Corrigendum to "Antibacterial coaxial hydro-membranes accelerate diabetic wound healing by tuning surface immunomodulatory functions" [Mater. Today Bio, 16 (2022)].

[This corrects the article DOI: 10.1016/j.mtbio.2022.100395.].

Antibacterial coaxial hydro-membranes accelerate diabetic wound healing by tuning surface immunomodulatory functions.

Diabetic foot ulcers, typical non-healing wounds, represent a severe clinical problem. Advanced glycation end-products (AGEs), which create a prolonged pro-inflammatory micro-environment in defective sites, can be responsible for refractoriness of these ulcers. Macrophages are polarized to the M2 phenotype to facilitate the transition from a pro-inflammatory microenvironment to an anti-inflammatory microenvironment, which has been demonstrated to be an effective way to accelerate diabetic wound closure. Herein, we developed coaxial hydro-membranes mimicking the extracellular matrix structure that are capable of anti-inflammatory and antibacterial functions for diabetic wound repair. These fibrous membranes maintain a moist microenvironment to support cell proliferation. Macrophages grow in an elongated shape on the surface of the fibrous membranes. The fibrous membranes effectively impaired macrophage AGE-induced M1 polarization and induced macrophage polarization towards the M2 phenotype. The effects of the fibrous membranes on the interactions between macrophages and repair cells under a diabetic condition were also investigated. Furthermore, in vivo results from a full-thickness diabetic wound model confirmed the potential of the coaxial hydro-membranes to accelerate wound healing. This study's results indicate that the developed bioactive anti-inflammatory and antibacterial wound dressing can affect AGE-induced macrophage activation and crosstalk between macrophages and fibroblasts for treating diabetic wounds.

Inhibiting Matrix Metalloproteinases Protects Evoked Electromyography Amplitudes and Muscle Tension in the Orbicularis Oris Muscle in a Rat Model of Facial Nerve Injury.

Facial nerve injury results in degradation of the neuromuscular junction (NMJ) and blocks neurotransmission between the pre- and postsynaptic structures, which are separated by a synaptic cleft. Matrix metalloproteinases (MMPs), enzymes that degrade and modify the extracellular matrix, play critical roles in regulating NMJ remodeling. We previously demonstrated that MMP1, MMP2, MMP3, MMP7, and MMP9 are overexpressed in facial nerve-innervated orbicularis oris muscle after facial nerve injury in a rat model. In the present study, the MMP inhibitor prinomastat was administered to rats after facial nerve injury. The MMP levels, agrin expression, and muscle-specific kinase (MuSK) phosphorylation were evaluated. Variations in evoked electromyography (EEMG) amplitude were also recorded. Compared with the control group, MMP expression in the orbicularis oris after facial nerve injury was significantly reduced in the prinomastat group. Inhibition of MMP expression maintained agrin expression and MuSK phosphorylation; the NMJ morphology was also protected after the injury. Moreover, prinomastat treatment sustained EEMG amplitude and muscle tension after the injury. These findings indicate that inhibiting MMPs can protect the function and morphology of the NMJ and demonstrate the need for protection of the NMJ at early stages after facial nerve injury.

Curcumin-incorporated 3D bioprinting gelatin methacryloyl hydrogel reduces reactive oxygen species-induced adipose-derived stem cell apoptosis and improves implanting survival in diabetic wounds.

