Coating biopolymer nanofibers with carbon nanotubes accelerates tissue healing and bone regeneration through orchestrated cell- and tissue-regulatory responses

An updated review and recent advancements in carbon-based bioactive coatings for dental implant applications

BACKGROUND

Surface coating of dental implants with a bioactive biomaterial is one of the distinguished approaches to improve the osseointegration potential, antibacterial properties, durability, and clinical success rate of dental implants. Carbon-based bioactive coatings, a unique class of biomaterial that possesses excellent mechanical properties, high chemical and thermal stability, osteoconductivity, corrosion resistance, and biocompatibility, have been utilized successfully for this purpose.

AIM

This review aims to present a comprehensive overview of the structure, properties, coating techniques, and application of the various carbon-based coatings for dental implant applicationswith a particular focuson Carbon-based nanomaterial (CNMs), which is an advanced class of biomaterials.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Available articles on carbon coatings for dental implants were reviewed using PubMed, Science Direct, and Google Scholar resources. Carbon-based coatings are non-cytotoxic, highly biocompatible, chemically inert, and osteoconductive, which allows the bone cells to come into close contact with the implant surface and prevents bacterial attachment and growth. Current research and advancements are now more focused on carbon-based nanomaterial (CNMs), as this emerging class of biomaterial possesses the advantage of both nanotechnology and carbon and aligns closely with ideal coating material characteristics. Carbon nanotubes, graphene, and its derivatives have received the most attention for dental implant coating. Various coating techniques are available for carbon-based materials, chosen according to substrate type, application requirements, and desired coating thickness. Vapor deposition technique, plasma spraying, laser deposition, and thermal spraying techniques are most commonly employed to coat the carbon structures on the implant surface. Longer duration trials and monitoring are required to ascertain the role of carbon-based bioactive coating for dental implant applications.

Bioactive Inorganic Materials for Innervated Multi-Tissue Regeneration

Tissue engineering aims to repair damaged tissues with physiological functions recovery. Although several therapeutic strategies are there for tissue regeneration, the functional recovery of regenerated tissues still poses significant challenges due to the lack of concerns of tissue innervation. Design rationale of multifunctional biomaterials with both tissue-induction and neural induction activities shows great potential for functional tissue regeneration. Recently, the research and application of inorganic biomaterials attracts increasing attention in innervated multi-tissue regeneration, such as central nerves, bone, and skin, because of its superior tunable chemical composition, topographical structures, and physiochemical properties. More importantly, inorganic biomaterials are easily combined with other organic materials, biological factors, and external stimuli to enhance their therapeutic effects. This review presents a comprehensive overview of recent advancements of inorganic biomaterials for innervated multi-tissue regeneration. It begins with introducing classification and properties of typical inorganic biomaterials and design rationale of inorganic-based material composites. Then, recent progresses of inorganic biomaterials in regenerating various nerves and nerve-innervated tissues with functional recovery are systematically reviewed. Finally, the existing challenges and future perspectives are proposed. This review may pave the way for the direction of inorganic biomaterials and offers a new strategy for tissue regeneration in combination of innervation.

Electrospun nanofibers of collagen and chitosan for tissue engineering and drug delivery applications: A review

Tissue engineering plays a vital role in the medical field that addresses the repair, regeneration, and replacement of damaged tissues or organs. The development of drug-eluting electrospun nanofiber composed of biological macromolecules plays a key role in providing localized drug delivery and structural support. This review examines the recent development and impact of electrospun nanofibers in the field of tissue engineering and explores their potential applications. This review also investigates into the fabrication techniques of nanofibers, highlighting the use of biopolymers like collagen and chitosan, chiefly, focuses on understanding the mechanisms of drug-releasing features of these nanofibers. Studies concerning the medical applications of these nanofibers, such as wound healing, skin regeneration, bone tissue engineering, and neural repair, were also reviewed. Beyond the application in tissue regeneration, this review also explores the potential efficacy of nanofibres in cancer therapy, antibacterial activity, enzyme immobilization, and biosensing applications. This study provides an up-to-date critical insight into the applications of electrospun nanofiber application and key scalable production processes, underscoring the potential economic impacts of advanced wound care technologies. While outlining current challenges, this paper also offers future perspectives on the design, application, and potential expansion of drug-eluting electrospun fibers in medical sciences, ultimately showcasing their pivotal role in advancing therapeutic outcomes.

Electrically-stimulated cellular and tissue events are coordinated through ion channel-mediated calcium influx and chromatin modifications across the cytosol-nucleus space

Electrical stimulation (ES) through biomaterials and devices has been implicated in activating diverse cell behaviors while facilitating tissue healing process. Despite its significance in modulating biological events, the mechanisms governing ES-activated cellular phenomena remain largely elusive. Here, we demonstrated that millisecond-pulsed temporal ES profoundly impacted a spectrum of cellular events across the membrane-cytosol-nuclear space. These include activated ion channels, intracellular calcium influx, actomyosin contractility, cell migration and proliferation, and secretome release. Such events were coordinated mainly through ES-activated ion channels and calcium oscillation dynamics. Notably, ES increased the chromatin accessibility of genes, particularly those associated with the ES-activated cellular events, underscoring the significance of epigenetic changes in ES-induced behavioral outcomes. We identified histone acetylation (mediated by histone acetyltransferases), among other chromatin modifications, is key in reshaping the chromatin landscape upon ES. These observations were further validated through experiments involving ex vivo skin tissue samples, including activated ion channels and calcium influx, increased cell proliferation and actomyosin contractility, elevated secretome profile, and more accessible chromatin structure following ES. This work provides novel insights into the mechanisms underlying ES-activated cell and tissue events, ultimately guiding design principles for the development of electrical devices and materials effective for tissue repair and wound healing.

Three-Dimensional Printed Cell-Adaptable Nanocolloidal Hydrogel Induces Endogenous Osteogenesis for Bone Repair

Repairing critical bone defects remains a formidable challenge in regenerative medicine. Scaffolds that can fill defects and facilitate bone regeneration have garnered considerable attention. However, scaffolds struggle to provide an ideal microenvironment for cell growth and differentiation at the interior of the bone defect sites. The scaffold's structure must meet specific requirements to support endogenous bone regeneration. Here, we introduce a novel 3D-printed nanocolloidal gelatin methacryloyl (GelMA) hydrogel, namely, the nG hydrogel, that was derived from the self-assembly of GelMA in the presence of Pluronics F68, emphasizing its osteoinductive capability conferred solely by the specific nanocolloidal structure. The nG hydrogel, exhibiting remarkable pore connectivity and cell-adaptable microscopic structure, induced the infiltration and migration of rat bone mesenchymal stem cells (rBMSCs) into the hydrogel with a large spreading area in vitro. Moreover, the nG hydrogel with interconnected nanospheres promoted the osteogenic differentiation of rBMSCs, leading to up-regulated expression of ALP, RUNX2, COL-1, and OCN, as well as augmented formation of calcium nodules. In the critical-sized rat calvarial defect model, the nG hydrogel demonstrated improved repair of bone defects, with enhanced recruitment of endogenous CD29+ and CD90+ stem cells and increased bone regeneration, as indicated by significantly higher bone mineral density (BMD) in vivo. Mechanistically, the integrin β1/focal adhesion kinase (FAK) mechanotransduction signaling pathway was up-regulated in the nG hydrogel group both in vitro and in vivo, which may partially account for its pronounced osteoinductive capability. In conclusion, the cell-adaptable nG hydrogel shows great potential as a near-future clinical translational strategy for the customized repair of critical-sized bone defects.

Nanotechnology at the crossroads of stem cell medicine

Nanotechnology in stem cell medicine is an interdisciplinary field which has gained a lot of interest recently. This domain addresses key challenges associated with stem cell medicine such as cell isolation, targeted delivery, and tracking. Nanotechnology-based approaches, including magnetic cell sorting, fluorescent tagging, and drug or biomolecule conjugation for delivery, have enhanced precision in stem cell isolation and guided cell migration, increasing the therapeutic potential. Recent studies have focused on using nanomaterials and scaffolds to drive stem cell differentiation by activating specific molecular pathways, achieved through embedding biomolecules within the scaffold or through the scaffold's material composition and structure alone. These innovations hold promise in therapeutic applications across various diseases, including cancer stem cell targeting, neurodegenerative disorders, pre-eclampsia, cardiovascular conditions, and organoid development. This review examines recent advancements in the field, explores potential applications like biosensors and nanochips, and highlights the challenges and research gaps.

