Design and Application of an In Situ Traceable Nitric Oxide Donor for Promoting the Healing of Wound Infections.

Therapies for wound infections require medications with antibacterial and wound-healing functions. However, it remains a challenge to produce a single drug that can perform dual functions. Nitric oxide (NO), with its antibacterial and wound-healing activities, is an ideal solution to address this challenge. However, many controlled-release strategies for NO rely on external probes for tracing the release in situ, making it difficult to precisely assess the location and magnitude. To address this issue, this study describes a novel NO donor, DHU-NO1, capable of efficiently releasing NO under mild conditions (450 nm illumination). Simultaneously, DHU-NO1 generates the fluorophore Azure B (AZB), which enables direct, non-consumptive tracing of the NO release by monitoring the fluorescence and absorption changes in AZB. Given that NO can be conveniently traced, the amount of released NO can be controlled during biological applications, thereby allowing both functions of NO to be performed. When applied to the affected area, DHU-NO1, illuminated by both a simple light-emitting diode (LED) light source and natural light, achieves significant antibacterial effects against wound infections and promotes wound healing in mice. This study offers a novel and effective approach for treating wound infections.

Multi-modal imaging for dynamic visualization of osteogenesis and implant degradation in 3D bioprinted scaffolds.

In situ monitoring of bone regeneration enables timely diagnosis and intervention by acquiring vital biological parameters. However, an existing gap exists in the availability of effective methodologies for continuous and dynamic monitoring of the bone tissue regeneration process, encompassing the concurrent visualization of bone formation and implant degradation. Here, we present an integrated scaffold designed to facilitate real-time monitoring of both bone formation and implant degradation during the repair of bone defects. Laponite (Lap), CyP-loaded mesoporous silica (CyP@MSNs) and ultrasmall superparamagnetic iron oxide nanoparticles (USPIO@SiO2) were incorporated into a bioink containing bone marrow mesenchymal stem cells (BMSCs) to fabricate functional scaffolds denoted as C@M/GLU using 3D bioprinting technology. In both in vivo and in vitro experiments, the composite scaffold has demonstrated a significant enhancement of bone regeneration through the controlled release of silicon (Si) and magnesium (Mg) ions. Employing near-infrared fluorescence (NIR-FL) imaging, the composite scaffold facilitates the monitoring of alkaline phosphate (ALP) expression, providing an accurate reflection of the scaffold's initial osteogenic activity. Meanwhile, the degradation of scaffolds was monitored by tracking the changes in the magnetic resonance (MR) signals at various time points. These findings indicate that the designed scaffold holds potential as an in situ bone implant for combined visualization of osteogenesis and implant degradation throughout the bone repair process.

Integrating Fluorescence and Magnetic Resonance Imaging in Biocompatible Scaffold for Real-Time Bone Repair Monitoring and Assessment.

In situ monitoring of bone tissue regeneration progression is critical for the development of bone tissue engineering scaffold. However, engineered scaffolds that can stimulate osteogenic progress and allow for non-invasive monitoring of in vivo bone regeneration simultaneously are rarely reported. Based on a hard-and-soft integration strategy, a multifunctional scaffold composed of 3D printed microfilaments and a hydrogel network containing simvastatin (SV), indocyanine green-loaded superamphiphiles, and aminated ultrasmall superparamagnetic iron oxide nanoparticles (USPIO-NH2 ) is fabricated. Both in vitro and in vivo results demonstrate that the as-prepared scaffold significantly promotes osteogenesis through controlled SV release. The biocomposite scaffold exhibits alkaline phosphatase-responsive near-infrared II fluorescence imaging. Meanwhile, USPIO-NH2 within the co-crosslinked nanocomposite network enables the visualization of scaffold degradation by magnetic resonance imaging. Therefore, the biocomposite scaffold enables or facilitates non-invasive in situ monitoring of neo-bone formation and scaffold degradation processes following osteogenic stimulation, offering a promising strategy to develop theranostic scaffolds for tissue engineering.

NIR light-facilitated bone tissue engineering.

