Nanomaterials for Angiogenesis in Skin Tissue Engineering

Advances in graphene-based 2D materials for tendon, nerve, bone/cartilage regeneration and biomedicine

Two-dimensional (2D) materials, especially graphene-based materials, have important implications for tissue regeneration and biomedicine due to their large surface area, transport properties, ease of functionalization, biocompatibility, and adsorption capacity. Despite remarkable progress in the field of tissue regeneration and biomedicine, there are still problems such as unclear long-term stability, lack of in vivo experimental data, and detection accuracy. This paper reviews recent applications of graphene-based materials in tissue regeneration and biomedicine and discusses current issues and prospects for the development of graphene-based materials with respect to promoting the regeneration of tendons, neuronal cells, bone, chondrocytes, blood vessels, and skin, as well as applications in sensing, detection, anti-microbial activity, and targeted drug delivery.

Nanotechnology in tissue engineering: expanding possibilities with nanoparticles

Tissue engineering is a multidisciplinary field that merges engineering, material science, and medical biology in order to develop biological alternatives for repairing, replacing, maintaining, or boosting the functionality of tissues and organs. The ultimate goal of tissue engineering is to create biological alternatives for repairing, replacing, maintaining, or enhancing the functionality of tissues and organs. However, the current landscape of tissue engineering techniques presents several challenges, including a lack of suitable biomaterials, inadequate cell proliferation, limited methodologies for replicating desired physiological structures, and the unstable and insufficient production of growth factors, which are essential for facilitating cell communication and the appropriate cellular responses. Despite these challenges, there has been significant progress made in tissue engineering techniques in recent years. Nanoparticles hold a major role within the realm of nanotechnology due to their unique qualities that change with size. These particles, which provide potential solutions to the issues that are met in tissue engineering, have helped propel nanotechnology to its current state of prominence. Despite substantial breakthroughs in the utilization of nanoparticles over the past two decades, the full range of their potential in addressing the difficulties within tissue engineering remains largely untapped. This is due to the fact that these advancements have occurred in relatively isolated pockets. In the realm of tissue engineering, the purpose of this research is to conduct an in-depth investigation of the several ways in which various types of nanoparticles might be put to use. In addition to this, it sheds light on the challenges that need to be conquered in order to unlock the maximum potential of nanotechnology in this area.

From Bone Remodeling to Wound Healing: An miR-146a-5p-Loaded Nanocarrier Targets Endothelial Cells to Promote Angiogenesis

Wound healing is a complex challenge that demands urgent attention in the clinical realm. Efficient angiogenesis is a pivotal factor in promoting wound healing. microRNA-146a (miR-146a) inhibitor has angiogenic potential in the periodontal ligament. However, free microRNAs (miRNAs) are poorly delivered into cells due to their limited tissue specificity and low intracellular delivery efficiency. To address this hurdle, we developed a nanocarrier for targeted delivery of the miR-146a inhibitor into endothelial cells. It is composed of a polyethylenimine (PEI)-modified mesoporous silica nanoparticle (MSN) core and a pentapeptide (YIGSR) layer that recognizes endothelial cells. In vitro, we defined that the miR-146a inhibitor and adiponectin (ADP) can modulate angiogenesis and the remodeling of periodontal tissues by activating the ERK and Akt signaling pathways. Then, we confirm the specificity of YIGSR to endothelial cells, and importantly, the nanocarrier effectively delivers the miR-146a inhibitor into endothelial cells, promoting angiogenesis. In a C57 mouse skin wound model, the miR-146a inhibitor is successfully delivered into endothelial cells at the wound site using the nanocarrier, resulting in the formation of new blood vessels with strong CD31 expression. Additionally, no significant differences are found in the expression levels of inflammatory markers interleukin-6 and tumor necrosis factor-α. This outcome not only brings new strategies for angiogenesis but also exhibits broader implications for bone remodeling and wound healing. The breakthrough holds significance for future research and clinical interventions.

Plant-Derived Exosomes as Novel Nanotherapeutics Contrive Glycolysis Reprogramming-Mediated Angiogenesis for Diabetic Ulcer Healing

Reversal of endothelial cell (EC) dysfunction under high-glucose (HG) conditions to achieve angiogenesis has remained a big challenge in diabetic ulcers. Herein, exosomes derived from medicinal plant ginseng (GExos) were shown as excellent nanotherapeutics with biomimetic cell membrane-like structures to be able to efficiently transfer the encapsulated active substances to ECs, resulting in a marked reprogramming of glycolysis by up-regulating anaerobic glycolysis and down-regulating oxidative stress, which further restore the proliferation, migration, and tubule formation abilities of ECs under HG conditions. In vivo, GExos enhance the angiogenesis and nascent vessel network reconstruction in full-thickness diabetic complicated skin ulcer wounds in mice with high biosafety. GExos were shown as promising nanotherapeutics in stimulating glycolysis reprogramming-mediated angiogenesis in diabetic ulcers, possessing wide application potential for reversing hyperglycemic dysangiogenesis and stimulating vascular regeneration.

Healing with precision: A multi-functional hydrogel-bioactive glass dressing boosts infected wound recovery and enhances neurogenesis in the wound bed

Chronic skin wounds, especially infected ones, pose a significant clinical challenge due to their increasing incidence and poor outcomes. The deteriorative microenvironment in such wounds, characterized by reduced extracellular matrix, impaired angiogenesis, insufficient neurogenesis, and persistent bacterial infection, has prompted the exploration of novel therapeutic strategies. In this study, we developed an injectable multifunctional hydrogel (GEL/BG@Cu + Mg) incorporating Gelatin-Tannic acid/ N-hydroxysuccinimide functionalized polyethylene glycol and Bioactive glass doped with copper and magnesium ions to accelerate the healing of infected wounds. The GEL/BG@Cu + Mg hydrogel composite demonstrates good biocompatibility, degradability, and rapid formation of a protective barrier to stop bleeding. Synergistic bactericidal effects are achieved through the photothermal properties of BG@Cu + Mg and sustained copper ions release, with the latter further promoting angiogenesis. Furthermore, the hydrogel enhances neurogenesis by stimulating axons and Schwann cells in the wound bed through the beneficial effects of magnesium ions. Our results demonstrate that the designed novel multifunctional hydrogel holds tremendous promise for treating infected wounds and allowing regenerative neurogenesis at the wound site, which provides a viable alternative for further improving clinical outcomes.

