Chitosan is an excellent carrier material for bioactive substances, and its binding ability is affected by the pH value of surrounding environments. Healthy skin is maintained in a slightly acidic environment, whereas the wound healing environment is normally neutral or slightly alkaline. In the present study, the authors proposed developing a thermally stable bioactive chitosan scaffold (T-CS) with pH-responsive exosome adsorption and release functions to promote wound healing. Our results revealed that T-CS could automatically capture exosomes from human umbilical cord mesenchymal stem cells in an acidic environment and release them in alkaline or neutral environments. The exosomes separated by T-CS and the traditional ultracentrifugation (UC) method exhibited similar size and protein markers. Furthermore, the exosomal biological activities of the T-CS (T-CS-E) and UC groups exhibited similar anti-inflammatory, proproliferation, promigration, and proendothelial cell-tube formation effects on human umbilical vein endothelial cells. Similar results were achieved in a mouse model by sustainably releasing exosomes. T-CS-E could facilitate wound healing by enhancing cell proliferation, inhibiting wound inflammation, and promoting vascularization. Therefore, this study developed a T-CS scaffold that integrates exosome isolation and application for wound healing, laying the foundation for future clinical use.

Hydrogel is a kind of carrier of powerful therapeutic bioactive molecules. Here, carboxymethyl chitosan-silk nanofiber (CCSF) composite hydrogels loaded with a small molecule compound, Forskolin, were prepared to achieve sustained release of the small molecule drug for promoting wound healing. In vitro, investigations confirmed that the innovative composite dressing is non-toxic and cyto-compatible. Specifically, it can encourage the proliferation of human umbilical vein endothelial cells (HUVECs) and mouse dermis fibroblasts, and inhibit the accumulation of intracellular reactive oxygen species (ROS) in the cells. The capacity of cell migration in myofibroblasts was restrained, also implying less scarring in vivo. Skin wound regeneration results showed that the Forskolin-loaded compound hydrogel accelerated wound closure, enhanced neovascularization, and promoted hair follicle regeneration. The multiple-material delivery system shows a promising application in skin wound repair.

Wound dressing diligently facilitate healing by fostering hemostasis, immunoregulation, the angiogenesis, and collagen deposition. Our methodology entails fabricating chitosan-taurine nanoparticles (CS-Tau) through an ionic gelation method. The morphology of CS-Tau was observed utilizing Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Dynamic Light Scattering (DLS). The nanoparticles are subsequently incorporated into carboxymethyl chitosan hydrogels for crosslinking by EDC-NHS, yielding hydrogel dressings (CMCS-CS-Tau) designed to extend the duration of taurine release. In vitro investigations confirmed that these innovative compound dressings displayed superior biodegradation, biocompatibility, cytocompatibility, and non-toxicity, in addition to possessing anti-inflammatory properties, and stimulating the proliferation and mobility of human umbilical vein endothelial cells (HUVECs). Experiments conducted on mice models with full-thickness skin removal demonstrated that CMCS-CS-Tau efficaciously aided in wound healing by spurring angiogenesis, and encouraging collagen deposition. CMCS-CS-Tau can also minimize inflammation and promote collagen deposition in chronic diabetic wound. Hence, CMCS-CS-Tau promotes both acute and chronic diabetic wound healing. Furthermore, the sustained release mechanism of CMCS-CS-Tau on taurine reveals promising potential for extending its clinical utility in relation to various biological effects of taurine.

Mesenchymal stem cell (MSC)-based therapy has been considered as a promising approach targeting a variety of intractable diseases due to remarkable multiple effect of MSCs, such as multilineage differentiation, immunomodulatory property, and pro-regenerative capacity. However, poor engraftment, low survival rate of transplanted MSC, and impaired donor-MSC potency under host age/disease result in unsatisfactory therapeutic outcomes. Enhancement strategies, including genetic manipulation, pre-activation, and modification of culture method, have been investigated to generate highly functional MSC, and approaches for MSC pre-activation are highlighted. In this review, we summarized the current approaches of MSC pre-activation and further classified, analysed the scientific principles and main characteristics of these manipulations, and described the pros and cons of individual pre-activation strategies. We also discuss the specialized tactics to solve the challenges in this promising field so that it improves MSC therapeutic functions to serve patients better.