In the last decades, near-infrared (NIR) light has attracted considerable attention due to its unique properties and numerous potential applications in bioimaging and disease treatment. Bone tissue engineering for bone regeneration with the help of biomaterials is currently an effective means of treating bone defects. As a controlled light source with deeper tissue penetration, NIR light can provide real-time feedback of key information on bone regeneration in vivo utilizing fluorescence imaging and be used for bone disease treatment. This review provides a comprehensive overview of NIR light-facilitated bone tissue engineering, from the introduction of NIR probes as well as NIR light-responsive materials, and the visualization of bone regeneration to the treatment of bone-related diseases. Furthermore, the existing challenges and future development directions of NIR light-based bone tissue engineering are also discussed. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.

Engineering Biomimetic Microenvironment for Organoid.

Organoid is an emerging frontier technology in the field of life science, in which pluripotent stem cells or tissue-derived differentiated/progenitor cells form 3D structures according to their multi-directional differentiation potential and self-assembly ability. Nowadays, although various types of organoids are widely investigated, their construction is still complicated in operation, uncertain in yield, and poor in reproducibility for the structure and function of native organs. Constructing a biomimetic microenvironment for stem cell proliferation and differentiation in vitro is recognized as a key to driving this field. This review reviews the recent development of engineered biomimetic microenvironments for organoids. First, the composition of the matrix for organoid culture is summarized. Then, strategies for engineering the microenvironment from biophysical, biochemical, and cellular perspectives are discussed in detail. Subsequently, the newly developed monitoring technologies are also reviewed. Finally, a brief conclusion and outlook are presented for the inspiration of future research.

Langmuir-Blodgett-Mediated Formation of Antibacterial Microneedles for Long-Term Transdermal Drug Delivery.

Microneedles (MNs) have become versatile platforms for minimally invasive transdermal drug delivery devices. However, there are concerns about MN-induced skin infections with long-term transdermal administration. Using the Langmuir-Blodgett (LB) technique, a simple method for depositing antibacterial nanoparticles of various shapes, sizes, and compositions onto MNs is developed. This strategy has merits over conventional dip coating techniques, including controlled coating layers, uniform and high coverage, and a straightforward fabrication process. This provides MNs with a fast-acting and long-lasting antibacterial effect. This study demonstrates that antibacterial MNs achieve superior bacterial elimination in vitro and in vivo without sacrificing payload capacity, drug release, or mechanical strength. It is believed that such a functional nanoparticle coating technique offers a platform for the expansion of MNs function, especially in long-term transdermal drug delivery fields.

Enhanced tissue infiltration and bone regeneration through spatiotemporal delivery of bioactive factors from polyelectrolytes modified biomimetic scaffold.

Efficient healing of bone defect is closely associated with the structured and functional characters of tissue engineered scaffolds. However, the development of bone implants with rapid tissue ingrowth and favorable osteoinductive properties remains a challenge. Herein, we fabricated polyelectrolytes modified-biomimetic scaffold with macroporous and nanofibrous structures as well as simultaneous delivery of BMP-2 protein and trace element strontium. The hierarchically structured scaffold incorporated with strontium-substituted hydroxyapatite (SrHA) was coated with polyelectrolyte multilayers of chitosan/gelatin via layer-by-layer assembly technique for BMP-2 immobilization, which endowed the composite scaffold with sequential release of BMP-2 and Sr ions. The integration of SrHA improved the mechanical property of composite scaffold, while the polyelectrolytes modification strongly increased the hydrophilicity and protein binding efficiency. In addition, polyelectrolytes modified-scaffold significantly facilitated cell proliferation in vitro, as well as enhanced tissue infiltration and new microvascular formation in vivo. Furthermore, the dual-factor loaded scaffold significantly enhanced the osteogenic differentiation of bone marrow mesenchymal stem cells. Moreover, both vascularization and new bone formation were significantly increased by the treatment of dual-factor delivery scaffold in the rat calvarial defects model, suggesting a synergistic effect on bone regeneration through spatiotemporal delivery of BMP-2 and Sr ions. Overall, this study demonstrate that the prepared biomimetic scaffold as dual-factor delivery system has great potential for bone regeneration application.

Bifunctional Hydrogel-Integrated 3D Printed Scaffold for Repairing Infected Bone Defects.

