Concentration-dependent osteogenic and angiogenic biological performances of calcium phosphate cement modified with copper ions

Improvement in mechanical strength and biological function of 3D-printed trimagnesium phosphate bioceramic scaffolds by incorporating strontium orthosilicate

Trimagnesium phosphate (TMP) bioceramic scaffolds are deemed as promising bone grafts, but their mechanical and biological properties are yet to be improved. In the study, strontium orthosilicate (SrOS) was used to modify the TMP scaffolds, whose macroporous structure was constructed by the filament deposition-type 3D printing method. The new phases of SrMg2(PO4)2 and Sr2MgSi2O7, which showed nanocrystalline topography, were produced in the 3D-printed TMP/SrOS bioceramic composite scaffolds. The compressive strength (1.8-64.1 MPa) and porosity (39.7%-71.4%) of the TMP/SrOS scaffolds could be readily tailored by changing the amounts of SrOS additives and the sintering temperature. The TMP/SrOS scaffolds gradually degraded in the aqueous solution, consequently releasing ions of magnesium, strontium and silicon. In contrast with the TMP scaffolds, the TMP/SrOS bioceramic scaffolds had profoundly higher compressive strength, and enhanced cell proliferative and osteogenic activities. The TMP/SrOS scaffolds incorporated with 5 wt% SrOS had the highest mechanical strength and beneficial cellular function, which made them promising for treating different sites of bone defects.

Efforts to promote osteogenesis-angiogenesis coupling for bone tissue engineering

Repair of bone defects exceeding a critical size has been always a big challenge in clinical practice. Tissue engineering has exhibited great potential to effectively repair the defects with less adverse effect than traditional bone grafts, during which how to induce vascularized bone formation has been recognized as a critical issue. Therefore, recently many studies have been launched to attempt to promote osteogenesis-angiogenesis coupling. This review summarized comprehensively and explored in depth current efforts to ameliorate the coupling of osteogenesis and angiogenesis from four aspects, namely the optimization of scaffold components, modification of scaffold structures, loading strategies for bioactive substances, and employment tricks for appropriate cells. Especially, the advantages and the possible reasons for every strategy, as well as the challenges, were elaborated. Furthermore, some promising research directions were proposed based on an in-depth analysis of the current research. This paper will hopefully spark new ideas and approaches for more efficiently boosting new vascularized bone formations.

A cigarette filter-derived biomimetic cardiac niche for myocardial infarction repair

Cell implantation offers an appealing avenue for heart repair after myocardial infarction (MI). Nevertheless, the implanted cells are subjected to the aberrant myocardial niche, which inhibits cell survival and maturation, posing significant challenges to the ultimate therapeutic outcome. The functional cardiac patches (CPs) have been proved to construct an elastic conductive, antioxidative, and angiogenic microenvironment for rectifying the aberrant microenvironment of the infarcted myocardium. More importantly, inducing implanted cardiomyocytes (CMs) adapted to the anisotropic arrangement of myocardial tissue by bioengineered structural cues within CPs are more conducive to MI repair. Herein, a functional Cig/(TA-Cu) CP served as biomimetic cardiac niche was fabricated based on structural anisotropic cigarette filter by modifying with tannic acid (TA)-chelated Cu2+ (TA-Cu complex) via a green method. This CP possessed microstructural anisotropy, electrical conductivity and mechanical properties similar to natural myocardium, which could promote elongation, orientation, maturation, and functionalization of CMs. Besides, the Cig/(TA-Cu) CP could efficiently scavenge reactive oxygen species, reduce CM apoptosis, ultimately facilitating myocardial electrical integration, promoting vascular regeneration and improving cardiac function. Together, our study introduces a functional CP that integrates multimodal cues to create a biomimetic cardiac niche and provides an effective strategy for cardiac repair.

Ion incorporation into bone grafting materials

The use of biomaterials in regenerative medicine has expanded to treat various disorders caused by trauma or disease in orthopedics and dentistry. However, the treatment of large and complex bone defects presents a challenge, leading to a pressing need for optimized biomaterials for bone repair. Recent advances in chemical sciences have enabled the incorporation of therapeutic ions into bone grafts to enhance their performance. These ions, such as strontium (for bone regeneration/osteoporosis), copper (for angiogenesis), boron (for bone growth), iron (for chemotaxis), cobalt (for B12 synthesis), lithium (for osteogenesis/cementogenesis), silver (for antibacterial resistance), and magnesium (for bone and cartilage regeneration), among others (e.g., zinc, sodium, and silica), have been studied extensively. This review aims to provide a comprehensive overview of current knowledge and recent developments in ion incorporation into biomaterials for bone and periodontal tissue repair. It also discusses recently developed biomaterials from a basic design and clinical application perspective. Additionally, the review highlights the importance of precise ion introduction into biomaterials to address existing limitations and challenges in combination therapies. Future prospects and opportunities for the development and optimization of biomaterials for bone tissue engineering are emphasized.