A rapid interactive chitosan-based medium with antioxidant and pro-vascularization properties for infected burn wound healing

Large-pore hydrogels are better suited to meet the management needs of nutrient transportation and gas exchange between infected burn wounds and normal tissues. However, better construction strategies are required to balance the pore size and mechanical strength of hydrogels to construct a faster substance/gas interaction medium between tissues. Herein, we developed spongy large pore size hydrogel (CS-TA@Lys) with good mechanical properties using a simple ice crystal-assisted method based on chitosan (CS), incorporating tannic acid (TA) and ε-polylysine (Lys). A large-pore and mechanically robust hydrogel medium was constructed based on hydrogen bonding between CS molecules. On this basis, a pro-restorative functional platform with antioxidation and pro-vascularization was constructed using TA and Lys. In vitro experiments displayed that the CS-TA@Lys hydrogel possessed favorable mechanical properties and fast interaction performances. In addition, the CS-TA@Lys hydrogel possessed the capacity to remove intra/extracellular reactive oxygen species (ROS) and possessed antimicrobial and pro-angiogenic properties. In vivo experiments displayed that the CS-TA@Lys hydrogel inhibited wound inflammation and promoted wound vascularization. In addition, the CS-TA@Lys hydrogel showed the potential for rapid hemostasis. This study provides a potential functional wound dressing with rapid interaction properties for skin wound repair.

A Multifunctional Nanozyme Integrating Antioxidant, Antimicrobial and Pro-Vascularity for Skin Wound Management

Background

Skin wounds are a prevalent issue that can have severe health consequences if not treated correctly. Nanozymes offer a promising therapeutic approach for the treatment of skin wounds, owing to their advantages in regulating redox homeostasis to reduce oxidative damage and kill bacteria. These properties make them an effective treatment option for skin wounds. However, most of current nanozymes lack the capability to simultaneously address inflammation, oxidative stress, and bacterial infection during the wound healing process. There is still great potential for nanozymes to increase their therapeutic functional diversity and efficacy.

Methods

Herein, copper-doped hollow mesopores cerium oxide (Cu-HMCe) nanozymes with multifunctional of antioxidant, antimicrobial and pro-vascularity is successfully prepared. Cu-HMCe can be efficiently prepared through a simple and rapid solution method and displays sound physiological stability. The biocompatibility, pro-angiogenic, antimicrobial, and antioxidant properties of Cu-HMCe were assessed. Moreover, a full-thickness skin defect infection model was utilized to investigate the wound healing capacity, as well as anti-inflammatory and pro-angiogenic properties of nanozymes in vivo.

Results

Both in vitro and in vivo experiments have substantiated Cu-HMCe's remarkable biocompatibility. Moreover, Cu-HMCe possesses potent antioxidant enzyme-like catalytic activity, effectively clearing DPPH radicals (with a scavenging rate of 80%), hydroxyl radicals, and reactive oxygen species. Additionally, Cu-HMCe exhibits excellent antimicrobial and pro-angiogenic properties, with over 70% inhibition of both E. coli and S. aureus. These properties collectively promote wound healing, and the wound treated with Cu-HMCe achieved a closure rate of over 90% on the 14th day.

Conclusion

The results indicate that multifunctional Cu-HMCe with antioxidant, antimicrobial, and pro-angiogenic properties was successfully prepared and exhibited remarkable efficacy in promoting wound healing. This nanozymes providing a promising strategy for skin repair.

Advancements in wound healing: integrating biomolecules, drug delivery carriers, and targeted therapeutics for enhanced tissue repair

Wound healing, a critical biological process vital for tissue restoration, has spurred a global market exceeding $15 billion for wound care products and $12 billion for scar treatment. Chronic wounds lead to delayed or impaired wound healing. Natural bioactive compounds, prized for minimal side effects, stand out as promising candidates for effective wound healing. In response, researchers are turning to nanotechnology, employing the encapsulation of these agents into drug delivery carriers. Drug delivery system will play a crucial role in enabling targeted delivery of therapeutic agents to promote tissue regeneration and address underlying issues such as inflammation, infection, and impaired angiogenesis in chronic wound healing. Drug delivery carriers offer distinct advantages, exhibiting a substantial ratio of surface area to volume and altered physical and chemical properties. These carriers facilitate sustained and controlled release, proving particularly advantageous for the extended process of wound healing, that typically comprise a diverse range of components, integrating both natural and synthetic polymers. Additionally, they often incorporate bioactive molecules. Despite their properties, including poor solubility, rapid degradation, and limited bioavailability, various natural bioactive agents face challenges in clinical applications. With a global research, emphasis on harnessing nanomaterial for wound healing application, this research overview engages advancing drug delivery technologies to augment the effectiveness of tissue regeneration using bioactive molecules. Recent progress in drug delivery has poised to enhance the therapeutic efficacy of natural compounds in wound healing applications.

Bioprinted dermis with human adipose tissue-derived microvascular fragments promotes wound healing

Tissue-engineered skin is an effective material for treating large skin defects in a clinical setting. However, its use is limited owing to vascular complications. Human adipose tissue-derived microvascular fragments (HaMVFs) are vascularized units that form vascular networks by rapid reassembly. In this study, we designed a vascularized bionic skin tissue using a three-dimensional (3D) bioprinter of HaMVFs and human fibroblasts encapsulated in a hybrid hydrogel composed of GelMA, HAMA, and fibrinogen. Tissues incorporating HaMVFs showed good in vitro vascularization and mechanical properties after UV crosslinking and thrombin exposure. Thus, the tissue could be sutured appropriately to the wound. In vivo, the vascularized 3D bioprinted skin promoted epidermal regeneration, collagen maturation in the dermal tissue, and vascularization of the skin tissue to accelerate wound healing. Overall, vascularized 3D bioprinted skin with HaMVFs is an effective material for treating skin defects and may be clinically applicable to reduce the necrosis rate of skin grafts.