Background: Gelatin methacryloyl (GelMA) hydrogels loaded with stem cells have proved to be an effective clinical treatment for wound healing. Advanced glycation end product (AGE), interacting with its particular receptor (AGER), gives rise to reactive oxygen species (ROS) and apoptosis. Curcumin (Cur) has excellent antioxidant activity and regulates intracellular ROS production and apoptosis. In this study, we developed a Cur-incorporated 3D-printed GelMA to insert into adipose-derived stem cells (ADSCs) and applied it to diabetic wounds. Methods: GelMA hydrogels with Cur were fabricated and their in vitro effects on ADSCs were investigated. We used structural characterization, western blot, ROS and apoptosis assay to evaluate the antioxidant and anti-apoptotic activity, and assessed the wound healing effects to investigate the mechanism underlying regulation of apoptosis by Cur via the AGE/AGER/nuclear factor-κB (NF-κB) p65 pathway. Results: A 10% GelMA scaffold exhibited appropriate mechanical properties and biocompatibility for ADSCs. The circular mesh structure demonstrated printability of 10% GelMA and Cur-GelMA bioinks. The incorporation of Cur into the 10% GelMA hydrogel showed an inhibitory effect on AGEs/AGER/NF-κB p65-induced ROS generation and ADSC apoptosis. Furthermore, Cur-GelMA scaffold promoted cell survival and expedited in vivo diabetic wound healing. Conclusions: The incorporation of Cur improved the antioxidant activity of 3D-printed GelMA hydrogel and mitigated AGE/AGER/p65 axis-induced ROS and apoptosis in ADSCs. The effects of scaffolds on wound healing suggested that Cur/GelMA-ADSC hydrogel could be an effective biological material for accelerating wound healing.

Neuregulin-1ß increases glucose uptake and promotes GLUT4 translocation in palmitate-treated C2C12 myotubes by activating PI3K/AKT signaling pathway.

Insulin resistance (IR) is a feature of type 2 diabetes (T2DM) accompanied by reduced glucose uptake and glucose transporter 4 (GLUT4) translocation by skeletal muscle. Neuregulin-1ß (NRG-1ß) is essential for myogenesis and the regulation of skeletal muscle metabolism. Neuregulin-1ß increases insulin sensitivity, promotes glucose uptake and glucose translocation in normal skeletal muscle. Here, we explored whether Neuregulin-1ß increased glucose uptake and GLUT4 translocation in palmitate (PA)-treated C2C12 myotubes. After C2C12 myoblasts differentiated into myotubes, we used palmitate to induce cellular insulin resistance. Cells were incubated with or without Neuregulin-1ß and glucose uptake was determined using the 2-NBDG assay. The expression level of glucose transporter 4 (GLUT4) was measured via immunofluorescence and Western blotting. MK2206, an inhibitor of AKT, was employed to reveal the important role played by AKT signaling in PA-treated C2C12 myotubes. We then established an animal model with T2DM and evaluated the effects of Neuregulin-1ß on body weight and the blood glucose level. The GLUT4 level in the gastrocnemius of T2DM mice was also measured. NRG-1ß not only increased glucose uptake by PA-treated myotubes but also promoted GLUT4 translocation to the plasma membrane. The effect of NRG-1ß on PA-treated C2C12 myotubes was associated with AKT activation. In T2DM mice, Neuregulin-1ß not only improved diabetes-induced weight loss and diabetes-induced hyperglycemia, but also promoted GLUT4 translocation in the gastrocnemius. In summary, Neuregulin-1ß increased glucose uptake and promoted translocation of GLUT4 to the plasma membrane in PA-treated C2C12 myotubes by activating the PI3K/AKT signaling pathway.

Heme oxygenase-1 induction mitigates burn-associated early acute kidney injury via the TLR4 signaling pathway.

OBJECTIVES: Early acute kidney injury (AKI) after burn contributes to disastrous prognoses for severely burned patients. Burn-induced renal oxidative stress and secondary proinflammatory mediator release contribute to early AKI development, and Toll-like receptor (TLR) 4 regulates inflammation. Heme oxygenase-1 (HO-1) is a stress-responsive enzyme that plays a vital role in protecting against ischemia-induced organ injury via its antioxidant properties and regulation of inflammation. We investigated the potential effect of HO-1 induction in preventing burn-induced early AKI and its related mechanism. METHODS: A classic major-burn rat model was established using a 100 °C water bath, and hemin was injected intraperitoneally immediately after the injury to induce HO-1. Histological staining and blood tests were used to assess AKI progression based on structural changes and function. Renal levels of HO-1, oxidative stress, proinflammatory mediators and TLR4-related signals were detected using ELISA, immunostaining, qRT-PCR, and western blotting. The selective TLR4 inhibitor TAK242 and TLR4 inducer LPS were introduced to determine the roles of HO-1 in burn-related renal inflammation and the TLR4 pathway. RESULTS: Hemin improved burn-induced renal histological damage and dysfunction, and this beneficial effect was related to reduced renal oxidative stress and the release of proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1ß, IL-6 and intracellular adhesion molecule-1 (ICAM-1). Hemin downregulated the expression of TLR4 and the subsequent phosphorylation of IKKα/ß, IκBα, and NF-κB p65;. TAK242 exerted an effect similar to but weaker than hemin; and LPS reversed the antiinflammatory effect of hemin and the regulation of TLR4 signals. These results suggested that the TLR4 signaling pathway mediated the HO-1-facilitated regulation of renal inflammation after burn. CONCLUSION: The present study demonstrated that HO-1 induction prevented burn-induced early AKI by targeting renal inflammation, which was mediated via regulation of the TLR4/NF-κB signaling pathway.