Antimicrobial and Cell-Friendly Properties of Cobalt and Nickel-Doped Tricalcium Phosphate Ceramics

β-Tricalcium phosphate (β-TCP) is widely used as bone implant material. It has been observed that doping the β-TCP structure with certain cations can help in combating bacteria and pathogenic microorganisms. Previous literature investigations have focused on tricalcium phosphate structures with silver, copper, zinc, and iron cations. However, there are limited studies available on the biological properties of β-TCP containing nickel and cobalt ions. In this work, Ca10.5-xNix(PO4)7 and Ca10.5-xCox(PO4)7 solid solutions with the β-Ca3(PO4)2 structure were synthesized by a high-temperature solid-state reaction. Structural studies revealed the β-TCP structure becomes saturated at 9.5 mol/% for Co2+ or Ni2+ ions. Beyond this saturation point, Ni2+ and Co2+ ions form impurity phases after complete occupying of the octahedral M5 site. The incorporation of these ions into the β-TCP crystal structure delays the phase transition to the α-TCP phase and stabilizes the structure as the temperature increases. Biocompatibility tests conducted on adipose tissue-derived mesenchymal stem cells (aMSC) using the (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay showed that all prepared samples did not exhibit cytotoxic effects. Furthermore, there was no inhibition of cell differentiation into the osteogenic lineage. Antibacterial properties were studied on the C. albicans fungus and on E. coli, E. faecalis, S. aureus, and P. aeruginosa bacteria strains. The Ni- and Co-doped β-TCP series exhibited varying degrees of bacterial growth inhibition depending on the doping ion concentration and the specific bacteria strain or fungus. The combination of antibacterial activity and cell-friendly properties makes these phosphates promising candidates for anti-infection bone substitute materials.

Dual Photo-Enhanced Interpenetrating Network Hydrogel with Biophysical and Biochemical Signals for Infected Bone Defect Healing

The healing of infected bone defects (IBD) is a complex physiological process involving a series of spatially and temporally overlapping events, including pathogen clearance, immunological modulation, vascularization, and osteogenesis. Based on the theory that bone healing is regulated by both biochemical and biophysical signals, in this study, a copper doped bioglass (CuBGs)/methacryloyl-modified gelatin nanoparticle (MA-GNPs)/methacrylated silk fibroin (SilMA) hybrid hydrogel is developed to promote IBD healing. This hybrid hydrogel demonstrates a dual-photocrosslinked interpenetrating network mechanism, wherein the photocrosslinked SilMA as the main network ensures structural integrity, and the photocrosslinked MA-GNPs colloidal network increases strength and dissipates loading forces. In an IBD model, the hydrogel exhibits excellent biophysical characteristics, such as adhesion, adaptation to irregular defect shapes, and in situ physical reinforcement. At the same time, by sequentially releasing bioactive ions such as Cu2+ , Ca2+ , and Si2+ ions from CuBGs on demand, the hydrogel spatiotemporally coordinates antibacterial, immunomodulatory and bone remodeling events, efficiently removing infection and accelerating bone repair without the use of antibiotics or exogenous recombinant proteins. Therefore, the hybrid hydrogel can be used as a simple and effective method for the treatment of IBD.

Can Graphene Pave the Way to Successful Periodontal and Dental Prosthetic Treatments? A Narrative Review

Graphene, as a promising material, holds the potential to significantly enhance the field of dental practices. Incorporating graphene into dental materials imparts enhanced strength and durability, while graphene-based nanocomposites offer the prospect of innovative solutions such as antimicrobial dental implants or scaffolds. Ongoing research into graphene-based dental adhesives and composites also suggests their capacity to improve the quality and reliability of dental restorations. This narrative review aims to provide an up-to-date overview of the application of graphene derivatives in the dental domain, with a particular focus on their application in prosthodontics and periodontics. It is important to acknowledge that further research and development are imperative to fully explore the potential of graphene and ensure its safe use in dental practices.

A novel anti-washout curing solution of calcium phosphate cement prepared via irradiation polymerization

The anti-washout ability of calcium phosphate cement (CPC) determines its effectiveness in clinical application. In the current research, the common method for improving the anti-washout ability of CPC is to add anti-washout polymer agents. Sodium polyacrylate powder is an excellent anti-washout agent but when bonded with CPC it basically degrades the anti-washout performance of CPC after γ-ray irradiation, and is widely used in the sterilization process of CPC products. Therefore, we propose a method for the preparation of a sodium polyacrylate solution through irradiation polymerization as curing solution for CPC. This method first uses γ-ray irradiation sterilization to improve the anti-washout ability of CPC directly. It not only avoids the adverse effects of γ-rays on anti-washout agents, but also the CPC blended using this sodium polyacrylate solution had good biological properties and injectability. It provides a new method for promoting the anti-washout properties of calcium phosphate cement, which is of great significance for expanding the clinical application of CPC.

