been developed rapidly and applied for regenerative medicine. A number of reports have demonstrated successful results of the treatment of ONFH by using stem cell transplantation. By the combination of minimally invasive hip decompression and injection of mesenchymal stem cells into the necrotic lesion, the retrospective analysis of patients treated revealed that significant pain relief was observed in 86% patients and they had no major complications after treatment. Thus, stem cell transplantation is anticipated to be applied as an innovative approach in the treatment of ONFH. This review will summarize results obtained from recent human and animal studies, which include the pathophysiological process of ONFH, current techniques and effects of using stem cells on the treatment of ONFH together with pharmacological aspects. Overall, the current evidence reveals the treatment of ONFH using stem cell technology as promising. Nonetheless, additional in-depth studies are necessary to better explore the application of this technology and seek more ideal approaches to minimize difficulties related to stem cells.

Structural characterization of a safflower polysaccharide and its promotion effect on steroid-induced osteonecrosis in vivo

A water-soluble polysaccharide (SPAW) was purified from Safflower and it was identified to be (1→3)-linked β-d-Glucan. The therapeutic effect and underlying mechanism of SPAW on steroid-induced avascular necrosis of the femoral head (SANFH) in a rabbit model was performed here. The abnormal histopathologic changes and apoptosis of femoral head in model group were significantly reverted after SPAW (25, 100 and 200 mg/kg) administration for 60 days, as evidenced by the a decline of empty lacunae rate, the average bone marrow fat cell size and the proportion of apoptotic cells. Furthermore, administration of SPAW significantly decreased the Bax and caspase-3 protein expression, but increased the protein expression of Bcl-2 when compared these in model rabbits. Meanwhile, increased hydroxyproline (HOP) and decreased serum hexosamine (HOM) concentration in rabbit serum were turned to the opposite way. The present study suggested that SPAW may provide an alternative treatment for the treatment of SANFH.

Mitochondrial Transcription Factor A added to Osteocytes in a Stressed Environment has a Cytoprotective Effect

The main precipitant of glucocorticoid-associated femoral head osteonecrosis is widely accepted to be an ischemic-hypoxic event, with oxidative stress also as an underlying factor. Mitochondrial DNA is more vulnerable to oxidative injury than the nucleus, and mitochondrial transcription factor A (TFAM), which plays roles in its function, preservation, and regulation is being increasingly investigated. In the present study we focused on the impact of TFAM on the relation between the oxidative injury induced by the addition of glucocorticoid to a hypoxic environment and osteocytic cell necrosis. Using cultured osteocytes MLO-Y4 in a 1% hypoxic environment (hypoxia) to which 1µM dexamethasone (Dex) was added (Dex(+)/hypoxia(+)), an immunocytochemical study was conducted using 8-hydroxy-2'-deoxyguanosine (8-OHdG), an index of oxidative stress, and hypoxia inducible factor-1α (HIF-1α), a marker of hypoxia. Next, after adding TFAM siRNA, TFAM knockdown, cultured for 24h, and mitochondrial membrane potential were measured, they were stained with ATP5A which labels adenosine triphosphate (ATP) production. Dex was added to MLO-Y4 to which TFAM had been added, and cultured for 24h in hypoxia. The ratio of dead cells to viable cells was determined and compared. Enhanced expression of 8-OHdG, HIF-1α was found in osteocytes following the addition of glucocorticoid in a hypoxic environment. With TFAM knockdown, as compared to normoxia, mitochondrial function significantly decreased. On the other hand, by adding TFAM, the incidence of osteocytic cell necrosis was significantly decreased as compared with Dex(+)/hypoxia(+). TFAM was confirmed to be important in mitochondrial function and preservation, inhibition of oxidative injury and maintenance of ATP production. Moreover, prevention of mitochondrial injury can best be achieved by decreasing the development of osteocytic cell necrosis.

Therapeutic interventions for COVID-19: a living overview of reviews

BACKGROUND

Coronavirus disease 2019 (COVID-19) has rapidly spread worldwide, but safe and effective treatment options remain unavailable. Numerous systematic reviews of varying qualities have tried to summarize the evidence on the available therapeutic interventions for COVID-19. This overview of reviews aims to provide a succinct summary of the findings of systematic reviews on different pharmacological and non-pharmacological therapeutic interventions for COVID-19.

METHODS

We searched PubMed, Embase, Google Scholar, Cochrane Database of Systematic Reviews, and WHO database of publications on COVID-19 from 1 December 2019 through to 11 June 2020 for peer-reviewed systematic review studies that reported on potential pharmacological or non-pharmacological therapies for COVID-19. Quality assessment was completed using A MeaSurement Tool to Assess systematic Reviews-2 (AMSTAR-2) measure.

RESULTS

Out of 816 non-duplicate studies, 45 were included in the overview. Antiviral and antibiotic agents, corticosteroids, and anti-malarial agents were the most common drug classes used to treat COVID-19; however, there was no direct or strong evidence to support their efficacy. Oxygen therapy and ventilatory support was the most common non-pharmacological supportive care. The quality of most of the included reviews was rated as low or critically low.