Chronic wound is one of the most common complications that are associated with diabetes. The cutaneous microbiome is known to play essential roles in the regulation of barrier function and protecting against potential assault. Thus, it is necessary to gain a better understanding of the relationship between microbial community and skin structures in unwounded diabetic skin to explore possible preventive strategies. To achieve the same, a pig diabetic model was built in the present study. Further,16S rDNA sequencing was used to characterize the skin bacteriome. It was observed that the pigs showed skin bacteriome similar to humans in the non-diabetes group, while it varied in the case of diabetes. Further, the β-diversity analysis showed that the bacterial community was significantly different under the diabetes group. More species differences were identified between the two groups at genus level. The predictive function analysis also showed the involvement of significantly different pathways of microbial gene function in diabetes. In agreement with this, skin histology analysis also showed signs of reduced epidermal thickness and rete ridges in diabetic skin. Less proliferation of keratinocytes and impaired TJ barrier was also detected. This evidence suggested that pigs might serve as the best surrogate for cutaneous microbiome studies. Altogether, the present study reported that the skin bacteriome and histology changed significantly in unwounded diabetic skin, which provided a theoretical basis for the regulation of disordered skin bacteriome. The findings of the study would assist in the improvement of the skin environment and prevention of skin infection and chronic wounds.

Traditional Chinese medicine (TCM) had been extensively used in China for wound management and had shown great potential in wound treatment while its mechanism is still needed to be addressed.

Background: Wound healing is a dynamic and complex process that is regulated by a variety of factors and pathways. This study sought to identify the mechanisms of the four-herb Chinese medicine ANBP in enhancing wound repair. Material/Methods: By comparing the group treated with ANBP for 6 h (Z6h) with the corresponding control group (C6h), we used the new high-throughput differential acetylation proteomics method to explore the mechanism of ANBP treatment and analyse and identify new targets of ANBP for promoting wound healing. Results: ANBP promoted skin wound healing in mice; the wound healing process was accelerated and the wound healing time was shortened (P<0.05). The upregulated proteins were distributed mostly in the mitochondria to nuclear respiratory chain complexes and cytoplasmic vesicles. The dominant pathways for upregulated proteins were fatty acid metabolism, pyruvate metabolism, and tricarboxylic acid cycle. Pdha1 was upregulated with the most acetylation sites, while the downregulated Ncl, and Pfkm were most acetylated. Conclusions: The findings from our study showed that ANBP improved cell aerobic respiration through enhanced glycolysis, pyruvic acid oxidative decarboxylation, and the Krebs cycle to produce more ATP for energy consumption, thus accelerating wound repair of skin.

I the original version of this article on p 9297, Figure 8 contains a mistake of the histochemical staining image on day 7 after the subcutaneous implantation of the NSF-MA scaffold. In the revised images provided below, the original histochemical staining image on day 7 after the subcutaneous implantation of the NSF-MA scaffold is included in Figure 8 to reveal the actual scaffold’s biocompatibility. This correction does not alter any conclusion of this work.

Fine tuning physical cues of silk fibroin (SF) biomaterials to match specific requirements for different soft tissues would be advantageous. Here, amorphous SF nanofibers were used to fabricate scaffolds with better hierarchical extracellular matrix (ECM) mimetic microstructures than previous silk scaffolds. Kinetic control was introduced into the scaffold forming process, resulting in the direct production of water-stable scaffolds with tunable secondary structures and thus mechanical properties. These biomaterials remained with amorphous structures, offering softer properties than prior scaffolds. The fine mechanical tunability of these systems provides a feasible way to optimize physical cues for improved cell proliferation and enhanced neovascularization in vivo. Multiple physical cues, such as partly ECM mimetic structures and optimized stiffness, provided suitable microenvironments for tissue ingrowth, suggesting the possibility of actively designing bioactive SF biomaterials. These systems suggest a promising strategy to develop novel SF biomaterials for soft tissue repair and regenerative medicine.

Persistent hyper-inflammation is a distinguishing pathophysiological characteristic of chronic wounds, and macrophage malfunction is considered as a major contributor thereof. In this review, we describe the origin and heterogeneity of macrophages during wound healing, and compare macrophage function in healing and non-healing wounds. We consider extrinsic and intrinsic factors driving wound macrophage dysregulation, and review systemic and topical therapeutic approaches for the restoration of macrophage response. Multidimensional analysis is highlighted through the integration of various high-throughput technologies, used to assess the diversity and activation states as well as cellular communication of macrophages in healing and non-healing wound. This research fills the gaps in current literature and provides the promising therapeutic interventions for chronic wounds.