Nanomaterials in Organoids: From Interactions to Personalized Medicine

Organoids are three-dimensional models of microscopic organisms created through the self-organization of various types of stem cells. They are widely unitized in personalized medicine due to their capacity to replicate the structure and functionality of native organs. Meanwhile, nanotechnology has been integrated into diagnostic and therapeutic tools to manage an array of medical conditions, given its unique characteristics of nanoscale. Nanomaterials have demonstrated potential in developing innovative and effective organoids. With a focus on studying the interaction of nanomaterials and organoid technology in personalized medicine, this Review examines the role of nanomaterials in regulating the fate of stem cells to construct different types of organoids. It also explores the potential of nanotechnology to create 3D microenvironments for organoids. Finally, perspectives and challenges of applying nanotechnology for organoids development toward the translation of personalized medicine are discussed.

Electrospun nanofibrous membranes meet antibacterial nanomaterials: From preparation strategies to biomedical applications

Electrospun nanofibrous membranes (eNFMs) have been extensively developed for bio-applications due to their structural and compositional similarity to the natural extracellular matrix. However, the emergence of antibiotic resistance in bacterial infections significantly impedes the further development and applications of eNFMs. The development of antibacterial nanomaterials substantially nourishes the engineering design of antibacterial eNFMs for combating bacterial infections without relying on antibiotics. Herein, a comprehensive review of diverse fabrication techniques for incorporating antibacterial nanomaterials into eNFMs is presented, encompassing an exhaustive introduction to various nanomaterials and their bactericidal mechanisms. Furthermore, the latest achievements and breakthroughs in the application of these antibacterial eNFMs in tissue regenerative therapy, mainly focusing on skin, bone, periodontal and tendon tissues regeneration and repair, are systematically summarized and discussed. In particular, for the treatment of skin infection wounds, we highlight the antibiotic-free antibacterial therapy strategies of antibacterial eNFMs, including (i) single model therapies such as metal ion therapy, chemodynamic therapy, photothermal therapy, and photodynamic therapy; and (ii) multi-model therapies involving arbitrary combinations of these single models. Additionally, the limitations, challenges and future opportunities of antibacterial eNFMs in biomedical applications are also discussed. We anticipate that this comprehensive review will provide novel insights for the design and utilization of antibacterial eNFMs in future research.

Oxidative stress modulating nanomaterials and their biochemical roles in nanomedicine

Many pathological conditions are predominantly associated with oxidative stress, arising from reactive oxygen species (ROS); therefore, the modulation of redox activities has been a key strategy to restore normal tissue functions. Current approaches involve establishing a favorable cellular redox environment through the administration of therapeutic drugs and redox-active nanomaterials (RANs). In particular, RANs not only provide a stable and reliable means of therapeutic delivery but also possess the capacity to finely tune various interconnected components, including radicals, enzymes, proteins, transcription factors, and metabolites. Here, we discuss the roles that engineered RANs play in a spectrum of pathological conditions, such as cancer, neurodegenerative diseases, infections, and inflammation. We visualize the dual functions of RANs as both generator and scavenger of ROS, emphasizing their profound impact on diverse cellular functions. The focus of this review is solely on inorganic redox-active nanomaterials (inorganic RANs). Additionally, we deliberate on the challenges associated with current RANs-based approaches and propose potential research directions for their future clinical translation.

How Is Bone Regeneration Influenced by Polymer Membranes? Insight into the Histological and Radiological Point of View in the Literature

The aim of this study was to analyze published works that investigate the in vivo bone regeneration capacity of polymeric membranes loaded with active substances and growth factors. This scoping review's purpose was to highlight the histological and radiological interpretation of the locally produced effects of the polymer membranes studied so far. For the selection of the articles, a search was made in the PubMed and ScienceDirect databases, according to the PRISMA algorithm, for research/clinical trial type studies. The search strategy was represented by the formula "((biodegradable scaffolds AND critical bone defect) OR (polymers AND mechanical properties) OR (3Dmaterials AND cytotoxicity) AND bone tissue regeneration)" for the PubMed database and "((biodegradable scaffolds AND polymers) OR (polymers AND critical bone defects) OR (biodegradable scaffolds AND mechanical properties) AND bone tissue regeneration)" for the ScienceDirect database. Ethical approval was not required. Eligibility criteria included eight clinical studies published between 2018 and 2023. Our analysis showed that polymer membranes that met most histopathological criteria also produced the most remarkable results observed radiologically. The top effective scaffolds were those containing active macromolecules released conditionally and staged. The PLGA and polycaprolactone scaffolds were found in this category; they granted a marked increase in bone density and improvement of osteoinduction. But, regardless of the membrane composition, all membranes implanted in created bone defects induced an inflammatory response in the first phase.

Interface properties of nanostructured carbon-coated biological implants: an overview

The interfaces between medical implants and living tissues are of great complexity because of the simultaneous occurrence of a wide variety of phenomena. The engineering of implant surfaces represents a crucial challenge in material science, but the further improvement of implant properties remains a critical task. It can be achieved through several processes. Among them, the production of specialized coatings based on carbon-based materials stands very promising. The use of carbon coatings allows one to simultaneously fine-tune tribological, mechanical, and chemical properties. Here, we review applications of nanostructured carbon coatings (nanodiamonds, carbon nanotubes, and graphene-related materials) for the improvement of the overall properties of medical implants. We are focusing on biological interactions, improved corrosion resistance, and overall mechanical properties, trying to provide a complete overview within the field.

A novel bi-layered asymmetric membrane incorporating demineralized dentin matrix accelerates tissue healing and bone regeneration in a rat skull defect model

Objectives: The technique of guided bone regeneration (GBR) has been widely used in the field of reconstructive dentistry to address hard tissue deficiency. The objective of this research was to manufacture a novel bi-layered asymmetric membrane that incorporates demineralized dentin matrix (DDM), a bioactive bone replacement derived from dentin, in order to achieve both soft tissue isolation and hard tissue regeneration simultaneously. Methods: DDM particles were harvested from healthy, caries-free permanent teeth. The electrospinning technique was utilized to synthesize bi-layered DDM-loaded PLGA/PLA (DPP) membranes. We analyzed the DPP bilayer membranes' surface topography, physicochemical properties and degradation ability. Rat skull critical size defects (CSDs) were constructed to investigate in vivo bone regeneration. Results: The synthesized DPP bilayer membranes possessed suitable surface characteristics, acceptable mechanical properties, good hydrophilicity, favorable apatite forming ability and suitable degradability. Micro-computed tomography (CT) showed significantly more new bone formation in the rat skull defects implanted with the DPP bilayer membranes. Histological evaluation further revealed that the bone was more mature with denser bone trabeculae. In addition, the DPP bilayer membrane significantly promoted the expression of the OCN matrix protein in vivo. Conclusions: The DPP bilayer membranes exhibited remarkable biological safety and osteogenic activity in vivo and showed potential as a prospective candidate for GBR applications in the future.

Comparison of the osteogenic potential of fibroblasts from different sources

OBJECTIVE

With the growing interest in the role of fibroblasts in osteogenesis, this study presents a comparative evaluation of the osteogenic potential of fibroblasts derived from three distinct sources: human gingival fibroblasts (HGFs), mouse embryonic fibroblasts (NIH3T3 cells), and mouse subcutaneous fibroblasts (L929 cells). MC3T3-E1 pre-osteoblast cells were employed as a positive control for osteogenic behavior.

DESIGN

Our assessment involved multiple approaches, including vimentin staining for cell origin verification, as well as ALP and ARS staining in conjunction with RT-PCR for osteogenic characterization.

RESULTS

Our findings revealed the superior osteogenic differentiation capacity of HGFs compared to MC3T3-E1 and NIH3T3 cells. Analysis of ALP staining confirmed that early osteogenic differentiation was most prominent in MC3T3-E1 cells at 7 days, followed by NIH3T3 and HGFs. However, ARS staining at 21 days demonstrated that HGFs produced the highest number of calcified nodules, indicating their robust potential for late-stage mineralization. This late-stage osteogenic potential of HGFs was further validated through RT-PCR analysis. In contrast, L929 cells displayed no significant osteogenic differentiation potential.