Multifunctional Three-Dimensional Printed Copper Loaded Calcium Phosphate Scaffolds for Bone Regeneration

Bone regeneration using inorganic nanoparticles is a robust and safe approach. In this paper, copper nanoparticles (Cu NPs) loaded with calcium phosphate scaffolds were studied for their bone regeneration potential in vitro. The pneumatic extrusion method of 3D printing was employed to prepare calcium phosphate cement (CPC) and copper loaded CPC scaffolds with varying wt% of copper nanoparticles. A new aliphatic compound Kollisolv MCT 70 was used to ensure the uniform mixing of copper nanoparticles with CPC matrix. The printed scaffolds were studied for physico-chemical characterization for surface morphology, pore size, wettability, XRD, and FTIR. The copper ion release was studied in phosphate buffer saline at pH 7.4. The in vitro cell culture studies for the scaffolds were performed using human mesenchymal stem cells (hMSCs). The cell proliferation study in CPC-Cu scaffolds showed significant cell growth compared to CPC. The CPC-Cu scaffolds showed improved alkaline phosphatase activity and angiogenic potential compared to CPC. The CPC-Cu scaffolds showed significant concentration dependent antibacterial activity in Staphylococcus aureus. Overall, the CPC scaffolds loaded with 1 wt% Cu NPs showed improved activity compared to other CPC-Cu and CPC scaffolds. The results showed that copper has improved the osteogenic, angiogenic and antibacterial properties of CPC scaffolds, facilitating better bone regeneration in vitro.

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.

The Roles of Exosomes upon Metallic Ions Stimulation in Bone Regeneration

Metallic ions have been widely investigated and incorporated into bone substitutes for bone regeneration owing to their superior capacity to induce angiogenesis and osteogenesis. Exosomes are key paracrine mediators that play a crucial role in cell-to-cell communication. However, the role of exosomes in metallic ion-induced bone formation and their underlying mechanisms remain unclear. Thus, this review systematically analyzes the effects of metallic ions and metallic ion-incorporated biomaterials on exosome secretion from mesenchymal stem cells (MSCs) and macrophages, as well as the effects of secreted exosomes on inflammation, angiogenesis, and osteogenesis. In addition, possible signaling pathways involved in metallic ion-mediated exosomes, followed by bone regeneration, are discussed. Despite limited investigation, metallic ions have been confirmed to regulate exosome production and function, affecting immune response, angiogenesis, and osteogenesis. Although the underlying mechanism is not yet clear, these insights enrich our understanding of the mechanisms of the metallic ion-induced microenvironment for bone regeneration, benefiting the design of metallic ion-incorporated implants.

Preparation and characterization of novel lithium magnesium phosphate bioceramic scaffolds facilitating bone generation

Both magnesium and lithium are able to stimulate osteogenic and angiogenic activities. In this study, lithium magnesium phosphate (Li_0.5Mg_2.75(PO₄)₂, Li₁Mg_2.5(PO₄)₂ and Li₂Mg₂(PO₄)₂) biomaterials were synthesized by a solid-state reaction method, and their bioceramic blocks and scaffolds were fabricated by compression molding and 3D printing, respectively. The results indicated that the lithium magnesium phosphates consisted of the Mg₃(PO₄)₂ phase and/or LiMgPO₄ phase. Compared with the lithium-free Mg₃(PO₄)₂ bioceramics, the lithium magnesium phosphate bioceramics showed a lower porosity and consequently a higher compressive strength, and stimulated in vitro cellular proliferation, osteogenic differentiation and proangiogenic activity. In vivo results manifested that the Li₂Mg₂(PO₄)₂ bioceramic scaffolds efficiently promoted bone regeneration of critical-size calvarial defects in rats. Benefiting from the high compressive strength and capacity of stimulating osteogenesis and angiogenesis, the Li₂Mg₂(PO₄)₂ bioceramic scaffolds are considered promising for efficiently repairing the bone defects.

Mechanisms of Hierarchical Topographies Tuning Bacteria and Cell Biological Responses to the Surfaces of Pure Titanium and Cu-Bearing Titanium Alloy

The competition between cells integration and bacterial colonization determines the fate of implantations. To reveal the effects of clinical implant topographies on osteoblast differentiation and bacterial biofilm formation, a series of micron/submicron/nano-hierarchical structures were created at pure titanium surfaces (Ti-I, Ti-II, Ti-III). It was found that the hierarchical structures promoted MC3T3-E1 cell differentiation through contact guidance and Ti-II processed the best osteogenic ability. Undesirably, hierarchical surfaces further accelerated the biofilm formation due to submicron structures with low interaction. To reduce the risk of bacterial infections, hierarchical structures were prepared on the antibacterial Cu-bearing titanium alloy surfaces (TiCu-I, TiCu-II, TiCu-III). Hierarchical topographies not only endowed TiCu surfaces with antibacterial trapping characteristics due to CuO doped in the outermost oxides layer but also shifted the corrosion behavior of TiCu alloy into activation-passivation, increasing the Cu-ion release rate and further promoting the osteogenic differentiation. TiCu-III possessed excellent antibacterial trapping ability and optimal osteogenic action. Finally, in the osteomyelitis-modeled mice, hierarchical topographies aggravated the bacterial infection around Ti implants, which entirely lost the osseointegration, while all of the TiCu surfaces significantly inhibited the infection and accelerated the formation of new bone tunnels around the implants. In vivo studies successfully confirmed the tuning mechanism of hierarchical topographies on the biological responses of bacteria and cells to the Ti and TiCu alloys, which would pave the way to develop novel biofunctionalized metal implants.