Cellulose Nanocrystal-Enhanced Thermal-Sensitive Hydrogels of Block Copolymers for 3D Bioprinting.

The hydrogel formed by polyethylene glycol-aliphatic polyester block copolymers is an ideal bioink and biomaterial ink for three-dimensional (3D) bioprinting because of its unique temperature sensitivity, mild gelation process, good biocompatibility, and biodegradability. However, the gel forming mechanism based only on hydrophilic-hydrophobic interaction renders the stability and mechanical strength of the formed hydrogels insufficient, and cannot meet the requirements of extrusion 3D printing. In this study, cellulose nanocrystals (CNC), which is a kind of rigid, hydrophilic, and biocompatible nanomaterial, were introduced to enhance the hydrogels so as to meet the requirements of extrusion 3D printing. First, a series of poly(ε-caprolactone/lactide)-b-poly(ethylene glycol)-b-poly(ε-caprolactone/lactide) (PCLA-PEG-PCLA) triblock copolymers with different molecular weights were prepared. The thermodynamic and rheological properties of CNC-enhanced hydrogels were investigated. The results showed that the addition of CNC significantly improved the thermal stability and mechanical properties of the hydrogels, and within a certain range, the enhancement effect was directly proportional to the concentration of CNC. More importantly, the PCLA-PEG-PCLA hydrogels enhanced by CNC could be extruded and printed through temperature regulation. The printed objects had high resolution and fidelity with effectively maintained structure. Moreover, the hydrogels have good biocompatibility with a high cell viability. Therefore, this is a simple and effective strategy. The addition of the hydrophilic rigid nanoparticles such as CNC improves the mechanical properties of the soft hydrogels which made it able to meet the requirements of 3D bioprinting.

Three-dimensional bioprinting of a full-thickness functional skin model using acellular dermal matrix and gelatin methacrylamide bioink.

Treatment of full-thickness skin defects still presents a significant challenge in clinical practice. Three-dimensional (3D) bioprinting technique offers a promising approach for fabricating skin substitutes. However, it is necessary to identify bioinks that have both sufficient mechanical properties and desirable biocompatibilities. In this study, we successfully fabricated acellular dermal matrix (ADM) and gelatin methacrylamide (GelMA) bioinks. The results demonstrated that ADM preserved the main extracellular matrix (ECM) components of the skin and GelMA had tunable mechanical properties. Both bioinks with shear-thinning properties were suitable for 3D bioprinting and GelMA bioink exhibited high printability. Additionally, the results revealed that 20% GelMA with sufficient mechanical properties was suitable to engineer epidermis, 1.5% ADM and 10% GelMA displayed relatively good cytocompatibilities. Here, we proposed a new 3D structure to simulate natural full-thickness skin, which included 20% GelMA with HaCaTs as an epidermal layer, 1.5% ADM with fibroblasts as the dermis, and 10% GelMA mesh with human umbilical vein endothelial cells (HUVECs) as the vascular network and framework. We demonstrated that this 3D bioprinting functional skin model (FSM) could not only promote cell viability and proliferation, but also support epidermis reconstruction in vitro. When transplanted in vivo, the FSM could maintain cell viability for at least 1 week. Furthermore, the FSM promoted wound healing and re-epithelization, stimulated dermal ECM secretion and angiogenesis, and improved wound healing quality. The FSM may provide viable functional skin substitutes for future clinical applications. STATEMENT OF SIGNIFICANCE: We propose a new 3D structure to simulate natural full-thickness skin, which included 20% GelMA with HaCaTs as an epidermal layer, 1.5% ADM with fibroblasts as the dermis, and 10% GelMA mesh with HUVECs as the vascular network. It could not only maintain a moist microenvironment and barrier function, but also recreate the natural skin microenvironment to promote cell viability and proliferation. This may provide viable functional skin substitutes for future clinical applications.