Biofabrication of biomimetic undulating microtopography at the dermal-epidermal junction and its effects on the growth and differentiation of epidermal cells

The undulating microtopography located at the junction of the dermis and epidermis of the native skin is called rete ridges (RRs), which plays an important role in enhancing keratinocyte function, improving skin structure and stability, and providing three-dimensional (3D) microenvironment for skin cells. Despite some progress in recent years, most currently designed and manufactured tissue-engineered skin models still cannot replicate the RRs, resulting in a lack of biological signals in the manufactured skin models. In this study, a composite manufacturing method including electrospinning, 3D printing, and functional coating was developed to produce the epidermal models with RRs. Polycaprolactone (PCL) nanofibers were firstly electrospun to mimic the extracellular matrix environment and be responsible for cell attachment. PCL microfibers were then printed onto top of the PCL nanofibers layer by 3D printing to quickly prepare undulating microtopography and finally the entire structures were dip-coated with gelatin hydrogel to form a functional coating layer. The morphology, chemical composition, and structural properties of the fabricated models were studied. The results proved that the multi-process composite fabricated models were suitable for skin tissue engineering. Live and dead staining, cell counting kit-8 (CCK-8) as well as histology (haematoxylin and eosin (HE) methodology) and immunofluorescence (primary and secondary antibodies combination assay) were used to investigate the viability, metabolic activity, and differentiation of skin cells forin vitroculturing.In vitroresults showed that each model had high cell viability, good proliferation, and the expression of differentiation marker. It was worth noting that the sizes of the RRs affected the cell growth status of the epidermal models. In addition, the unique undulation characteristics of the epidermal-dermal junction can be reproduced in the developed epidermal models. Overall, thesein vitrohuman epidermal models can provide valuable reference for skin transplantation, screening and safety evaluation of drugs and cosmetics.

The recent development of carbon-based nanoparticles as a novel approach to skin tissue care and management - A review

Since the skin is the first barrier of the body's defense against pathogens, delays in the healing process are affected by infections. Therefore, applying advanced substitute assistance improves the patient's quality of life. Carbon-based nanomaterials show better capabilities than conventional methods for managing skin wound infections. Due to their physicochemical properties such as small size, large surface area, great surface-to-volume ratio, and excellent ability to communicate with the cells and tissue, carbon-based nanoparticles have been considered in regenerative medicine. moreover, the carbon nano family offers attractive potential in wound healing via the improvement of angiogenesis and antibacterial compared to traditional approaches become one of the particular research interests in the field of skin tissue engineering. This review emphasizes the wound-healing process and the role of carbon-based nanoparticles in wound care management interaction with tissue engineering technology.

Targeting DNA methylation and demethylation in diabetic foot ulcers

BACKGROUND

Poor wound healing is a significant complication of diabetes, which is commonly caused by neuropathy, trauma, deformities, plantar hypertension and peripheral arterial disease. Diabetic foot ulcers (DFU) are difficult to heal, which makes patients susceptible to infections and can ultimately conduce to limb amputation or even death in severe cases. An increasing number of studies have found that epigenetic alterations are strongly associated with poor wound healing in diabetes.

AIM OF REVIEW

This work provides significant insights into the development of therapeutics for improving chronic diabetic wound healing, particularly by targeting and regulating DNA methylation and demethylation in DFU. Key scientific concepts of review: DNA methylation and demethylation play an important part in diabetic wound healing, via regulating corresponding signaling pathways in different breeds of cells, including macrophages, vascular endothelial cells and keratinocytes. In this review, we describe the four main phases of wound healing and their abnormality in diabetic patients. Furthermore, we provided an in-depth summary and discussion on how DNA methylation and demethylation regulate diabetic wound healing in different types of cells; and gave a brief summary on recent advances in applying cellular reprogramming techniques for improving diabetic wound healing.

Cerium oxide nanoparticles: Synthesis methods and applications in wound healing

Wound care and treatment can be critical from a clinical standpoint. While different strategies for the management and treatment of skin wounds have been developed, the limitations inherent in the current approaches necessitate the development of more effective alternative strategies. Advances in tissue engineering have resulted in the development of novel promising approaches for accelerating wound healing. The use of various biomaterials capable of accelerating the regeneration of damaged tissue is critical in tissue engineering. In this regard, cerium oxide nanoparticles (CeO2 NPs) have recently received much attention because of their excellent biological properties, such as antibacterial, anti-inflammatory, antioxidant, and angiogenic features. The incorporation of CeO2 NPs into various polymer-based scaffolds developed for wound healing applications has led to accelerated wound healing due to the presence of CeO2 NPs. This paper discusses the structure and functions of the skin, the wound healing process, different methods for the synthesis of CeO2 NPs, the biological properties of CeO2 NPs, the role of CeO2 NPs in wound healing, the use of scaffolds containing CeO2 NPs for wound healing applications, and the potential toxicity of CeO2 NPs.

A multifunctional hydrogel dressing with high tensile and adhesive strength for infected skin wound healing in joint regions

Most hydrogel dressings are designed for skin wounds in flat areas, and few are focused on the joint skin regions which undergo frequent movement. The mismatch of mechanical properties and poor fit between a hydrogel dressing and a wound in joint skin results in hydrogel shedding, bacterial infection and delayed healing. Therefore, it is of great significance to design and prepare a multifunctional hydrogel with high tensile and tissue-adhesive strength as well as other therapeutic effects for the treatment of joint skin wounds. In this work, a multifunctional hydrogel was reasonably prepared by simply mixing polyvinyl alcohol (PVA), borax, tannic acid (TA) and iron(III) chloride in certain proportions, which was further used to treat the skin wounds at the joint of the hind limb. Acting as the physical crosslinkers, borax and TA dynamically bond with PVA and provide the resulting hydrogel with strong tensile, fast shape-adaptive and self-healing properties. The photothermal bacteriostatic activity of the hydrogel is attributed to the formation of a metallic polyphenol network (MPN) between ferric ions and TA. In addition, the hydrogel exhibits high levels of adhesion, hemostatic performance, antioxidant abilities, and biocompatibility, and shows great potential to promote joint skin wound healing.