Application of Copper Nanoparticles in Dentistry

Nanoparticles based on metal and metallic oxides have become a novel trend for dental applications. Metal nanoparticles are commonly used in dentistry for their exclusive shape-dependent properties, including their variable nano-sizes and forms, unique distribution, and large surface-area-to-volume ratio. These properties enhance the bio-physio-chemical functionalization, antimicrobial activity, and biocompatibility of the nanoparticles. Copper is an earth-abundant inexpensive metal, and its nanoparticle synthesis is cost effective. Copper nanoparticles readily intermix and bind with other metals, ceramics, and polymers, and they exhibit physiochemical stability in the compounds. Hence, copper nanoparticles are among the commonly used metal nanoparticles in dentistry. Copper nanoparticles have been used to enhance the physical and chemical properties of various dental materials, such as dental amalgam, restorative cements, adhesives, resins, endodontic-irrigation solutions, obturation materials, dental implants, and orthodontic archwires and brackets. The objective of this review is to provide an overview of copper nanoparticles and their applications in dentistry.

Bone Regeneration and Oxidative Stress: An Updated Overview

Bone tissue engineering is a complex domain that requires further investigation and benefits from data obtained over past decades. The models are increasing in complexity as they reveal new data from co-culturing and microfluidics applications. The in vitro models now focus on the 3D medium co-culturing of osteoblasts, osteoclasts, and osteocytes utilizing collagen for separation; this type of research allows for controlled medium and in-depth data analysis. Oxidative stress takes a toll on the domain, being beneficial as well as destructive. Reactive oxygen species (ROS) are molecules that influence the differentiation of osteoclasts, but over time their increasing presence can affect patients and aid the appearance of diseases such as osteoporosis. Oxidative stress can be limited by using antioxidants such as vitamin K and N-acetyl cysteine (NAC). Scaffolds and biocompatible coatings such as hydroxyapatite and bioactive glass are required to isolate the implant, protect the zone from the metallic, ionic exchange, and enhance the bone regeneration by mimicking the composition and structure of the body, thus enhancing cell proliferation. The materials can be further functionalized with growth factors that create a better response and higher chances of success for clinical use. This review highlights the vast majority of newly obtained information regarding bone tissue engineering, such as new co-culturing models, implant coatings, scaffolds, biomolecules, and the techniques utilized to obtain them.

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

The use of copper (Cu²⁺) and cobalt (Co²⁺) has been described to stimulate blood vessel formation, a key process for the success of tissue regeneration. However, understanding how different concentrations of these ions affect cellular response is important to design scaffolds for their delivery to better fine tune the angiogenic response. On the one hand, gene expression analysis and the assessment of tubular formation structures with human umbilical vein endothelial cells (HUVEC) revealed that high concentrations (10μM) of Cu²⁺ in early times and lower concentrations (0.1 and 1μM) at later times (day 7) enhanced angiogenic response. On the other hand, higher concentrations (25μM) of Co²⁺ during all time course increased the angiogenic gene expression and 0.5, 5 and 25μM enhanced the ability to form tubular structures. To further explore synergistic effects combining both ions, the non-toxic concentrations were used simultaneously, although results showed an increased cell toxicity and no improvement of angiogenic response. These results provide useful information for the design of Cu²⁺ or Co²⁺ delivery scaffolds in order to release the appropriate concentration during time course for blood vessel stimulation.

Inorganic Agents for Enhanced Angiogenesis of Orthopedic Biomaterials

Aseptic loosening of a permanent prosthesis remains one of the most common reasons for bone implant failure. To improve the fixation between implant and bone tissue as well as enhance blood vessel formation, bioactive agents are incorporated into the surface of the biomaterial. This study reviews and compares five bioactive elements (copper, magnesium, silicon, strontium, and zinc) with respect to their effect on the angiogenic behavior of endothelial cells (ECs) when incorporated on the surface of biomaterials. Moreover, it provides an overview of the state-of-the-art methodologies used for the in vitro assessment of the angiogenic properties of these elements. Two databases are searched using keywords containing ECs and copper, magnesium, silicon, strontium, and zinc. After applying the defined inclusion and exclusion criteria, 59 articles are retained for the final assessment. An overview of the angiogenic properties of five bioactive elements and the methods used for assessment of their in vitro angiogenic potential is presented. The findings show that silicon and strontium can effectively enhance osseointegration through the simultaneous promotion of both angiogenesis and osteogenesis. Therefore, their integration onto the surface of biomaterials can ultimately decrease the incidence of implant failure due to aseptic loosening.

Copper-based biomaterials for bone and cartilage tissue engineering

Backgroud

Tissue engineering using cells, scaffolds, and bioactive molecules can promote the repair and regeneration of injured tissues. Copper is an essential element for the human body that is involved in many physiological activities and in recent years, copper has been used increasingly in tissue engineering.

Methods

The current advances of copper-based biomaterial for bone and cartilage tissue engineering were searched on PubMed and Web of Science.

