Recent advances of nanoparticles on bone tissue engineering and bone cells.

With the development of biotechnology, biomaterials have been rapidly developed and shown great potential in bone regeneration therapy and bone tissue engineering. Nanoparticles have attracted the attention of researches and have applied in various fields especially in the biomedical field as the special physicochemical properties. Nanoparticles were found to regulate bone remodeling depending on their size, shape, composition, and charge. Therefore, in-depth research was necessary to provide the basic support to select the most suitable nanoparticles for bone relate diseases treatment. This article reviews the current development of nanoparticles in bone tissue engineering, focusing on drug delivery, gene delivery, and cell labeling. In addition, the research progress on the interaction of nanoparticles with bone cells, focusing on osteoblasts, osteoclasts, and bone marrow mesenchymal stem cells, and the underlying mechanism were also reviewed. Finally, the current challenges and future research directions are discussed. Thus, detailed study of nanoparticles may reveal new therapeutic strategies to improve the effectiveness of bone regeneration therapy or other bone diseases.

Electromagnetic fields regulate iron metabolism in living organisms: A review of effects and mechanism.

The emergence, evolution, and spread of life on Earth have all occurred in the geomagnetic field, and its extensive biological effects on living organisms have been documented. The charged characteristics of metal ions in biological fluids determine that they are affected by electromagnetic field forces, thus affecting life activities. Iron metabolism, as one of the important metal metabolic pathways, keeps iron absorption and excretion in a relatively balanced state, and this process is precisely and completely controlled. It is worth paying attention to how the iron metabolism process of living organisms is changed when exposed to electromagnetic fields. In this paper, the processes of iron absorption, storage and excretion in animals (mammals, fish, arthropods), plants and microorganisms exposed to electromagnetic field were summarized in detail as far as possible, in order to discover the regulation of iron metabolism by electromagnetic field. Studies and data on the effects of electromagnetic field exposure on iron metabolism in organisms show that exposure profiles vary widely across species and cell lines. This process involves a variety of factors, and the complexity of the results is not only related to the magnetic flux density/operating frequency/exposure time and the heterogeneity of the observed object. A systematic review of the biological regulation of iron metabolism by electromagnetic field exposure will not only contributes to a more comprehensive understanding of its biological effects and mechanism, but also is necessary to improve human awareness of the health related risks of electromagnetic field exposure.

A static magnetic field improves bone quality and balances the function of bone cells with regulation on iron metabolism and redox status in type 1 diabetes.

Osteoporosis is one of the chronic complications of type 1 diabetes with high risk of fracture. The prevention of diabetic osteoporosis is of particular importance. Static magnetic fields (SMFs) exhibit advantages on improvement of diabetic complications. The biological effects and mechanism of SMFs on bone health of type 1 diabetic mice and functions of bone cells under high glucose have not been clearly clarified. In animal experiment, six-week-old male C57BL/6J mice were induced to type 1 diabetes and exposed to SMF of 0.4-0.7 T for 4 h/day lasting for 6 weeks. Bone mass, biomechanical strength, microarchitecture and metabolism were determined by DXA, three-point bending assay, micro-CT, histochemical and biochemical methods. Exposure to SMF increased BMD and BMC of femur, improved biomechanical strength with higher ultimate stress, stiffness and elastic modulus, and ameliorated the impaired bone microarchitecture in type 1 diabetic mice by decreasing Tb.Pf, Ct.Po and increasing Ct.Th. SMF enhanced bone turnover by increasing the level of markers for bone formation (OCN and Collagen I) as well as bone resorption (CTSK and NFAT2). In cellular experiment, MC3T3-E1 cells or primary osteoblasts and RAW264.7 cells were cultured in 25 mM high glucose-stimulated diabetic marrow microenvironment under differentiation induction and exposed to SMF. SMF promoted osteogenesis with higher ALP level and mineralization deposition in osteoblasts, and it also enhanced osteoclastogenesis with higher TRAP activity and bone resorption in osteoclasts under high glucose condition. Further, SMF increased iron content with higher FTH1 expression and regulated the redox level through activating HO-1/Nrf2 in tibial tissues, and lowered hepatic iron accumulation by BMP6-mediated regulation of hepcidin and lipid peroxidation in mice with type 1 diabetes. Thus, SMF may act as a potential therapy for improving bone health in type 1 diabetes with regulation on iron homeostasis metabolism and redox status.

Phenethyl isothiocyanate induces oxidative cell death in osteosarcoma cells with regulation on mitochondrial network, function and metabolism.