Novel Strategies for Angiogenesis in Tissue Injury: Therapeutic Effects of iPSCs-Derived Exosomes

Regeneration after tissue injury is a dynamic and complex process, and angiogenesis is necessary for normal physiological activities and tissue repair. Induced pluripotent stem cells are a new approach in regenerative medicine, which provides good model for the study of difficult-to-obtain human tissues, patient-specific therapy, and tissue repair. As an innovative cell-free therapeutic strategy, the main advantages of the treatment of induced pluripotent stem cells (iPSCs)-derived exosomes are low in tumorigenicity and immunogenicity, which become an important pathway for tissue injury. This review focuses on the mechanism of the angiogenic effect of iPSCs-derived exosomes on wound repair in tissue injury and their potential therapeutic targets, with a view to providing a theoretical basis for the use of iPSCs-derived exosomes in clinical therapy.

Roles of long non-coding RNAs in angiogenesis-related diseases: Focusing on non-neoplastic aspects

Angiogenesis is a key process in organ and tissue morphogenesis, as well as growth during human development, and is coordinated by pro- and anti-angiogenic factors. When this balance is affected, the related physiological and pathological changes lead to disease. Long non-coding RNAs (lncRNAs) are an important class of non-coding RNAs that do not encode proteins, but play a dynamic role in regulating gene expression. LncRNAs have been reported to be extensively involved in angiogenesis, particularly tumor angiogenesis. The non-tumor aspects have received relatively little attention and summary, but there is a broad space for research and exploration on lncRNA-targeted angiogenesis in this area. In this review, we focus on lncRNAs in angiogenesis-related diseases other than tumors, such as atherosclerosis, myocardial infarction, stroke, diabetic complications, hypertension, osteoporosis, dermatosis, as well as, endocrine, neurological, and other systemic disorders. Moreover, multiple cell types have been implicated in lncRNA-targeted angiogenesis, but only endothelial cells have attracted widespread attention. Thus, we explore the roles of other cells. Finally, we summarize the potential research directions in the area of lncRNAs and angiogenesis that can be undertaken by combining cutting-edge technology and interdisciplinary research, which will provide new insights into the involvement of lncRNAs in angiogenesis-related diseases.

Sustained release of magnesium and zinc ions synergistically accelerates wound healing

Skin wounds are a major medical challenge that threaten human health. Functional hydrogel dressings demonstrate great potential to promote wound healing. In this study, magnesium (Mg) and zinc (Zn) are introduced into methacrylate gelatin (GelMA) hydrogel via low-temperature magnetic stirring and photocuring, and their effects on skin wounds and the underlying mechanisms are investigated. Degradation testing confirmed that the GelMA/Mg/Zn hydrogel released magnesium ions (Mg²⁺) and zinc ions (Zn²⁺) in a sustained manner. The Mg²⁺ and Zn²⁺ not only enhanced the migration of human skin fibroblasts (HSFs) and human immortalized keratinocytes (HaCats), but also promoted the transformation of HSFs into myofibroblasts and accelerated the production and remodeling of extracellular matrix. Moreover, the GelMA/Mg/Zn hydrogel enhanced the healing of full-thickness skin defects in rats via accelerated collagen deposition, angiogenesis and skin wound re-epithelialization. We also identified the mechanisms through which GelMA/Mg/Zn hydrogel promoted wound healing: the Mg²⁺ promoted Zn²⁺ entry into HSFs and increased the concentration of Zn²⁺ in HSFs, which effectively induced HSFs to differentiate into myofibroblasts by activating the STAT3 signaling pathway. The synergistic effect of Mg²⁺ and Zn²⁺ promoted wound healing. In conclusion, our study provides a promising strategy for skin wounds regeneration.

Surface modification of polycaprolactone nanofibers through hydrolysis and aminolysis: a comparative study on structural characteristics, mechanical properties, and cellular performance

Hydrolysis and aminolysis are two main commonly used chemical methods for surface modification of hydrophobic tissue engineering scaffolds. The type of chemical reagents along with the concentration and treatment time are main factors that determine the effects of these methods on biomaterials. In the present study, electrospun poly (ℇ-caprolactone) (PCL) nanofibers were modified through hydrolysis and aminolysis. The applied chemical solutions for hydrolysis and aminolysis were NaOH (0.5-2 M) and hexamethylenediamine/isopropanol (HMD/IPA, 0.5-2 M) correspondingly. Three distinct incubation time points were predetermined for the hydrolysis and aminolysis treatments. According to the scanning electron microscopy results, morphological changes emerged only in the higher concentrations of hydrolysis solution (1 M and 2 M) and prolonged treatment duration (6 and 12 h). In contrast, aminolysis treatments induced slight changes in the morphological features of the electrospun PCL nanofibers. Even though surface hydrophilicity of PCL nanofibers was noticeably improved through the both methods, the resultant influence of hydrolysis was comparatively more considerable. As a general trend, both hydrolysis and aminolysis resulted in a moderate decline in the mechanical performance of PCL samples. Energy dispersive spectroscopy analysis indicated elemental changes after the hydrolysis and aminolysis treatments. However, X-ray diffraction, thermogravimetric analysis, and infrared spectroscopy results did not show noticeable alterations subsequent to the treatments. The fibroblast cells were well spread and exhibited a spindle-like shape on the both treated groups. Furthermore, according to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the surface treatment procedures ameliorated proliferative properties of PCL nanofibers. These findings represented that the modified PCL nanofibrous samples by hydrolysis and aminolysis treatments can be considered as the potentially favorable candidates for tissue engineering applications.

Antioxidant Biomaterials in Cutaneous Wound Healing and Tissue Regeneration: A Critical Review

Natural-based biomaterials play an important role in developing new products for medical applications, primarily in cutaneous injuries. A large panel of biomaterials with antioxidant properties has revealed an advancement in supporting and expediting tissue regeneration. However, their low bioavailability in preventing cellular oxidative stress through the delivery system limits their therapeutic activity at the injury site. The integration of antioxidant compounds in the implanted biomaterial should be able to maintain their antioxidant activity while facilitating skin tissue recovery. This review summarises the recent literature that reported the role of natural antioxidant-incorporated biomaterials in promoting skin wound healing and tissue regeneration, which is supported by evidence from in vitro, in vivo, and clinical studies. Antioxidant-based therapies for wound healing have shown promising evidence in numerous animal studies, even though clinical studies remain very limited. We also described the underlying mechanism of reactive oxygen species (ROS) generation and provided a comprehensive review of ROS-scavenging biomaterials found in the literature in the last six years.

