Nitrogen-Doped Multiwalled Carbon Nanotubes Enhance Bone Remodeling through Immunomodulatory Functions

Advances in engineered nanosystems: immunomodulatory interactions for therapeutic applications

Advances in nanotechnology have led to significant progress in the design and fabrication of nanoparticles (NPs) with improved therapeutic properties. NPs have been explored for modulating the immune system, serving as carriers for drug delivery or vaccine adjuvants, or acting as therapeutics themselves against a wide range of deadly diseases. The combination of NPs with immune system-targeting moieties has facilitated the development of improved targeted immune therapies. Targeted delivery of therapeutic agents using NPs specifically to the disease-affected cells, distinguishing them from other host cells, offers the major advantage of concentrating the therapeutic effect and reducing systemic side effects. Furthermore, the properties of NPs, including size, shape, surface charge, and surface modifications, influence their interactions with the targeted biological components. This review aims to provide insights into these diverse emerging and innovative approaches that are being developed and utilized for modulating the immune system using NPs. We reviewed various types of NPs composed of different materials and their specific application for modulating the immune system. Furthermore, we focused on the mechanistic effects of these therapeutic NPs on primary immune components, including T cells, B cells, macrophages, dendritic cells, and complement systems. Additionally, a recent overview of clinically approved immunomodulatory nanomedicines and potential future perspectives, offering new paradigms of this field, is also highlighted.

Graphene: A Multifaceted Carbon-Based Material for Bone Tissue Engineering Applications

Tissue engineering is an emerging technological field that aims to restore and replace human tissues. A significant number of individuals require bone replacement annually as a result of skeletal abnormalities or accidents. In recent decades, notable progress has been made in the field of biomedical research, specifically in the realm of sophisticated and biocompatible materials. The purpose of these biomaterials is to facilitate bone tissue regeneration. Carbon nanomaterial-based scaffolds are particularly notable due to their accessibility, mechanical durability, and biofunctionality. The scaffolds exhibit the capacity to enhance cellular proliferation, mitigate cell damage, induce bone tissue growth, and maintain biological compatibility. Therefore, they play a crucial role in the development of the bone matrix and the necessary cellular interactions required for bone tissue restoration. The attachment, growth, and specialization of osteogenic stem cells on biomaterial scaffolds play critical roles in bone tissue engineering. The optimal biomaterial should facilitate the development of bone tissue in a manner that closely resembles that of human bone. This comprehensive review encompasses the examination of graphene oxide (GO), carbon nanotubes (CNTs), fullerenes, carbon dots (CDs), nanodiamonds, and their respective derivatives. The biomaterial frameworks possess the ability to replicate the intricate characteristics of the bone microenvironment, thereby rendering them suitable for utilization in tissue engineering endeavors.

A 3D Bioprinted Nanoengineered Hydrogel with Photoactivated Drug Delivery for Tumor Apoptosis and Simultaneous Bone Regeneration via Macrophage Immunomodulation

One of the significant challenges in bone tissue engineering (BTE) is the healing of traumatic tissue defects owing to the recruitment of local infection and delayed angiogenesis. Herein, a 3D printable multi-functional hydrogel composing polyphenolic carbon quantum dots (CQDs, 100 µg mL-1 ) and gelatin methacryloyl (GelMA, 12 wt%) is reported for robust angiogenesis, bone regeneration and anti-tumor therapy. The CQDs are synthesized from a plant-inspired bioactive molecule, 1, 3, 5-trihydroxybenzene. The 3D printed GelMA-CQDs hydrogels display typical shear-thinning behavior with excellent printability. The fabricated hydrogel displayed M2 polarization of macrophage (Raw 264.7) cells via enhancing anti-inflammatory genes (e.g., IL-4 and IL10), and induced angiogenesis and osteogenesis of human bone mesenchymal stem cells (hBMSCs). The bioprinted hBMSCs are able to produce vessel-like structures after 14 d of incubation. Furthermore, the 3D printed hydrogel scaffolds also show remarkable near infra-red (NIR) responsive properties under 808 nm NIR light (1.0 W cm-2 ) irradiation with controlled release of antitumor drugs (≈49%) at pH 6.5, and thereby killing the osteosarcoma cells. Therefore, it is anticipated that the tissue regeneration and healing ability with therapeutic potential of the GelMA-CQDs scaffolds may provide a promising alternative for traumatic tissue regeneration via augmenting angiogenesis and accelerated immunomodulation.

Bioinspired Hierarchical Carbon Structures as Potential Scaffolds for Wound Healing and Tissue Regeneration Applications

Engineered bio-scaffolds for wound healing provide an attractive treatment option for tissue engineering and traumatic skin injuries since they can reduce dependence on donors and promote faster repair through strategic surface engineering. Current scaffolds present limitations in handling, preparation, shelf life, and sterilization options. In this study, bio-inspired hierarchical all-carbon structures comprising carbon nanotube (CNT) carpets covalently bonded to flexible carbon fabric have been investigated as a platform for cell growth and future tissue regeneration applications. CNTs are known to provide guidance for cell growth, but loose CNTs are susceptible to intracellular uptake and are suspected to cause in vitro and in vivo cytotoxicity. This risk is suppressed in these materials due to the covalent attachment of CNTs on a larger fabric, and the synergistic benefits of nanoscale and micro-macro scale architectures, as seen in natural biological materials, can be obtained. The structural durability, biocompatibility, tunable surface architecture, and ultra-high specific surface area of these materials make them attractive candidates for wound healing. In this study, investigations of cytotoxicity, skin cell proliferation, and cell migration were performed, and results indicate promise in both biocompatibility and directed cell growth. Moreover, these scaffolds provided cytoprotection against environmental stressors such as Ultraviolet B (UVB) rays. It was seen that cell growth could also be tailored through the control of CNT carpet height and surface wettability. These results support future promise in the design of hierarchical carbon scaffolds for strategic wound healing and tissue regeneration applications.

