Effects of Cu-doped 45S5 bioactive glass on the lipid peroxidation-associated growth of human osteoblast-like cellsin vitro

The impact of copper on bone metabolism

Copper is an essential trace element for the human body. Abnormalities in copper metabolism can lead to bone defects, mainly by directly affecting the viability of osteoblasts and osteoclasts and their bone remodeling function, or indirectly regulating bone metabolism by influencing enzyme activities as cofactors. Copper ions released from biological materials can affect osteoblasts and osteoclasts, either directly or indirectly by modulating the inflammatory response, oxidative stress, and rapamycin signaling. This review presents an overview of recent progress in the impact of copper on bone metabolism. Translational potential of this article: The impact of copper on bone metabolism can provide insights into clinical application of copper-containing supplements and biomaterials.

Devitrite (Na2Ca3Si6O16) phase dominated nanostructured 45S5 bioactive glass: exploring its structural and biological properties

This research study is primarily centred around calcination temperature and time influence on phase formation in bioactive glasses (BGs). In the present study, BG with a nominal composition of 45S5 was synthesized through the sol-gel process. The developed BGs then underwent heat treatment for various sintering durations and temperatures. X-ray diffraction (XRD) patterns of the BGs reveals that the sintering process led to the crystallization of both devitrite (Na2Ca3Si6O16) and combeite (Na2Ca2Si3O9) phases. The field emission scanning electron microscopy study divulges morphological alterations, from sheet-like to rod-like structures to eventually transforming into spherical and sheet-like structures. The surface area and Type-IV mesoporous porosity were validated through Brunauer Emmett Teller analysis, highlighting a notable increase in pore volume and mechanical strength at a lower sintering temperature.In vitroapatite formation was carried out in Hank's balance salt in order to evaluate the bioactivity of the glass. After 7 d of immersion in simulated body fluid (SBF), XRD patterns and scanning electron microscopy micrographs results showed that formation of hydroxyapatite layer on the surface of the BGs. The BG compatibility with erythrocytes (red blood cells) was also studied, and the results revealed that there was only a low 2% lysis, showing good hemocompatibility. The drug loading and release behaviour of the BGs was studied in thein vitroanalysis. The findings showed a high drug encapsulation effectiveness of up to 90% and continuous drug release from the BGs for 24 h. The materials biocompatibility was unambiguously confirmed by cytocompatibility and proliferation studies. This study provides compelling evidence for the exceptional efficacy and promise of the distinct 45S5 BGs in advancing the field of regenerative medicine.

Preparation of Cu2+/TA/HAP composite coating with anti-bacterial and osteogenic potential on 3D-printed porous Ti alloy scaffolds for orthopedic applications

Because of stress shielding effects, traditional titanium (Ti) alloy scaffolds have a high elastic modulus, which might promote looseness and bone disintegration surrounding the implant, increasing the likelihood of a second surgery. In contrast, 3D-printed porous Ti alloy scaffolds can reduce the scaffold weight while enhancing biocompatibility. Further, these scaffolds' porous nature allows bone tissue ingrowth as well as strong pore connectivity, which can improve nutrient absorption. Nevertheless, bare Ti alloy implants may fail because of inadequate bone integration; hence, adding a coating on the implant surface is an effective technique for improving implant stability. In this study, a composite coating comprising hydroxyapatite (HAP), chitosan (CS), tannic acid (TA) and copper ions (Cu2+) (Cu2+/TA/HAP composite coating) was prepared on the surface of 3D printed porous Ti alloy scaffolds using electrophoretic deposition. Using the standard plate count method, Live/Dead bacteria staining assay, FITC Phalloidin and 4',6-diamidino-2-phenylindole staining assay, and live/dead staining of cells we determined that the composite coating has better antibacterial properties and cytocompatibility as well as lower cytotoxicity. The Alkaline Phosphatase assay revealed that the coating results showed good osteogenesis potential. Overall, the composite coatings produced in this investigation give new potential for the application of Ti alloys in clinics.

Comparison of the differentiation of ovine fetal bone-marrow mesenchymal stem cells towards osteocytes on chitosan/alginate/CuO-NPs and chitosan/alginate/FeO-NPs scaffolds

In the current study, the creation of a chitosan/alginate scaffold hydrogel with and without FeO-NPs or CuO-NPs was studied. From fetal ovine bone marrow mesenchymal stem cells (BM-MSCs) were isolated and cultivated. Their differentiation into osteocyte and adipose cells was investigated. Also, on the scaffolds, cytotoxicity and apoptosis were studied. To investigate the differentiation, treatment groups include: (1) BM-MSCs were plated in DMEM culture medium with high glucose containing 10% FBS and antibiotics (negative control); (2) BM-MSCs were plated in osteogenic differentiation medium (positive control); (3) positive control group + FeO-NPs, (4) positive control group + CuO-NPs; (5) BM-MSCs were plated in osteogenic differentiation medium on chitosan/alginate scaffold; (6) BM-MSCs were plated in osteogenic differentiation medium on chitosan/alginate/FeO-NPs scaffold; and (7) BM-MSCs were plated in osteogenic differentiation medium on chitosan/alginate/CuO-NPs scaffold. Alkaline phosphatase enzyme concentrations, mineralization rate using a calcium kit, and mineralization measurement by alizarin staining quantification were evaluated after 21 days of culture. In addition, qRT-PCR was used to assess the expression of the ALP, ColA, and Runx2 genes. When compared to other treatment groups, the addition of CuO-NPs in the chitosan/alginate hydrogel significantly increased the expression of the ColA and Runx2 genes (p < 0.05). However, there was no significant difference between the chitosan/alginate hydrogel groups containing FeO-NPs and CuO-NPs in the expression of the ALP gene. It appears that the addition of nanoparticles, in particular CuO-NPs, has made the chitosan/alginate scaffold more effective in supporting osteocyte differentiation.

Associations of blood trace elements with bone mineral density: a population-based study in US adults

BACKGROUND

This study aimed to investigate the association between blood trace elements and bone mineral density (BMD) and to determine the association between blood trace elements and the risk of low BMD/osteoporosis among US adults.

