Influence of Cobalt Ions on Collagen Gel Formation and Their Interaction with Osteoblasts

Collagen-Electrohydrodynamic Hierarchical Lithography for Biomimetic Photonic Micro-Nanomaterials

Biologically engineered nanomaterials give rise to unique and intriguing properties, which are not available in nature. The full-realization of such has been hindered by the lack of robust and straightforward techniques to produce the required architectures. Here a new bottomup bionano-engineering route is developed to construct nanomaterials using a guided assembly of collagen building blocks, establishing a lithographic process for three-dimensional collagen-based hierarchical micronano-architectures. By introducing optimized hybrid electro-hydrodynamic micronano-lithography exploiting collagen molecules as biological building blocks to self-assemble into a complex variety of structures, quasi-ordered mimics of metamaterials-like are constructed. The tailor-designed engineered apparatus generates the underlying substrates with vertical orientation of collagen at controlled speeds. Templating these hierarchical structures into inorganic materials allows the replication of their network into periodic metal micronano-assemblies. These generate substrates with interesting optical properties, suggesting that size-and-orientation dependent nanofilaments with varying degree of lateral order yield distinctly coloured structures with characteristic optical spectra correlated with observed colours, which varying diameters and interspacing, are attributable to coherent scattering by different periodicity of each fibrous micronano-structure. The artificial mimics display similar optical characteristics to the natural butterfly wing's structure, known to exhibit extraordinary electromagnetic properties, driving future applications in cloaking, super-lenses, photovoltaics and photodetectors.

Osteogenic-angiogenic coupled response of cobalt-containing mesoporous bioactive glasses in vivo

The incorporation of cobalt ions into the composition of bioactive glasses has emerged as a strategy of interest for bone regeneration purposes. In the present work, we have designed a set of bioactive mesoporous glasses SiO2-CaO-P2O5-CoO (Co-MBGs) with different amounts of cobalt. The physicochemical changes introduced by the Co2+ ion, the in vitro effects of Co-MBGs on preosteoblasts and endothelial cells and their in vivo behaviour using them as bone grafts in a sheep model were studied. The results show that Co2+ ions neither destroy mesoporous ordering nor inhibit in vitro bioactive behaviour, exerting a dual role as network former and modifier for CoO concentrations above 3 % mol. On the other hand, the activity of Co-MBGs on MC3T3-E1 preosteoblasts and HUVEC vascular endothelial cells is dependent on the concentration of CoO present in the glass. For low Co-MBGs concentrations (1mg/ml) cell viability is not affected, while the expression of osteogenic (ALP, RUNX2 and OC) and angiogenic (VEGF) genes is stimulated. For Co-MBGs concentration of 5 mg/ml, cell viability decreases as a function of the CoO content. In vivo studies show that the incorporation of Co2+ ions to the MBGs improves the bone regeneration activity of these materials, despite the deleterious effect that this ion has on bone-forming cells for any of the Co-MBG compositions studied. This contradictory effect is explained by the marked increase in angiogenesis that takes place inside the bone defect, leading to an angiogenesis-osteogenesis coupling that compensates for the partial decrease in osteoblast cells. STATEMENT OF SIGNIFICANCE: The development of new bone grafts implies to address the need for osteogenesis-angiogenesis coupling that allows bone regeneration with viable tissue in the long term. In this sense the incorporation of cobalt ions into the composition of bioactive glasses has emerged as a strategy of great interest in this field. Due to the potential cytotoxic effect of cobalt ions, there is an important controversy regarding the suitability of their incorporation in bone grafts. In this work, we address this controversy after the implantation of cobalt-doped mesoporous bioactive glasses in a sheep model. The incorporation of cobalt ions in bioactive glasses improves the bone regeneration ability of these bone grafts, due to enhancement of the angiogenesis-osteogenesis coupling.