Tissue-derived extracellular vesicles: Isolation, purification, and multiple roles in normal and tumor tissues

Extracellular vesicles (EVs) are particles released from cells, and their lipid bilayer membrane encloses large amounts of bioactive molecules that endow EVs with intercellular or inter-tissue communicational abilities. Tissue-derived extracellular vesicles (Ti-EVs) are EVs directly separated from the interstitial space of tissue. They could better reflect the actual physiological or pathological state of the tissue microenvironment compared with cell line-derived EVs and biofluid EVs, indicating their potential roles in elucidating the underlying mechanism of pathogenesis and guiding the diagnosis, therapeutic targeting, and cell-free treatment of diseases. However, there have been a relatively limited number of investigations of Ti-EVs. In this review, we have summarized general procedures for Ti-EVs isolation, as well as some caveats with respect to operations after the isolation step, such as purification and storage. In addition, we have also briefly concluded the current research trends on EVs from various normal and tumor tissues, aiming to cast new light on the future research direction of Ti-EVs.

Structural and antibacterial studies of novel ZnO and ZnxMn(1-x)O nanostructured titanium scaffolds for biomedical applications

In the biomedical field, the demand for the development of broad-spectrum biomaterials able to inhibit bacterial growth is constantly increasing. Chronic infections represent the most serious and devastating complication related to the use of biomaterials. This is particularly relevant in the orthopaedic field, where infections can lead to implant loosening, arthrodesis, amputations and sometimes death. Antibiotics are the conventional approach for implanted-associated infections, but they have the limitation of increasing antibiotic resistance, a critical worldwide healthcare issue. In this context, the development of anti-infective biomaterials and infection-resistant surfaces can be considered the more effective strategy to prevent the implant colonisation and biofilm formation by bacteria, so reducing the occurrence of implant-associated infections. In the last years, inorganic nanostructures have become extremely appealing for chemical modifications or coatings of Ti surfaces, since they do not generate antibiotic resistance issues and are featured by superior stability, durability, and full compatibility with the sterilization process. In this work, we present a simple, rapid, and cheap chemical nanofunctionalization of titanium (Ti) scaffolds with colloidal ZnO and Mn-doped ZnO nanoparticles (NPs), prepared by a sol-gel method, exhibiting antibacterial activity. ZnO NPs and Zn_xMn_(1-x)O NPs formation with a size around 10-20nm and band gap values of 3.42 eV and 3.38 eV, respectively, have been displayed by characterization studies. UV-Vis, fluorescence, and Raman investigation suggested that Mn ions acting as dopants in the ZnO lattice. Ti scaffolds have been functionalized through dip coating, obtaining ZnO@Ti and Zn_xMn_(1-x)O@Ti biomaterials characterized by a continuous nanostructured film. ZnO@Ti and Zn_xMn_(1-x)O@Ti displayed an enhanced antibacterial activity against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa) bacterial strains, compared to NPs in solution with better performance of Zn_xMn_(1-x)O@Ti respect to ZnO@Ti. Notably, it has been observed that Zn_xMn_(1-x)O@Ti scaffolds reach a complete eradication for S. aureus and 90 % of reduction for P. aeruginosa. This can be attributed to Zn²⁺ and Mn²⁺ metal ions release (as observed by ICP MS experiments) that is also maintained over time (72 h). To the best of our knowledge, this is the first study reported in the literature describing ZnO and Mn-doped ZnO NPs nanofunctionalized Ti scaffolds with improved antibacterial performance, paving the way for the realization of new hybrid implantable devices through a low-cost process, compatible with the biotechnological industrial chain method.

Nanomaterials supported by polymers for tissue engineering applications: A review

In the biomedical sciences, particularly in wound healing, tissue engineering, and regenerative medicine, the development of natural-based biomaterials as a carrier has revealed a wide range of advantages. Tissue engineering is one of the therapeutic approaches used to replace damaged tissue. Polymers have received a lot of attention for their beneficial interactions with cells, but they have some drawbacks, such as poor mechanical properties. Due to their relatively large surface area, nanoparticles can cause significant changes in polymers and improve their mechanical properties. The nanoparticles incorporated into biomaterial scaffolds have been associated with positive effects on cell adhesion, viability, proliferation, and migration in the majority of studies. This review paper discusses recent applications of polymer-nanoparticle composites in the development of tissue engineering scaffolds, as well as the effects of these nanomaterials in the fields of cardiovascular, neural, bone, and skin tissue engineering.

A Graphene Oxide-Angiogenin Theranostic Nanoplatform for the Therapeutic Targeting of Angiogenic Processes: The Effect of Copper-Supplemented Medium

Graphene oxide (GO) nanosheets with different content in the defective carbon species bound to oxygen sp3 were functionalized with the angiogenin (ANG) protein, to create a novel nanomedicine for modulating angiogenic processes in cancer therapies. The GO@ANG nanocomposite was scrutinized utilizing UV-visible and fluorescence spectroscopies. GO exhibits pro- or antiangiogenic effects, mostly attributed to the disturbance of ROS concentration, depending both on the total concentration (i.e., >100 ng/mL) as well as on the number of carbon species oxidized, that is, the C/O ratio. ANG is considered one of the most effective angiogenic factors that plays a vital role in the angiogenic process, often in a synergic role with copper ions. Based on these starting hypotheses, the GO@ANG nanotoxicity was assessed with the MTT colorimetric assay, both in the absence and in the presence of copper ions, by in vitro cellular experiments on human prostatic cancer cells (PC-3 line). Laser confocal microscopy (LSM) cell imaging evidenced an enhanced internationalization of GO@ANG than bare GO nanosheets, as well as significant changes in cell cytoskeleton organization and mitochondrial staining compared to the cell treatments with free ANG.