The clinical treatment of infectious bone defects is difficult and time-consuming due to the coexistence of infection and bone defects, and the simultaneous control of infection and repair of bone defects is considered a promising therapy. In this study, a dual-drug delivery scaffold system was fabricated by the combination of a three-dimensional (3D) printed scaffold with hydrogel for infected bone defects repair. The 3D printed polycaprolactone scaffold was incorporated with biodegradable mesoporous silica nanoparticles containing the small molecular drug fingolimod (FTY720) to provide structural support and promote angiogenesis and osteogenesis. The vancomycin (Van)-loaded hydrogel was prepared from aldehyde hyaluronic acid (AHA) and carboxymethyl chitosan (NOCC) by the Schiff base reaction, which can fill the pores of the 3D-printed scaffold to produce a bifunctional composite scaffold. The in vitro results demonstrated that the composite scaffold had Van concentration-dependent antimicrobial properties. Furthermore, the FTY720-loaded composite scaffold demonstrated excellent biocompatibility, vascularization, and osteogenic ability in vitro. In the rat femoral defect model with bacterial infection, the dual-drug composite scaffold showed a better outcome in both infection control and bone regeneration compared to other groups. Therefore, the prepared bifunctional composite scaffold has potential application in the treatment of infected bone defects.

Flowerbed-Inspired Biomimetic Scaffold with Rapid Internal Tissue Infiltration and Vascularization Capacity for Bone Repair.

The favorable microstructure and bioactivity of tissue-engineered bone scaffolds are closely associated with the regenerative efficacy of bone defects. For the treatment of large bone defects, however, most of them fail to meet requirements such as adequate mechanical strength, highly porous structure, and excellent angiogenic and osteogenic activities. Herein, inspired by the characteristics of a "flowerbed", we construct a short nanofiber aggregates-enriched dual-factor delivery scaffold via 3D printing and electrospinning techniques for guiding vascularized bone regeneration. By the assembly of short nanofibers containing dimethyloxalylglycine (DMOG)-loaded mesoporous silica nanoparticles with a 3D printed strontium-contained hydroxyapatite/polycaprolactone (SrHA@PCL) scaffold, an adjustable porous structure can be easily realized by changing the density of nanofibers, while strong compressive strength will be acquired due to the framework role of SrHA@PCL. Owing to the different degradation performance between electrospun nanofibers and 3D printed microfilaments, a sequential release behavior of DMOG and Sr ions is achieved. Both in vivo and in vitro results demonstrate that the dual-factor delivery scaffold has excellent biocompatibility, significantly promotes angiogenesis and osteogenesis by stimulating endothelial cells and osteoblasts, and effectively accelerates tissue ingrowth and vascularized bone regeneration through activating the hypoxia inducible factor-1α pathway and immunoregulatory effect. Overall, this study has provided a promising strategy for constructing a bone microenvironment-matched biomimetic scaffold for bone regeneration.

Tunable metacrylated silk fibroin-based hybrid bioinks for the bioprinting of tissue engineering scaffolds.

Three-dimensional (3D) bioprinting is a powerful technique for the production of tissue-like structures to study cell behavior and tissue properties. A major challenge in 3D extrusion bioprinting is the limited diversity of bioinks, which fulfills the requirements of shear-thinning and strain recovery behaviors and can be solidified by a crosslinking process to retain their shape after printing. Herein, we aimed to develop a natural biopolymer-based formula with dual crosslinking performance to formulate a cell-laden bioink. In this study, methacrylate gelatin (GelMA) and methacrylated silk fibroin (SFMA) with different degrees of methacrylation were fabricated into hybrid bioinks. The GelMA/SFMA bioink of an optimal degree provides excellent rheological properties for extrusion bioprinting, and its hydrogel precursor polymer can form a polymer network at a low temperature and the high shape fidelity of the printed construct through photocrosslinking. Moreover, the hydrogel bioink can encapsulate different types of cells together to create 3D printed constructs that mimic the cellular microenvironment at a microscale level. Human umbilical vein endothelial cells (HUVECs) and rat pheochromocytoma (PC12) cells encapsulated in the 3D printed constructs can maintain high viability and proliferation ability for a long time. Furthermore, the GelMA/SFMA hydrogels were implanted in the subcutaneous tissue of SD rats for the evaluation of biocompatibility and degradability in vivo. Thus, the proposed GelMA/SFMA bioink expands the palette of available bioinks and offers opportunities for biomedical applications such as tissue engineering and soft robotics in clinical applications.

Three-dimensional bioprinted BMSCs-laden highly adhesive artificial periosteum containing gelatin-dopamine and graphene oxide nanosheets promoting bone defect repair.