CONCLUSION

This overview of reviews demonstrates that although some therapeutic interventions may be beneficial to specific subgroups of COVID-19 patients, the available data are insufficient to strongly recommend any particular treatment option to be used at a population level. Future systematic reviews on COVID-19 treatments should adhere to the recommended systematic review methodologies and ensure that promptness and comprehensiveness are balanced.The reviews of this paper are available via the supplemental material section.

Serum levels of carotenoids in patients with osteonecrosis of the femoral head are lower than in healthy, community-living people

PURPOSE

Oxidative stress is closely associated with the pathogenesis of nontraumatic osteonecrosis of the femoral head (ONFH). This study aimed to determine whether the serum levels of antioxidant nutrients were decreased in patients with ONFH.

METHODS

We analyzed the serum levels of antioxidant nutrients in 39 patients with ONFH (ONFH group) and 78 age- and gender-matched healthy people (control group) who voluntarily participated in the Yakumo study, which is a comprehensive health examination program. We measured and compared the serum levels of α-tocopherol (vitamin E) and total carotenoids, including zeaxanthin/lutein, β-cryptoxanthin, lycopene, α-carotene, and β-carotene, in the ONFH and control groups using high-performance liquid chromatography.

RESULTS

The mean serum levels of total carotenoids were significantly lower in the ONFH group than in the control group (2.36 ± 1.26 and 3.79 ± 2.36 µmol/l, respectively, p < 0.001). However, no significant difference was found in α-tocopherol between the two groups (26.37 ± 6.90 µmol/l in the ONFH group and 26.24 ± 6.28 µmol/l in the control group, p = 0.920). Among each carotenoid, the serum levels of zeaxanthin/lutein, lycopene, and β-carotene were significantly lower in the ONFH group than in the control group ( p < 0.001).

CONCLUSIONS

The serum levels of carotenoids were lower in patients with ONFH than in healthy, community-living people. This result suggests that carotenoids may be related to the pathogenesis of ONFH.

The Effects of Tocotrienol on Bone Peptides in a Rat Model of Osteoporosis Induced by Metabolic Syndrome: The Possible Communication between Bone Cells

A positive association between metabolic syndrome (MetS) and osteoporosis has been demonstrated in previous animal studies. The mechanisms of MetS in orchestrating the bone remodelling process have traditionally focused on the interactions between mature osteoblasts and osteoclasts, while the role of osteocytes is unexplored. Our earlier studies demonstrated the bone-promoting effects of tocotrienol using a rat model of osteoporosis induced by MetS. This study aimed to investigate the expression of osteocyte-derived peptides in the bone of rats with MetS-induced osteoporosis treated with tocotrienol. Age-matched male Wistar rats (12-week-old; n = 42) were divided into seven experimental groups. Two groups served as the baseline and normal group, respectively. The other five groups were fed with a high-carbohydrate high-fat (HCHF) diet to induce MetS. The five groups of HCHF animals were treated with tocopherol-stripped corn oil (vehicle), annatto tocotrienol (60 and 100 mg/kg), and palm tocotrienol (60 and 100 mg/kg) starting from week 8. At the end of the study, the rats were sacrificed and their right tibias were harvested. Protein was extracted from the metaphyseal region of the proximal right tibia and levels of bone peptides, including osteoprotegerin (OPG), soluble receptor activator of nuclear factor-kappa B ligand (sRANKL), sclerostin (SOST), Dickkopf-related protein 1 (DKK-1), fibroblast growth factor-23 (FGF-23), and parathyroid hormone (PTH), were measured. The vehicle-treated animals displayed higher levels of sRANKL, SOST, DKK-1, FGF-23, and PTH as compared to the normal animals. Oral supplementation of annatto and palm tocotrienol (60 and 100 mg/kg) reduced the levels of sRANKL and FGF-23 in the HCHF animals. Only 100 mg/kg annatto and palm tocotrienol lowered SOST and DKK-1 levels in the HCHF animals. In conclusion, tocotrienol exerts potential skeletal-promoting benefit by modulating the levels of osteocytes-derived bone-related peptides.