Phenethyl isothiocyanate (PEITC), a kind of isothiocyanate available in cruciferous vegetables, exhibits inhibitory effects on cancers. PEITC has been extensively recorded for its effect on regulation of redox status in cancer cells. Our previous studies revealed that PEITC induced ROS-dependent cell death in osteosarcoma. Mitochondria are the main sites for ROS generation and play significant role in deciding cell fate. To dissect the mechanism of PEITC's action on osteosarcoma cells, we detected the changes on mitochondrial network, function and metabolism in K7M2 and 143B cells. Here, PEITC induced cytosolic, lipid and mitochondrial ROS production in osteosarcoma cells. It changed mitochondrial morphology from elongated to punctate network and decreased mitochondrial mass. Meantime, PEITC increased mitochondrial transmembrane potential in short time, decreased it with time prolonged, and later collapsed it in K7M2 cells, and reduced it in 143B cells. PEITC inhibited proliferation potential of osteosarcoma cells with damage on mitochondrial respiratory chain complexes. Further, PEITC-treated osteosarcoma cells experienced a sudden increase in ATP level, and later its content was decreased. Moreover, PEITC downregulated the expressions of mitochondrial respiratory chain complexes including COX IV, UQCR, SDHA and NDUFA9 in 143B cells and COX IV in K7M2 cells. At last, by using ρ0 cells derived from K7M2 and 143B cells, we found that osteosarcoma cells that depleted mtDNA were less sensitive to PEITC-induced changes on cellular morphology, cytoskeleton filament, mitochondrial transmembrane potential and ROS generation. In conclusion, our study demonstrated that mitochondria may play important role in PEITC-induced oxidative cell death in osteosarcoma cells.

Exposure to a static magnetic field attenuates hepatic damage and function abnormality in obese and diabetic mice.

Static magnetic fields (SMFs) exhibit significant effect on health care. However, the effect of SMF on hepatic metabolism and function in obesity and diabetes are still unknown. Liver is not only the main site for glucolipid metabolism but also the core part for iron metabolism regulation. Dysregulations of iron metabolism and redox status are risk factors for the development of hepatic injury and affect glucolipid metabolism in obesity and diabetes. Mice of HFD-induced obesity and HFD/streptozocin-induced diabetes were exposed to a moderate-intensity SMF (0.4-0.7 T, direction: upward, 4 h/day, 8 weeks). Results showed that SMF attenuated hepatic damage by decreasing inflammation and fibrosis in obese and diabetic mice. SMF had no effects on improving glucose/insulin tolerance but regulated proteins (GLUT1 and GLUT4) and genes (G6pc, Pdk4, Gys2 and Pkl) participating in glucose metabolism with phosphorylation of Akt/AMPK/GSK3ß. SMF also reduced lipid droplets accumulation through decreasing Plin2 and Plin5 and regulated lipid metabolism with elevated hepatic expressions of PPARγ and C/EBPα in obese mice. In addition, SMF decreased hepatic iron deposition with lower FTH1 expression and modulated systematic iron homeostasis via BMP6-mediated regulation of hepcidin. Moreover, SMF balanced hepatic redox status with regulation on mitochondrial function and MAPKs/Nrf2/HO-1 pathway. Finally, we found that SMF activated hepatic autophagy and enhanced lipophagy by upregulating PNPLA2 expression in obese and diabetic mice. Our results demonstrated that SMF significantly ameliorated the development of hepatic injury in obese and diabetic mice by inhibiting inflammatory level, improving glycolipid metabolism, regulating iron metabolism, balancing redox level and activating autophagy.

1-2 ​T static magnetic field combined with Ferumoxytol prevent unloading-induced bone loss by regulating iron metabolism in osteoclastogenesis.