The periosteum is a connective tissue membrane adhering to the surface of bone tissue that primarily provides nutrients and regulates osteogenesis during bone development and injury healing. However, building an artificial periosteum with good adhesion properties and satisfactory osteogenesis for bone defect repair remains a challenge, especially using three-dimensional (3D) bioprinting. In this study, dopamine was first grafted onto the molecular chain of gelatin usingN-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride andN-hydroxysuccinimide (NHS) to activate the carboxyl group and produce modified gelatin-dopamine (GelDA). Next, a methacrylated gelatin, methacrylated silk fibroin, GelDA, and graphene oxide nanosheet composite bioink loaded with bone marrow mesenchymal stem cells was prepared and used for bioprinting. The physicochemical properties, biocompatibility, and osteogenic roles of the bioink and 3D bioprinted artificial periosteum were then systematically evaluated. The results showed that the developed bioink showed good thermosensitivity and printability and could be used to build 3D bioprinted artificial periosteum with satisfactory cell viability and high adhesion. Finally, the 3D bioprinted artificial periosteum could effectively enhance osteogenesis bothin vitroandin vivo. Thus, the developed 3D bioprinted artificial periosteum can prompt new bone formation and provides a promising strategy for bone defect repair.

Rapid mineralization of graphene-based 3D porous scaffolds by semi-dry electrodeposition for photothermal treatment of tumor-induced bone defects.

Graphene-based three-dimensional (3D) porous scaffolds have been extensively investigated in the photothermal treatment of tumor-induced bone defects due to their photothermal and osteogenic capacity. However, scaffold processing destroys conjugated graphene structure and reduces its photothermal conversion efficiency. In this study, a graphene-based 3D scaffold (GS) with intact conjugated structure was prepared by chemical vapor deposition (CVD). GS was rapidly mineralized biomimetically by a newly developed semi-dry electrochemical deposition method to form a hydroxyapatite (HA) incorporated graphene scaffold (HA-GS). The simulation of the charged particle dynamics provides a better understanding of the mechanism of semi-dry electrodeposition. This scaffold exhibits high photothermal sensitivity that generates sufficient thermal energy for photothermal therapy even under near-infrared irradiation (980 nm) with extremely low power density (0.2 W/cm2). Moreover, osteogenic activity was improved by HA-GS compared with GS. Compared with the blank GS, the HA-GS scaffold deposited with HA also showed regulation of macrophage-derived chemokine (MDC) and remodeled the immune microenvironment of the wound after photothermal therapy. In vivo experiments further verified that HA-GS can ablate osteosarcoma through a photothermal effect. These results suggest that the as-prepared HA-GS may be adopted as a promising multifunctional bone scaffold against tumor-induced bone defect. STATEMENT OF SIGNIFICANCE: The hydroxyapatite (HA) incorporated graphene scaffold (HA-GS) scaffold was prepared by semi-dry electrodeposition first time. The prepared HA-GS has a high photothermal conversion efficiency (it can rise to 48 °C under the 5 min irradiation of 980 nm near-infrared laser at 0.2 W/cm2). The mineralized layer prepared by semi-dry electrodeposition is not only osteoinductive, but also reduces the inflammatory response after photothermal therapy. This modulates the immune microenvironment at the bone tumor invasion site, thereby promoting defect repair.

Vascularized nanocomposite hydrogel mechanically reinforced by polyelectrolyte-modified nanoparticles.