METHODS

We performed a cross-sectional study using data from National Health and Nutrition Examination Survey (NHANES, 2011-2016). Multivariable linear regression models were employed to assess the associations of BMD in lumbar spine (LS-BMD), pelvic (PV-BMD) and total femur (TF-BMD) with blood trace elements, including Fe, Zn, Cu, Se, Mn, Cd, Pb, Hg. Additionally, the associations of low BMD/osteoporosis with blood trace elements were also evaluated using multivariable logistic regression.

RESULTS

Higher blood Pb levels were found associated with decreased LS-BMD (p for trend < 0.001), PV-BMD (p for trend = 0.007), and TF-BMD (p for trend = 0.003) in female, while higher blood Se levels were associated with increased PV-BMD in female (p for trend = 0.042); no linear association between BMD and other blood trace element was observed. Also, significant associations were found between Pb levels and the prevalence of low BMD (p for trend = 0.030) and the prevalence of osteoporosis (p for trend = 0.036), while association between other blood trace elements and low BMD/osteoporosis was not observed.

CONCLUSION

This study provides comprehensive insight into the association between blood trace elements and BMD and supports a detrimental effect of blood Pb levels on bone mass in women. Considering our analysis from a representative US general population, further study is warranted for the extreme levels of blood trace elements on bone metabolism.

Antibacterial Biomaterial Based on Bioglass Modified with Copper for Implants Coating

Biofilm-related implant infections pose a substantial threat to patients, leading to inflammation in the surrounding tissue, and often resulting in implant loss and the necessity for additional surgeries. Overcoming this implantology challenge is crucial to ensure the success and durability of implants. This study shows the development of antibacterial materials for implant coatings by incorporating copper into 45S5 Bioglass^®. By combining the regenerative properties of Bioglass^® with the antimicrobial effects of copper, this material has the potential to prevent infections, enhance osseointegration and improve the long-term success of implants. Bioglasses modified with various concentrations of CuO (from 0 to 8 mol%) were prepared with the melt-quenching technique. Structural analysis using Raman and FTIR spectroscopies did not reveal significant alterations in the bioglasses structure with the addition of Cu. The antibacterial activity of the samples was assessed against Gram-positive and Gram-negative bacteria, and the results demonstrated significant inhibition of bacterial growth for the bioglass with 0.5 mol% of CuO. Cell viability studies indicated that the samples modified with up to 4 mol% of CuO maintained good cytocompatibility with the Saos-2 cell line at extract concentrations up to 25 mg/mL. Furthermore, the bioactivity assessment demonstrated the formation of a calcium phosphate (CaP)-rich layer on the surfaces of all bioglasses within 24 h. Our findings show that the inclusion of copper in the bioglass offers a significant enhancement in its potential as a coating material for implants, resulting in notable advancements in both antibacterial efficacy and osteointegration properties.

Electrophoretic Deposition, Microstructure, and Selected Properties of Poly(lactic-co-glycolic) Acid-Based Antibacterial Coatings on Mg Substrate

There is an urgent need to develop biodegradable implants that can degrade once they have fulfilled their function. Commercially pure magnesium (Mg) and its alloys have the potential to surpass traditional orthopedic implants due to their good biocompatibility and mechanical properties, and most critically, biodegradability. The present work focuses on the synthesis and characterization (microstructural, antibacterial, surface, and biological properties) of poly(lactic-co-glycolic) acid (PLGA)/henna (Lawsonia inermis)/Cu-doped mesoporous bioactive glass nanoparticles (Cu-MBGNs) composite coatings deposited via electrophoretic deposition (EPD) on Mg substrates. PLGA/henna/Cu-MBGNs composite coatings were robustly deposited on Mg substrates using EPD, and their adhesive strength, bioactivity, antibacterial activity, corrosion resistance, and biodegradability were thoroughly investigated. Scanning electron microscopy and Fourier transform infrared spectroscopy studies confirmed the uniformity of the coatings' morphology and the presence of functional groups that were attributable to PLGA, henna, and Cu-MBGNs, respectively. The composites exhibited good hydrophilicity with an average roughness of 2.6 μm, indicating desirable properties for bone forming cell attachment, proliferation, and growth. Crosshatch and bend tests confirmed that the adhesion of the coatings to Mg substrates and their deformability were adequate. Electrochemical Tafel polarization tests revealed that the composite coating adjusted the degradation rate of Mg substrate in a human physiological environment. Incorporating henna into PLGA/Cu-MBGNs composite coatings resulted in antibacterial activity against Escherichia coli and Staphylococcus aureus. The coatings stimulated the proliferation and growth of osteosarcoma MG-63 cells during the initial incubation period of 48 h (determined by the WST-8 assay).

Cuproptosis-a potential target for the treatment of osteoporosis

Osteoporosis is an age-related disease of bone metabolism marked by reduced bone mineral density and impaired bone strength. The disease causes the bones to weaken and break more easily. Osteoclasts participate in bone resorption more than osteoblasts participate in bone formation, disrupting bone homeostasis and leading to osteoporosis. Currently, drug therapy for osteoporosis includes calcium supplements, vitamin D, parathyroid hormone, estrogen, calcitonin, bisphosphates, and other medications. These medications are effective in treating osteoporosis but have side effects. Copper is a necessary trace element in the human body, and studies have shown that it links to the development of osteoporosis. Cuproptosis is a recently proposed new type of cell death. Copper-induced cell death regulates by lipoylated components mediated via mitochondrial ferredoxin 1; that is, copper binds directly to the lipoylated components of the tricarboxylic acid cycle, resulting in lipoylated protein accumulation and subsequent loss of iron-sulfur cluster proteins, leading to proteotoxic stress and eventually cell death. Therapeutic options for tumor disorders include targeting the intracellular toxicity of copper and cuproptosis. The hypoxic environment in bone and the metabolic pathway of glycolysis to provide energy in cells can inhibit cuproptosis, which may promote the survival and proliferation of various cells, including osteoblasts, osteoclasts, effector T cells, and macrophages, thereby mediating the osteoporosis process. As a result, our group tried to explain the relationship between the role of cuproptosis and its essential regulatory genes, as well as the pathological mechanism of osteoporosis and its effects on various cells. This study intends to investigate a new treatment approach for the clinical treatment of osteoporosis that is beneficial to the treatment of osteoporosis.