Astaxanthin protects against early acute kidney injury in severely burned rats by inactivating the TLR4/MyD88/NF-κB axis and upregulating heme oxygenase-1.

Early acute kidney injury (AKI) contributes to severe morbidity and mortality in critically burned patients. Renal inflammation plays a vital role in the progression of early AKI, acting as a therapeutic target. Astaxanthin (ATX) is a strong antioxidant widely distributed in marine organisms that exerts many biological effects in trauma and disease. ATX is also suggested to have anti-inflammatory activity. Hence, we attempted to explore the role of ATX in protecting against early postburn AKI via its anti-inflammatory effects and the related mechanisms. A severely burned model was established for histological and biochemical assessments based on adult male rats. We found that oxidative stress-induced tissue inflammation participated in the development of early AKI after burn injury and that the MyD88-dependent TLR4/NF-κB pathway was activated to regulate renal inflammation. The TLR4 and NF-κB inhibitors TAK242 and PDTC showed similar effects in attenuating burn-induced renal inflammation and early AKI. Upon ATX treatment, the release of inflammatory mediators in the kidneys was downregulated, while the TLR4/MyD88/NF-κB axis was inhibited in a dose-related manner. TAK242 and PDTC could enhance the anti-inflammatory effect of high-dose ATX, whereas lipopolysaccharide (LPS) reversed its action. Furthermore, the expression of heme oxygenase (HO)-1 was upregulated by ATX in a dose-related manner. Collectively, the above data suggest that ATX protects against renal inflammation in a dose-related manner by regulating the TLR4/MyD88/NF-κB axis and HO-1 and ultimately prevents early AKI following severe burns.

ASMq protects against early burn wound progression in rats by alleviating oxidative stress and secondary mitochondria­associated apoptosis via the Erk/p90RSK/Bad pathway.

Burn wounds present an evolutionary progression, in which the initial wound tissue deepens and expands following thermal injury. Progressive tissue damage in the zone of stasis may worsen burn injury, which is associated with oxidative stress and secondary apoptosis, and worsen the prognosis of patients with burn wounds. The mitochondrial apoptotic pathway is involved in receiving oxidative signals and regulating tissue apoptosis. Previously, Abnormal Savda Munziq (ASMq), a natural compound of traditional Uyghur Medicine, which includes ten types of herb, has been reported to exhibit a number of effects, including anti­inflammatory, antioxidative and anti­apoptotic activities. The present study demonstrated that ASMq protected against early burn wound progression following thermal injury in rats; this effect may be mediated by its ability to attenuate oxidative stress­induced mitochondria­associated apoptosis. The present study may provide a novel therapeutic method to prevent early burn wound progression following burn injury.

Locally activated mitophagy contributes to a "built-in" protection against early burn-wound progression in rats.