Localized and sustained osteogenic-angiogenic stimulation to bone defects is critical for effective bone repair. Here, desferrioxamine (DFO) was loaded on silk fibroin nanofibers and blended with hydroxyapatite nanorods (HA), forming injectable DFO-loaded silk fibroin-HA nanocomposite hydrogels. The composite hydrogels remained homogeneous distribution of HA with high ratio (60 %) and also higher stiffness than that of pure silk fibroin nanofiber hydrogels, which provided stable osteogenic stimulation niches for tissue regeneration. Without the scarify of injectability, the hydrogels achieved slow delivery of DFO for above 60 days, resulting in suitable angiogenesis in vitro and in vivo and better osteogenesis than DFO-free systems. Compared to previous injectable silk fibroin-HA hydrogels, the introduction of vascularization capacity further stimulated the osteogenic differentiation of stem cells and accelerated new bone formation. Quicker and better bone healing were detected at defect sites after the injection of DFO-loaded nanocomposite hydrogels, indicating the effective synergistic effect of osteogenic and angiogenic cues. This work provides a simple and effective strategy of introducing angiogenic cues to bone matrices. We believe that the injectable nanocomposite hydrogels are suitable for the regeneration of bone tissues.

To determine the prevalence and clinical features of olfactory and taste disorders among coronavirus disease 2019 (COVID-19) patients in China. A cross-sectional study was performed in Wuhan from April 3, 2020 to April 15, 2020. A total of 187 patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) completed face-to-face interviews or telephone follow-ups. We found that the prevalence of olfactory and taste disorders was significantly lower in the Chinese cohort than in foreign COVID-19 cohorts. Females were more prone to olfactory and taste disorders. In some patients, olfactory and taste disorders precede other symptoms and can be used as early screening and warning signs.

Small molecules loaded into biological materials present a promising strategy for stimulating endogenous repair mechanisms for in situ skin regeneration. Lithium can modulate various biologic processes, promoting proliferation, angiogenesis, and decreasing inflammation. However, its role in skin repair is rarely reported. In this study, we loaded lithium chloride (LiCl) into the chitosan (CHI) hydrogel and develop a sterile and biocompatible sponge scaffold through freeze-drying. In-vitro assessment demonstrated that the CHI-LiCl composite scaffolds (CLiS) possessed favorable cytocompatibility, swelling and biodegradation. We created full-thickness skin wounds in male C57BL/c mice to evaluate the healing capacity of CLiS. Compared with the wounds of control and CHI scaffold (CS) groups, the wounds in the CLiS-treated group showed reduced inflammation, improved angiogenesis, accelerated re-epithelialization, sustained high expression of β-catenin with a small amount of regenerated hair follicles. Therefore, CLiS may be a promising therapeutic dressing for skin wound repair and regeneration.

Small molecules play remarkable roles in promoting tissue regeneration, but are limited by their burst release. Small molecules such as deferoxamine (DFO) have been released slowly from silk hydrogels and stimulated angiogenesis and wound healing, but failed to achieve functional recovery of skin. Various bioactive molecules are required to create a suitable niche for better skin regeneration by controlling their release behaviors. Herein, a small molecule SB216763, a GSK-3 inhibitor, was loaded on silk fibroin nanofibers (SNF), and then mixed with chitosan (CS) to prepare the small molecule-loaded composite bionic scaffolds (CSNF-SB). Given the interaction of SNF and SB216763, the sustained release of SB216763 for more than 21 days was achieved for SNF and CSNF-SB composite scaffolds. Compared to drug-free CSNF scaffolds, CSNF-SB showed better cell adhesion and proliferation capacity, suggesting bioactivity. The upregulated expression of β-catenin in fibroblasts in vitro revealed that the released small molecules maintained their function in composite scaffolds. Quicker and better wound healing was realized with the drug-loaded scaffolds, which was significantly superior to that treated with drug-free scaffolds. Unlike the DFO-loaded silk hydrogel system, hair follicle neogenesis was also found in the drug-loaded-scaffold treatment wounds, demonstrating functional recovery. Therefore, silk nanofibers as versatile carriers for different small bioactive molecules could be used to fabricate scaffolds with optimized niches and then achieve functional recovery of tissues. The small molecule-loaded bionic scaffolds have a promising future in skin tissue regeneration.