The Role of Trace Elements and Minerals in Osteoporosis: A Review of Epidemiological and Laboratory Findings

The objective of the present study was to review recent epidemiological and clinical data on the association between selected minerals and trace elements and osteoporosis, as well as to discuss the molecular mechanisms underlying these associations. We have performed a search in the PubMed-Medline and Google Scholar databases using the MeSH terms "osteoporosis", "osteogenesis", "osteoblast", "osteoclast", and "osteocyte" in association with the names of particular trace elements and minerals through 21 March 2023. The data demonstrate that physiological and nutritional levels of trace elements and minerals promote osteogenic differentiation through the up-regulation of BMP-2 and Wnt/β-catenin signaling, as well as other pathways. miRNA and epigenetic effects were also involved in the regulation of the osteogenic effects of trace minerals. The antiresorptive effect of trace elements and minerals was associated with the inhibition of osteoclastogenesis. At the same time, the effect of trace elements and minerals on bone health appeared to be dose-dependent with low doses promoting an osteogenic effect, whereas high doses exerted opposite effects which promoted bone resorption and impaired bone formation. Concomitant with the results of the laboratory studies, several clinical trials and epidemiological studies demonstrated that supplementation with Zn, Mg, F, and Sr may improve bone quality, thus inducing antiosteoporotic effects.

A Metal‐Ion‐Incorporated Mussel‐Inspired Poly(Vinyl Alcohol)‐Based Polymer Coating Offers Improved Antibacterial Activity and Cellular Mechanoresponse Manipulation

Cobalt (Co^II) ions have been an attractive candidate for the biomedical modification of orthopedic implants for decades. However, limited research has been performed into how immobilized Co^II ions affect the physical properties of implant devices and how these changes regulate cellular behavior. In this study we modified biocompatible poly(vinyl alcohol) with terpyridine and catechol groups (PVA‐TP‐CA) to create a stable surface coating in which bioactive metal ions could be anchored, endowing the coating with improved broad‐spectrum antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as enhanced surface stiffness and cellular mechanoresponse manipulation. Strengthened by the addition of these metal ions, the coating elicited enhanced mechanosensing from adjacent cells, facilitating cell adhesion, spreading, proliferation, and osteogenic differentiation on the surface coating. This dual‐functional PVA‐TP‐CA/Co surface coating offers a promising approach for improving clinical implantation outcomes.

Evidence for Quantum Chemical Effects in Receptor-Ligand Binding Between Integrin and Collagen Fragments - A Computational Investigation With an Impact on Tissue Repair, Neurooncolgy and Glycobiology

The collagen-integrin interactions are mediated by the doubly charged Mg2+ cation. In nature this cation seems to have the optimal binding strength to stabilize this complex. It is essential that the binding is not too weak so that the complex becomes unstable, however, it is also of importance that the ligand-receptor binding is still labile enough so that the ligand can separate from the receptor in a suited environment. In the case of crystal growing for experimentally useful integrin-collagen fragment complexes it turned out that Co2+ cations are ideal mediators to form stable complexes for such experiments. Although, one can argue that Co2+ is in this context an artificial cation, however, it is now of special interest to test the impact of this cation in cell-culture experiments focusing on integrin-ligand interactions. In order to examine, in particular, the role cobalt ions we have studied a Co2+ based model system using quantum chemical calculations. Thereby, we have shown that hybrid and long-range corrected functional, which are approximations provide already a sufficient level of accuracy. It is of interest to study a potential impact of cations on the binding of collagen-fragments including collagens from various species because different integrins have numerous biological functions (e.g. Integrin - NCAM (Neural cell adhesion molecule) interactions) and are triggered by intact and degraded collagen fragments. Since integrin-carbohydrate interactions play a key role when bio-medical problems such as tumor cell adhesion and virus-host cell infections have to be addressed on a sub-molecular level it is essential to understand the interactions with heavy-metal ions also at the sub-atomic level. Our findings open new routes, especially, in the fields of tissue repair and neuro-oncology for example for cell-culture experiments with different ions. Since Co2+ ions seem to bind stronger to integrin than Mg2+ ions it should be feasible to exchange these cations in suited tumor tissues although different cations are present in other metalloproteins which are active in such tissues. Various staining methods can be applied to document the interactions of integrins with carbohydrate chains and other target structures. Thereby, it is possible to study a potential impact of these interactions on biological functions. It was therefore necessary to figure out first which histological-glycobiological experimental settings of tumor cells are suited for our purpose. Since the interactions of several metalloproteins (integrin, ADAM12) with polysialic acid and the HNK-1 epitope play a crucial role in tumor tissues selected staining methods are proper tools to obtain essential information about the impact of the metal ions under study.