AIMS: Deep burn-wounds undergo a dynamic progression in the initial or periburn area after insults, and the zone of stasis is the crucial region suffering the deterioration, considered as salvageable. Few studies explored the role of mitochondria in this process. This study is to clarify a possible "built-in" protection of mitophagy. MAIN METHODS: A classic "comb" scald rat model was established. Histological and blood-flow observation were processed based on hematoxylin-eosin staining and laser analysis. Oxidative and apoptotic status were analyzed by commercial kits. Transmission-electron microscope, immunofluorescence staining, and western blot were applied to detect the mitophagy in the zone of stasis and potential regulators. Adenovirus-based gene-silence contributed to determine the role of HIF-1α as a regulatory mediator. KEY FINDINGS: We found that burn-caused typical ischemia and histological deterioration in the zone of stasis, in parallel with increases in oxidative stress and apoptosis. Mitochondrial damage was involved in the aforementioned changes. Furthermore, we detected mitophagy in burn-wounds, which was contradictory to the burn-wound conversion. HIF-1α expression was closely related to the level of mitophagy, while BNIP3 and PARKIN are involved downstream. SIGNIFICANCE: We demonstrate that burn-induced mitochondrial impairment contributes to the mobilization of injurious mechanisms in the zone of stasis and that mitophagy provides a beneficial way to protect against burn-wound progression via the elimination of damaged mitochondria. Our findings offer insights into mitochondrial quality control in burn-wound progression and suggest the novel concept that HIF-1α may be a therapeutic target due to its possible regulation on BNIP3- or PARKIN-mediated mitophagy.

Crystallization enhanced thermal-sensitive hydrogels of PCL-PEG-PCL triblock copolymer for 3D printing.

Temperature-sensitive hydrogels with mild gel-forming process, good biocompatibility and biodegradability have been widely studied as bioinks and biomaterial inks for 3D bioprinting. However, the hydrogels synthesized via copolymerization of aliphatic polyesters and polyethylene glycols have low mechanical strength and cannot meet the needs of 3D printing. In this paper, we propose a strategy of enhancing the strength of hydrogels by introducing crystallization between blocks to meet the requirements of 3D bioprinting inks. A series of polycaprolactone-polyethylene glycol-polycaprolactone (PCL-PEG-PCL) triblock polymers were prepared by ring-opening polymerization, of which the strong crystallinity of polycaprolactone blocks improved the printability and enhanced the mechanical properties of the ink. It was found that the resulted hydrogels were temperature-responsive, and the PCL blocks could form a crystalline phase in the state of the hydrogel, thereby significantly increasing the modulus of the hydrogel. Moreover, the mechanical strength of the hydrogel could be adjusted by changing the composition ratio of each block of the copolymer. The 3D printing results showed that the PCL-PEG-PCL hydrogel with crystallinity can not only be extruded and printed via temperature adjustment, but also the three-dimensional structure can be effectively maintained after 3D printing. The gels demonstrated good cell compatibility, and the cell survival rate was maintained at a high level.

Clinical decision model for the reconstruction of 175 cases of scalp avulsion/defect.

PURPOSE: It has been reported widely on various methods of repairing scalp avulsion/defect, including anastomotic vessels for total scalp avulsion and dermal grafts (skin grafting, latissimus dorsi or anterior serratus flap, "visor flap" repair.). The long-term retrospective study, however, with large sample size remains rare; and there is no report on decision-making tree for repairing emergency scalp avulsion/defects under critical conditions. METHODS: The decision-making model is provided for surgeons to design the scalp reconstruction based on the retrospective analysis of 175 cases of scalp avulsion/scalp defect. In this 10-year retrospective study, 175 cases of the repair of scalp avulsion and scalp defects in a single center were analyzed. The clinical decision model was generated based on representative cases. RESULTS: For patients with scalp avulsion/defects, a comprehensive examination and evaluation on systemic injury and complication should be conducted first for saving lives and reducing trauma effects. To make more reasonable clinical decisions, it is also required to determine the location, size, depth of scalp defect the injury area of cranial periosteum, injury of blood vessel or other adjacent organs, and whether the scalp can be reused. Meanwhile, it is necessary to evaluate whether the patient can tolerate long-term anastomotic vascular surgery according to the vital signs and physical status. CONCLUSION: The primary treatment goal is to decrease traumatic effects and save patient's life while repairing and reconstructing scalp avulsions and scalp defects. In addition, it is necessary to comprehensively consider the anatomical, functional and cosmetic characteristics of scalp, surgical equipment, team technical skillsets and patient's own pursuit to optimize a reasonable surgical solution.