Spatial Delivery of Triple Functional Nanoparticles via an Extracellular Matrix-Mimicking Coaxial Scaffold Synergistically Enhancing Bone Regeneration

It remains a major challenge to simultaneously achieve bone regeneration and prevent infection in the complex microenvironment of repairing bone defects. Here, we developed a novel ECM-mimicking scaffold by coaxial electrospinning to be endowed with multibiological functions. Lysophosphatidic acid (LPA) and zinc oxide (ZnO) nanoparticles were loaded into the poly-lactic-co-glycolic acid/polycaprolactone (PLGA/PCL, PP) sheath layer of coaxial nanofibers, and deferoxamine (DFO) nanoparticles were loaded into its core layer. The novel scaffold PP-LPA-ZnO/DFO maintained a porous nanofibrous architecture after incorporating three active nanoparticles, showing better physicochemical properties and eximious biocompatibility. In vitro studies showed that the bio-scaffold loaded with LPA nanoparticles had excellent cell adhesion, proliferation, and differentiation for MC3T3-E1 cells and synergistic osteogenesis with the addition of ZnO and DFO nanoparticles. Further, the PP-LPA-ZnO/DFO scaffold promoted tube formation and facilitated the expression of vascular endothelial markers in HUVECs. In vitro antibacterial studies against Escherichia Coli and Staphylococcus aureus demonstrated effective antibacterial activity of the PP-LPA-ZnO/DFO scaffold. In vivo studies showed that the PP-LPA-ZnO/DFO scaffold exhibited excellent biocompatibility after subcutaneous implantation and remarkable osteogenesis at 4 weeks post-implantation in the mouse alveolar bone defects. Importantly, the PP-LPA-ZnO/DFO scaffold showed significant antibacterial activity, prominent neovascularization, and new bone formation in the rat fenestration defect model. Overall, the spatially sustained release of LPA, ZnO, and DFO nanoparticles through the coaxial scaffold synergistically enhanced biocompatibility, osteogenesis, angiogenesis, and effective antibacterial properties, which is ultimately beneficial for bone regeneration. This project provides the optimized design of bone regenerative biomaterials and a new strategy for bone regeneration, especially in the potentially infected microenvironment.

Nanobiotechnology: Applications in Chronic Wound Healing

Wounds occur when skin integrity is broken and the skin is damaged. With progressive changes in the disease spectrum, the acute wounds caused by mechanical trauma have been become less common, while chronic wounds triggered with aging, diabetes and infection have become more frequent. Chronic wounds now affect more than 6 million people in the United States, amounting to 10 billion dollars in annual expenditure. However, the treatment of chronic wounds is associated with numerous challenges. Traditional remedies for chronic wounds include skin grafting, flap transplantation, negative-pressure wound therapy, and gauze dressing, all of which can cause tissue damage or activity limitations. Nanobiotechnology — which comprises a diverse array of technologies derived from engineering, chemistry, and biology — is now being applied in biomedical practice. Here, we review the design, application, and clinical trials for nanotechnology-based therapies for chronic wound healing, highlighting the clinical potential of nanobiotechnology in such treatments. By summarizing previous nanobiotechnology studies, we lay the foundation for future wound care via a nanotech-based multifunctional smart system.

Borate Bioactive Glasses (BBG): Bone Regeneration, Wound Healing Applications, and Future Directions

Since the early 2000s, borate bioactive glasses (BBGs) have been extensively investigated for biomedical applications. The research so far indicates that BBGs frequently exhibit superior bioactivity and bone healing capacity compared to silicate glasses. They are also suitable candidates as drug delivery devices for infection or disease treatment such as osteoporosis. Additionally, BBGs are also an excellent option for wound healing applications, which includes the availability of commercial (FDA approved) microfibrous BBG dressings to treat chronic wounds. By addition of modifying ions, the bone or wound healing capacity of BBGs can be enhanced. For instance, addition of copper ions into BBGs was shown to drastically increase blood vessel formation for wound healing applications. Moreover, addition of ions such as magnesium, strontium, and cobalt improves bone healing. Other recent research interest related to BBGs is focused on nerve and muscle regeneration applications, while cartilage regeneration is also suggested as a potential application field for BBGs. BBGs are commonly produced by melt-quenching; however, sol-gel processing of BBGs is emerging and appears to be a promising alternative. In this review paper, the physical and biological characteristics of BBGs are analyzed based on the available literature, the applications of BBGs are discussed, and future research directions are suggested.

Advances in Hyaluronic Acid for Biomedical Applications

Hyaluronic acid (HA) is a large non-sulfated glycosaminoglycan that is the main component of the extracellular matrix (ECM). Because of its strong and diversified functions applied in broad fields, HA has been widely studied and reported previously. The molecular properties of HA and its derivatives, including a wide range of molecular weights but distinct effects on cells, moisture retention and anti-aging, and CD44 targeting, promised its role as a popular participant in tissue engineering, wound healing, cancer treatment, ophthalmology, and cosmetics. In recent years, HA and its derivatives have played an increasingly important role in the aforementioned biomedical fields in the formulation of coatings, nanoparticles, and hydrogels. This article highlights recent efforts in converting HA to smart formulation, such as multifunctional coatings, targeted nanoparticles, or injectable hydrogels, which are used in advanced biomedical application.

Inorganic Nanomaterials in Tissue Engineering

In recent decades, the demand for replacement of damaged or broken tissues has increased; this poses the attention on problems related to low donor availability. For this reason, researchers focused their attention on the field of tissue engineering, which allows the development of scaffolds able to mimic the tissues' extracellular matrix. However, tissue replacement and regeneration are complex since scaffolds need to guarantee an adequate hierarchical structured morphology as well as adequate mechanical, chemical, and physical properties to stand the stresses and enhance the new tissue formation. For this purpose, the use of inorganic materials as fillers for the scaffolds has gained great interest in tissue engineering applications, due to their wide range of physicochemical properties as well as their capability to induce biological responses. However, some issues still need to be faced to improve their efficacy. This review focuses on the description of the most effective inorganic nanomaterials (clays, nano-based nanomaterials, metal oxides, metallic nanoparticles) used in tissue engineering and their properties. Particular attention has been devoted to their combination with scaffolds in a wide range of applications. In particular, skin, orthopaedic, and neural tissue engineering have been considered.