Alterations in Blood Metabolic Parameters of Immature Mice After Subchronic Exposure to Cobalt Chloride

The wide use of cobalt (Co) in food, industry, and medical devices requires full elucidation of its biological effects on tissues and organs. The aim was to assess serum metabolic alterations in immature mice after subchronic exposure to CoCl₂. Pregnant ICR mice were subjected to a daily dose of 75 mg cobalt chloride/kg body weight (CoCl₂x6H₂O) 2-3 days before they gave birth, and treatment continued until days 25 and 30 after delivery. The compound was dissolved in and obtained with regular tap water. ICP-DRC-MS analysis showed significantly elevated serum Co²⁺ and diverse alterations in metabolic parameters of 25- and 30-day-old pups after exposure to CoCl₂. Cholesterol and urea levels were significantly elevated in day 25 mice while HDL-C and LDL-C were reduced. In day 30, Co-exposed mice LDL-C and triglycerides were significantly increased while the total cholesterol level remained unchanged. Alkaline phosphatase was significantly reduced in day 25 Co-exposed mice. Blood glucose level of Co-exposed mice remained close to the untreated controls. Total protein content was slightly increased in day 30 mice. Co-exposure reduced albumin content and albumin/globulin ratio but increased significantly globulin content. Co administration showed strong correlation with cholesterol, urea, and HDL-C in both day 25 and 30 mice. Inverse correlation was found with alkaline phosphatase and albumin for day 25 and with triglycerides, globulin, and total protein content in day 30 Co-exposed mice. Subchronic CoCl₂ exposure of immature mice induced significant changes in key metabolic parameters suggesting possible further disturbances in energy metabolism, osteogenesis, and reproduction.

Hydrogel-Assisted Electrospinning for Fabrication of a 3D Complex Tailored Nanofiber Macrostructure

Electrospinning has shown great potential in tissue engineering and regenerative medicine due to a high surface-area-to-volume ratio and an extracellular matrix-mimicking structure of electrospun nanofibers, but the fabrication of a complex three-dimensional (3D) macroscopic configuration with electrospun nanofibers remains challenging. In the present study, we developed a novel hydrogel-assisted electrospinning process (GelES) to fabricate a 3D nanofiber macrostructure with a 3D complex but tailored configuration by utilizing a 3D hydrogel structure as a grounded collector instead of a metal collector in conventional electrospinning. The 3D hydrogel collector was discovered to effectively concentrate the electric field toward itself similar to the metal collector, thereby depositing electrospun nanofibers directly on its exterior surface. Synergistic advantages of the hydrogel (e.g., biocompatibility and thermally reversible sol-gel transition) and the 3D nanofiber macrostructure (e.g., mechanical robustness and high permeability) provided by the GelES process were demonstrated in a highly permeable tubular tissue graft and a robust drug- or cell-encapsulation construct. GelES is expected to broaden potential applications of electrospinning to not only provide in vivo drug/cell delivery and tissue regeneration but also an in vitro drug testing platform by increasing the degree of freedom in the configuration of the 3D nanofiber macrostructure.