CONCLUSIONS

In light of these findings, HGFs emerge as the preferred choice for seed cells in bone tissue engineering applications. This study provides valuable insights into the potential utility of HGFs in the fields of bone tissue engineering and regenerative medicine.

Recent advances of nanoparticles on bone tissue engineering and bone cells

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

Construction of chitosan-gelatin polysaccharide-protein composite hydrogel via mechanical stretching and its biocompatibility in vivo

Natural polysaccharides and protein macromolecules are the important components of extracellular matrix (ECM), but individual component generally exhibits weak mechanical property, limited biological function or strong immunogenicity in tissue engineering. Herein, gelatin (Gel) was deposited to the stretched (65 %) chitosan (CS) hydrogel substrates to fabricate the polysaccharide-protein CS-Gel-65 % composite hydrogels to mimic the natural component of ECM and improve the above deficiencies. CS hydrogel substrates under different stretching deformations exhibited tunable morphology, chemical property and wettability, having a vital influence on the secondary structures of deposited fibrous Gel protein, namely appearing with the decreased β-sheet content in stretched CS hydrogel. Gel also produced a more homogenous distribution on the stretched CS hydrogel substrate due to the unfolding of Gel and increased interactions between Gel and CS than on the unstretched substrate. Moreover, the polysaccharide-protein composite hydrogel possessed enhanced mechanical property and oriented structure via stretching-drying method. Besides, in vivo subcutaneous implantation indicated that the CS-Gel-65 % composite hydrogel showed lower immunogenicity, thinner fibrous capsule, better angiogenesis effect and increased M2/M1 of macrophage phenotype. Polysaccharide-protein CS-Gel-65 % composite hydrogel offers a novel material as a tissue engineering scaffold, which could promote angiogenesis and build a good immune microenvironment for the damaged tissue repair.

Efficient healing of diabetic wounds by MSC-EV-7A composite hydrogel via suppression of inflammation and enhancement of angiogenesis

Diabetes mellitus (DM) is characterized by prolonged hyperglycemia, impaired vascularization, and serious complications, such as blindness and chronic diabetic wounds. About 25% of patients with DM are estimated to encounter impaired healing of diabetic wounds, often leading to lower limb amputation. Multiple factors are attributed to the non-healing of diabetic wounds, including hyperglycaemia, chronic inflammation, and impaired angiogenesis. It is imperative to develop more efficient treatment strategies to tackle healing difficulties in diabetic wounds. Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) are promising for diabetic wound healing considering their anti-inflammatory, pro-angiogenic and pro-proliferative activities. A histone deacetylase 7 (HDAC7)-derived 7-amino-acid peptide (7A) was shown to be highly effective for angiogenesis. However, it has never been investigated whether MSC-EVs are synergistic with 7A for the healing of diabetic wounds. Herein, we propose that MSC-EVs can be combined with 7A to greatly promote diabetic wound healing. The combination of EVs and 7A significantly improved the migration and proliferation of skin fibroblasts. Moreover, EVs alone significantly suppressed LPS-induced inflammation in macrophages, and notably, the combination treatment showed an even better suppression effect. Importantly, the in vivo study revealed that the combination therapy consisting of EVs and 7A in an alginate hydrogel was more efficient for the healing of diabetic wounds in rats than monotherapy using either EV or 7A hydrogels. The underlying mechanisms include suppression of inflammation, improvement of skin cell proliferation and migration, and enhanced collagen fiber disposition and angiogenesis in wounds. In summary, the MSC-EV-7A hydrogel potentially constitutes a novel therapy for efficient healing of chronic diabetic wounds.

Biomedical Applications of CNT-Based Fibers

Carbon nanotubes (CNTs) have been regarded as emerging materials in various applications. However, the range of biomedical applications is limited due to the aggregation and potential toxicity of powder-type CNTs. To overcome these issues, techniques to assemble them into various macroscopic structures, such as one-dimensional fibers, two-dimensional films, and three-dimensional aerogels, have been developed. Among them, carbon nanotube fiber (CNTF) is a one-dimensional aggregate of CNTs, which can be used to solve the potential toxicity problem of individual CNTs. Furthermore, since it has unique properties due to the one-dimensional nature of CNTs, CNTF has beneficial potential for biomedical applications. This review summarizes the biomedical applications using CNTF, such as the detection of biomolecules or signals for biosensors, strain sensors for wearable healthcare devices, and tissue engineering for regenerating human tissues. In addition, by considering the challenges and perspectives of CNTF for biomedical applications, the feasibility of CNTF in biomedical applications is discussed.

A Review on Carbon Nanotubes Family of Nanomaterials and Their Health Field

The use of carbon nanotubes (CNTs), which are nanometric materials, in pathogen detection, protection of environments, food safety, and in the diagnosis and treatment of diseases, as efficient drug delivery systems, is relevant for the improvement and advancement of pharmacological profiles of many molecules employed in therapeutics and in tissue bioengineering. It has contributed to the advancement of science due to the development of new tools and devices in the field of medicine. CNTs have versatile mechanical, physical, and chemical properties, in addition to their great potential for association with other materials to contribute to applications in different fields of medicine. As, for example, photothermal therapy, due to the ability to convert infrared light into heat, in tissue engineering, due to the mechanical resistance, flexibility, elasticity, and low density, in addition to many other possible applications, and as biomarkers, where the electronic and optics properties enable the transduction of their signals. This review aims to describe the state of the art and the perspectives and challenges of applying CNTs in the medical field. A systematic search was carried out in the indexes Medline, Lilacs, SciELO, and Web of Science using the descriptors "carbon nanotubes", "tissue regeneration", "electrical interface (biosensors and chemical sensors)", "photosensitizers", "photothermal", "drug delivery", "biocompatibility" and "nanotechnology", and "Prodrug design" and appropriately grouped. The literature reviewed showed great applicability, but more studies are needed regarding the biocompatibility of CNTs. The data obtained point to the need for standardized studies on the applications and interactions of these nanostructures with biological systems.

Carbon-based nanocomposites for biomedical applications

Carbon nanomaterials have attracted significant attention in the biomedical field, including for biosensing, drug delivery, and tissue engineering applications. Based on their inherent properties such as their unique structure and high conductivity, carbon nanomaterials can overcome the current limitations in biomedical research such as poor stability of biomolecules, low sensitivity and selectivity of biosensors, and difficulty in precise drug delivery. In addition, recently, several novel nanomaterials have been integrated with carbon nanomaterials to develop carbon-based nanocomposites for application in biomedical research. In this review, we discuss recent studies on carbon-based nanocomposites and their biomedical applications. First, we discuss the representative carbon nanomaterials and nanocomposites composed of carbon and other novel nanomaterials. Next, applications of carbon nanomaterials and nanocomposites in the biomedical field are discussed according to topics in the biomedical field. We have discussed the recent studies on biosensors, drug delivery, and tissue engineering. In conclusion, we believe that this review provides the potential and applicability of carbon nanomaterials and their nanocomposites and suggests future directions of the application of carbon-based nanocomposites in biomedical applications.

Research progress of vascularization strategies of tissue-engineered bone

The bone defect caused by fracture, bone tumor, infection, and other causes is not only a problematic point in clinical treatment but also one of the hot issues in current research. The development of bone tissue engineering provides a new way to repair bone defects. Many animal experimental and rising clinical application studies have shown their excellent application prospects. The construction of rapid vascularization of tissue-engineered bone is the main bottleneck and critical factor in repairing bone defects. The rapid establishment of vascular networks early after biomaterial implantation can provide sufficient nutrients and transport metabolites. If the slow formation of the local vascular network results in a lack of blood supply, the osteogenesis process will be delayed or even unable to form new bone. The researchers modified the scaffold material by changing the physical and chemical properties of the scaffold material, loading the growth factor sustained release system, and combining it with trace elements so that it can promote early angiogenesis in the process of induced bone regeneration, which is beneficial to the whole process of bone regeneration. This article reviews the local vascular microenvironment in the process of bone defect repair and the current methods of improving scaffold materials and promoting vascularization.