Nanostructured 3D-Printed Hybrid Scaffold Accelerates Bone Regeneration by Photointegrating Nanohydroxyapatite

Nanostructured biomaterials that replicate natural bone architecture are expected to facilitate bone regeneration. Here, nanohydroxyapatite (nHAp) with vinyl surface modification is acquired by silicon-based coupling agent and photointegrated with methacrylic anhydride-modified gelatin to manufacture a chemically integrated 3D-printed hybrid bone scaffold (75.6 wt% solid content). This nanostructured procedure significantly increases its storage modulus by 19.43-fold (79.2 kPa) to construct a more stable mechanical structure. Furthermore, biofunctional hydrogel with biomimetic extracellular matrix is anchored onto the filament of 3D-printed hybrid scaffold (HGel-g-nHAp) by polyphenol-mediated multiple chemical reactions, which contributes to initiate early osteogenesis and angiogenesis by recruiting endogenous stem cells in situ. Significant ectopic mineral deposition is also observed in subcutaneously implanted nude mice with storage modulus enhancement of 25.3-fold after 30 days. Meanwhile, HGel-g-nHAp realizes substantial bone reconstruction in the rabbit cranial defect model, achieving 61.3% breaking load strength and 73.1% bone volume fractions in comparison to natural cranium 15 weeks after implantation. This optical integration strategy of vinyl modified nHAp provides a prospective structural design for regenerative 3D-printed bone scaffold.

A CS-based composite scaffold with excellent photothermal effect and its application in full-thickness skin wound healing

The development of natural polymer-based scaffolds with excellent biocompatibility, antibacterial activity, and blood compatibility, able to facilitate full-thickness skin wound healing, remains challenging. In this study, we have developed three chitosan (CS)-based porous scaffolds, including CS, CS/CNT (carbon nanotubes) and CS/CNT/HA (nano-hydroxyapatite, n-HA) using a freeze-drying method. All three scaffolds have a high swelling ratio, excellent antibacterial activity, outstanding cytocompatibility and blood compatibility in vitro. The introduction of CNTs exhibited an obvious increase in mechanical properties and exerts excellent photothermal response, which displays excellent healing performance as a wound dressing in mouse full-thickness skin wound model when compared to CS scaffolds. CS/CNT/HA composite scaffolds present the strongest ability to promote full-thickness cutaneous wound closure and skin regeneration, which might be ascribed to the synergistic effect of photothermal response from CNT and excellent bioactivity from n-HA. Overall, the present study indicated that CNT and n-HA can be engineered as effective constituents in wound dressings to facilitate full-thickness skin regeneration.

Zuo-Gui-Wan Aqueous Extract Ameliorates Glucocorticoid-Induced Spinal Osteoporosis of Rats by Regulating let-7f and Autophagy

OBJECTIVE

This study proposes to explore the protective effect of Zuo-Gui-Wan (ZGW) aqueous extract on spinal glucocorticoid-induced osteoporosis (GIOP) in vivo and in vitro, and the underlying mechanisms of ZGW in GIOP and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) were conducted.

METHODS

In vivo, SD rats were randomly divided into three groups: control group (CON), dexamethasone (DEXM) group, and ZGW group, which were given vehicle, DEXM injection, and ZGW intragastric administration at the same time. Vertebral bone microarchitecture, biomechanics, histomorphology, serum AKP activity, and the autophagosome of osteoblasts were examined. The mRNA expressions of let-7f, autophagy-associated genes (mTORC1, Beclin-1, ATG12, ATG5, and LC3), Runx2, and CTSK were examined. In vitro, the let-7f overexpression/silencing vector was constructed and transfected to evaluate the osteogenic differentiation of BMSCs. Western blot was employed to detect the expression of autophagy-associated proteins (ULK2, ATG5, ATG12, Beclin-1, LC3).

RESULTS

In vivo, ZGW promoted the bone quantity, quality, and strength; alleviated histological damage; increased the serum AKP activity; and reduced the autophagosome number in osteoblasts. Moreover, ZGW increased the let-7f, mTORC1, and Runx2 mRNA expressions and reduced the Beclin-1, ATG12, ATG5, LC3, and CTSK mRNA expressions. In vitro, bioinformatics prediction and dual luciferase reporter gene assay verified that let-7f targeted the binding to ULK2 and negatively regulated the ULK2 expression. Furthermore, by let-7f overexpression/silencing, ZGW may promote osteoblast differentiation of BMSCs by regulating let-7f and autophagy as evidenced by Western blot (ULK2, ATG5, ATG12, Beclin-1, LC3).

CONCLUSIONS

ZGW may ameliorate GC-induced spinal osteoporosis by promoting osteoblast differentiation of BMSCs by activation of let-7f and suppression of autophagy.