Cell-Seeded Biomaterial Scaffolds: The Urgent Need for Unanswered Accelerated Angiogenesis

One of the most arduous challenges in tissue engineering is neovascularization, without which there is a lack of nutrients delivered to a target tissue. Angiogenesis should be completed at an optimal density and within an appropriate period of time to prevent cell necrosis. Failure to meet this challenge brings about poor functionality for the tissue in comparison with the native tissue, extensively reducing cell viability. Prior studies devoted to angiogenesis have provided researchers with some biomaterial scaffolds and cell choices for angiogenesis. For example, while most current angiogenesis approaches require a variety of stimulatory factors ranging from biomechanical to biomolecular to cellular, some other promising stimulatory factors have been underdeveloped (such as electrical, topographical, and magnetic). When it comes to choosing biomaterial scaffolds in tissue engineering for angiogenesis, key traits rush to mind including biocompatibility, appropriate physical and mechanical properties (adhesion strength, shear stress, and malleability), as well as identifying the appropriate biomaterial in terms of stability and degradation profile, all of which may leave essential trace materials behind adversely influencing angiogenesis. Nevertheless, the selection of the best biomaterial and cells still remains an area of hot dispute as such previous studies have not sufficiently classified, integrated, or compared approaches. To address the aforementioned need, this review article summarizes a variety of natural and synthetic scaffolds including hydrogels that support angiogenesis. Furthermore, we review a variety of cell sources utilized for cell seeding and influential factors used for angiogenesis with a concentrated focus on biomechanical factors, with unique stimulatory factors. Lastly, we provide a bottom-to-up overview of angiogenic biomaterials and cell selection, highlighting parameters that need to be addressed in future studies.

The diameter factor of aligned membranes facilitates wound healing by promoting epithelialization in an immune way

Topographical properties, such as pattern and diameter, of biomaterials play important roles in influencing cell activities and manipulating the related immune response during wound healing. We prepared aligned electrospinning membranes with different fiber diameters, including 319 ± 100 nm (A300), 588 ± 132 nm (A600), and 1048 ± 130 nm (A1000), by adjusting the distance from the tip to the collector, the injection rate, and the concentration of the solution. The A300 membranes significantly improved cell proliferation and spreading and facilitated wound healing (epithelization and vascularization) with the regeneration of immature hair follicles compared to the other membranes. Transcriptomics revealed the underlying molecular mechanism that A300 could promote immune-related processes towards a pro-healing direction, significantly promoting keratinocyte migration and skin wound healing. All the results indicated that wound healing requires the active participation of the immune process, and that A300 was a potential candidate for guided skin regeneration applications.

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It is still unclear which diameter interval of aligned membranes is most suitable for tissue regeneration.

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Outstanding performances in the wound healing process was presented by the A300 membranes.

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The transcriptome revealed that A300 could promote immune related processes towards a pro-healing direction.

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A300 promoted keratinocytes migration and final wound healing partially through MMP12.

The Bioactivity of Scutellariae Radix Carbonisata-Derived Carbon Dots: Antiallergic Effect

Chinese medicine is a treasure of the Chinese nation, and charcoal drugs are a class of medicine with distinctive characteristics. Scutellariae Radix Carbonisata (SRC) could be a sort of calcined herb medicate that has been utilized in traditional Chinese medicine (TCM) clinics to treat hypersensitivities. However, to date, the function of the carbonized part and action mechanisms of SRCs have not been elucidated. In this study, novel water-soluble carbon dots (CDs, named SRC-CDs) ranging from 2 to 9 nm were observed and separated from aqueous extracts of SRC. These SRC-CDs were characterized using transmission electron microscopy (TEM) and high-resolution TEM, as well as Fourier transform infrared, ultraviolet-visible, and fluorescence spectroscopy, to determine particle size, morphology, chemical structure, and optical properties. Then, the in vitro antiallergic efficacy of the SRC-CDs was studied in a C48/80-induced RBL-2H3 cell model, in which remarkable antiallergic effects were revealed. These results will provide new solution directions and technical methods for follow-up research of charcoal drugs and new understanding of potential biomedical applications of CDs.

Zinc Oxide Nanoparticles Exhibit Favorable Properties to Promote Tissue Integration of Biomaterials

Due to the demographic change, medicine faces a growing demand for tissue engineering solutions and implants. Often, satisfying tissue regeneration is difficult to achieve especially when co-morbidities hamper the healing process. As a novel strategy, we propose the incorporation of zinc oxide nanoparticles (ZnO NPs) into biomaterials to improve tissue regeneration. Due to their wide range of biocompatibility and their antibacterial properties, ZnO NPs are already discussed for different medical applications. As there are versatile possibilities of modifying their form, size, and function, they are becoming increasingly attractive for tissue engineering. In our study, in addition to antibacterial effects of ZnO NPs, we show for the first time that ZnO NPs can foster the metabolic activity of fibroblasts as well as endothelial cells, both cell types being crucial for successful implant integration. With the gelatin sponge method performed on the chicken embryo’s chorioallantoic membrane (CAM), we furthermore confirmed the high biocompatibility of ZnO NPs. In summary, we found ZnO NPs to have very favorable properties for the modification of biomaterials. Here, incorporation of ZnO NPs could help to guide the tissue reaction and promote complication-free healing.

The Current Challenges on Spray-Based Cell Delivery to the Skin Wounds

Cell delivery through spray instruments is a promising and effective method in tissue engineering and regenerative medicine. It is used for treating different acute and chronic wounds, including burns with different etiologies, chronic diabetic or venous wounds, postcancer surgery, and hypopigmentation disorders. Cell spray can decrease the needed donor site area compared with conventional autologous skin grafting. Keratinocytes, fibroblasts, melanocytes, and mesenchymal stem cells are promising cell sources for cell spray procedures. Different spray instruments are designed and utilized to deliver the cells to the intended skin area. In an efficient spray instrument, cell viability and wound coverage are two determining parameters influenced by various physical and biological factors such as air pressure, spraying distance, viscosity of suspension, stiffness of the wound surface, and velocity of impact. Besides, to improve cell delivery by spray instruments, some matrices and growth factors can be added to cell suspensions. This review focuses on the different types of cells and spray instruments used in cell delivery procedures. It also discusses physical and biological parameters associated with cell viability and wound coverage in spray instruments. Moreover, the recent advances in codelivery of cells with biological glues and growth factors, as well as clinical translation of cell spraying, have been reviewed. Impact statement Skin wounds are a group of prevalent injuries that can lead to life-threatening complexities. As a focus of interest, stem cell therapy and spray-based cell delivery have effectively decreased associated morbidity and mortality. This review summarizes a broad scope of recent evidence related to spray-based cell therapy, instruments, and approaches adopted to make the process more efficient in treating skin wounds. An overview including utilized cell types, clinical cases, and current challenges is also provided.