Double hits with bioactive nanozyme based on cobalt-doped nanoglass for acute and diabetic wound therapies through anti-inflammatory and pro-angiogenic functions

Regeneration of pathological wounds, such as diabetic ulcers, poses a significant challenge in clinical settings, despite the widespread use of drugs. To overcome clinical side effects and complications, drug-free therapeutics need to be developed to promote angiogenesis while overcoming inflammation to restore regenerative events. This study presents a novel bioactive nanozyme based on cobalt-doped nanoglass (namely, CoNZ), which exhibits high enzymatic/catalytic activity while releasing therapeutic ions. Cobalt oxide "Co3O4" tiny crystallites produced in situ through a chemical reaction with H2O2 within CoNZ nanoparticles play a crucial role in scavenging ROS. Results showed that CoNZ-treatment to full-thickness skin wounds in mice significantly accelerated the healing process, promoting neovascularization, matrix deposition, and epithelial lining while reducing pro-inflammatory signs. Notably, CoNZ was highly effective in treating pathological wounds (streptozotocin-induced diabetic wounds). Rapid scavenging of ROS by CoNZ and down-regulation of pro-inflammatory markers while up-regulating tissue healing signs with proliferative cells and activated angiogenic factors contributed to the observed healing events. In vitro experiments involving CoNZ-cultures with macrophages and endothelial cells exposed to high glucose and ROS-generating conditions further confirmed the effectiveness of CoNZ. CoNZ-promoted angiogenesis was attributed to the release of cobalt ions, as evidenced by the comparable effects of CoNZ-extracted ionic medium in enhancing endothelial migration and tubule formation via activated HIF-1α. Finally, we compared the in vivo efficacy of CoNZ with the clinically-available drug deferoxamine. Results demonstrated that CoNZ was as effective as the drug in closing the diabetic wound, indicating the potential of CoNZ as a novel drug-free therapeutic approach.

Carbon nanotube nanocomposite scaffolds: advances in fabrication and applications for tissue regeneration and cancer therapy

Carbon nanotube (CNT) nanocomposite scaffolds have emerged as highly promising frameworks for tissue engineering research. By leveraging their intrinsic electrical conductivity and valuable mechanical properties, CNTs are commonly dispersed into polymers to create robust, electrically conductive scaffolds that facilitate tissue regeneration and remodeling. This article explores the latest progress and challenges related to CNT dispersion, functionalization, and scaffold printing techniques, including electrospinning and 3D printing. Notably, these CNT scaffolds have demonstrated remarkable positive effects across various cell culture systems, stimulating neuronal growth, promoting cardiomyocyte maturation, and facilitating osteocyte differentiation. These encouraging results have sparked significant interest within the regenerative medicine field, including neural, cardiac, muscle, and bone regenerations. However, addressing the concern of CNT cytotoxicity in these scaffolds remains critical. Consequently, substantial efforts are focused on exploring strategies to minimize cytotoxicity associated with CNT-based scaffolds. Moreover, researchers have also explored the intriguing possibility of utilizing the natural cytotoxic properties of CNTs to selectively target cancer cells, opening up promising avenues for cancer therapy. More research should be conducted on cutting-edge applications of CNT-based scaffolds through phototherapy and electrothermal ablation. Unlike drug delivery systems, these novel methodologies can combine 3D additive manufacturing with the innate physical properties of CNT in response to electromagnetic stimuli to efficiently target localized tumors. Taken together, the unique properties of CNT-based nanocomposite scaffolds position them as promising candidates for revolutionary breakthroughs in both regenerative medicine and cancer treatment. Continued research and innovation in this area hold significant promise for improving healthcare outcomes.

Conducting polymer-based scaffolds for neuronal tissue engineering

Neuronal tissue engineering has immense potential for treating neurological disorders and facilitating nerve regeneration. Conducting polymers (CPs) have emerged as a promising class of materials owing to their unique electrical conductivity and biocompatibility. CPs, such as poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-hexylthiophene) (P3HT), polypyrrole (PPy), and polyaniline (PANi), have been extensively explored for their ability to provide electrical cues to neural cells. These polymers are widely used in various forms, including porous scaffolds, hydrogels, and nanofibers, and offer an ideal platform for promoting cell adhesion, differentiation, and axonal outgrowth. CP-based scaffolds can also serve as drug delivery systems, enabling localized and controlled release of neurotrophic factors and therapeutic agents to enhance neural regeneration and repair. CP-based scaffolds have demonstrated improved neural regeneration, both in vitro and in vivo, for treating spinal cord and peripheral nerve injuries. In this review, we discuss synthesis and scaffold processing methods for CPs and their applications in neuronal tissue regeneration. We focused on a detailed literature review of the central and peripheral nervous systems.

State-of-the-art polyetheretherketone three-dimensional printing and multifunctional modification for dental implants

Polyetheretherketone (PEEK) is a high-performance thermoplastic polymer with an elastic modulus close to that of the jawbone. PEEK has the potential to become a new dental implant material for special patients due to its radiolucency, chemical stability, color similarity to teeth, and low allergy rate. However, the aromatic main chain and lack of surface charge and chemical functional groups make PEEK hydrophobic and biologically inert, which hinders subsequent protein adsorption and osteoblast adhesion and differentiation. This will be detrimental to the deposition and mineralization of apatite on the surface of PEEK and limit its clinical application. Researchers have explored different modification methods to effectively improve the biomechanical, antibacterial, immunomodulatory, angiogenic, antioxidative, osteogenic and anti-osteoclastogenic, and soft tissue adhesion properties. This review comprehensively summarizes the latest research progress in material property advantages, three-dimensional printing synthesis, and functional modification of PEEK in the fields of implant dentistry and provides solutions for existing difficulties. We confirm the broad prospects of PEEK as a dental implant material to promote the clinical conversion of PEEK-based dental implants.

Attributes of Nanomaterials and Nanotopographies for Improved Bone Tissue Engineering and Regeneration

Bone tissue engineering (BTE) is a multidisciplinary area that can solve the limitation of conventional grafting methods by developing viable and biocompatible bone replacements. The three essential components of BTE, i.e., Scaffold material and Cells and Growth factors altogether, facilitate support and guide for bone formation, differentiation of the bone tissues, and enhancement in the cellular activities and bone regeneration. However, there is a scarcity of the appropriate materials that can match the mechanical property as well as functional similarity to native tissue, considering the bone as hard tissue. In such scenarios, nanotechnology can be leveraged upon to achieve the desired aspects of BTE, and that is the key point of this review article. This review article examines the significant areas of nanotechnology research that have an impact on regeneration of bone: (a) scaffold with nanomaterials helps to enhance physicochemical interactions, biocompatibility, mechanical stability, and attachment; (b) nanoparticle-based approaches for delivering bioactive chemicals, growth factors, and genetic material. The article begins with the introduction of components and healing mechanisms of bone and the factors associated with them. The focus of this article is on the various nanotopographies that are now being used in scaffold formation, by describing how they are made, and how these nanotopographies affect the immune system and potential underlying mechanisms. The advantages of 4D bioprinting in BTE by using nanoink have also been mentioned. Additionally, we have investigated the importance of an in silico approach for finding the interaction between drugs and their related receptors, which can help to formulate suitable systems for delivery. This review emphasizes the role of nanoscale approach and how it helps to increase the efficacy of parameters of scaffold as well as drug delivery system for tissue engineering and bone regeneration.

Three-Dimensional Bioprinting of Human Organs and Tissues: Bioethical and Medico-Legal Implications Examined through a Scoping Review

Three-dimensional bioprinting is a rapidly evolving technology that holds the promise of addressing the increasing demand for organs, tissues, and personalized medicine. By employing computer-aided design and manufacturing processes, 3D bioprinting allows for the precise deposition of living cells, biomaterials, and biochemicals to create functional human tissues and organs. The potential applications of this technology are vast, including drug testing and development, disease modeling, regenerative medicine, and ultimately, organ transplantation. However, as with any groundbreaking technology, 3D bioprinting presents several ethical, legal, and regulatory concerns that warrant careful consideration. As the technology progresses towards clinical applications, it is essential to address these challenges and establish appropriate frameworks to guide the responsible development of 3D bioprinting. This article, utilizing the Arksey and O'Malley scoping review model, is designed to scrutinize the bioethical implications, legal and regulatory challenges, and medico-legal issues that are intertwined with this rapidly evolving technology.