Bioinformatics-Based Analysis of Key Genes in Steroid-Induced Osteonecrosis of the Femoral Head That Are Associated with Copper Metabolism

Osteonecrosis of the femoral head (ONFH) is a common disabling disease. Copper has positive effects on cells that regulate bone metabolism. However, the relationship between copper metabolism (CM) and steroid-induced ONFH (SONFH) remains unclear. The GSE123568 dataset was downloaded from the Gene Expression Omnibus. The differentially expressed CM-related SONFH genes (DE-CMR-SONFHGs) were identified via differential analysis and weighted gene coexpression network analysis (WGCNA). Receiver operating characteristic (ROC) analysis was performed for the predictive accuracy of key genes. Targeting drugs and the copper death-related genes (CDRGs) relevant to key genes were investigated. The bioinformatics results were confirmed via quantitative real-time polymerase chain reaction (qRT–PCR) and Western blot (WB) analysis. Two out of 106 DE-CMR-SONFHGs were identified as key genes (PNP and SLC2A1), which had diagnostic value in distinguishing SONFH from control samples and were related to various immune cell infiltrations. Eleven PMP-targeting drugs and five SLC2A1-targeting drugs were identified. The qRT–PCR, as well as WB, results confirmed the downregulation PNP and SLC2A1 and high expression of the CDRGs DLD, PDHB, and MTF1, which are closely related to these two key genes. In conclusion, PNP and SLC2A1 were identified as key genes related to SONFH and may provide insights for SONFH treatment.

Iron, Zinc, Copper, Cadmium, Mercury, and Bone Tissue

The paper presents the current understanding on the effects of five metals on bone tissue, namely iron, zinc, copper, cadmium, and mercury. Iron, zinc, and copper contribute significantly to human and animal metabolism when present in sufficient amounts, but their excess or shortage increases the risk of developing bone disorders. In contrast, cadmium and mercury serve no physiological purpose and their long-term accumulation damages the osteoarticular system. We discuss the methods of action and interactions between the discussed elements as well as the concentrations of each element in distinct bone structures.

Copper regulation of immune response and potential implications for treating orthopedic disorders

Copper is an indispensable trace metal element in human body, and copper deficiency is rare in clinic. However, diseases associated with serum copper deficiency, such as leukopenia, neutropenia, arthritis, osteoporosis, and bone defects, are well known. Copper ions can also achieve the effect of fighting pathogenic bacteria through the "contact killing" characteristic. Copper ion is also an important cofactor of bone matrix synthase, plays an important role in the pathophysiology of orthopedic diseases. The present review highlights the biological functions of copper in immunity, bone diseases and stem cells, as well as potential drug development targeting copper status for diagnostics and therapeutics of copper-associated bone diseases.

Association between bone trace elements and osteoporosis in older adults: a cross-sectional study

Objectives:

Metal micronutrients deficiency may be one of the risk factors for the development of osteoporosis. This study aimed to measure the trace element contents in human bone tissue to analyze the relationship between micronutrients and osteoporosis.

Design:

A cross-sectional survey was performed on data from 51 elderly patients with proximal femoral fracture.

Methods:

The concentrations of calcium, phosphorus, manganese, iron, copper, and zinc in bone tissue samples from 51 elderly patients with proximal femoral fracture were determined by energy-dispersive X-ray fluorescence (EDX). Subjects were divided into osteoporosis and non-osteoporosis groups according to their bone mineral density (BMD) T-score values. The difference in metal elements concentrations in bone tissue between the two groups was compared, and the role of metal elements in osteoporosis was discussed.

Results:

There was no statistical difference in age, sex, body mass index (BMI), serum albumin, biochemical blood indices, and bone turnover markers between the two groups. The Mann–Whitney U test was used to compare the difference in metal elements concentrations in bone tissue samples between the two groups. The results showed that manganese, copper, and zinc concentrations in the cancellous bone were significantly higher in the non-osteoporosis group than in the osteoporosis group. Multivariate logistic regression analysis indicated that high bone zinc concentration [odds ratio = 0.26, 95% confidence interval (CI) = 0.075–0.928, p = 0.038] was negatively correlated with osteoporosis.

Conclusion:

Manganese, copper, and zinc play an essential role in bone mineralization and metabolism. Among them, zinc may be most closely related to osteoporosis and play a key role in bone development and maintenance of bone mass. Therefore, we believe that the design of zinc-rich compounds or nutrients as a new complementary factor to increase the intake of zinc for the elderly could be able to prevent and intervene in the occurrence of osteoporosis in the early stage.

Combined Effects of Polydopamine-Assisted Copper Immobilization on 3D-Printed Porous Ti6Al4V Scaffold for Angiogenic and Osteogenic Bone Regeneration

Numerous studies have demonstrated that biological compounds and trace elements such as dopamine (DA) and copper ions (Cu) could be modified onto the surfaces of scaffolds using a one-step immersion process which is simple, inexpensive and, most importantly, non-cytotoxic. The development and emergence of 3D printing technologies such as selective laser melting (SLM) have also made it possible for us to fabricate bone scaffolds with precise structural designs using metallic compounds. In this study, we fabricated porous titanium scaffolds (Ti) using SLM and modified the surface of Ti with polydopamine (PDA) and Cu. There are currently no other reported studies with such a combination for osteogenic and angiogenic-related applications. Results showed that such modifications did not affect general appearances and microstructural characteristics of the porous Ti scaffolds. This one-step immersion modification allowed us to modify the surfaces of Ti with different concentrations of Cu ions, thus allowing us to fabricate individualized scaffolds for different clinical scenarios. The modification improved the hydrophilicity and surface roughness of the scaffolds, which in turn led to promote cell behaviors of Wharton’s jelly mesenchymal stem cells. Ti itself has high mechanical strength, therefore making it suitable for surgical handling and clinical applications. Furthermore, the scaffolds were able to release ions in a sustained manner which led to an upregulation of osteogenic-related proteins (bone alkaline phosphatase, bone sialoprotein and osteocalcin) and angiogenic-related proteins (vascular endothelial growth factor and angiopoietin-1). By combining additive manufacturing, Ti6Al4V scaffolds, surface modification and Cu ions, the novel hybrid 3D-printed porous scaffold could be fabricated with ease and specifically benefited future bone regeneration in the clinic.