Applications of nanomaterials in tissue engineering

Recent advancement in nanotechnology has brought prominent benefits in tissue engineering, which has been used to repair or reconstruct damaged tissues or organs and design smart drug delivery systems. With numerous applications of nanomaterials in tissue engineering, it is vital to choose appropriate nanomaterials for different tissue engineering applications because of the tissue heterogeneity. Indeed, the use of nanomaterials in tissue engineering is directly determined by the choice. In this review, we mainly introduced the use of nanomaterials in tissue engineering. First, the basic characteristics, preparation and characterization methods of the types of nanomaterials are introduced briefly, followed by a detailed description of the application and research progress of nanomaterials in tissue engineering and drug delivery. Finally, the existing challenges and prospects for future applications of nanomaterials in tissue engineering are discussed.

Gliadin-mediated green preparation of hybrid zinc oxide nanospheres with antibacterial activity and low toxicity

The development of inorganic antibacterial agents that impart antibacterial properties to biomaterials has attracted wide attention. The paper introduced a kind of hybrid nanosphere antibacterial agent composed of wheat gliadin (WG) and zinc oxide (ZnO), with antibacterial efficacy and low toxicity. The ZnO/WG hybrid nanospheres were environment-friendly integrated by molecular self-assembly co-precipitating and freeze-drying transformation, and were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic absorption spectroscopy (AAS), specific surface and pore size analysis, bacteriostasis test, reactive oxygen species (ROS) determination and safety evaluation. It was found that the prepared hybrid nanospheres were composed of two components, WG and ZnO, with a diameter scope of 100–200 nm; the content of ZnO in the hybrid nanospheres can reach 46.9–70.2% (w/w); the bacteriostasis tests proved that the prepared ZnO/WG nanospheres generating ROS, have a significant inhibitory effect on E. coli and S. aureus; furthermore, the ZnO/WG nanospheres are relatively safe and highly biocompatible in cells and mice. Therefore, the prepared novel ZnO/WG hybrid nanospheres were supposed to apply in the preparation of anti-infective wound dressings, tissue engineering skin scaffold materials, food, and cosmetics preservatives, and so on.

Nanocomposite scaffolds for accelerating chronic wound healing by enhancing angiogenesis

Skin is the body's first barrier against external pathogens that maintains the homeostasis of the body. Any serious damage to the skin could have an impact on human health and quality of life. Tissue engineering aims to improve the quality of damaged tissue regeneration. One of the most effective treatments for skin tissue regeneration is to improve angiogenesis during the healing period. Over the last decade, there has been an impressive growth of new potential applications for nanobiomaterials in tissue engineering. Various approaches have been developed to improve the rate and quality of the healing process using angiogenic nanomaterials. In this review, we focused on molecular mechanisms and key factors in angiogenesis, the role of nanobiomaterials in angiogenesis, and scaffold-based tissue engineering approaches for accelerated wound healing based on improved angiogenesis.

Aloe vera: A Medicinal Plant Used in Skin Wound Healing

Skin injury is a major problem threatening human physical and mental health, and how to promote wound healing has been the focus. Developing new wound dressings is an important strategy in skin regeneration. Aloe vera is a medicinal plant with a long history, complex constituents, and various pharmacological activities. Many studies have shown that A. vera plays an important role in promoting wound healing. Adding A. vera to wound dressing has become an ideal way. This review will describe the process of skin injury and wound healing and analyze the role of A. vera in wound healing. In addition, the types of wound dressing and the applications of A. vera in wound dressing will be discussed.

Utilization of Carbon Nanotubes in Manufacturing of 3D Cartilage and Bone Scaffolds

Cartilage and bone injuries are prevalent ailments, affecting the quality of life of injured patients. Current methods of treatment are often imperfect and pose the risk of complications in the long term. Therefore, tissue engineering is a rapidly developing branch of science, which aims at discovering effective ways of replacing or repairing damaged tissues with the use of scaffolds. However, both cartilage and bone owe their exceptional mechanical properties to their complex ultrastructure, which is very difficult to reproduce artificially. To address this issue, nanotechnology was employed. One of the most promising nanomaterials in this respect is carbon nanotubes, due to their exceptional physico-chemical properties, which are similar to collagens-the main component of the extracellular matrix of these tissues. This review covers the important aspects of 3D scaffold development and sums up the existing research tackling the challenges of scaffold design. Moreover, carbon nanotubes-reinforced bone and cartilage scaffolds manufactured using the 3D bioprinting technique will be discussed as a novel tool that could facilitate the achievement of more biomimetic structures.

Benlysta-Loaded Sodium Alginate Hydrogel and Its Selective Functions in Promoting Skin Cell Growth and Inhibiting Inflammation

Benlysta is a new drug approved by the US Food and Drug Administration (US FDA) in 2019 for the treatment of systemic lupus erythematosus. In this study, we loaded the benlysta in the traditional sodium alginate (SA) hydrogel to investigate the potential application of the drug-loaded hydrogel for skin dressing or hypodermic drug. Live/dead staining images and the CCK-8 results showed that the benlysta-loaded hydrogel could promote the growth of human epidermal cells (HaCat), fibroblasts (L929), and endothelial cells while inhibiting the aggregation of inflammatory cells (macrophages). In addition, the hydrogel degradation and drug release are slow and controllable, and the gel time of drug-loaded hydrogel can be adjusted by adding sodium alginate ratios according to the requirement. In summary, we prepared a time-dependent drug-loaded hydrogel for potential application in the treatment of skin injury that may be caused by other diseases.

Advances in the application of gold nanoparticles in bone tissue engineering

The materials used in bone tissue engineering (BTE) have been advancing with each passing day. With the continuous development of nanomedicine, gold nanoparticles (GNPs), which are easy to be synthesized and functionalized, have attracted increasing attention. Recent years have witnessed this amazing material, i.e., GNPs characterized with large surface area to volume ratio, biocompatibility, medical imaging property, hypotoxicity, translocation into the cells, high reactivity, and other properties, perform distinct functions in BTE. However, the low stability of GNPs in the biotic environment makes them in the requirements of modification or recombination before being used. After being combined with the advantages of other materials, the structures of GNPs have exhibited great potential in stem cells, scaffolds, delivery systems, medical imaging, and other aspects. This review will focus on the advances in the application of GNPs after modification or recombination with other materials to BTE.