Tubular nanomaterials for bone tissue engineering

Nanomaterial composition, morphology, and mechanical performance are critical parameters for tissue engineering. Within this rapidly expanding space, tubular nanomaterials (TNs), including carbon nanotubes (CNTs), titanium oxide nanotubes (TNTs), halloysite nanotubes (HNTs), silica nanotubes (SiNTs), and hydroxyapatite nanotubes (HANTs) have shown significant potential across a broad range of applications due to their high surface area, versatile surface chemistry, well-defined mechanical properties, excellent biocompatibility, and monodispersity. These include drug delivery vectors, imaging contrast agents, and scaffolds for bone tissue engineering. This review is centered on the recent developments in TN-based biomaterials for structural tissue engineering, with a strong focus on bone tissue regeneration. It includes a detailed literature review on TN-based orthopedic coatings for metallic implants and composite scaffolds to enhance in vivo bone regeneration.

Early In Vivo Osteogenic and Inflammatory Response of 3D Printed Polycaprolactone/Carbon Nanotube/Hydroxyapatite/Tricalcium Phosphate Composite Scaffolds

The development of advanced biomaterials and manufacturing processes to fabricate biologically and mechanically appropriate scaffolds for bone tissue is a significant challenge. Polycaprolactone (PCL) is a biocompatible and degradable polymer used in bone tissue engineering, but it lacks biofunctionalization. Bioceramics, such as hydroxyapatite (HA) and β tricalcium phosphate (β-TCP), which are similar chemically to native bone, can facilitate both osteointegration and osteoinduction whilst improving the biomechanics of a scaffold. Carbon nanotubes (CNTs) display exceptional electrical conductivity and mechanical properties. A major limitation is the understanding of how PCL-based scaffolds containing HA, TCP, and CNTs behave in vivo in a bone regeneration model. The objective of this study was to evaluate the use of three-dimensional (3D) printed PCL-based composite scaffolds containing CNTs, HA, and β-TCP during the initial osteogenic and inflammatory response phase in a critical bone defect rat model. Gene expression related to early osteogenesis, the inflammatory phase, and tissue formation was evaluated using quantitative real-time PCR (RT-qPCR). Tissue formation and mineralization were assessed by histomorphometry. The CNT+HA/TCP group presented higher expression of osteogenic genes after seven days. The CNT+HA and CNT+TCP groups stimulated higher gene expression for tissue formation and mineralization, and pro- and anti-inflammatory genes after 14 and 30 days. Moreover, the CNT+TCP and CNT+HA/TCP groups showed higher gene expressions related to M1 macrophages. The association of CNTs with ceramics at 10wt% (CNT+HA/TCP) showed lower expressions of inflammatory genes and higher osteogenic, presenting a positive impact and balanced cell signaling for early bone formation. The association of CNTs with both ceramics promoted a minor inflammatory response and faster bone tissue formation.

The combined use of carbon nanotubes with synthetic ceramics enhances posterolateral fusion: an experimental study in a rat spinal fusion model

PURPOSE

The aim of the present study was to evaluate the effectiveness of carbon nanotubes (CNTs)/ HA-tricalcium phosphate (TCP) composite in a posterolateral spinal fusion model.

METHODS

At first, CNTs and CNTs/HA-TCP composites were prepared. Twenty adult male Sprague Dawley rats were randomized into four groups with five rats in each group. Decortication was carried out in standard manner in all animals. Group 1 (only decortication), group 2 (CNTs), group 3 (HA-TCP) and group 4 (CNTs/HA-TCP) were formed. Eight weeks later, all animals were killed and obtained fusion segments were evaluated by manual palpation, histomorphometry and micro-computed tomography (mCT).

RESULTS

In all evaluations, highest fusion values were obtained in Group 4. In mCT investigations, bone volume/ tissue volume (BV/TV) ratio was found to be significantly higher in composite group (group 4) only compared to ceramic group (group 3) (p < 0.001). Although in Group 2, in which only CNTs were used, the ratio was found to be statistically significantly higher than group 1(p < 0.001), the difference was not considered as significant in terms of fusion and in addition in group 2, CNTs were completely surrounded by fibrous tissue, i.e., no bone formation was observed.

CONCLUSIONS

The CNTs/HA-TCP composite is a promising synthetic bone graft substitute for spinal fusion. Although CNTs are inadequate in producing spinal fusion when they are used alone, due to their high biocompatibility due to their high biocompatibility, and multiple effect on bone regeneration, they seem to increase fusion rates significantly when they are used in combination with ceramic-based synthetic grafts.

Nanomaterial-Based Scaffolds for Tissue Engineering Applications: A Review on Graphene, Carbon Nanotubes and Nanocellulose

Nanoscale biomaterials have garnered immense interest in the scientific community in the recent decade. This review specifically focuses on the application of three nanomaterials, i.e., graphene and its derivatives (graphene oxide, reduced graphene oxide), carbon nanotubes (CNTs) and nanocellulose (cellulose nanocrystals or CNCs and cellulose nanofibers or CNFs), in regenerating different types of tissues, including skin, cartilage, nerve, muscle and bone. Their excellent inherent (and tunable) physical, chemical, mechanical, electrical, thermal and optical properties make them suitable for a wide range of biomedical applications, including but not limited to diagnostics, therapeutics, biosensing, bioimaging, drug and gene delivery, tissue engineering and regenerative medicine. A state-of-the-art literature review of composite tissue scaffolds fabricated using these nanomaterials is provided, including the unique physicochemical properties and mechanisms that induce cell adhesion, growth, and differentiation into specific tissues. In addition, in vitro and in vivo cytotoxic effects and biodegradation behavior of these nanomaterials are presented. We also discuss challenges and gaps that still exist and need to be addressed in future research before clinical translation of these promising nanomaterials can be realized in a safe, efficacious, and economical manner.

Towards a Material-by-Design Approach to Electrospun Scaffolds for Tissue Engineering Based on Statistical Design of Experiments (DOE)

Electrospinning bears great potential for the manufacturing of scaffolds for tissue engineering, consisting of a porous mesh of ultrafine fibers that effectively mimic the extracellular matrix (ECM) and aid in directing stem cell fate. However, for engineering purposes, there is a need to develop material-by-design approaches based on predictive models. In this methodological study, a rational methodology based on statistical design of experiments (DOE) is discussed in detail, yielding heuristic models that capture the linkage between process parameters (Xs) of the electrospinning and scaffold properties (Ys). Five scaffolds made of polycaprolactone are produced according to a 2²-factorial combinatorial scheme where two Xs, i.e., flow rate and applied voltage, are varied between two given levels plus a center point. The scaffolds were characterized to measure a set of properties (Ys), i.e., fiber diameter distribution, porosity, wettability, Young's modulus, and cell adhesion on murine myoblast C1C12 cells. Simple engineering DOE models were obtained for all Ys. Each Y, for example, the biological response, can be used as a driver for the design process, using the process-property model of interest for accurate interpolation within the design domain, enabling a material-by-design strategy and speeding up the product development cycle. The implications are also illustrated in the context of the design of multilayer scaffolds with microstructural gradients and controlled properties of each layer. The possibility of obtaining statistical models correlating between diverse output properties of the scaffolds is highlighted. Noteworthy, the featured DOE approach can be potentially merged with artificial intelligence tools to manage complexity and it is applicable to several fields including 3D printing.

A Novel Construct of Coral Granules-Poly-L-Lactic Acid Nanomembrane Sandwich Double Stem Cell Sheet Transplantation as Regenerative Therapy of Bone Defect Model

OBJECTIVES

We examined the use of a new approach in nanotechnology and stem cell research as regenerative therapy for bone tissue defects.