Results

Various forms of copper-based biomaterials, including pure copper, copper ions, copper nanoparticles, copper oxides, and copper alloy are introduced. The incorporation of copper into base materials provides unique properties, resulting in tuneable porosity, mechanical strength, degradation, and crosslinking of scaffolds. Copper also shows promising biological performance in cell migration, cell adhesion, osteogenesis, chondrogenesis, angiogenesis, and antibacterial activities. In vivo applications of copper for bone and cartilage tissue engineering are discussed.

Conclusion

This review focuses on copper’s physiochemical and biological effects, and its applications in bone and cartilage tissue engineering. The potential limitations and future perspectives are also discussed.

Translational potential of this article

This review introduces the recent advances in copper-based biomaterial for bone and cartilage tissue engineering. This revie could guide researchers to apply copper in biomaterials, improving the generation of bone and cartilages, decrease the possibility of infection and shorten the recovery time so as to decrease medical costs.

Influence of Cu2+ on Osteoclast Formation and Activity In Vitro

Background: Copper-containing biomaterials are increasingly applied for bone regeneration due to their pro-angiogenetic, pro-osteogenetic and antimicrobial properties. Therefore, the effect of Cu²⁺ on osteoclasts, which play a major role in bone remodeling was studied in detail. Methods: Human primary osteoclasts, differentiated from human monocytes were differentiated or cultivated in the presence of Cu²⁺. Osteoclast formation and activity were analyzed by measurement of osteoclast-specific enzyme activities, gene expression analysis and resorption assays. Furthermore, the glutathione levels of the cells were checked to evaluate oxidative stress induced by Cu²⁺. Results: Up to 8 µM Cu²⁺ did not induce cytotoxic effects. Activity of tartrate-resistant acid phosphatase (TRAP) was significantly increased, while other osteoclast specific enzyme activities were not affected. However, gene expression of TRAP was not upregulated. Resorptive activity of osteoclasts towards dentin was not changed in the presence of 8 µM Cu²⁺ but decreased in the presence of extracellular bone matrix. When Cu²⁺ was added to mature osteoclasts TRAP activity was not increased and resorption decreased only moderately. The glutathione level of both differentiating and mature osteoclasts was significantly decreased in the presence of Cu²⁺. Conclusions: Differentiating and mature osteoclasts react differently to Cu²⁺. High TRAP activities are not necessarily related to high resorption.

A convenient approach by using poly-(HEMA-co-NIPAM)/Cu2+ solution sol-gel transition for wound protection and healing

Rapid and convenient wound healing is crucial for reducing potential post-traumatic wound complications. In this study, a temperature-sensitive polymer of poly-(HEMA-co-NIPAM) (PHN) was synthesized by free-radical polymerization, in which the solution quickly underwent a sol-gel transition above 29°C, thus responding to a typical body temperature and facilitating wound sealing. PHN solution incorporated with copper ions (PHN-Cu) not only exhibited excellent antibacterial properties, but also expedited wound closure and facilitated tissue angiogenesis. The in vivo and in vitro experiments showed that the PHN-Cu had a higher wound closure rate and demonstrated an ability to promote skin tissue angiogenesis. Such a versatile, convenient aqueous solution could enable nonprofessionals to promptly treat wounds in a short time after injury, thus providing suitable conditions for later treatment, and can be used as a convenient method to clean wounds.

Nanotherapeutics for regeneration of degenerated tissue infected by bacteria through the multiple delivery of bioactive ions and growth factor with antibacterial/angiogenic and osteogenic/odontogenic capacity

Therapeutic options are quite limited in clinics for the successful repair of infected/degenerated tissues. Although the prevalent treatment is the complete removal of the whole infected tissue, this leads to a loss of tissue function and serious complications. Herein the dental pulp infection, as one of the most common dental problems, was selected as a clinically relevant case to regenerate using a multifunctional nanotherapeutic approach. For this, a mesoporous bioactive glass nano-delivery system incorporating silicate, calcium, and copper as well as loading epidermal growth factor (EGF) was designed to provide antibacterial/pro-angiogenic and osteo/odontogenic multiple therapeutic effects. Amine-functionalized Cu-doped bioactive glass nanospheres (Cu-BGn) were prepared to be 50-60 nm in size, mesoporous, positive-charged and bone-bioactive. The Cu-BGn could release bioactive ions (copper, calcium and silicate ions) with therapeutically-effective doses. The Cu-BGn treatment to human umbilical vein endothelial cells (HUVEC) led to significant enhancement of the migration, tubule formation and expression of angiogenic gene (e.g. vascular endothelial growth factor, VEGF). Furthermore, the EGF-loaded Cu-BGn (EGF@Cu-BGn) showed pro-angiogenic effects with antibacterial activity against E. faecalis, a pathogen commonly involved in the pulp infection. Of note, under the co-culture condition of HUVEC with E. faecalis, the secretion of VEGF was up-regulated. In addition, the osteo/odontogenic stimulation of the EGF@Cu-BGn was evidenced with human dental pulp stem cells. The local administration of the EGF@Cu-BGn in a rat molar tooth defect infected with E. faecalis revealed significant in vivo regenerative capacity, highlighting the nanotherapeutic uses of the multifunctional nanoparticles for regenerating infected/damaged hard tissues.