Objective: With the deepening of magnetic biomedical effects and electromagnetic technology, some medical instruments based on static magnetic field (SMF) have been used in orthopedic-related diseases treatment. Studies have shown SMF could combat osteoporosis by regulating the differentiation of mesenchymal stem cells (MSCs), osteoblast and osteoclast. With the development of nanotechnology, iron oxide nanoparticles (IONPs) have been reported to regulate the process of bone anabolism. As for SMF combined with IONPs, studies indicated osteogenic differentiation of MSCs were promoted by the combination of SMF and IONPs. However, there are few reports on the effects of SMF combined with IONPs on osteoclast. Herein, the purpose of this study was to investigate the effects of high static magnetic field (HiSMF) combined with IONPs on unloading-induced bone loss in vivo and osteoclastic formation in vitro, and elucidated the potential molecular mechanisms. Methods: In vivo, C57BL/6 â€‹J male mice were unloaded via tail suspension or housed normally. The hindlimb of mice were fixed and exposed to 1-2 â€‹T SMF for 1 â€‹h every day, 10 â€‹mg/kg of Ferumoxytol or saline were injected by tail vein once a week, last for 4 weeks. Bone microstructure, mechanical properties, and osteoclastogenesis were examined respectively. In vitro, the RAW264.7 â€‹cells were used to assess the effects of 1-2 â€‹T SMF combined with IONPs in osteoclastogenesis. The iron content was detected by atomic absorption spectrometry and Prussian blue staining. DCFH-DA and MitoSOX™ fluorescence staining were used to assess oxidative stress levels. NF-κB and MAPK signaling pathways were examined by western blot assay. Results: In vivo, the results showed 1-2 â€‹T SMF and IONPs prevented the damage to bone microstructure and improved the mechanical properties, diminished the number of osteoclasts in unloaded mice, 1-2 â€‹T SMF combined with IONPs was found more effective. The iron content in the liver and spleen was reduced by the combination of 1-2 â€‹T SMF and IONPs, enhancing iron levels in the femur. In vitro, osteoclast formation was inhibited by 1-2 â€‹T SMF and IONPs treatment, and 1-2 â€‹T SMF combined with IONPs had a more pronounced effect. Moreover, iron uptake of IONPs in osteoclast was reduced to 1-2 â€‹T SMF exposure. Oxidative stress levels were decreased in osteoclast differentiation under 1-2 â€‹T SMF combined with IONPs treatment. Molecularly, the expression of NF-κB and MAPK signaling pathways were inhibited under 1-2 â€‹T SMF combined with IONPs in osteoclastogenesis. Conclusions: Synthetically, our research illustrated 1-2 â€‹T SMF combined with IONPs prevented unloading-induced bone loss by regulating iron metabolism in osteoclastogenesis.Translational potential of this article: As a non-invasive alternative therapy, some medical instruments based on SMF have been used for orthopedic-related diseases treatment for their portability, cheapness and safety. Ferumoxytol (Feraheme™), the first FDA-approved IONP drug for the treatment of iron deficiency anemia, has been also adapted in translational research for osteoporosis. Based on the above-mentioned two points, we found the synergistic effects of SMF and Ferumoxytol for treatment of experimental osteoporosis. These results show translational potentials for clinical application.

Iron plays a role in sulfasalazine-induced ferroptosis with autophagic flux blockage in K7M2 osteosarcoma cells.

Osteosarcoma is the most common primary bone malignancy in children and young adults, with a very poor prognosis. It is of great importance to develop targeted therapeutic strategies for osteosarcoma. Sulfasalazine (SAS) is an FDA-approved drug for the treatment of Crohn's disease, rheumatoid arthritis, and inflammatory bowel disease. It acts as an inhibitor of cystine/glutamate system, which is important for cellular glutathione synthesis and maintenance of GPx4 activity. Nowadays, SAS has been repurposed as an antitumor drug for inducing ferroptosis in cancers. This study aimed to uncover the role of iron in SAS-induced ferroptotic cell death in K7M2 osteosarcoma cells. Herein, SAS led to an iron-dependent cell death mode in K7M2 cells, accompanied with decreased antioxidant defense and increased production of cytosolic and lipid reactive oxygen species. Results also showed that iron supplement with ferric ammonium citrate (FAC) or ferrous ammonium sulfate (FAS) exacerbated the declined cell viability of SAS-treated K7M2 cells, while in the case of iron depletion, it weakened such suppression. Furthermore, iron promoted SAS-induced alterations on cell cycle, cytoskeleton, mitochondria morphology and function, and redox system. Iron also induced the dysfunction of autophagic activity in SAS-treated K7M2 cells. In conclusion, our study uncovered the essential role of iron in SAS's effects on K7M2 cells and provided the potential combined therapy of inhibition on antioxidant defense and an increase in oxidative potential, which further disturbed the redox status in tumor cells.

Magnetic fields as a potential therapy for diabetic wounds based on animal experiments and clinical trials.

Diabetes mellitus (DM) is a chronic metabolic disorder with various complications that poses a huge worldwide healthcare burden. Wounds in diabetes, especially diabetic foot ulcers (DFUs), are difficult to manage, often leading to prolonged wound repair and even amputation. Wound management in people with diabetes is an extremely clinical and social concern. Nowadays, physical interventions gain much attention and have been widely developed in the fields of tissue regeneration and wound healing. Magnetic fields (MFs)-based devices are translated into clinical practice for the treatment of bone diseases and neurodegenerative disorder. This review attempts to give insight into the mechanisms and applications of MFs in wound care, especially in improving the healing outcomes of diabetic wounds. First, we discuss the pathological conditions associated with chronic diabetic wounds. Next, the mechanisms involved in MFs' effects on wounds are explored. At last, studies and reports regarding the effects of MFs on diabetic wounds from both animal experiments and clinical trials are reviewed. MFs exhibit great potential in promoting wound healing and have been practised in the management of diabetic wounds. Further studies on the exact mechanism of MFs on diabetic wounds and the development of suitable MF-based devices could lead to their increased applications into clinical practice.

ß-Phenethyl Isothiocyanate Induces Cell Death in Human Osteosarcoma through Altering Iron Metabolism, Disturbing the Redox Balance, and Activating the MAPK Signaling Pathway.