MATERIALS AND METHODS

We compared in vitro osteogenic potential of human Wharton jelly mesenchymal stem cells using coral granules and poly-L-lactic acid nanofiber according to proliferation (by cck-8 kit) and osteogenes (runt-related transcription factor 2, alkaline phosphatase, osteonectin) by quantitative reverse transcription-polymerase chain reaction, alkaline phosphatase assay, calcium measurement, and assessment of mineralization by Alizarin red and von Kossa staining. To overcome the limitations of natural coral, we made a modification by packaging the coral granules-human Wharton jelly mesenchymal stem cells by nanomembrane-human Wharton jelly mesenchymal stem cells to form sandwich double cell sheets and compared this hole with other holes (one was filled by human Wharton jelly mesenchymal stem cell suspension, and the other was filled by coral granules saturated with preinduced mesenchymal stem cells) by radiological and histopathological studies for repairing the bone gap.

RESULTS

Collagen-coated poly-L-lactic acid showed higher mRNA levels for all osteogenes (P < .001), higher alkaline phosphatase and calcium content (P < .001), and greater stainability. Our in vivo experiment showed that the holes implanted with sandwich double cell sheet-poly-L-lactic acid coral were completely filled mature compact bone. The holes implanted with human Wharton jelly mesenchymal stem cells alone were filled with immature compact bone. Holes implanted with coral granules-human Wharton jelly mesenchymal stem cells were filled with condensed connective tissue.

CONCLUSIONS

Poly-L-lactic acid nanofiber has greater osteogenic differentiating effect than the coral granules. The new approach of sDCS-PLLA-coral construct proved success for bone regeneration and repairing the bone gap and this may improve the design of tissue constructs for bone tissue regenerative therapy.

Random and aligned electrostatically spun PLLA nanofibrous membranes enhance bone repair in mouse femur midshaft defects

Long-segment bone defects are a common clinical challenge and abstract biomaterials are a promising therapy. Poly-L-lactic acid (PLLA) nanofibrous membranes prepared by electrostatic spinning have a good bone repair potential. However, there are random and aligned surface morphologies of electrostatic spun PLLA nanofibrous membranes, which can affect the migration, proliferation, and differentiation ability of cells. The role of surface morphology in the repair of long bone defects in vivo is currently unknown. In this study, random and aligned electrostatically spun PLLA nanofibrous membranes were prepared, characterised, and implanted into a femur midshaft defect mouse model. The ability of electrostatically spun PLLA nanofibrous membranes to enhance bone repair was tested using X-ray photography, high-resolution micro-computed tomography (micro-CT), and pathological section specimens. The results showed that both random and aligned electrostatically spun PLLA nanofibrous membranes enhanced bone regeneration at bone defects, but the aligned ones exhibited superior results. These results provide a theoretical basis for engineering the surface morphology of bone repair materials.

Enhanced osteogenesis by addition of cancellous bone chips at xenogenic bone augmentation: In vitro and in vivo experiments

OBJECTIVES

To investigate and compare the influence of deproteinized bovine bone mineral (DBBM) combined with autologous cortical (CorBC) or cancellous bone chips (CanBC) as bone grafts on guided bone regeneration (GBR) in vivo and in vitro.

MATERIALS AND METHODS

Defects were created in the mandibular buccal alveolar ridges in dogs and randomly filled with 3 groups of bone grafts: DBBM, DBBM + CorBC, or DBBM + CanBC. Osteogenesis was evaluated by sequential fluorescent labeling and histological analysis. Moreover, rat bilateral calvaria defects were randomly grafted with DBBM, DBBM + CorBC, or DBBM + CanBC. A blank group was included as control. Defect healing was assessed by histological staining, micro-CT, and quantitative polymerase chain reaction. In vitro migration, proliferation, and osteogenic differentiation assays were performed by stimulating rat bone marrow mesenchymal stem cells (rBMSCs) with cortical (CorBCM) or cancellous bone conditioned medium (CanBCM) to unveil the cellular mechanism.

RESULTS

In the canine model, the augmented sites of DBBM + CanBC exhibited higher mineralized tissue proportion than the other two groups (DBBM: 0.61 ± 0.03 versus DBBM + CorBC: 0.69 ± 0.07 versus DBBM + CanBC: 0.86 ± 0.06; p < .05). In the rat model, the BV/TV value of DBBM + CanBC (0.51 ± 0.01) was higher than those of DBBM + CorBC (0.41 ± 0.02), DBBM (0.31 ± 0.01), and Control (0.10 ± 0.01; p < .01). Further radiological, histological and transcriptional results showed similar trends. In vitro experiments revealed that CorBCM and especially CanBCM could enhance rBMSCs migration, proliferation, and osteogenic differentiation.

CONCLUSION

In vivo and in vitro experiments verified favorable synergistic effect of mixing autologous bone chips with DBBM on osteogenesis. Furthermore, CanBC presented more powerful osteogenic effect than CorBC.

Nanoceria-GO-intercalated multicellular spheroids revascularize and salvage critical ischemic limbs through anti-apoptotic and pro-angiogenic functions

Critical limb ischemia (CLI) is a serious form of peripheral arterial disease that involves severe blockage of blood flow in lower extremities, often leading to foot necrosis and limb loss. Lack of blood flow and high pro-inflammation with overproduced reactive oxygen species (ROS) in CLI aggravate the degenerative events. Among other therapies, cell delivery is considered potential for restoring regenerative capacity, and preservation of cell survival under high oxidative stress has been challenging and prerequisite to harness cellular functions. Here, we introduce a multicellular delivery system that is intercalated with nanoceria-decorated graphene oxide (CeGO), which is considered to have high ROS scavenging ability while providing cell-matrix interaction signals. The CeGO nano-microsheets (8-nm-nanoceria/0.9-μm-GO) incorporated in HUVEC/MSC (7/3) could form cell-material hybrid spheroids mediated by cellular contraction. Under in vitro oxidative-stress-challenge with H₂O₂, the CeGO-intercalation enhanced the survival and anti-apoptotic capacity of cellular spheroids. Pro-angiogenic events of cellular spheroids, including cell sprouting and expression of angiogenic markers (HIF1α, VEGF, FGF2, eNOS) were significantly enhanced by the CeGO-intercalation. Proteomics analysis also confirmed substantial up-regulation of a series of angiogenesis-related secretome molecules. Such pro-angiogenic events with CeGO-intercalation were proven to be mediated by the APE/Ref-1 signaling pathway. When delivered to ischemic hindlimb in mice, the CeGO-cell spheroids could inhibit the accumulation of in vivo ROS rapidly, preserving high cell survival rate (cells were more proliferative and less apoptotic vs. those in cell-only spheroids), and up-regulated angiogenic molecular expressions. Monitoring over 28 days revealed significantly enhanced blood reperfusion and tissue recovery, and an ultimate limb salvage with the CeGO-cell delivery (∼60% salvaged vs. ∼29% in cell-only delivery vs. 0% in ischemia control). Together, the CeGO intercalated in HUVEC/MSC delivery is considered a potential nano-microplatform for CLI treatment, by scavenging excessive ROS and enhancing transplanted cell survival, while stimulating angiogenic events, which collectively help revascularization and tissue recovery, salvaging critical ischemic limbs.

RRBP1 depletion of bone metastatic cancer cells contributes to enhanced expression of the osteoblastic phenotype

Bone metastatic cancer-secreted extracellular factors are capable of modifying the bone microenvironment through interacting with bone cells, including osteoblasts. Reticulum ribosome-binding protein 1 (RRBP1) is substantially expressed in certain bone metastatic cancer cells. This study was undertaken to determine whether RRBP1 from bone metastatic cancer cells affects the osteoblastic phenotype expression. Breast and prostate cancer cells, MDA-MB-231 and PC3, were cultured, respectively, followed by collecting conditioned mediums (CMs) and identifying the abundance of RRBP1 in CMs using LC-MS/MS. MC3T3-E1 cells were cultured with a mixed medium (including CMs from shRRBP1-transduced two-type cancer cells) with or without endoplasmic reticulum (ER) stress inhibitor 4-PBA, followed by measuring the levels of osteoblastic phenotype expression and biomarkers of ER stress using western blotting, qPCR, and ARS staining, respectively. Similar experiments were performed in shRrbp1-transduced MC3T3-E1 cells cultured with a mixed medium (including CMs from the two-type cancer cells). Bone formation parameters were measured in the tibia of nude mice injected with shRRBP1-transduced two-type cancer cells using micro-CT analysis. These results showed that RRBP1 is the sole shared high-abundance protein in CMs from the two-type cancer cells, involving osteoblast differentiation. CMs from shRRBP1-transduced two-type cells boosted the osteoblastic phenotype expression partially through increasing ER stress. CMs from the two-type cancer cells partially offset the similar alterations induced by shRrbp1 in MC3T3-E1 cells. Injection with shRRBP1-transduced two-type cells ameliorated the bone lesions in nude mice. Therefore, RRBP1 depletion of bone metastatic cancer enhanced the osteoblastic phenotype expression, suggesting a role of RRBP1 in the bone microenvironment.

