Assessing the potential role of copper and cobalt in stimulating angiogenesis for tissue regeneration

High VEGF Secretion Using Co and B Co-doped Bioactive Mesoporous Glass Nanoparticles for Enhanced Angiogenesis

This investigation presents a novel approach to engineering mesoporous bioactive glass nanoparticles (MBGNs) through selective ion doping. This method can significantly potentiate their physicochemical properties and biological performance. We elucidate the effects of boron (B) and cobalt (Co) doping, individually and in combination, on MBGNs' structural, functional, and biocompatible characteristics. Using microemulsion-assisted sol-gel synthesis, we fabricated MBGNs with sizes ranging from 150 to 250 nm and shapes that shifted from spherical to more irregular shapes upon co-doping, as observed by SEM and TEM. We assessed the materials' amorphous nature and molecular structure through XRD and FTIR, respectively, noting the preservation of bioactivity-associated Si-O-Si groups. This can influence the nucleation and growth of the mineral phases similar to those found in natural tissues, forming a bioactive coating on the material surface. Nitrogen adsorption-desorption isotherms confirmed a mesoporous structure with increased specific surface area upon co-doping. The release behavior of Ca and Si in simulated body fluids studied by ICP-OES indicated alterations after adding Co and B, modifying their release kinetics. Bone regeneration relies on osteogenesis and vascular network formation for nutrient and oxygen supply. This study highlights the synergistic effect of B and Co co-doping, enhancing both angiogenesis and osteogenesis beyond single-ion doping. Biocompatibility studies with MG-63 and HDFa cell lines indicated that B enhanced cell viability, while the viability effect of Co was concentration-dependent. Cytotoxicity was assessed through lactate dehydrogenase (LDH) assays and is shown in high concentrations in the case of reference and B-doped sample, which was significantly reduced in the case of co-doped material. The newly developed nanoparticles showed a 10-fold increase in vascular endothelial growth factor (VEGF) secretion compared to the control sample (p < 0.05, one-way ANOVA), as determined by enzyme-linked immunosorbent assay (ELISA) in treated cells. Based on present results, the co-doped system shows a strong potential impact on angiogenesis with no effect on cell cytotoxicity.

Quaternized chitosan-based photothermal antibacterial hydrogel with pro-vascularization and on-demand degradation properties for enhanced infected wound healing

Compromised skin barrier fails to prevent pathogenic bacterial invasion, leading to wound infection and potentially severe tissue damage, for which conventional wound dressings provide inadequate therapeutic outcomes. Herein, we have developed a multifunctional injectable hydrogel (QCS-APA/P@D@C) based on quaternized chitosan (QCS) and aldehyde-modified aliphatic polycarbonate (APA), incorporating Prussian Blue (PB) @Polydopamine (PDA) @Cu (P@D@C) submicron particles (SPs). This novel hydrogel exhibits photothermal antibacterial properties, on-demand removal capability, and Cu2+-facilitated wound healing enhancement. The QCS-APA/P@D@C hydrogel, crosslinked via dynamic Schiff-base bonds, exhibits remarkable antibacterial efficacy (>99 %) against various bacteria, including multidrug-resistant (MDR) bacteria, through the synergistic effects of QCS, Cu2+, and 808 nm near-infrared (NIR) photothermal effect. The hydrogel demonstrates rapid degradation (~12 min) upon exposure to N-acetylcysteine (NAC), facilitating on-demand removal and minimizing secondary trauma during dressing changes. Furthermore, the sustained release of Cu2+ within 1-10 μM significantly enhances the migration and tube formation of human umbilical vein endothelial cells (HUVECs). In a Staphylococcus aureus (S. aureus)-infected wound model of Sprague-Dawley (SD) rats, the QCS-APA/P@D@C hydrogel demonstrated effectively modulating wound inflammation, promoting collagen deposition and angiogenesis, and accelerating wound closure. These findings demonstrate that the QCS-APA/P@D@C hydrogel can effectively promote the healing of bacterially infected wounds.