Effect of Copper and Selenium Supplementation on the Level of Elements in Rats' Femurs under Neoplastic Conditions

A study was conducted to determine the effect of long-term supplementation with selenium and copper, administered at twice the level used in the standard diet of rats, on the content of selected elements in the femoral bones of healthy rats and rats with implanted LNCaP cancer cells. After an adaptation period, the animals were randomly divided into two experimental groups. The rats in the experimental group were implanted with prostate cancer cells. The rats in the control group were kept in the same conditions as those in the experimental group and fed the same diet, but without implanted cancer cells. The cancer cells (LNCaP) were intraperitoneally implanted in the amount of 1 × 106 (in PBS 0.4 mL) at the age of 90 days. The content of elements in the samples was determined by a quadrupole mass spectrometer with inductively coupled plasma ionization (ICP-MS). In the femoral bones of rats with implanted LNCaP cells, in the case of the standard diet and the copper-enriched diet, there was a marked decreasing trend in the content of the analysed elements relative to the control rats. This may indicate slow osteolysis taking place in the bone tissue. Contrasting results were obtained for the diet enriched with selenium; there was no significant reduction in the level of these elements, and there was even an increase in the concentrations of Fe and K in the bones of rats with implanted LNCaP cells. Particularly, numerous changes in the mineral composition of the bones were generated by enriching the diet with copper. The elements that most often underwent changes (losses) in the bones were cobalt, iron, manganese and molybdenum. The changes observed, most likely induced by the implantation of LNCaP cells, may indicate a disturbance of mineral homeostasis.

Mechanical Characterization and In Vitro Assay of Biocompatible Titanium Alloys

Metals that come into contact with the body can cause reactions in the body, so biomaterials must be tested to avoid side effects. Mo, Zr, and Ta are non-toxic elements; alloyed with titanium, they have very good biocompatibility properties and mechanical properties. The paper aims to study an original Ti20Mo7ZrxTa system (5, 10, 15 wt %) from a mechanical and in vitro biocompatibility point of view. Alloys were examined by optical microstructure, tensile strength, fractographic analysis, and in vitro assay. The obtained results indicate very good mechanical and biological properties, recommending them for future orthopedic medical applications.

The concentrations of bone calcium, phosphorus and trace metal elements in elderly patients with intertrochanteric hip fractures

INTRODUCTION

Trace metal elements may play a crucial role in bone mineralization and metabolism. However, the quantification of trace element concentrations in human bone tissue has received little attention.

MATERIALS AND METHODS

Bone tissue samples were collected from 55 elderly patients (15 males and 40 females) with intertrochanteric hip fractures. The calcium, phosphorus, manganese, iron, copper, and zinc concentrations in the cortical bone zone, cancellous bone zone, and junction zone between cortical and cancellous bone were determined by energy-dispersive X-ray fluorescence (EDX). The differences in trace element concentrations in the three regions were compared, and the correlation between gender and bone trace element contents of the bones was analyzed using the Kruskal-Wallis's test. The correlation between age, body mass index (BMI), and bone calcium, phosphorus concentrations, and trace elements in three bone zones was determined using Spearman correlation analysis.

RESULTS

The Kruskal-Wallis test showed no difference in bone phosphorus concentration among the three regions. In contrast, the difference in the concentrations of bone calcium and four metal elements was statistically significant (P<0.01). In addition, no statistical differences were observed in the concentrations of trace elements among the three regions in elderly male and female patients. Spearman correlation analysis showed a strong negative correlation between bone calcium and phosphorus in three bone regions (r=-0.999, -0.95, -0.998, P < 0.01) and a significant positive correlation between trace metal elements in the cancellous bone zone. In the junction zone, the BMI showed a strong positive correlation with bone calcium content (r=0.347, P=0.009) and a significant negative correlation with phosphorus content (r=-0.349, P=0.009).

CONCLUSION

Bone calcium and phosphorus were the main components of hydroxyapatite, and these two elements accounted for the majority of bone mineral salts. Trace metal elements are essential for bone metabolism and specific synergistic interactions. BMI may be associated with bone calcium and phosphorus contents in elderly patients with osteoporosis.

Insights into oxidative stress in bone tissue and novel challenges for biomaterials

The presence of Reactive Oxygen Species (ROS) in bone can influence resident cells behaviour as well as the extra-cellular matrix composition and the tissue architecture. Aging, in addition to excessive overloads, unbalanced diet, smoking, predisposing genetic factors, lead to an increase of ROS and, if it is accompanied with an inappropriate production of scavengers, promotes the generation of oxidative stress that encourages bone catabolism. Furthermore, bone injuries can be triggered by numerous events such as road and sports accidents or tumour resection. Although bone tissue possesses a well-known repair and regeneration capacity, these mechanisms are inefficient in repairing large size defects and bone grafts are often necessary. ROS play a fundamental role in response after the implant introduction and can influence its success. This review provides insights on the mechanisms of oxidative stress generated by an implant in vivo and suitable ways for its modulation. The local delivery of active molecules, such as polyphenols, enhanced bone biomaterial integration evidencing that the management of the oxidative stress is a target for the effectiveness of an implant. Polyphenols have been widely used in medicine for cardiovascular, neurodegenerative, bone disorders and cancer, thanks to their antioxidant and anti-inflammatory properties. In addition, the perspective of new smart biomaterials and molecular medicine for the oxidative stress modulation in a programmable way, by the use of ROS responsive materials or by the targeting of selective molecular pathways involved in ROS generation, will be analysed and discussed critically.

Open Curettage With Bone Augmentation for Symptomatic Tumors and Tumor-like Lesions of Calcaneus: A Comparison of Bioactive Glass Versus Allogeneic Bone

Few studies have characterized the clinical outcomes of 45S5 Bioglass® applied as a bone graft to that of allogeneic bone applied in calcaneal open curettage. Therefore, the purpose of the present investigation was to compare the outcomes of patients with calcaneal tumors and tumor-like lesions treated by open curettage with 45S5 Bioglass® or allogeneic bone. Of the 31 patients who underwent open curettage (18 cases of unicameral bone cysts, 7 cases of aneurysmal bone cysts, and 6 cases of intraosseous lipoma), 16 (52%) received grafts with 45S5 Bioglass® and 15 (48%) with allogeneic bone. All the feet achieved bone fusion according to the modified Neer radiographic classification system at the last follow-up examination. The mean bone ingrowth time for the grafts with 45S5 Bioglass® versus allogeneic bone was 3.71 ± 0.86 versus 4.46 ± 1.04 months (p = .038), the mean bone healing time was 4.86 ± 0.93 versus 5.73 ± 1.07 months (p = .021), and the mean incision drying time was 7.2 ± 1.8 versus 8.2 ± 1.5 days (p = .047), respectively. No differences were found in the postoperative American Orthopaedic Foot and Ankle Society ankle-hindfoot scale scores between the 2 groups (p = .213). These results show that 45S5 Bioglass® can better facilitate the formation of new bone with a faster drying time of the incision than allogeneic bone. Although both materials can benefit the clinical outcomes of calcaneal tumors and tumor-like lesions, further studies are needed to observe the long-term complications and lesion recurrence rates.