Scar formation is usually the pathological consequence of skin trauma. And hypertrophic scars (HSs) frequently occur in people after being injured deeply. HSs are unusually considered as the result of tissue contraction and excessive extracellular matrix component deposition. Myofibroblasts, as the effector cells, mainly differentiated from fibroblasts, play the crucial role in the pathophysiology of HSs. A number of growth factors, inflammatory cytokines involved in the process of HS occurrence. Currently, with in-depth exploration and clinical research of HSs, various creative and effective treatments budded. In here, we summarize the progress in the molecular mechanism of HSs, and review the available biotherapeutic methods for their pathophysiological characteristics. Additionally, we further prospected that the comprehensive therapy may be more suitable for HS treatment.

Hypertrophic scars (HTS) commonly occurred after burn and trauma. It was characterized by the excessive deposition of extracellular matrix with the inadequate remodeling, which could result in severe physiological and psychological problems. However, the effective available prevention and treatment measures were still limited. The main pathological feature of HTS was the excessive formation of myofibroblasts, and they persist in the repaired tissue. To better understand the mechanics of this process, this review focused on the characteristics and formation of myofibroblasts, the main effector cells in HTS. We summarized the present theories and opinions on myofibroblasts formation from the perspective of related signaling pathways and epigenetic regulation, such as DNA methylation, miRNA/lncRNA/ceRNA action, histone modification, and so forth for a better understanding on the development of HTS. This information might assist in developing effective experimental and clinical treatment strategies. Additionally, we also summarized currently known clinical strategies for HTS treatment, including traditional drugs, molecular medicine, stem cells, and exosomes.

An injectable hydrogel is a powerful carrier for therapeutic bioactive molecules. Here, an injected concentrated conditioned medium (CCM)-silk nanofiber composite hydrogel was developed to achieve the sustained release of multiple proteins and better wound healing. All the encapsulated proteins showed slow delivery for more than 9 days in vitro. Bioactive molecules such as transforming growth factor-beta1 (TGF-β1), insulin-like growth factor binding protein-1 (IGFBP-1), and platelet-derived growth factor-AB (PDGF-AB) were successfully released from CCM-loaded hydrogels, and they induced the proliferation and migration of fibroblasts and endothelial cells in a dose- and time-dependent manner. The differentiation of fibroblasts into myofibroblasts was also inhibited, implying less scar formation in vivo. Skin wound regeneration results indicated that the CCM-loaded hydrogel enhanced neovascularization, accelerated wound closure, and promoted hair follicle regeneration. The injectable multiple protein delivery system shows a promising application in skin wound repair.

Skin regeneration is a vexing problem in the field of regenerative medicine. A bioactive molecule-based strategy has been frequently used in skin wound healing in recent years. Bioactive molecules are practical tools for regulating cellular processes and have been applied to control cellular differentiation, dedifferentiation, and reprogramming. In this review, we focus on recent progress in the use of bioactive molecules in skin regenerative medicine, by which desired cell types can be generated in vitro for cell therapy and conventional therapeutics can be developed to repair and regenerate skin in vivo through activation of the endogenous repairing potential. We further prospect that the bioactive molecule-base method might be one of the promising strategies to achieve in situ skin regeneration in the future.

Background: Tissue contraction and the extracellular matrix deposition are part of the pathogenesis of hypertrophic scars. The transcriptional factor NFE2L2 inhibits fibroblast differentiation in idiopathic pulmonary fibrosis and promotes myofibroblast dedifferentiation. Our previous study showed that the transcription factor NFE2L2 was strongly induced on treatment with arsenic trioxide (ATO). Objective: The present study sought to investigate the effect of ATO on myofibroblast formation to determine its potential role in hypertrophic scar treatment. Methods: Small interfering RNA against NFE2L2 was used on treatment with ATO in human skin myofibroblasts. The expression levels of fibrosis markers were assessed by reverse transcription polymerase chain reaction, western blot, and immunofluorescence staining. The transforming growth factor-beta 1 (TGF-beta 1)/Smad2/3 signaling was detected by western blot. A rabbit ear model was used to evaluate the antifibrotic role of ATO. Results: At the cellular level, ATO abolished fibroblast differentiation in response to TGF-beta 1. ATO reduced TGF-beta 1-induced reactive oxygen species accumulation through increased expression of the antioxidant gene HO-1 in fibroblasts. In addition, ATO promoted the nuclear translocation of NFE2L2 and inhibited the phosphorylation of Smad2/3. In the rabbit ear model, ATO prevented the progression of hypertrophic scar formation. Conclusions: This study provides the first evidence implying that ATO inhibits the formation of myofibroblasts in vivo and in vitro and provides a possible treatment for hypertrophic scars.