Copper containing silicocarnotite bioceramic with improved mechanical strength and antibacterial activity

Copper is well known for its multifunctional biological effects including antibacterial and angiogenic activities, while silicon-containing bioceramic has proved to possess superior biological properties to hydroxyapatite (HA). In this work, CuO was introduced to silicocarnotite (Ca₅(PO₄)₂SiO₄, CPS) to simultaneously enhance its mechanical and antibacterial properties, and its cytocompatibility was also evaluated. Results showed that CuO could significantly facilitate the densification process of CPS bioceramic through liquid-phase sintering. The bending strength of CPS with the addition of 3.0 wt% CuO improved from 29.2 MPa to 63.4 MPa after sintered at 1200 °C. Moreover, Cu-CPS bioceramics demonstrated superior in vitro antibacterial property against both S. aureus and E. coli strains by destroying their membrane integrity, and the antibacterial activity augmented with CuO content. Meanwhile, the released Cu ions from Cu-CPS bioceramics could promote the proliferation of human umbilical vein endothelial cells (HUVECs), and the in vitro cytocompatibility exhibited concentration dependence on Cu ions. These suggest that Cu-CPS bioceramics might be promising candidates for bone tissue regeneration with an ability to prevent postoperative infections.

Complementary and synergistic effects on osteogenic and angiogenic properties of copper-incorporated silicocarnotite bioceramic: In vitro and in vivo studies

Promoting bone regeneration to treat bone defects is a challenging problem in orthopedics, and developing novel biomaterials with both osteogenic and angiogenic activities is sought as a feasible solution. Here, copper-silicocarnotite [Cu-Ca₅(PO₄)₂SiO₄, Cu-CPS] was designed and fabricated. In this study, the Cu-CPS ceramics demonstrated better mechanical, osteogenic, and angiogenic properties in vitro and in vivo than pure CPS one. Particularly, CPS with 1.0 wt% CuO (1.0Cu-CPS) exhibited the best performance. Additionally, hydroxyapatite with 1.0 wt% CuO (1.0Cu-HA) was used to explore the respective effects of copper and silicon (Si). According to the in vitro results, it indicated that Cu enhanced the osteogenic activity of CPS ceramics although Si played a dominate role in the osteogenic process. Moreover, Cu could promote an early stage of angiogenesis, and the complementary effect of Si and Cu was found in the late phase. Furthermore, the in vivo results illustrated that the synergistic effect of Cu and Si improved bone and vessel regeneration during the degradation of Cu-CPS scaffolds (P < 0.05). Therefore, Cu-CPS ceramics could improve osteogenesis and angiogenesis through the simultaneous effects of Cu and Si, thus, offering a promising treatment option in orthopedic application for bone tissue regeneration.

Biological properties of copper-doped biomaterials for orthopedic applications: A review of antibacterial, angiogenic and osteogenic aspects

Copper is an essential trace element required for human life, and is involved in several physiological mechanisms. Today researchers have found and confirmed that Cu has biological properties which are particularly useful for orthopedic biomaterials applications such as implant coatings or biodegradable filler bone substitutes. Indeed, Cu exhibits antibacterial functions, provides angiogenic ability and favors osteogenesis; these represent major key points for ideal biomaterial integration and the healing process that follows. The antibacterial performances of copper-doped biomaterials present an interesting alternative to the massive use of prophylactic antibiotics and help to limit the development of antibiotic resistance. By stimulating blood vessel growth and new bone formation, copper contributes to the improved bio-integration of biomaterials. This review describes the bio-functional advantages offered by Cu and focuses on the antibacterial, angiogenic and osteogenic properties of Cu-doped biomaterials with potential for orthopedic applications.

Creation of Bony Microenvironment with Extracellular Matrix Doped-Bioactive Ceramics to Enhance Osteoblast Behavior and Delivery of Aspartic Acid-Modified BMP-2 Peptides

Introduction

Decellularized matrix from porcine small intestinal submucosa (SIS) endows scaffolds with an ECM-like surface, which enhances stem cell self-renewal, proliferation, and differentiation. Mesoporous bioactive glass (MBG) is extensively recognized as an excellent bio-ceramic for fabricating bone grafts.

Materials and Methods

In the current study, SIS was doped on an MBG scaffold (MBG/SIS) using polyurethane foam templating and polydopamine chemistry method. To mimic the bony environment of a natural bone matrix, an ECM-inspired delivery system was constructed by coupling the BMP2-related peptide P28 to a heparinized MBG/SIS scaffold (MBG/SIS-H-P28). The release of P28 from MBG/SIS-H-P28 and its effects on the proliferation, viability, and osteogenic differentiation of bone marrow stromal stem cells were investigated in vitro and in vivo.

Results

Our research indicated that the novel tissue-derived ECM scaffold MBG/SIS has a hierarchical and interconnected porous architecture, and superior biomechanical properties. MBG/SIS-H-P28 released P28 in a controlled manner, with the long-term release time of 40 d. The results of in vitro experiments showed improvements in cell proliferation, cell viability, alkaline phosphatase activity, and mRNA expression levels of osteogenesis-related genes (Runx-2, OCN, OPN, and ALP) compared to those of MBG/SIS or MBG/SIS-P28 and MBG/SIS-H-P28. The in vivo results demonstrated that MBG/SIS-H-P28 scaffolds evidently increased bone formation in rat calvarial critical-sized defect compared to that in controls.