Cu-Co Co-Doped Microporous Coating on Titanium with Osteogenic and Antibacterial Properties

Titanium (Ti) and its alloys are widely used in bone surgery by virtue of their excellent mechanical properties and good biocompatibility; however, complications such as loosening and sinking have been reported post-implantation. Herein we deposited a copper-cobalt (Cu-Co) co-doped titanium dioxide (TUO) coating on the surface of Ti implants by microarc oxidation. The osteogenic and antimicrobial properties of the coating were evaluated by in vitro experiments, and we also assessed β-catenin expression levels on different sample surfaces. Our results revealed that the coating promoted the adhesion, proliferation, and differentiation of MG63 osteoblasts, and TUO coating promoted β-catenin expression; moreover, the proliferation of Staphylococcus aureus was inhibited. To summarize, we report that Cu-Co co-doping can enhance the osteogenic and antibacterial activities of orthopedic Ti implants, leading to potentially improved clinical performance.

Copper as Dietary Supplement for Bone Metabolism: A Review

While in vitro and animal studies of osteoblastic and osteoclastic activity as well as bone resistance for copper are numerous, and the results encouraging in terms of regulation, human studies are scarce. The aim of this narrative review was to investigate the correlation of blood copper, daily copper intake, and copper supplementation with bone mineral density. This review included 10 eligible studies: five studies concerned copper blood levels, one study concerned daily copper intake, and four studies concerned copper supplementation. Blood copper levels did not show statistically significant differences in four of the studies analyzed, while only one study showed differences between osteoporotic and healthy women, although only with women between 45 and 59 years of age and not between 60 and 80 years of age. The dietary copper intake among women with or without osteoporosis did not show any differences. Only one study with a small sample of subjects carried out these assessments; therefore, it is a topic that the literature must deepen with further studies. The two studies that analyzed the integration of copper (2.5-3 mg/day) only showed good results in terms of slowing down bone mineral loss and reducing resorption markers, confirming the effectiveness of copper supplementation on bone metabolism.

Copper-containing bioactive glasses and glass-ceramics: From tissue regeneration to cancer therapeutic strategies

Copper is one of the most used therapeutic metallic elements in biomedicine, ranging from antibacterial approaches to cancer theranostics. This element could be easily incorporated into different types of biomaterials; specifically, copper-doped bioactive glasses (BGs) provide great opportunities for biomedical engineers and clinicians as regards their excellent biocompatibility and regenerative potential. Although copper-incorporated BGs are mostly used in bone tissue engineering, accelerated soft tissue healing is achievable, too, with interesting potentials in wound treatment and skin repair. Copper can modulate the physico-chemical properties of BGs (e.g., reactivity with bio-fluids) and improve their therapeutic potential. Improving cell proliferation, promoting angiogenesis, reducing or even prohibiting bacterial growth are counted as prominent biological features of copper-doped BGs. Recent studies have also suggested the suitability of copper-doped BGs in cancer photothermal therapy (PTT). However, more research is needed to determine the extent to which copper-doped BGs are actually applicable for tissue engineering and regenerative medicine strategies in the clinic. Moreover, copper-doped BGs in combination with polymers may be considered in the future to produce relatively soft, pliable composites and printable inks for use in biofabrication.

Dual-function membranes based on alginate/methyl cellulose composite for control drug release and proliferation enhancement of fibroblast cells

Membranes based on natural polymers are highly promising therapies for skin damaged sites as they can mimic its biological microstructure to support the fibroblasts cells survival and proliferation. In addition, these membranes could be loaded with active molecules that help in skin regeneration and eliminate the potential bacterial infection. This research aims to formulate novel medicated membranes for controlled release and cytocompatibility elevation of fibroblast cells for engineering of soft tissue. Pre-formulation researches have been conducted for membranes of sodium alginate (Alg)/methyl cellulose (MC) that used loaded with undoped, Bi doped and Bi, Cu co-doped SrTiO₃ using solvent casting technique. In addition, another group of these membranes were loaded with DOXycycline antibiotic (DOX) as model drug as well as for eliminating the potential bacterial infections. The prepared membranes were evaluated by XRD, SEM-EDX, FTIR, Zetasizer, and swelling behaviour was also tested. Profiles of the released drug were determined using phosphate-buffered saline (PBS) (pH 7.4) at 37 °C for 30 days. The investigation of the cytocompatibility and proliferation of fibroblast cells with the prepared membranes were conducted. The XRD, FTIR and SEM data recognised the possible interaction that takes place among Alg and MC, through presence of hydrogen bonds. Existence of the nano-particles within the membrane polymer matrix enhanced the membrane stability and enhanced the drug release rate (from 20 to 45%). Medication release mechanism elucidated that DOX was released from all the fabricated membranes through the relaxation of polymer matrix that takes place after swelling. The filler type and/or dopant type possess no remarkable influence on the cytotoxicity of the membranes against the investigated cells when compared to their individual influence on the same cells. Cells attachments results have revealed an impressive effect for DOX-loaded membranes on the cells affinity and growth. These membranes are recommended for treatments of skin infections.