A Retrospective Multicenter Study of 1898 Liquefied Petroleum Gas-Related Burn Patients in Eastern China From 2011 to 2015.

Liquefied petroleum gas (LPG) is a widely used environment-friendly fuel. Previous studies have shown an increasing number of LPG-related burns. Our study was designed to evaluate the epidemiologic pattern of these injuries and provide recommendations for burn prevention. This retrospective study included all patients with LPG-related burns from eight burn centers in Zhejiang Province, China between 2011 and 2015. Database variables included patient demographics, accident characteristics, and injury characteristics. The association between different categorical variables was identified using the chi-square test. And the association between two or more means of quantitative variables was analyzed by the one-way analysis of variance or t-test. A total of 1898 patients were included, 47.31% were males and 52.69% were females. The predominant age group was 31 to 70 years (74.50%), and the majority were poorly educated and the incidence peaked from June to September. The most common place of occurrence was home (74.08%) and gas leak (96.52%) was the most common cause. The four limbs (43.33%) were the most frequently affected areas; the mean burn area was 25.19 ± 20.97% of the total body surface area and most patients (46.89%) suffered from moderate burns. The mean length of hospital stay was 17.66 ± 16.55 days and the majority of patients (89.36%) recovered with a 0.84% mortality rate. Our findings reflected that the increase in incidence rate was alarming, and the causes resulting in LPG-related burns have not gained much attention yet. Therefore, this calls for simple but strict measures aiming at each hazardous step during the use of LPG to prevent these burn injuries.

Analysis of binding interaction between pegylated puerarin and bovine serum albumin by spectroscopic methods and dynamic light scattering.

The interaction between bovine serum albumin (BSA) and pegylated puerarin (Pur) in aqueous solution was investigated by UV-Vis spectroscopy, fluorescence spectroscopy and circular dichroism spectra (CD), as well as dynamic light scattering (DLS). The fluorescence of BSA was strongly quenched by the binding of pegylated Pur to BSA. The binding constants and the number of binding sites of mPEG(5000)-Pur with BSA were 2.67±0.12 and 1.37±0.05 folds larger after pegylating, which were calculated from the data obtained from fluorescence quenching experiments. The enthalpy change (ΔH) and entropy change (ΔS) were calculated to be 4.09 kJ mol(-1) and 20.01 J mol(-1) K(-1), respectively, according to Van't Hoff equation, indicating that the hydrophobic force plays a main role in the binding interaction between pegylated Pur and BSA. In addition, the negative sign for Gibbs free energy change (ΔG) implies that the interaction process is spontaneous. Moreover, the results of synchronous fluorescence and CD spectra demonstrated that the microenvironment and the secondary conformation of BSA were changed. Comparing with Pur, all our data collected indicated that pegylated Pur interacted with BSA in the same way as that of Pur, but docked into the hydrophobic pocket of BSA with more accessibility and stronger binding force. DLS measurements showed monomethoxy polyethylene glycol (mPEG) have an effect on BSA conformation, and revealed that changes in BSA size might be due to increases in binding constant and the absolute values of ΔG after Pur pegylation.

[Agrobacterium tumefaciens mediated Chitinase and beta-1,3-glucanase gene transformation for Pinellia ternata].

OBJECTIVE: To obtain transgenic Pinellia ternata plants resistant to fungus by transfer Chitinase and beta-1,3-Glucanase gene from Trichoderma harzianum. METHOD: Using hygromycin phosphotransferase as the selection marker, the Chitinase gene (ech42), beta-1,3-Glucanase gene (gluc78) and both gene pCAMBIA(ech42 + gluc78) driven by CaMV35S promoter were transferred into P. ternata callus via Agrobacterium-mediated transformation. RESULT: PCR results confirmed that the regenerants were identified to be transgenic lines and the RT-PCR results confirmed that foreign genes construction were transfer to mRNA. Two foreign genes were inherited stably to T5 generation according to PCR results of the lines. CONCLUSION: The results showed that chitinase gene ech42 and beta-1, 3-glucanase gene gluc78 respectively or together introducing and co-integrating into P. ternata