Strategies for promoting neurovascularization in bone regeneration

Bone tissue relies on the intricate interplay between blood vessels and nerve fibers, both are essential for many physiological and pathological processes of the skeletal system. Blood vessels provide the necessary oxygen and nutrients to nerve and bone tissues, and remove metabolic waste. Concomitantly, nerve fibers precede blood vessels during growth, promote vascularization, and influence bone cells by secreting neurotransmitters to stimulate osteogenesis. Despite the critical roles of both components, current biomaterials generally focus on enhancing intraosseous blood vessel repair, while often neglecting the contribution of nerves. Understanding the distribution and main functions of blood vessels and nerve fibers in bone is crucial for developing effective biomaterials for bone tissue engineering. This review first explores the anatomy of intraosseous blood vessels and nerve fibers, highlighting their vital roles in bone embryonic development, metabolism, and repair. It covers innovative bone regeneration strategies directed at accelerating the intrabony neurovascular system over the past 10 years. The issues covered included material properties (stiffness, surface topography, pore structures, conductivity, and piezoelectricity) and acellular biological factors [neurotrophins, peptides, ribonucleic acids (RNAs), inorganic ions, and exosomes]. Major challenges encountered by neurovascularized materials during their clinical translation have also been highlighted. Furthermore, the review discusses future research directions and potential developments aimed at producing bone repair materials that more accurately mimic the natural healing processes of bone tissue. This review will serve as a valuable reference for researchers and clinicians in developing novel neurovascularized biomaterials and accelerating their translation into clinical practice. By bridging the gap between experimental research and practical application, these advancements have the potential to transform the treatment of bone defects and significantly improve the quality of life for patients with bone-related conditions.

MT2A promotes angiogenesis in chronically ischemic brains through a copper-mitochondria regulatory mechanism

BACKGROUND

Approximately half of patients with chronic ischemic cerebrovascular disease (CICD) exhibit poor revascularization. Metallothionein 2 A (MT2A) has a high affinity for metal ions and is potentially capable of chelating toxic copper ions to alleviate the impairment of angiogenesis. Therefore, we hypothesized that MT2A could promote angiogenesis in chronically ischemic brains by neutralizing excessive copper ions during copper overload (CPO).

METHODS

We first collected dura matter (DM) samples from CICD patients and examined the expression of cuproptosis-related genes (DLAT, FDX1, and SDHB) to confirm the inhibitory effect of CPO on angiogenesis. Then, we treated human umbilical vein endothelial cells (HUVECs) with different concentrations of elesclomol and CuCl2 to determine the optimal concentration for inducing CPO. HUVEC activity and mitochondrial structure and function were detected to explore the ability of MT2A to alleviate CPO-induced damage. Finally, a rat model of 2-vessel occlusion plus encephalo-myo-synangiosis (2VO + EMS) with CPO was established to test the proangiogenic effect of MT2A through the copper-mitochondria regulatory mechanism in chronically ischemic brains.

RESULTS

Compared with those from Matsushima grade A patients, DM samples from Matsushima grade C patients presented significantly greater DLAT and FDX1 expression and significantly lower SDHB expression. The optimal drug concentration for inducing CPO was subsequently determined, and in vitro experiments revealed that HUVEC activity was significantly decreased in the CPO group under hypoxic culture, accompanied by increased DLAT oligomerization, decreased SDHB expression, increased HSP70 expression. Moreover, significantly more common mitochondrial aberrations and significantly lower mitochondrial activity were detected in the CPO group compare with the control group. Additionally, MT2A overexpression alleviated CPO-induced mitochondrial dysfunction and cytotoxicity, improving HUVEC viability. In vivo, a CPO rat model was established, and CPO inhibited cerebral angiogenesis in 2VO + EMS model rats. Moreover, significantly greater CD31 expression, less DLAT accumulation, more mitochondria, and fewer mitochondrial abnormalities were observed in the CPOMT2A+ group than in the CPO group, accompanied by significantly improved cerebral blood perfusion and cognitive function.

CONCLUSION

MT2A can promote angiogenesis in chronically ischemic brains by neutralizing excessive copper ions and rescuing CPO-induced mitochondrial dysfunction.

Skin repair and infection control in diabetic, obese mice using bioactive laser-activated sealants