Vascularization plays an important role in the initial stage of triggering bone defect repair. The combination of bioactive small molecule drugs and biomaterials has been a powerful strategy for vascularization in bone tissue engineering. In this study, an in situ crosslinked aldehyde hyaluronic acid (AHA)/N,O-carboxymethyl chitosan (NOCC) nanocomposite hydrogel doped with sphingosine 1-phosphate (S1P)-loaded polyelectrolyte-modified mesoporous silica nanoparticles (MSNs) was developed. The alginate/chitosan polyelectrolyte-modified MSNs (MSNs-ALG/CHI) were prepared via the electrostatic interaction. The incorporation of MSNs-ALG/CHI not only achieved a sustained release profile of the angiogenic drug, but also improved the mechanical property of the AHA/NOCC hydrogel due to the Schiff base reaction between the amino group in chitosan and the aldehyde group in AHA. In addition, in vitro cell experiments demonstrated that the nanocomposite hydrogel provided favorable support for cell adhesion and proliferation, and the S1P-loaded nanocomposite hydrogel was able to recruit endothelial cells. More importantly, the chicken chorioallantoic membrane (CAM) assay confirmed that the S1P-loaded nanocomposite hydrogel could significantly enhance capillary formation. More cell infiltration and better angiogenesis in the S1P loaded nanocomposite hydrogel were observed compared to the group without S1P loading after being implanted subcutaneously for 2 weeks. Furthermore, the subcutaneous implantation experiment further demonstrated that the incorporation of the S1P-loaded nanocomposite hydrogel could improve the tissue infiltration and new vessel formation within the macroporous poly(L-lactic acid)/polycaprolactone scaffold. Our results suggest that the nanocomposite hydrogel will be an excellent drug delivery system and the S1P-loaded nanocomposite hydrogel has great potential for vascularized bone regeneration application.

Inhibition of Sympathetic Activation by Delivering Calcium Channel Blockers from a 3D Printed Scaffold to Promote Bone Defect Repair.

Enhancing osteogenesis by promoting neural network reconstruction and neuropeptide release is considered to be an attractive strategy for repairing of critical size bone defects. However, traumatic bone defects often activate the damaged sympathetic nervous system (SNS) in the defect area and release excessive catecholamine to hinder bone defect repair. Herein, a 3D printed scaffold loaded with the calcium channel blocker-nifedipine is proposed to reduce the concentration of catecholamine present in the bone defect region and to accelerate bone healing. To this end, nifedipine-loaded ethosome and laponite are added into a mixed solution containing sodium alginate, methacrylated gelatin, and bone mesenchymal stem cells (BMSCs) to prepare a cell-laden scaffold using 3D bioprinting. The released nifedipine is able to close the calcium channels of nerve cells, thereby blocking sympathetic activation and ultimately inhibiting the release of catecholamine by sympathetic nerve cells, which further promotes the osteogenic differentiation and migration of BMSCs, inhibits osteoclastogenesis in vitro, and effectively improves bone regeneration in a rat critical-size calvarial defect model. Therefore, the results suggest that sustained release of nifedipine from the scaffold can effectively block SNS activation, providing promising strategies for future treatment of bone defects.

3D bioprinted gelatin/gellan gum-based scaffold with double-crosslinking network for vascularized bone regeneration.

Three-dimensional (3D) bioprinting holds promise for precise repair of bone defects, but rapid formation of effective vascularized tissue by 3D-printed construct is still a challenge. In this study, deferoxamine (DFO)-loaded ethosomes (Eth) were combined with gelatin methacrylate (GelMA)/gellan gum methacrylate (GGMA) hybrid bioink to fabricate 3D-printed scaffold by photo- and ion-crosslinking. The GelMA/GGMA bioinks showed excellent printability and improved mechanical property through the double-crosslinking method. In vitro experiments showed that Eth-DFO@GelMA/GGMA scaffold had good cytocompatibility while achieved sustained release of DFO, which significantly promoted endothelial cells migration and tube formation, mineralized matrix deposition and alkaline phosphatase expression of osteoblast. In vivo experiments of rat cranial defect model demonstrated that composite scaffold could promote angiogenesis and bone regeneration by activating the hypoxia-inducible factor 1-α (HIF1-α) signaling pathway. In conclusion, this 3D bioprinted Eth-DFO@GelMA/GGMA scaffold can couple angiogenesis and osteogenesis, and will be a promising candidate for the bone defects treatment.

Tumor cell membrane-camouflaged responsive nanoparticles enable MRI-guided immuno-chemodynamic therapy of orthotopic osteosarcoma.