Metal-Specific Biomaterial Accumulation in Human Peri-Implant Bone and Bone Marrow

Metallic implants are frequently used in medicine to support and replace degenerated tissues. Implant loosening due to particle exposure remains a major cause for revision arthroplasty. The exact role of metal debris in sterile peri-implant inflammation is controversial, as it remains unclear whether and how metals chemically alter and potentially accumulate behind an insulating peri-implant membrane, in the adjacent bone and bone marrow (BM). An intensively focused and bright synchrotron X-ray beam allows for spatially resolving the multi-elemental composition of peri-implant tissues from patients undergoing revision surgery. In peri-implant BM, particulate cobalt (Co) is exclusively co-localized with chromium (Cr), non-particulate Cr accumulates in the BM matrix. Particles consisting of Co and Cr contain less Co than bulk alloy, which indicates a pronounced dissolution capacity. Particulate titanium (Ti) is abundant in the BM and analyzed Ti nanoparticles predominantly consist of titanium dioxide in the anatase crystal phase. Co and Cr but not Ti integrate into peri-implant bone trabeculae. The characteristic of Cr to accumulate in the intertrabecular matrix and trabecular bone is reproducible in a human 3D in vitro model. This study illustrates the importance of updating the view on long-term consequences of biomaterial usage and reveals toxicokinetics within highly sensitive organs.

Characterization and Potential of a Bilayered Hydrogel of Gellan Gum and Demineralized Bone Particles for Osteochondral Tissue Engineering

Osteochondral (OC) tissue engineering (TE) is a promising strategy to regenerate acute or degenerative chondral and OC lesions. However, advancing a proper model for OC TE is still under way. Herein, a bilayer hydrogel (BH) based on gellan gum (GG) hydrogel and demineralized bone particles (DBPs) is suggested as a new model. The BH composite can be fabricated easily with a cell-friendly biomaterial and cross-linker. The BH composite was characterized by a morphological method and physicochemical aspect. The mechanical and rheological characters were further confirmed to verify its applicability in OC TE. The thermodynamic property of the composite was determined to analyze thermal stability and interaction among matrices. The bioactivity of the material was studied by treating simulated body fluid (SBF) solution for 28 days to examine the formation of crystalline structure in the BH construct. In vitro studies were carried out to study the viability and biochemical characters of the developed biomaterial. An in vivo study was performed to analyze the biocompatibility of the material and regeneration of the injured OC region implanted with BH composites. The data displayed stable physicochemical properties and mechanical characters when the DBPs were incorporated with a proper amount. The bioactivity of the DBP-loaded hydrogels displayed a high amount of apatite formation. The cytotoxicity of the fabricated material was low, which allows application in vitro and in vivo. The biochemical studies displayed a high level of alkaline phosphatase (ALP) activity and gene expression, which shows promising application of DBP-loaded GG in the bone layer of the BH model. The long-term in vivo study displayed excellent biocompatibility and great potential in the OC defected region. Overall, these results suggest the significance of combined and innovative approaches to improve the therapeutic strategies for OC regeneration, and the BH model suggested in this study can be a promising biomaterial model for OC TE.

Biological responses to physicochemical properties of biomaterial surface

Biomedical scientists use chemistry-driven processes found in nature as an inspiration to design biomaterials as promising diagnostic tools, therapeutic solutions, or tissue substitutes. While substantial consideration is devoted to the design and validation of biomaterials, the nature of their interactions with the surrounding biological microenvironment is commonly neglected. This gap of knowledge could be owing to our poor understanding of biochemical signaling pathways, lack of reliable techniques for designing biomaterials with optimal physicochemical properties, and/or poor stability of biomaterial properties after implantation. The success of host responses to biomaterials, known as biocompatibility, depends on chemical principles as the root of both cell signaling pathways in the body and how the biomaterial surface is designed. Most of the current review papers have discussed chemical engineering and biological principles of designing biomaterials as separate topics, which has resulted in neglecting the main role of chemistry in this field. In this review, we discuss biocompatibility in the context of chemistry, what it is and how to assess it, while describing contributions from both biochemical cues and biomaterials as well as the means of harmonizing them. We address both biochemical signal-transduction pathways and engineering principles of designing a biomaterial with an emphasis on its surface physicochemistry. As we aim to show the role of chemistry in the crosstalk between the surface physicochemical properties and body responses, we concisely highlight the main biochemical signal-transduction pathways involved in the biocompatibility complex. Finally, we discuss the progress and challenges associated with the current strategies used for improving the chemical and physical interactions between cells and biomaterial surface.