Conventional wound approximation devices, including sutures, staples, and glues, are widely used but risk of wound dehiscence, local infection, and scarring can be exacerbated in these approaches, including in diabetic and obese individuals. This study reports the efficacy and quality of tissue repair upon photothermal sealing of full-thickness incisional skin wounds using silk fibroin-based laser-activated sealants (LASEs) containing copper chloride salt (Cu-LASE) or silver nanoprisms (AgNPr-LASE), which absorb and convert near-infrared (NIR) laser energy to heat. LASE application results in rapid and effective skin sealing in healthy, immunodeficient, as well as diabetic and obese mice. Although lower recovery of epidermal structure and function was seen with AgNPr-LASE sealing, likely because of the hyperthermia induced by laser and presence of this material in the wound space, this approach resulted in higher enhancement in recovery of skin biomechanical strength compared to sutures and Cu-LASEs in diabetic, obese mice. Histological and immunohistochemical analyses revealed that AgNPr-LASEs resulted in significantly lower neutrophil migration to the wound compared to Cu-LASEs and sutures, indicating a more muted inflammatory response. Cu-LASEs resulted in local tissue toxicity likely because of effects of copper ions as manifested in the form of a significant epidermal gap and a 'depletion zone', which was a region devoid of viable cells proximal to the wound. Compared to sutures, LASE-mediated sealing, in later stages of healing, resulted in increased angiogenesis and diminished myofibroblast activation, which can be indicative of lower scarring. AgNPr-LASE loaded with vancomycin, an antibiotic drug, significantly lowered methicillin-resistant Staphylococcus aureus (MRSA) load in a pathogen challenge model in diabetic and obese mice and also reduced post-infection inflammation of tissue compared to antibacterial sutures. Taken together, these attributes indicate that AgNPr-LASE demonstrated a more balanced quality of tissue sealing and repair in diabetic and obese mice and can be used for combating local infections, that can result in poor healing in these individuals.

Impact of Metal Ions on Cellular Functions: A Focus on Mesenchymal Stem/Stromal Cell Differentiation

Metals play a crucial role in the human body, especially as ions in metalloproteins. Essential metals, such as calcium, iron, and zinc are crucial for various physiological functions, but their interactions within biological networks are complex and not fully understood. Mesenchymal stem/stromal cells (MSCs) are essential for tissue regeneration due to their ability to differentiate into various cell types. This review article addresses the effects of physiological and unphysiological, but not directly toxic, metal ion concentrations, particularly concerning MSCs. Overloading or unbalancing of metal ion concentrations can significantly impair the function and differentiation capacity of MSCs. In addition, excessive or unbalanced metal ion concentrations can lead to oxidative stress, which can affect viability or inflammation. Data on the effects of metal ions on MSC differentiation are limited and often contradictory. Future research should, therefore, aim to clarify the mechanisms by which metal ions affect MSC differentiation, focusing on aspects such as metal ion interactions, ion concentrations, exposure duration, and other environmental conditions. Understanding these interactions could ultimately improve the design of biomaterials and implants to promote MSC-mediated tissue regeneration. It could also lead to the development of innovative therapeutic strategies in regenerative medicine.

Copper metabolism and cuproptosis in human malignancies: Unraveling the complex interplay for therapeutic insights

Copper, a vital trace element, orchestrates diverse cellular processes ranging from energy production to antioxidant defense and angiogenesis. Copper metabolism and cuproptosis are closely linked in the context of human diseases, with a particular focus on cancer. Cuproptosis refers to a specific type of copper-mediated cell death or copper toxicity triggered by disruptions in copper metabolism within the cells. This phenomenon encompasses a spectrum of mechanisms, such as oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, and perturbations in metal ion equilibrium. Mechanistically, cuproptosis is driven by copper binding to the lipoylated enzymes within the tricarboxylic acid (TCA) cycle. This interaction participates in protein aggregation and proteotoxic stress, ultimately culminating in cell death. Targeting copper metabolism and its associated pathways in cancer cells hold therapeutic potential by selectively targeting and eliminating cancerous cells. Strategies to modulate copper levels, enhance copper excretion, or interfere with cuproptotic pathways are being explored to identify novel therapeutic targets for cancer therapy and improve patient outcomes. Understanding the relationship between cuproptosis and copper metabolism in human malignancies remains an active area of research. This review provides a comprehensive overview of the association among copper metabolism, copper homeostasis, and carcinogenesis, explicitly emphasizing the cuproptosis mechanism and its implications for cancer pathogenesis. Additionally, we emphasize the therapeutic aspects of targeting copper and cuproptosis for cancer treatment.

Advancements in incorporating metal ions onto the surface of biomedical titanium and its alloys via micro-arc oxidation: a research review

The incorporation of biologically active metallic elements into nano/micron-scale coatings through micro-arc oxidation (MAO) shows significant potential in enhancing the biological characteristics and functionality of titanium-based materials. By introducing diverse metal ions onto titanium implant surfaces, not only can their antibacterial, anti-inflammatory and corrosion resistance properties be heightened, but it also promotes vascular growth and facilitates the formation of new bone tissue. This review provides a thorough examination of recent advancements in this field, covering the characteristics of commonly used metal ions and their associated preparation parameters. It also highlights the diverse applications of specific metal ions in enhancing osteogenesis, angiogenesis, antibacterial efficacy, anti-inflammatory and corrosion resistance properties of titanium implants. Furthermore, the review discusses challenges faced and future prospects in this promising area of research. In conclusion, the synergistic approach of micro-arc oxidation and metal ion doping demonstrates substantial promise in advancing the effectiveness of biomedical titanium and its alloys, promising improved outcomes in medical implant applications.