Osteosarcoma is a refractory bone disease in young people that needs the updating and development of effective treatment. Although nanotechnology is widely applied in cancer therapy, poor targeting and inadequate efficiency hinder its development. In this study, we prepared alendronate (ALD)/K7M2 cell membranes-coated hollow manganese dioxide (HMnO2) nanoparticles as a nanocarrier to load Ginsenoside Rh2 (Rh2) for Magnetic Resonance imaging (MRI)-guided immuno-chemodynamic combination osteosarcoma therapy. Subsequently, the ALD and K7M2 cell membranes were successively modified on the surface of HMnO2 and loaded with Rh2. The tumor microenvironment (TME)-activated Rh2@HMnO2-AM nanoparticles have good bone tumor-targeting and tumor-homing capabilities, excellent GSH-sensitive drug release profile and MRI capability, and attractive immuno-chemodynamic combined therapeutic efficiency. The Rh2@HMnO2-AM nanoparticles can effectively trigger immunogenic cell death (ICD), activate CD4+/CD8+ T cells in vivo, and upregulate BAX, BCL-2 and Caspase-3 in cellular level. Further results revealed that Rh2@HMnO2-AM enhanced the secretion of IL-6, IFN-γ and TNF-α in serum and inhibited the generation of FOXP3+ T cells (Tregs) in tumors. Moreover, the Rh2@HMnO2-AM treatment significant restricted tumor growth in-situ tumor-bearing mice. Therefore, Rh2@HMnO2-AM may serve as an effective and bio-friendly nanoparticle platform combined with immunotherapy and chemodynamic therapy to provide a novel approach to osteosarcoma therapy.

Prodrug inspired bi-layered electrospun membrane with properties of enhanced tissue integration for guided tissue regeneration.

Guided tissue regeneration (GTR) membranes play a vital role in periodontal surgery. Recently a series of composite electrospun membranes have been fabricated to improve the unexpected biodegradation of collagen-based GTR membranes. However, their tissue integrity needs to be studied in depth. In this study, a bi-layered electrospun membrane (BEM) inspired by "prodrug" was fabricated, which contained a dense-layer (BEM-DL) and a potential loose-layer (BEM-LL). The nanofibers of BEM-DL were composed of poly(l-lactic-co-glycolic acid) and tilapia skin collagen (TSC). Whereas the BEM-LL consisted of two types of nanofibers, one was the same as BEM-DL and the other was made from TSC. The morphology, degradation in vitro, cytocompatibility and biocompatibility in rats were investigated with a poly(lactic-co-glycolic acid) electrospun membrane (PLGA) as the negative control. The pore size of BEM-LL soaked for 7 days became larger than the original sample (164.8 ± 90.9 and 52.5 ± 21.0 µm2 , respectively), which was significantly higher (p < .05) than that of BEM-DL and PLGA. The BEM-LL displayed a larger weight loss rate of 82.3 ± 3.6% than the BEM-DL of 46.0 ± 2.8% at day 7 because of the rapid degradation of TSC fibers. The cytocompatibility test demonstrated that L929 cells were only spread on the surface of the BEM-DL while MC3T3-E1 cells grew into the BEM-LL layer. The subcutaneous implantation test further proved that BEM-DL performed as a cellular barrier, whereas BEM-LL was conducive to cell infiltration as deep as 200 µm with reduced fibrous encapsulation. Herein, the BEM inspired by "prodrug" is a promising GTR membrane with a property of enhanced tissue integration.

Transcutaneous tumor vaccination combined with anti-programmed death-1 monoclonal antibody treatment produces a synergistic antitumor effect.

Transcutaneous immunization (TCI) has the advantages of safety, high efficiency, non-invasiveness and convenient use. The key for a TCI system is transdermal targeted delivery of antigen to dendritic cells (DCs), the most powerful antigen presenting cells. DCs also play an important role in tumor immunotherapy, which provides a huge imagination for the application of TCI to tumor treatment. In this study, a transcutaneous tumor vaccine (TTV) delivery system was developed using the electrospun silk fibroin (SF) and polyvinyl alcohol (PVA) composite nanofibrous patch loaded with mannosylated polyethyleneimine (PEIman)-modified ethosome (Eth) (termed Eth-PEIman). Eth-PEIman showed a good performance in targeting DCs, and the carriers loaded with antigen (encapsulated in Eths) and adjuvant (absorbed in PEIman) were observed effectively induce DCs maturation in vitro. With the tyrosinase-related protein-2 (TRP2) peptide as antigen and oligodeoxynucleotides containing unmethylated CpG motifs as adjuvant, the TTV-loaded patches (TTVP) significantly inhibited the growth of melanoma in a syngeneic mouse model for melanoma by subcutaneous injection of B16F10 cell lines. Moreover, the combined application of the TTVP and anti-programmed death-1 monoclonal antibody (aPD-1) produced a synergistic antitumor effect, which could be related to the infiltration of more CD4+ and CD8+ T cells in the tumor tissues. The application of TTVP also increased the expression of IL-12, which may be part of the mechanism of synergistic antitumor effect between the TTVP and aPD-1. These results suggest that the combination of the TTVP and immune checkpoint blockers could be an effective strategy for tumor treatment. STATEMENT OF SIGNIFICANCE: Transcutaneous immunization has the advantages of safety, high efficiency, non-invasiveness and convenient use. In this study, a novel transcutaneous tumor vaccine patch (TTVP) was developed using tumor antigens-loaded ethosomes that can target dendritic cells percutaneously. Our data demonstrated that the TTVP can significantly inhibit tumor growth. Furthermore, the combination of TTVP and aPD-1 produced a synergistic anti-melanoma effect. Considering its convenience and non-invasiveness, this TTVP system could find good application prospects in immunotherapy. The combination of TTVP and aPD-1 could be a useful strategy for the prevention and treatment of tumors.