Copper-doped Ordered Mesoporous Bioactive Glass: A Promising Multifunctional Platform for Bone Tissue Engineering †

The design and development of biomaterials with multifunctional properties is highly attractive in the context of bone tissue engineering due to the potential of providing multiple therapies and, thus, better treatment of diseases. In order to tackle this challenge, copper-doped silicate mesoporous bioactive glasses (MBGs) were synthesized via a sol-gel route coupled with an evaporation-induced self-assembly process by using a non-ionic block co-polymer as a structure directing agent. The structure and textural properties of calcined materials were investigated by X-ray powder diffraction, scanning-transmission electron microscopy and nitrogen adsorption-desorption measurements. In vitro bioactivity was assessed by immersion tests in simulated body fluid (SBF). Preliminary antibacterial tests using Staphylococcus aureus were also carried out. Copper-doped glasses revealed an ordered arrangement of mesopores (diameter around 5 nm) and exhibited apatite-forming ability in SBF along with promising antibacterial properties. These results suggest the potential suitability of copper-doped MBG powder for use as a multifunctional biomaterial to promote bone regeneration (bioactivity) and prevent/combat microbial infection at the implantation site, thereby promoting tissue healing.

Roles and Functions of ROS and RNS in Cellular Physiology and Pathology

Our common knowledge on oxidative stress has evolved substantially over the years, being focused mostly on the fundamental chemical reactions and the most relevant chemical species involved in human pathophysiology of oxidative stress-associated diseases. Thus, reactive oxygen species and reactive nitrogen species (ROS and RNS) were identified as key players in initiating, mediating, and regulating the cellular and biochemical complexity of oxidative stress either as physiological (acting pro-hormetic) or as pathogenic (causing destructive vicious circles) processes. The papers published in this particular Special Issue of Cells show an impressive range on the pathophysiological relevance of ROS and RNS, including the relevance of second messengers of free radicals like 4-hydroxynonenal, allowing us to assume that the future will reveal even more detailed mechanisms of their positive and negative effects that might improve the monitoring of major modern diseases, and aid the development of advanced integrative biomedical treatments.

Antibacterial Activity and Cytocompatibility of Bone Cement Enriched with Antibiotic, Nanosilver, and Nanocopper for Bone Regeneration

Bacterial infections due to bone replacement surgeries require modifications of bone cement with antibacterial components. This study aimed to investigate whether the incorporation of gentamicin or nanometals into bone cement may reduce and to what extent bacterial growth without the loss of overall cytocompatibility and adverse effects in vitro. The bone cement Cemex was used as the base material, modified either with gentamicin sulfate or nanometals: Silver or copper. The inhibition of bacterial adhesion and growth was examined against five different bacterial strains along with integrity of erythrocytes, viability of blood platelets, and dental pulp stem cells. Bone cement modified with nanoAg or nanoCu revealed greater bactericidal effects and prevented the biofilm formation better compared to antibiotic-loaded bone cement. The cement containing nanoAg displayed good cytocompatibility without noticeable hemolysis of erythrocytes or blood platelet disfunction and good viability of dental pulp stem cells (DPSC). On the contrary, the nanoCu cement enhanced hemolysis of erythrocytes, reduced the platelets aggregation, and decreased DPSC viability. Based on these studies, we suggest the modification of bone cement with nanoAg may be a good strategy to provide improved implant fixative for bone regeneration purposes.

Short Overview of ROS as Cell Function Regulators and Their Implications in Therapy Concepts

The importance of reactive oxygen species (ROS) has been gradually acknowledged over the last four decades. Initially perceived as unwanted products of detrimental oxidative stress, they have been upgraded since, and now ROS are also known to be essential for the regulation of physiological cellular functions through redox signaling. In the majority of cases, metabolic demands, along with other stimuli, are vital for ROS formation and their actions. In this review, we focus on the role of ROS in regulating cell functioning and communication among themselves. The relevance of ROS in therapy concepts is also addressed here.

Toward Highly Dispersed Mesoporous Bioactive Glass Nanoparticles With High Cu Concentration Using Cu/Ascorbic Acid Complex as Precursor

Copper (Cu) ions have a variety of advantageous biological functionalities, such as proangiogenic and bactericidal activities. Given the intrinsic biodegradability and biocompatibility, silicate-based mesoporous bioactive glass nanoparticles (MBGNs) are considered as promising platforms for the delivery of Cu ions. However, effective incorporation of Cu into MBGNs still faces challenges, e.g., particle aggregation, the formation of insoluble crystalline Cu-based nanoparticles, and a low loading amount of Cu. We report a novel method to synthesize chemically homogenous and highly dispersed Cu-containing MBGNs (Cu-MBGNs) with tunable Cu concentration by using ascorbic acid/Cu complexes as the precursor of Cu in a microemulsion-assisted sol-gel approach. Cu-MBGNs exhibited a sphere-like shape with a particle size between 100 and 300 nm while their pore size varied from 2 to 10 nm. The inclusion of Cu, regardless of the incorporated concentration, did not significantly affect the morphology of particles. ICP-AES results indicated that the concentration of Cu in the particles could be conveniently tuned from 0 to ~6 mol% by controlling the amount of ascorbic acid/Cu complexes added, while the formation of crystalline Cu-based nanoparticles was avoided. The amorphous feature of Cu-MBGNs was proved by XRD, while the predominant oxidation state of Cu was evidenced to be Cu2+ by XPS. The incorporation of Cu did not inhibit the apatite-forming ability (bioactivity) of the particles in contact with simulated body fluid. Cu-MBGNs exhibited the capability of releasing Cu, Si, and Ca ions over time in the physiological fluid. The concentration of released Cu ions could be controlled by selecting specific Cu-MBGNs of different Cu contents. The dissolution products of most Cu-MBGNs at the dosage of 1, 0.1, and 0.01 mg/mL did not exhibit cytotoxicity, while only 7Cu-MBGN was cytotoxic at the dosage of 1 mg/mL. This study provided a feasible strategy to synthesize highly dispersed amorphous Cu-MBGNs with high Cu concentrations for biomedical applications. The particles exhibit great potential as building blocks for developing composite 3D scaffolds, coatings, and drug carriers, particularly when a large amount of particles incorporated may compromise the properties of (polymer) matrix materials while a relatively high concentration of released Cu ions is still required.