Metal ions: the unfading stars of bone regeneration-from bone metabolism regulation to biomaterial applications

In recent years, bone regeneration has emerged as a remarkable field that offers promising guidance for treating bone-related diseases, such as bone defects, bone infections, and osteosarcoma. Among various bone regeneration approaches, the metal ion-based strategy has surfaced as a prospective candidate approach owing to the extensive regulatory role of metal ions in bone metabolism and the diversity of corresponding delivery strategies. Various metal ions can promote bone regeneration through three primary strategies: balancing the effects of osteoblasts and osteoclasts, regulating the immune microenvironment, and promoting bone angiogenesis. In the meantime, the complex molecular mechanisms behind these strategies are being consistently explored. Moreover, the accelerated development of biomaterials broadens the prospect of metal ions applied to bone regeneration. This review highlights the potential of metal ions for bone regeneration and their underlying mechanisms. We propose that future investigations focus on refining the clinical utilization of metal ions using both mechanistic inquiry and materials engineering to bolster the clinical effectiveness of metal ion-based approaches for bone regeneration.

Transition metals in angiogenesis - A narrative review

The aim of this paper is to offer a narrative review of the literature regarding the influence of transition metals on angiogenesis, excluding lanthanides and actinides. To our knowledge there are not any reviews up to date offering such a summary, which inclined us to write this paper. Angiogenesis describes the process of blood vessel formation, which is an essential requirement for human growth and development. When the complex interplay between pro- and antiangiogenic mediators falls out of balance, angiogenesis can quickly become harmful. As it is so fundamental, both its inhibition and enhancement take part in various diseases, making it a target for therapeutic treatments. Current methods come with limitations, therefore, novel agents are constantly being researched, with metal agents offering promising results. Various transition metals have already been investigated in-depth, with studies indicating both pro- and antiangiogenic properties, respectively. The transition metals are being applied in various formulations, such as nanoparticles, complexes, or scaffold materials. Albeit the increasing attention this field is receiving, there remain many unanswered questions, mostly regarding the molecular mechanisms behind the observed effects. Notably, approximately half of all the transition metals have not yet been investigated regarding potential angiogenic effects. Considering the promising results which have already been established, it should be of great interest to begin investigating the remaining elements whilst also further analyzing the established effects.

Novel Metal Nanomaterials to Promote Angiogenesis in Tissue Regeneration

Angiogenesis-the formation of new blood vessels from existing blood vessels-has drawn significant attention in medical research. New techniques have been developed to control proangiogenic factors to obtain desired effects. Two important research areas are 1) understanding cellular mechanisms and signaling pathways involved in angiogenesis and 2) discovering new biomaterials and nanomaterials with proangiogenic effects. This paper reviews recent developments in controlling angiogenesis in the context of regenerative medicine and wound healing. We focus on novel proangiogenic materials that will advance the field of regenerative medicine. Specifically, we mainly focus on metal nanomaterials. We also discuss novel technologies developed to carry these proangiogenic inorganic molecules efficiently to target sites. We offer a comprehensive overview by combining existing knowledge regarding metal nanomaterials with novel developments that are still being refined to identify new nanomaterials.

Cobalt-containing borate bioactive glass fibers for treatment of diabetic wound

Impaired angiogenesis is one of the predominant reasons for non-healing diabetic wounds. Cobalt is well known for its capacity to induce angiogenesis by stabilizing hypoxia-inducible factor-1α (HIF-1α) and subsequently inducing the production of vascular endothelial growth factor (VEGF). In this study, Co-containing borate bioactive glasses and their derived fibers were fabricated by partially replacing CaO in 1393B3 borate glass with CoO. Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) analyses were performed to characterize the effect of Co incorporation on the glass structure, and the results showed that the substitution promoted the transformation of [BO3] into [BO4] units, which endow the glass with higher chemical durability and lower reaction rate with the simulated body fluid (SBF), thereby achieving sustained and controlled Co2+ ion release. In vitro biological assays were performed to assess the angiogenic potential of the Co-containing borate glass fibers. It was found that the released Co2+ ion significantly enhanced the proliferation, migration and tube formation of the Human Umbilical Vein Endothelial Cells (HUVECs) by upregulating the expression of angiogenesis-related proteins such as HIF-1α and VEGF. Finally. In vivo results demonstrated that the Co-containing fibers accelerated full-thickness skin wound healing in streptozotocin (STZ)-induced diabetic rat model by promoting angiogenesis and re-epithelialization.