Conclusion

MBG/SIS-H-P28 scaffolds show potential as ideal platforms for delivery of P28 and for providing a bony environment for bone regeneration.

[Three-dimensional printed Ti6Al4V-4Cu alloy promotes osteogenic gene expression through bone immune regulation]

Objective

To investigate the effects of three-dimensional (3D) printed Ti6Al4V-4Cu alloy on inflammation and osteogenic gene expression in mouse bone marrow mesenchymal stem cells (BMSCs) and mouse mononuclear macrophage line RAW264.7.

Methods

Ti6Al4V and Ti6Al4V-4Cu alloys were prepared by selective laser melting, and the extracts of the two materials were prepared according to the biological evaluation standard of medical devices. The effects of two kinds of extracts on the proliferation of mouse BMSCs and mouse RAW264.7 cells were detected by cell counting kit 8 method. After co-cultured with mouse BMSCs for 3 days, the expression of osteogenesis- related genes [collagen type Ⅰ (Col-Ⅰ), alkaline phosphatase (ALP), Runx family transcription factor 2 (Runx-2), osteoprotegerin (OPG), and osteopontin (OPN)] were detected by real-time fluorescence quantitative PCR. After co-cultured with mouse RAW264.7 cells for 1 day, the expressions of inflammation-related genes [interleukin 4 (IL-4) and nitric oxide synthase 2 (iNOS)] were detected by real-time fluorescence quantitative PCR, and the supernatants of the two groups were collected to detect the secretion of vascular endothelial growth factor a (VEGF-a) and bone morphogenetic protein 2 (BMP-2) by ELISA. The osteogenic conditioned medium were prepared with the supernatants of the two groups and co-cultured with BMSCs for 3 days. The expressions of osteogenesis-related genes (Col-Ⅰ, ALP, Runx-2, OPG, and OPN) were detected by real-time fluorescence quantitative PCR.

Results

Compared with Ti6Al4V alloy extract, Ti6Al4V-4Cu alloy extract had no obvious effect on the proliferation of BMSCs and RAW264.7 cells, but it could promote the expression of OPG mRNA in BMSCs, reduce the expression of iNOS mRNA in RAW264.7 cells, and promote the expression of IL-4 mRNA. It could also promote the secretions of VEGF-a and BMP-2 in RAW264.7 cells. Ti6Al4V-4Cu osteogenic conditioned medium could promote the expressions of Col-Ⅰ, ALP, Runx-2, OPG, and OPN mRNAs in BMSCs. The differences were all significant ( P<0.05).

Conclusion

3D printed Ti6Al4V-4Cu alloy can promote RAW264.7 cells to secret VEGF-a and BMP-2 by releasing copper ions, thus promoting osteogenesis through bone immune regulation, which lays a theoretical foundation for the application of metal prosthesis.

Improved osteogenesis and angiogenesis of a novel copper ions doped calcium phosphate cement

Improving the angio1genesis potential of bone-repairing materials is vital for the repair of cancerous bone defects. It can further facilitate the delivery of active substances with osteogenesis and anti-tumor functions, ultimately promoting the formation of new bone tissues. Copper ions (Cu²⁺) have been proved to be beneficial to angiogenesis. This study developed a new type of Cu-containing calcium phosphate cement (Cu-CPC) by incorporating with copper phosphate (CuP) nanoparticles with a photothermal anti-tumor effect. The results revealed that the main phases of all hydrated CPCs were hydroxyapatite, unreacted tricalcium phosphate and calcium carbonate. But the hydration products of CPC became thinner after the incorporation of Cu²⁺. With the increase of CuP concentration, the setting time of CPC was prolonged while the injectability and the compressive strength were increased. The release concentration of Cu²⁺in vitro was among 0.01 to 0.74 mg/mL, which showed a positive relation with CuP content. Mouse bone marrow stromal cells (mBMSCs) displayed higher adhesion activity, proliferation performance and expression of osteogenic genes and proteins on CPC with 0.01 wt% CuP (0.01Cu-CPC) and 0.05 wt% CuP (0.05Cu-CPC). When human umbilical vein endothelial cells were co-cultured with 0.01Cu-CPC and 0.05Cu-CPC extracts, the proliferation and angiogenesis-related gene and protein expression were significantly increased, and the in vitro tube formation capacity was promoted. However, higher CuP content inhibited the proliferation of mBMSCs. In conclusion, CPC with 0.01 wt% and 0.05 wt% CuP nanoparticles has the potential to promote bone formation around cancerous bone defects, which would be promising for bone regeneration and treatment of bone tumors.