Osteosarcoma is the most common primary malignancy of the skeleton in children and adults. The outcomes of people with osteosarcomas are unsatisfied. ß-Phenethyl isothiocyanate (PEITC) exhibits chemoprevention and chemotherapeutic activities against many human cancers. The molecular mechanism underlying its action on osteosarcoma is still unknown. This study was aimed at investigating the effect of PEITC on human osteosarcoma both in vitro and in vivo. The results showed that PEITC reduced cell viability, inhibited proliferation, and caused G2/M cell cycle arrest in four human osteosarcoma cell lines (MNNG/HOS, U-2 OS, MG-63, and 143B). Then, we found that PEITC altered iron metabolism related to the processes of iron import, storage, and export, which resulted in increased labile iron. Expectedly, PEITC caused oxidative stress as a consequence of GSH depletion-inducing ROS generation and lipid peroxidation. Multiple cell death modalities, including ferroptosis, apoptosis, and autophagy, were triggered in human osteosarcoma cells. Three MAPKs (ERK, p38, and JNK) were all activated after PEITC treatment; however, they presented different responses among the four human osteosarcoma cell lines. ROS generation was proved to be the major cause of PEITC-induced decreased proliferative potential, altered iron metabolism, cell death, and activated MAPKs in human osteosarcoma cells. In addition, PEITC also significantly delayed tumor growth in a xenograft osteosarcoma mouse model with a 30 mg/kg administration dose. In conclusion, this study reveals that PEITC simultaneously triggers ferroptosis, apoptosis, and autophagy in human osteosarcoma cells by inducing oxidative stress.

PEITC triggers multiple forms of cell death by GSH-iron-ROS regulation in K7M2 murine osteosarcoma cells.

Phenethyl isothiocyanate (PEITC) is an isothiocyanate that largely exists in cruciferous vegetables and exhibits chemopreventive and chemotherapeutic potential against various cancers. However, it is little known about the molecular mechanisms of its antitumor action against osteosarcoma, which is the second highest cause of cancer-related death in children and adolescents. In this study, we investigated the effects of PEITC on K7M2 murine osteosarcoma both in vitro and in vivo. We found that treatment with PEITC dose-dependently inhibited the viability of K7M2 murine osteosarcoma cells with an IC50 value of 33.49 µM at 24 h. PEITC (1, 15, 30 µM) dose-dependently inhibited the cell proliferation, caused G2/M cell cycle arrest, depleted glutathione (GSH), generated reactive oxygen species (ROS), altered iron metabolism, and triggered multiple forms of cell death, namely ferroptosis, apoptosis, and autophagy in K7M2 cells. We further revealed that PEITC treatment activated MAPK signaling pathway, and ROS generation was a major cause of PEITC-induced cell death. In a syngeneic orthotopic osteosarcoma mouse model, administration of PEITC (30, 60 mg/kg every day, ig, for 24 days) significantly inhibited the tumor growth, but higher dose of PEITC (90 mg/kg every day) compromised its anti-osteosarcoma effect. Histological examination showed that multiple cell death processes were initiated, iron metabolism was altered and MAPK signaling pathway was activated in the tumor tissues. In conclusion, we demonstrate that PEITC induces ferroptosis, autophagy, and apoptosis in K7M2 osteosarcoma cells by activating the ROS-related MAPK signaling pathway. PEITC has promising anti-osteosarcoma activity. This study sheds light on the redox signaling-based chemotherapeutics for cancers.

Unraveling the Potential Role of Glutathione in Multiple Forms of Cell Death in Cancer Therapy.

Glutathione is the principal intracellular antioxidant buffer against oxidative stress and mainly exists in the forms of reduced glutathione (GSH) and oxidized glutathione (GSSG). The processes of glutathione synthesis, transport, utilization, and metabolism are tightly controlled to maintain intracellular glutathione homeostasis and redox balance. As for cancer cells, they exhibit a greater ROS level than normal cells in order to meet the enhanced metabolism and vicious proliferation; meanwhile, they also have to develop an increased antioxidant defense system to cope with the higher oxidant state. Growing numbers of studies have implicated that altering the glutathione antioxidant system is associated with multiple forms of programmed cell death in cancer cells. In this review, we firstly focus on glutathione homeostasis from the perspectives of glutathione synthesis, distribution, transportation, and metabolism. Then, we discuss the function of glutathione in the antioxidant process. Afterwards, we also summarize the recent advance in the understanding of the mechanism by which glutathione plays a key role in multiple forms of programmed cell death, including apoptosis, necroptosis, ferroptosis, and autophagy. Finally, we highlight the glutathione-targeting therapeutic approaches toward cancers. A comprehensive review on the glutathione homeostasis and the role of glutathione depletion in programmed cell death provide insight into the redox-based research concerning cancer therapeutics.