Inhibition of Osteocyte Membrane Repair Activity via Dietary Vitamin E Deprivation Impairs Osteocyte Survival

Osteocytes experience plasma membrane disruptions (PMD) that initiate mechanotransduction both in vitro and in vivo in response to mechanical loading, suggesting that osteocytes use PMD to sense and adapt to mechanical stimuli. PMD repair is crucial for cell survival; antioxidants (e.g., alpha-tocopherol, also known as Vitamin E) promote repair while reactive oxygen species (ROS), which can accumulate during exercise, inhibit repair. The goal of this study was to determine whether depleting Vitamin E in the diet would impact osteocyte survival and bone adaptation with loading. Male CD-1 mice (3 weeks old) were fed either a regular diet (RD) or Vitamin E-deficient diet (VEDD) for up to 11 weeks. Mice from each dietary group either served as sedentary controls with normal cage activity, or were subjected to treadmill exercise (one bout of exercise or daily exercise for 5 weeks). VEDD-fed mice showed more PMD-affected osteocytes (+ 50%) after a single exercise bout suggesting impaired PMD repair following Vitamin E deprivation. After 5 weeks of daily exercise, VEDD mice failed to show an exercise-induced increase in osteocyte PMD formation, and showed signs of increased osteocytic oxidative stress and impaired osteocyte survival. Surprisingly, exercise-induced increases in cortical bone formation rate were only significant for VEDD-fed mice. This result may be consistent with previous studies in skeletal muscle, where myocyte PMD repair failure (e.g., with muscular dystrophy) initially triggers hypertrophy but later leads to widespread degeneration. In vitro, mechanically wounded MLO-Y4 cells displayed increased post-wounding necrosis (+ 40-fold) in the presence of H₂O₂, which could be prevented by Vitamin E pre-treatment. Taken together, our data support the idea that antioxidant-influenced osteocyte membrane repair is a vital aspect of bone mechanosensation in the osteocytic control of PMD-driven bone adaptation.

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.

Multiscale Stem Cell Technologies for Osteonecrosis of the Femoral Head

The last couple of decades have seen brilliant progress in stem cell therapies, including native, genetically modified, and engineered stem cells, for osteonecrosis of the femoral head (ONFH). In vitro studies evaluate the effect of endogenous or exogenous factor or gene regulation on osteogenic phenotype maintenance and/or differentiation towards osteogenic lineage. The preclinical and clinical outcomes accelerate the clinical translation. Bone marrow mesenchymal stem cells and adipose-derived stem cells have demonstrated better effects in the treatment of femoral head necrosis. Various materials have been used widely in the ONFH treatment in both preclinical and clinical trials. In a word, in vivo and multiscale efforts are expected to overcome obstacles in the approaches for treating ONFH and provide clinical relevance and commercial strategies in the future. Therefore, we will discuss the above aspects in this paper and present our opinions.

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.

Current and emerging pharmacological therapy for non-alcoholic fatty liver disease

The main treatment of patients with non-alcoholic fatty liver disease (NAFLD) is life style modification including weight reduction and dietary regimen. Majority of patients are safely treated with this management and pharmacologic interventions are not recommended. However, a subgroup of NAFLD patients with non-alcoholic steatohepatitis (NASH) who cannot achieve goals of life style modification may need pharmacological therapy. One major obstacle is measurement of histological outcome by liver biopsy which is an invasive method and is not recommended routinely in these patients. Several medications, mainly targeting baseline mechanism of NAFLD, have been investigated in clinical trials for treatment of NASH with promising results. At present, only pioglitazone acting as insulin sensitizing agent and vitamin E as an anti-oxidant have been recommended for treatment of NASH by international guidelines. Lipid lowering agents including statins and fibrates, pentoxifylline, angiotensin receptor blockers, ursodeoxycholic acid, probiotics and synbiotics are current agents with beneficial effects for treatment of NASH but have not been approved yet. Several emerging medications are in development for treatment of NASH. Obeticholic acid, liraglutide, elafibranor, cenicriviroc and aramchol have been tested in clinical trials or are completing trials. Here in, current and upcoming medications with promising results in clinical trial for treatment of NAFLD were reviewed.

Cortisol inhibits mTOR signaling in avascular necrosis of the femoral head

BACKGROUND

ANFH is a major health problem, to which long lasting and definitive treatments are lacking. The aim of this study is to study RNA alterations attributed to cortisol-induced ANFH.

METHODS

Rat models were stratified into three groups: in vitro group (n = 20) for molecular biological assays, control group (n = 3), and ANFH group induced using lipopolysaccharide and dexamethasone (n = 3). Bone marrow-derived endothelial progenitor cells (BM-EPCs) were extracted from the rats. An RNA expression array was performed on BM-EPCs, and enriched genes were subject to pathway analysis. In vitro studies following findings of array results were also performed using the isolated BM-EPCs.

RESULTS

Significant alterations in mammalian target of rapamycin (mTOR) and HIF signaling pathways were identified in BM-EPCs of ANFH. By applying cortisol and dexamethasone to BM-EPCs, significant changes in mTOR and HIF elements were identified. The alteration of HIF pathways appeared to be downstream of mTOR signaling. Glucocorticoid receptor (GR) expression was related to glucocorticoid-dependent mRNA expression of mTOR/HIF genes. mTOR-dependent angiogenesis but not anabolism was the target of GR in ANFH. Inhibition of mTOR signaling also induced apoptosis of BM-EPCs via CHOP-dependent DR5 induction in response to GR stimulation.

CONCLUSION

Decreased mTOR signaling in response to GR stimulation leading to downregulated HIF pathway as well as increased apoptosis could be the pathophysiology.