Angiogenic and immunomodulation role of ions for initial stages of bone tissue regeneration

It is widely known that bone has intrinsic capacity to self-regenerate after injury. However, the physiological regeneration process can be impaired when there is an extensive damage. One of the main reasons is due to the inability to establish a new vascular network that ensures oxygen and nutrient diffusion, leading to a necrotic core and non-junction of bone. Initially, bone tissue engineering (BTE) emerged to use inert biomaterials to just fill bone defects, but it eventually evolved to mimic bone extracellular matrix and even stimulate bone physiological regeneration process. In this regard, the stimulation of osteogenesis has gained a lot of attention especially in the proper stimulation of angiogenesis, being critical to achieve a successful osteogenesis for bone regeneration. Besides, the immunomodulation of a pro-inflammatory environment towards an anti-inflammatory one upon scaffold implantation has been considered another key process for a proper tissue restoration. To stimulate these phases, growth factors and cytokines have been extensively used. Nonetheless, they present some drawbacks such as low stability and safety concerns. Alternatively, the use of inorganic ions has attracted higher attention due to their higher stability and therapeutic effects with low side effects. This review will first focus in giving fundamental aspects of initial bone regeneration phases, focusing mainly on inflammatory and angiogenic ones. Then, it will describe the role of different inorganic ions in modulating the immune response upon biomaterial implantation towards a restorative environment and their ability to stimulate angiogenic response for a proper scaffold vascularization and successful bone tissue restoration. STATEMENT OF SIGNIFICANCE: The impairment of bone tissue regeneration when there is excessive damage has led to different tissue engineered strategies to promote bone healing. Significant importance has been given in the immunomodulation towards an anti-inflammatory environment together with proper angiogenesis stimulation in order to achieve successful bone regeneration rather than stimulating only the osteogenic differentiation. Ions have been considered potential candidates to stimulate these events due to their high stability and therapeutic effects with low side effects compared to growth factors. However, up to now, no review has been published assembling all this information together, describing individual effects of ions on immunomodulation and angiogenic stimulation, as well as their multifunctionality or synergistic effects when combined together.

Cobalt-Doped Mesoporous Silica Coated Magnetic Nanoparticles Promoting Accelerated Bone Healing in Distraction Osteogenesis

INTRODUCTION

Large bone abnormalities are commonly treated using distraction osteogenesis (DO), but it is not suitable for a long-term application; therefore, there is an urgent need for adjuvant therapy that can accelerate bone repair.

METHODS

We have synthesized mesoporous silica-coated magnetic nanoparticles doped with cobalt ions (Co-MMSNs) and assessed their capacity to quicken bone regrowth in a mouse model of DO. Furthermore, local injection of the Co-MMSNs significantly accelerated bone healing in DO, as demonstrated by X-ray imaging, micro-CT, mechanical tests, histological evaluation, and immunochemical analysis.

RESULTS

In vitro, the Co-MMSNs exhibited good biocompatibility and induced angiogenic gene expression and osteogenic development in bone mesenchymal stem cells. And the Co-MMSNs can promote bone regeneration in a rat DO model.

DISCUSSION

This study demonstrated the significant potential of Co-MMSNs to shorten the DO treatment duration and effectively reduce the incidence of complications.

Preparation and Properties of Bimetallic Chitosan Spherical Microgels

The aim of this work was to prepare bimetallic chitosan microgels with high sphericity and investigate the influences of metal-ion type and content on the size, morphology, swelling, degradation and biological properties of microgels. Amino and hydroxyl groups of chitosan (deacetylation degree, DD, of 83.2% and 96.9%) served as ligands in the Cu2+–Zn2+/chitosan complexes with various contents of cupric and zinc ions. The electrohydrodynamic atomization process was used to produce highly spherical microgels with a narrow size distribution and with surface morphology changing from wrinkled to smooth by increasing Cu2+ ions’ quantity in bimetallic systems for both used chitosans. The size of the bimetallic chitosan particles was estimated to be between 60 and 110 µm for both used chitosans, and FTIR spectroscopy indicated the formation of complexes through physical interactions between the chitosans’ functional groups and metal ions. The swelling capacity of bimetallic chitosan particles decreases as the DD and copper (II) ion content increase as a result of stronger complexation with respect to zinc (II) ions. Bimetallic chitosan microgels showed good stability during four weeks of enzymatic degradation, and bimetallic systems with smaller amounts of Cu2+ ions showed good cytocompatibility for both used chitosans.