Effects of strontium amount on the mechanical strength and cell-biological performance of magnesium-strontium phosphate bioceramics for bone regeneration

Magnesium and strontium are able to enhance osteogenesis and suppress osteoclastic activities simultaneously, and they were nontoxic in wide concentration ranges; these make the magnesium-strontium phosphate bioceramics suitable for treating osteoporotic bone defects. The aim of this study was to investigate the effects of strontium amount on the mechanical strength and cell-biological performance of magnesium-strontium phosphate [Mg_xSr_3-x(PO₄)₂; 3-x = 0, 0.1, 0.25, 0.5, 0.75, 1] bioceramics, which were sintered at 1100 °C. The results indicated that the magnesium-strontium phosphate bioceramics except Mg_2.9Sr_0.1(PO₄)₂ and Mg_2.25Sr_0.75(PO₄)₂ bioceramics had considerable compressive strength. The variation in magnesium and strontium contents did not regularly affect the in vitro osteogenic differentiation and osteoclastic activities. The Mg_2.75Sr_0.25(PO₄)₂ bioceramic had the most desirable overall performance, as reflected by considerably high compressive strength, enhanced in vitro osteogenesis and inhibited osteoclastic activities. Therefore, the Mg_2.75Sr_0.25(PO₄)₂ bioceramic is considered a promising biomaterial for osteoporotic bone regeneration.

Improving osteogenesis of calcium phosphate bone cement by incorporating with manganese doped β-tricalcium phosphate

Lack of osteogenic capacity limits the bone repair effect of calcium phosphate cement (CPC). In present work, bivalent manganese ion (Mn²⁺) doped β-tricalcium phosphate (Mn-TCP) was incorporated into CPC to enhance its osteogenic ability. The incorporation of Mn-TCP promoted the hydration reaction of CPC. The presence of Mn²⁺ made the hydration products finer. When adding 10 wt% Mn-TCP in CPC (Mn-CPC-1), the setting time of CPC was shortened, whereas the strength and injectability were not changed. Mouse Bone marrow mesenchymal stem cells (mBMSCs) on Mn-CPC-1 and CPC with 20 wt% Mn-TCP (Mn-CPC-2) presented better adhesion and spreading behaviors. Besides, Mn-CPC-1 promoted the gene levels of ALP, Col-I and OC while Mn-CPC-2 promoted the gene levels of Runx2 and OC. Cellular behaviors were related to two points: one was the increase of adsorption capacity of proteins (e.g. BSA) after changing the surface properties of bone cements; and the other was the biological role of Mn²⁺ released from CPC in osteogenesis. All the results indicated that CPC incorporated with 10 wt% Mn-TCP has good osteogenesis and proper physicochemical properties, which will be a prospective biomaterial applying in the area of bone regeneration.

Nanocellulose/bioactive glass cryogels as scaffolds for bone regeneration

A major challenge exists in the preparation of scaffolds for bone regeneration, namely, achieving simultaneously bioactivity, biocompatibility, mechanical performance and simple manufacturing. Here, cellulose nanofibrils (CNF) are introduced for the preparation of scaffolds taking advantage of their biocompatibility and ability to form strong 3D porous networks from aqueous suspensions. CNF are made bioactive for bone formation through a simple and scalable strategy that achieves highly interconnected 3D networks. The resultant materials optimally combine morphological and mechanical features and facilitate hydroxyapatite formation while releasing essential ions for in vivo bone repair. The porosity and roughness of the scaffolds favor several cell functions while the ions act in the expression of genes associated with cell differentiation. Ion release is found critical to enhance the production of the bone morphogenetic protein 2 (BMP-2) from cells within the fractured area, thus accelerating the in vivo bone repair. Systemic biocompatibility indicates no negative effects on vital organs such as the liver and kidneys. The results pave the way towards a facile preparation of advanced, high performance CNF-based scaffolds for bone tissue engineering.

Development of Composite Scaffolds Based on Cerium Doped-Hydroxyapatite and Natural Gums-Biological and Mechanical Properties

Hydroxyapatite (HAp) is a ceramic material composing the inorganic portion of bones. Ionic substitutions enhance characteristics of HAp, for example, calcium ions (Ca²⁺) by cerium ions (Ce³⁺). The use of HAp is potentialized through biopolymers, cashew gum (CG), and gellan gum (GG), since CG/GG is structuring agents in the modeling of structured biocomposites, scaffolds. Ce-HApCG biocomposite was synthesized using a chemical precipitation method. The obtained material was frozen (–20 °C for 24 h), and then vacuum dried for 24 h. The Ce-HApCG was characterized by X-Ray diffractograms (XRD), X-ray photoemission spectra (XPS), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and energy dispersive spectroscopy (EDS). XRD and FTIR showed that Ce-HApCG was successfully synthesized. XRD showed characteristic peaks at 2θ = 25.87 and 32.05, corresponding to the crystalline planes (0 0 2) and (2 1 1), respectively, while phosphate bands were present at 1050 cm⁻¹ and 1098 cm⁻¹, indicating the success of composite synthesis. FESEM showed pores and incorporated nanostructured granules of Ce-HApCG. The mechanical test identified that Ce-HApCG has a compressive strength similar to the cancellous bone’s strength and some allografts used in surgical procedures. In vitro tests (MTT assay and hemolysis) showed that scaffold was non-toxic and exhibited low hemolytic activity. Thus, the Ce-HApCG has potential for application in bone tissue engineering.