CoCrMo-Nanoparticles induced peri-implant osteolysis by promoting osteoblast ferroptosis via regulating Nrf2-ARE signalling pathway.

OBJECTIVES: Aseptic loosening (AL) is the most common reason of total hip arthroplasty (THA) failure and revision surgery. Osteolysis, caused by wear particles released from implant surfaces, has a vital role in AL. Although previous studies suggest that wear particles always lead to osteoblast programmed death in the process of AL, the specific mechanism remains incompletely understood and osteoblast ferroptosis maybe a new mechanism of AL. MATERIALS AND METHODS: CoCrMo nanoparticles (CoNPs) were prepared to investigate the influence of ferroptosis in osteoblasts and calvaria resorption animal models. Periprosthetic osteolytic bone tissue was collected from patients who underwent AL after THA to verify osteoblast ferroptosis. RESULTS: Our study demonstrated that CoNPs induced significant ferroptosis in osteoblasts and particles induced osteolysis (PIO) animal models. Blocking ferroptosis with specific inhibitor Ferrostatin-1 dramatically reduced particle-induced ferroptosis in vitro. Moreover, in osteoblasts, CoNPs significantly downregulated the expression of Nrf2 (nuclear factor erythroid 2-related factor 2), a core element in the antioxidant response. The overexpression of Nrf2 by siKeap1 or Nrf2 activator Oltipraz obviously upregulated antioxidant response elements (AREs) and suppressed ferroptosis in osteoblasts. Furthermore, in PIO animal models, the combined utilization of Ferrostatin-1 and Oltipraz dramatically ameliorated ferroptosis and the severity of osteolysis. CONCLUSIONS: These results indicate that CoNPs promote osteoblast ferroptosis by regulating the Nrf2-ARE signalling pathway, which suggests a new mechanism underlying PIO and represents a potential therapeutic approach for AL.

Evaluation of a novel tilapia-skin acellular dermis matrix rationally processed for enhanced wound healing.

Acellular Dermal Matrix (ADM) is mainly made with human or porcine skins and has the risk of zoonotic virus transmission. The fish skin-derived ADM could overcome the shortcoming. Fish skin acellular matrix has been used as wound dressing, but there is few systematic studies on tilapia-skin acellular dermal matrix (TS-ADM). In the present study, a novel TS-ADM was made by an alkaline decellularization process and γ-irradiation. The physical properties, biocompatibility, pre-clinical safety and wound healing activity of TS-ADM were systematically evaluated for its value as a functionally bioactive wound dressing. Histopathological analysis (hematoxylin and eosin staining, 4,6-diamidino-2-phenylindole (DAPI) staining) and DNA quantification both proved that the nuclear components of tilapia skin were removed sufficiently in TS-ADM. Compared to the commercial porcine acellular dermal matrix (DC-ADM), TS-ADM has distinctive features in morphology, thermal stability, degradability and water vapor transmission. TS-ADM was more readily degradable than DC-ADM in vitro and in vivo. In both rat and mini-pig skin wound healing experiments, TS-ADM was shown to significantly promote granulation growth, collagen deposition, angiogenesis and re-epithelialization, which may be attributed to the high expression of transforming growth factor-beta 1 (TGF-ß1), alpha-smooth muscle actin (α-SMA) and CD31. Herein, the novel TS-ADM, used as a low-cost bioactive dressing, could form a microenvironment conducive to wound healing.