Diabetic bone regeneration with nanoceria-tailored scaffolds by recapitulating cellular microenvironment: Activating integrin/TGF-β co-signaling of MSCs while relieving oxidative stress

Regenerating defective bone in patients with diabetes mellitus remains a significant challenge due to high blood glucose level and oxidative stress. Here we aim to tackle this issue by means of a drug- and cell-free scaffolding approach. We found the nanoceria decorated on various types of scaffolds (fibrous or 3D-printed one; named nCe-scaffold) could render a therapeutic surface that can recapitulate the microenvironment: modulating oxidative stress while offering a nanotopological cue to regenerating cells. Mesenchymal stem cells (MSCs) recognized the nanoscale (tens of nm) topology of nCe-scaffolds, presenting highly upregulated curvature-sensing membrane protein, integrin set, and adhesion-related molecules. Osteogenic differentiation and mineralization were further significantly enhanced by the nCe-scaffolds. Of note, the stimulated osteogenic potential was identified to be through integrin-mediated TGF-β co-signaling activation. Such MSC-regulatory effects were proven in vivo by the accelerated bone formation in rat calvarium defect model. The nCe-scaffolds further exhibited profound enzymatic and catalytic potential, leading to effectively scavenging reactive oxygen species in vivo. When implanted in diabetic calvarium defect, nCe-scaffolds significantly enhanced early bone regeneration. We consider the currently-exploited nCe-scaffolds can be a promising drug- and cell-free therapeutic means to treat defective tissues like bone in diabetic conditions.

Biocompatibility Assessment of Two Commercial Bone Xenografts by In Vitro and In Vivo Methods

Bone substitutes based on xenografts have been used for a long time in bone regeneration thanks to their inductive capacity for bone tissue regeneration. Some bone-based scaffolds have been modified by adding collagen and other proteins to improve their regenerative capacity and prevent migration and aggregation, especially particles. However, rejection of this graft has been reported due to protein residues caused by poor material preparation. We compared the in vitro and in vivo biological response of two commercial xenografts (InterOss^®, F1 and InterOss^® Collagen, F2) and a commercial porcine collagen membrane (InterCollagen^® Guide, F3) as a rapid degradation control. Fourier Transform Infrared Spectroscopy (FT-IR) analysis evidenced the presence of hydroxyl, orthophosphate, and carbonate groups of the xenografts and amide groups of collagen. Thermogravimetric analysis (TGA) of the xenografts demonstrated their thermal stability and the presence of a few amounts of organic material. The study by differential scanning calorimetry showed the presence of endothermic peaks typical of the dehydration of the xenografts (F1 and F2) and for the collagen membrane (F3), the beginning of structural three-dimensional protein changes. Subsequently, in vitro biocompatibility tests were carried out for the materials with Artemia salina and MTT cell viability with HeLa cells, demonstrating the high biocompatibility of the materials. Finally, in vivo biocompatibility was studied by implanting xenografts in biomodels (Wistar rats) at different periods (30, 60, and 90 days). The F1 xenograft (InterOss) remained remarkably stable throughout the experiment (90 days). F2 (InterOss Collagen) presented a separation of its apatite and collagen components at 60 days and advanced resorption at 90 days of implantation. Finally, the collagen membrane (F3) presented faster resorption since, at 90 days, only some tiny fragments of the material were evident. All the in vivo and in vitro test results demonstrated the biocompatibility of the xenografts, demonstrating the potential of these materials for tissue engineering.

Single-Walled Carbon Nanotube Membranes Accelerate Active Osteogenesis in Bone Defects: Potential of Guided Bone Regeneration Membranes

Carbon nanotubes (CNTs) are potentially important biomaterials because of their chemical, physical, and biological properties. Our research indicates that CNTs exhibit high compatibility with bone tissue. The guided bone regeneration (GBR) technique is commonly applied to reconstruct alveolar bone and treat peri-implant bone defects. In GBR, bone defects are covered with a barrier membrane to prevent the entry of nonosteogenic cells such as epithelial cells and fibroblasts. The barrier membrane also maintains a space for new bone formation. However, the mechanical and biological properties of materials previously used in clinical practice sometimes delayed bone regeneration. In this study, we developed a CNT-based membrane for GBR exhibiting high strength to provide a space for bone formation and provide cellular shielding to induce osteogenesis. The CNT membrane was made via the dispersion of single-walled CNTs (SWCNTs) in hyaluronic acid solution followed by filtration. The CNT membrane assumed a nanostructure surface due to the bundled SWCNTs and exhibited high strength and hydrophilicity after oxidation. In addition, the membrane promoted the proliferation of osteoblasts but not nonosteogenic cells. CNT membranes were used to cover experimental bone defects made in rat calvaria. At 8 weeks after surgery, more extensive bone formation was observed in membrane-covered defects compared with bone defects not covered with membrane. Almost no diffusion of CNTs was observed around the membrane. These results indicate that the CNT membrane has adequate strength, stability, and surface characteristics for osteoblasts, and its shielding properties promote bone formation. Demonstration of the safety and osteogenic potential of the CNT membranes through further animal studies should facilitate their clinical application in GBR.

Bioactive Materials Promote Wound Healing through Modulation of Cell Behaviors

Skin wound repair is a multistage process involving multiple cellular and molecular interactions, which modulate the cell behaviors and dynamic remodeling of extracellular matrices to maximize regeneration and repair. Consequently, abnormalities in cell functions or pathways inevitably give rise to side effects, such as dysregulated inflammation, hyperplasia of nonmigratory epithelial cells, and lack of response to growth factors, which impedes angiogenesis and fibrosis. These issues may cause delayed wound healing or even non-healing states. Current clinical therapeutic approaches are predominantly dedicated to preventing infections and alleviating topical symptoms rather than addressing the modulation of wound microenvironments to achieve targeted outcomes. Bioactive materials, relying on their chemical, physical, and biological properties or as carriers of bioactive substances, can affect wound microenvironments and promote wound healing at the molecular level. By addressing the mechanisms of wound healing from the perspective of cell behaviors, this review discusses how bioactive materials modulate the microenvironments and cell behaviors within the wounds during the stages of hemostasis, anti-inflammation, tissue regeneration and deposition, and matrix remodeling. A deeper understanding of cell behaviors during wound healing is bound to promote the development of more targeted and efficient bioactive materials for clinical applications.

Surface-Engineered Hybrid Gelatin Methacryloyl with Nanoceria as Reactive Oxygen Species Responsive Matrixes for Bone Therapeutics

Designing various transplantable biomaterials, especially nanoscale matrixes for bone regeneration, involves precise tuning of topographical features. The cellular fate on such engineered surfaces is highly influenced by many factors imparted by the surface modification (hydrophilicity, stiffness, porosity, roughness, ROS responsiveness). Herein, hybrid matrixes of gelatin methacryloyl (GelMA) decorated with uniform layers of nanoceria (nCe), called Ce@GelMA, were developed without direct incorporation of nCe into the scaffolds. The fabrication involves a simple base-mediated in situ deposition in which uniform nCe coatings were first made on GelMA hydrogels and then nCe layered GelMA scaffolds were made by cryodesiccation. In this hybrid platform, degradable GelMA biopolymer provides the porous microstructure and nCe provides the nanoscaled biointerface. The surface morphology and elemental composition of the matrixes analyzed by field emission scanning electron microscopy (FE-SEM) and energy-dispersive spectroscopy (EDS) show uniform nCe distribution. The surface nanoroughness and chemistry of the matrixes were also characterized using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The presence of nCe on GelMA enhanced its mechanical properties as confirmed by compressive modulus analysis. Substantial bonelike nanoscale hydroxyapatite formation was observed on scaffolds after simulated body fluid (SBF) immersion, which was confirmed by SEM, X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. Moreover, the developed scaffolds could also be used as an antioxidant matrix owing to the reactive oxygen species (ROS) scavenging property of nCe as assessed by 3,3',5,5'-tetramethylbenzidine (TMB) assay. The enhanced proliferation and viability of rat bone marrow mesenchymal stem cells (rMSCs) on the scaffold surface after 3 days of culture ensures the biocompatibility of the proposed material. Considering all, it is proposed that the micro/nanoscaled matrix could mimic the composition and function of hard tissues and could be utilized as degradable scaffolds in engineering bones.