Beneficial Effects of Vitamins K and D3 on Redox Balance of Human Osteoblasts Cultured with Hydroxyapatite-Based Biomaterials

Hydroxyapatite-based biomaterials are commonly used in surgery to repair bone damage. However, the introduction of biomaterials into the body can cause metabolic alterations, including redox imbalance. Because vitamins D3 and K (K1, MK-4, MK-7) have pronounced osteoinductive, anti-inflammatory, and antioxidant properties, it is suggested that they may reduce the adverse effects of biomaterials. The aim of this study was to investigate the effects of vitamins D3 and K, used alone and in combination, on the redox metabolism of human osteoblasts (hFOB 1.19 cell line) cultured in the presence of hydroxyapatite-based biomaterials (Maxgraft, Cerabone, Apatos, and Gen-Os). Culturing of the osteoblasts in the presence of hydroxyapatite-based biomaterials resulted in oxidative stress manifested by increased production of reactive oxygen species and decrease of glutathione level and glutathione peroxidase activity. Such redox imbalance leads to lipid peroxidation manifested by an increase of 4-hydroxynonenal level, which is known to influence the growth of bone cells. Vitamins D3 and K were shown to help maintain redox balance and prevent lipid peroxidation in osteoblasts cultured with hydroxyapatite-based biomaterials. The strongest effect was observed for the combination of vitamin D3 and MK-7. Moreover, vitamins promoted growth of the osteoblasts, manifested by increased DNA biosynthesis. Therefore, it is suggested that the use of vitamins D3 and K may protect redox balance and support the growth of osteoblasts affected by hydroxyapatite-based biomaterials.

Cu-Releasing Bioactive Glass Coatings and Their in Vitro Properties

Bioactive glasses are well-known materials suitable for bone-related applications thanks to their biocompatibility and osteoconductivity. In order to improve their in vivo performance, the modification of the glass composition by adding ions with specific biological functions is required. As copper (Cu) possesses antibacterial properties, in this study, 5 wt % of CuO has been added to the 45S5 bioactive glass composition. The investigation of the effect of the Cu-containing bioactive glass on cellular behavior has revealed that the presence of Cu induces an early differentiation of human mesenchymal stem cells through osteoblast phenotype, promotes the expression of anti-inflammatory interleukin, and reduces proinflammatory interleukin expression. With the aim to produce coatings with antibacterial properties, the Cu-containing bioactive glass was used as the target material for the pulsed laser deposition (PLD) of bioactive thin films. PLD experiments were carried out at different substrate temperatures to study the effect on the film's characteristics. All of the films are compact, crack-free, and characterized by a rough morphology and good wettability. The in vitro bioactivity was demonstrated by the apatite growth on the coating surface, after soaking in simulated body fluid, revealed by Raman spectroscopy and scanning electron microscopy-energy dispersive X-ray analyses. The antibacterial study proved that the material showed more effective activity against three Gram-negative bacteria ( Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica) rather than against Gram-positive bacteria ( Staphylococcus aureus).

Cell-Type-Specific Modulation of Hydrogen Peroxide Cytotoxicity and 4-Hydroxynonenal Binding to Human Cellular Proteins In Vitro by Antioxidant Aloe vera Extract

Although Aloe vera contains numerous bioactive components, the activity principles of widely used A. vera extracts are uncertain. Therefore, we analyzed the effects of genuine A. vera aqueous extract (AV) on human cells with respect to the effects of hydrogen peroxide (H₂O₂) and 4-hydroxynonenal (HNE). Fully developed A. vera leaves were harvested and analyzed for vitamin C, carotenoids, total soluble phenolic content, and antioxidant capacity. Furthermore, human cervical cancer (HeLa), human microvascular endothelial cells (HMEC), human keratinocytes (HaCat), and human osteosarcoma (HOS) cell cultures were treated with AV extract for one hour after treatment with H₂O₂ or HNE. The cell number and viability were determined using Trypan Blue, and endogenous reactive oxygen species (ROS) production was determined by fluorescence, while intracellular HNE–protein adducts were measured for the first time ever by genuine cell-based HNE–His ELISA. The AV extract expressed strong antioxidant capacities (1.1 mmol of Trolox eq/g fresh weight) and cell-type-specific influence on the cytotoxicity of H₂O₂, as well as on endogenous production of ROS and HNE–protein adducts induced by HNE treatment, while AV itself did not induce production of ROS or HNE–protein adducts at all. This study, for the first time, revealed the importance of HNE for the activity principles of AV. Since HMEC cells were the most sensitive to AV, the effects of AV on microvascular endothelia could be of particular importance for the activity principles of Aloe vera extracts.

Antioxidative 1,4-Dihydropyridine Derivatives Modulate Oxidative Stress and Growth of Human Osteoblast-Like Cells In Vitro

Oxidative stress has been implicated in pathophysiology of different human stress- and age-associated disorders, including osteoporosis for which antioxidants could be considered as therapeutic remedies as was suggested recently. The 1,4-dihydropyridine (DHP) derivatives are known for their pleiotropic activity, with some also acting as antioxidants. To find compounds with potential antioxidative activity, a group of 27 structurally diverse DHPs, as well as one pyridine compound, were studied. A group of 11 DHPs with 10-fold higher antioxidative potential than of uric acid, were further tested in cell model of human osteoblast-like cells. Short-term combined effects of DHPs and 50 µM H₂O₂ (1-h each), revealed better antioxidative potential of DHPs if administered before a stressor. Indirect 24-h effect of DHPs was evaluated in cells further exposed to mild oxidative stress conditions induced either by H₂O₂ or tert-butyl hydroperoxide (both 50 µM). Cell growth (viability and proliferation), generation of ROS and intracellular glutathione concentration were evaluated. The promotion of cell growth was highly dependent on the concentrations of DHPs used, type of stressor applied and treatment set-up. Thiocarbatone III-1, E2-134-1 III-4, Carbatone II-1, AV-153 IV-1, and Diethone I could be considered as therapeutic agents for osteoporosis although further research is needed to elucidate their bioactivity mechanisms, in particular in respect to signaling pathways involving 4-hydroxynoneal and related second messengers of free radicals.