Nanoparticles: Excellent Materials Yet Dangerous When They Become Airborne

Since the rise and rapid development of nanoscale science and technology in the late 1980s, nanomaterials have been widely used in many areas including medicine, electronic products, crafts, textiles, and cosmetics, which have provided a lot of convenience to people's life. However, while nanomaterials have been fully utilized, their negative effects, also known as nano pollution, have become increasingly apparent. The adverse effects of nanomaterials on the environment and organisms are mainly based on the unique size and physicochemical properties of nanoparticles (NPs). NPs, as the basic unit of nanomaterials, generally refer to the ultrafine particles whose spatial scale are defined in the range of 1-100 nm. In this review, we mainly introduce the basic status of the types and applications of NPs, airborne NP pollution, and the relationship between airborne NP pollution and human diseases. There are many sources of airborne NP pollutants, including engineered nanoparticles (ENPs) and non-engineered nanoparticles (NENPs). The NENPs can be further divided into those generated from natural activities and those produced by human activities. A growing number of studies have found that exposure to airborne NP pollutants can cause a variety of illnesses, such as respiratory diseases, cardiovascular diseases, and neurological disorders. To deal with the ever increasing numbers and types of NPs being unleashed to the air, we believe that extensive research is needed to provide a comprehensive understanding of NP pollution hazards and their impact mechanisms. Only in this way can we find the best solution and truly protect the safety and quality of life of human beings.

Novel insights into nanomaterials for immunomodulatory bone regeneration

Bone defect repair caused by trauma, congenital malformation, tumors, infection or systemic diseases remains the focus of attention in regeneration medicine. Recent advances in osteoimmunology indicate that immune cells and correlative cytokines modulate the delicate balance between osteoblasts and osteoclasts and induce a favorable microenvironment for bone regeneration. With superior attributes that imitate the three-dimensional architecture of natural bone, excellent fabricability, mechanical and biological properties, nanomaterials (NMs) are becoming attractive in the field of bone tissue engineering. Particularly, it could be an effective strategy for immunomodulatory bone regeneration by engineering NMs involved in composition nature, nanoarchitectural morphology, surface chemistry, topography and biological molecules, whose mechanisms potentially refer to regulating the phenotype of high-plastic immune cells and inducing cytokine secretion to accelerate osteogenesis. Despite these prominent achievements, the employment of NMs is poorly translated into clinical trials due to the lack of knowledge about the interaction between NMs and the immune system. For this reason, we sketch out the hierarchical structure of bone and its natural healing process, followed by discussion about the effects of immune cells on bone regeneration. Novel horizons focusing on recent progressions in the architectural and physicochemical performances of NMs and their impacts on the body defence mechanism are also emphasized, hoping to provide novel insights for the fabrication of bone graft materials in tissue engineering.

Dental Applications of Carbon Nanotubes

Glass ionomer cements and resin-based composites are promising materials in restorative dentistry. However, their limited mechanical properties and the risk of bulk/marginal fracture compromise their lifespan. Intensive research has been conducted to understand and develop new materials that can mimic the functional behavior of the oral cavity. Nanotechnological approaches have emerged to treat oral infections and become a part of scaffolds for tissue regeneration. Carbon nanotubes are promising materials to create multifunctional platforms for dental applications. This review provides a comprehensive survey of and information on the status of this state-of-the-art technology and describes the development of glass ionomers reinforced with carbon nanotubes possessing improved mechanical properties. The applications of carbon nanotubes in drug delivery and tissue engineering for healing infections and lesions of the oral cavity are also described. The review concludes with a summary of the current status and presents a vision of future applications of carbon nanotubes in the practice of dentistry.

3D Printing of Thermoresponsive Hydrogel Laden with an Antimicrobial Agent towards Wound Healing Applications

Thermoresponsive hydrogel-based wound dressings with an incorporated antimicrobial agent can be fabricated employing 3D printing technology. A novel printable ink containing poly(N-isopropylacrylamide) (PNIPAAm) precursors, sodium alginate (ALG), methylcellulose (MC) that is laden with a mixture of octenidine dihydrochloride and 2-phenoxyethanol (Octenisept®, OCT) possess accurate printability and shape fidelity. This study also provides the protocol of ink's use for the 3D printing of hydrogel scaffolds. The hydrogel's physicochemical properties and drug release profiles from the hydrogel specimens to the external solution have been determined at two temperatures (20 and 37 °C). The release test showed a sustained OCT delivery into ultrapure water and the PBS solution. The temperature-responsive hydrogel exhibited antimicrobial activity against Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa and demonstrated non-cytotoxicity towards fibroblasts. The thermoresponsive behavior along with biocompatibility, antimicrobial activity, and controlled drug release make this hydrogel a promising class of materials for wound dressing applications.

Fabrication of Polyurethane/Polylactide (PU/PLDL) Nanofibers Using Electrospinning Method

Polylactide and aliphatic polyurethane are biodegradable synthetic polymers which are broadly used as biomaterials in regenerative medicine for implants and scaffolds for tissue engineering. In this paper, the detailed studies of the fabrication of the electrospun fibers of polyurethane/polylactide mixtures were described. The influence of the used solvent (dimethylformamide (DMF)) and diluents (acetone and dichloromethane (DCM)) on the rheological parameters and electrospinning of the described mixtures was examined. Rheological studies showed that polyure-thane/polylactide mixtures have mostly non-Newtonian character, strongly influenced by the diluent. Solutions containing 50 wt.% or more of polyurethane became less viscous after the addition of DCM or acetone, whereas those with bigger amount of polylactide showed higher viscosity after the addition of DCM and lower viscosity after the addition of acetone. Optimized electrospinning process has been elaborated. Fibers with diameters from 250 nm up to 1 µm have been produced and compared. Pure acetone worsened the electrospinning process, but the more DCM was in the mixture, the thinner and more aligned fibers were produced.

Microconvex Dot-Featured Silk Fibroin Films for Promoting Human Umbilical Vein Endothelial Cell Angiogenesis via Enhancing the Expression of bFGF and VEGF

Insufficient vascularization of grafts often leads to delayed tissue ingrowth and impaired tissue function in tissue engineering. The surface topography of grafts plays critical roles in angiogenesis. In the present study, we prepared silk fibroin (SF)-based microtopography films with the number of convex dots ranging from 37 to 4835/mm². The convex dot-featured topography surfaces were characterized by scanning electron microscopy, a Profilm3D optical profilometer, atomic force microscopy, and a contact angle goniometer. The effect of microtopographic films on the proliferation, adhesion, and expression of angiogenic factors of human umbilical vein endothelial cells (HUVECs) was investigated. Our results demonstrated that the SF film surface with 2899 convex dots/mm² significantly enhanced adhesion, viability, and levels of vascular endothelial growth factors and basic fibroblast growth factors of HUVECs and significantly downregulated the level of α-SMA in human aortic smooth muscle cells, indicating that the microtopographic films could promote angiogenesis. Furthermore, in vitro results showed that HUVEC proliferation was positively correlated with yes-associated protein (YAP) activation, suggesting that the enhanced angiogenesis was mediated via the YAP pathway. Finally, mice subcutaneous embedding model results indicated that the SF film surface with 2899 convex dots/mm² could significantly enhance angiogenesis in vivo. Altogether, our results showed that the SF film surface with 2899 convex dots/mm² promoted the angiogenesis of HUVECs and offered a novel angiogenesis-promoting strategy of implant surface design for tissue engineering.