Production and Physicochemical Characterization of Cu-Doped Silicate Bioceramic Scaffolds

Development of ion-releasing implantable biomaterials is a valuable approach for advanced medical therapies. In the effort of tackling this challenge, we explored the feasibility of porous bioceramic scaffolds releasing copper ions, which are potentially able to elicit angiogenetic and antibacterial effects. First, small amounts of CuO were incorporated in the base silicate glass during melting and the obtained powders were further processed to fabricate glass–ceramic scaffolds by sponge replica method followed by sinter crystallization. As the release of copper ions from these foams in simulated body fluid (SBF) was very limited, a second processing strategy was developed. Silicate glass–ceramic scaffolds were coated with a layer of Cu-doped mesoporous glass, which exhibited favorable textural properties (ultrahigh specific surface area >200 m²/g, mesopore size about 5 nm) for modulating the release of copper. All the produced scaffolds, containing biocompatible crystals of wollastonite (CaSiO₃), revealed high stability in a biological environment. Furthermore, the materials had adequate compressive strength (>10 MPa) for allowing safe manipulation during surgery. Overall, the results achieved in the present work suggest that these Cu-doped glass-derived scaffolds show promise for biomedical application and motivate further investigation of their suitability from a biological viewpoint.

Contribution of the HNE-immunohistochemistry to modern pathological concepts of major human diseases

Excessive production of reactive oxygen species can induce peroxidation of the polyunsaturated fatty acids thus generating reactive aldehydes like 4-hydroxy-2-nonenal (HNE), denoted as "the second messenger of free radicals". Because HNE has high binding affinity for cysteine, histidine and lysine it forms relatively stable and hardly metabolized protein adducts. By changing structure and function of diverse structural and regulatory proteins, HNE achieves not only cytotoxic, but also regulatory functions in various pathophysiological processes. Numerous animal model studies and clinical trials confirmed HNE as one of the crucial factors in development and progression of many disorders, in particular of cancer, (neuro)degenerative, metabolic and inflammatory diseases. Since HNE has multiple biological effects and is in the living system usually bound to proteins and peptides, many research groups work on development of specific immunochemical methods targeting the HNE-histidine adducts as major bioactive marker of lipid peroxidation, following the research pathway initiated by Hermann Esterbauer, who discovered HNE in 60's. Such immunohistochemical studies did not only prove the high biomedical importance of HNE, but have also given new insights into major diseases of the modern man. Immunohistochemical studies have shown reversibility of formation of the HNE-protein adducts, as well as differential onset of the HNE-mediated lipid peroxidation between age- associated atherosclerosis and photoaging, revealing eventually selective anti-cancer effects of HNE produced by non-malignant cells in vicinity of cancer. This review summarizes some of the HNE-histidine immunohistochemistry findings we believe are of broad biomedical interest and could inspire new studies in the field.

PDLLA scaffolds with Cu- and Zn-doped bioactive glasses having multifunctional properties for bone regeneration

Novel multifunctional scaffolds for bone regeneration can be developed by incorporation of bioactive glasses (BG) doped with therapeutic and antibacterial metal ions, such as copper (Cu) and zinc (Zn), into a biodegradable polymer. In this context, porous composite materials of biodegradable poly(d, l-lactide) (PDLLA) mixed with sol-gel BG of chemical composition 60SiO₂ ; 25CaO; 11Na₂ O; and 4P₂ O₅ (mol %) doped with either 1 mol % of CuO or ZnO, and with both metals, were prepared. The cytocompatibility of the scaffolds on bone marrow stromal cells (ST-2) depended on both, the amount of glass filler and the concentration of metal ion, as evaluated by lactate dehydrogenase (LDH) activity, cell viability (water-soluble tetrazolium salt [WST-8]), and by cell morphology (scanning electron microscopy [SEM]) tests. In particular, scaffolds having a filler content of 10 wt % showed the highest cytocompatibility. In addition, compared to the neat polymer, the scaffolds containing Cu promoted the angiogenesis marker (Vascular endothelial growth factor concentration) to a larger extent while scaffolds containing Zn increased the osteogenesis marker (specific alkaline phosphatase-activity). Noteworthy, the scaffolds with both metal ions showed a combined effect on both properties. Cu- and Zn-doped glasses also provided higher antibacterial capacity to PDLLA-based scaffolds against methicillin-resistant S. aureus bacteria than undoped glass. In combination, our results showed that by a proper addition of Cu- and Zn-doped BG to a PDLLA matrix, multifunctional composite scaffolds with enhanced biological activity can be designed for bone tissue regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 746-756, 2017.

Sol-gel synthesis and in vitro bioactivity of copper and zinc-doped silicate bioactive glasses and glass-ceramics

Metal doping of bioactive glasses based on ternary 60SiO2-36CaO-4P2O5 (58S) and quaternary 60SiO2-25CaO-11Na2O-4P2O5 (NaBG) mol% compositions synthesized using a sol-gel process was analyzed. In particular, the effect of incorporating 1, 5 and 10 mol% of CuO and ZnO (replacing equivalent quantities of CaO) on the texture, in vitro bioactivity, and cytocompatibility of these materials was evaluated. Our results showed that the addition of metal ions can modulate the textural property of the matrix and its crystal structure. Regarding the bioactivity, after soaking in simulated body fluid (SBF) undoped 58S and NaBG glasses developed an apatite surface layer that was reduced in the doped glasses depending on the type of metal and its concentration with Zn displaying the largest inhibitions. Both the ion release from samples and the ion adsorption from the medium depended on the type of matrix with 58S glasses showing the highest values. Pure NaBG glass was more cytocompatible to osteoblast-like cells (SaOS-2) than pure 58S glass as tested by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. The incorporation of metal ions decreased the cytocompatibility of the glasses depending on their concentration and on the glass matrix doped. Our results show that by changing the glass composition and by adding Cu or Zn, bioactive materials with different textures, bioactivity and cytocompatibility can be synthesized.

Overview on major lipid peroxidation bioactive factor 4-hydroxynonenal as pluripotent growth-regulating factor

The reactive aldehyde 4-hydroxynonenal (HNE) is major bioactive marker of lipid peroxidation generated under oxidative stress from polyunsaturated fatty acids. Biomedical significance of HNE was first revealed in pathogenesis of various degenerative and malignant diseases. Thus, HNE was considered for decades only as cytotoxic molecule, "second toxic messenger of free radicals" responsible for numerous undesirable consequences of oxidative stress. However, the increase of knowledge on physiology of redox signaling revealed also desirable, physiological roles of HNE, especially in the field of cellular signaling pathways regulating proliferation, differentiation, and apoptosis. These pluripotent effects of HNE can be explained by its concentration-dependent interactions with the cytokine networks and complex cellular antioxidant systems also showing cell and tissue specificities. Therefore, this paper gives a comprehensive, yet short overview on HNE as pluripotent growth-regulating factor.