Glucose-responsive multifunctional metal-organic drug-loaded hydrogel for diabetic wound healing

Poloxam Thermosensitive Hydrogels Loaded with hFGF2-Linked Camelina Lipid Droplets Accelerate Skin Regeneration in Deep Second-Degree Burns

Burn injuries are difficult to manage due to the defect of large skin tissues, leading to major disability or even death. Human fibroblast growth factor 2 (hFGF2) is known to promote burn wound healing. However, direct administration of hFGF2 to the wound area would affect the bioactivity. To provide a supportive environment for hFGF2 and control its release in a steady fashion, in this research, we developed novel thermosensitive poloxam hydrogels delivered with hFGF2-linked Camelina lipid droplets (CLD-hFGF2 hydrogels). Cryopreserved scanning electron microscopy (SEM) results indicated that the incorporation of CLD-hFGF2 does not significantly affect the inner structure of hydrogels. The rheological properties showed that CLD-hFGF2 hydrogels gelated in response to temperature, thus optimizing the delivery method. In vitro, CLD-hFGF2 could be released from hydrogels for 3 days after drug delivery (the release rate was 72%), and the release solution could still promote the proliferation and migration of NIH3T3 cells. In vivo, compared with hydrogels alone or with direct CLD-hFGF2 administration, CLD-hFGF2 hydrogels had the most obvious effect on deep second-degree burn wound healing. This work indicates that CLD-hFGF2 hydrogels have potential application value in burn wound healing.

Stimuli-responsive therapeutic systems for the treatment of diabetic infected wounds

Diabetic wound infection is a common disease that has significantly reduced people's quality of life. Although tremendous achievements have been made in clinical treatment, the crucial challenge in diabetic infected wound management stems from the detrimental diabetic wound environment and the emergence of bacterial resistance after long-term medication, which result in a reduced efficacy, an increased dosage of medication, and severe side effects. To tackle these issues, it is of great significance to develop an innovative treatment strategy for diabetic wound infection therapy. Currently, the exploitation of nanobiomaterial-based therapeutic systems for diabetic infected wounds is booming, and therapeutic systems with a stimuli-responsive performance have received extensive attention. These therapeutic systems are able to accelerate diabetic infected wound healing due to the on-demand release of therapeutic agents in diabetic infected wounds in response to stimulating factors. Based on the characteristics of diabetic infected wounds, many endogenous stimuli-responsive (e.g., glucose, enzyme, hypoxia, and acidity) therapeutic systems have been employed for the targeted treatment of infected wounds in diabetic patients. Additionally, exogenous stimulants, including light, magnetism, and temperature, are also capable of achieving on-demand drug release and activation. In this review, the characteristics of diabetic infected wounds are presented, and then exogenous/endogenous stimuli therapeutic systems for the treatment of diabetic infected wounds are summarized. Finally, the current challenges and future outlook of stimuli-responsive therapeutic systems are also discussed.

Regenerative antibacterial hydrogels from medicinal molecule for diabetic wound repair

Hydrogel products for chronic diabetic wounds, a serious and prevalent complication of diabetes, show limited effects on disability and remain nonspecific. Thus, improvements in the usage of pharmaceutical molecule in the hydrogels are highly desirable to increase the therapeutic effect of hydrogels. In this study, thioctic acid (a common medicine molecule in diabetes treatment) is used for preparing regenerative antibacterial hydrogels (RAH) which contains in situ synthesized silver nanoparticles (AgNPs). The RAH shows regenerative, self-healing and injectable ability, because of the reversible hydrogen and coordination bonds. With good regenerative capacity, RAH can be stored as powder to avoid the water loss and facilitate storage availability. Owing to the antioxidant properties of thioctic acid, the RAH can decrease the oxidative damage and retain cell proliferation efficiency. Due to the in situ synthesized AgNPs, the RAH also exhibits extraordinary antimicrobial capacities against MDR bacteria. All of these superiorities enable RAH to be a promising therapy for chronic diabetic wounds.

Current Advances in the Development of Hydrogel-Based Wound Dressings for Diabetic Foot Ulcer Treatment

Diabetic foot ulcers (DFUs) are one of the most prevalent complications associated with diabetes mellitus. DFUs are chronic injuries that often lead to non-traumatic lower extremity amputations, due to persistent infection and other ulcer-related side effects. Moreover, these complications represent a significant economic burden for the healthcare system, as expensive medical interventions are required. In addition to this, the clinical treatments that are currently available have only proven moderately effective, evidencing a great need to develop novel strategies for the improved treatment of DFUs. Hydrogels are three-dimensional systems that can be fabricated from natural and/or synthetic polymers. Due to their unique versatility, tunability, and hydrophilic properties, these materials have been extensively studied for different types of biomedical applications, including drug delivery and tissue engineering applications. Therefore, this review paper addresses the most recent advances in hydrogel wound dressings for effective DFU treatment, providing an overview of current perspectives and challenges in this research field.

A rapid-triggered approach towards antibacterial hydrogel wound dressing with synergic photothermal and sterilization profiles

Developing non-antibiotic-dependent antibacterial hydrogels for repairing infected skin defect remains largely unexplored. Herein, a synergic photothermal and synergic antibacterial hydrogel was designed via one-pot approach to cope with full-thickness skin wound infection. In this work, the mixture of silver‑sodium lignin sulfonate nanoparticles (Ag-SLS NPs) and polypyrrole-polydopamine nanoparticles (PPy-PDA NPs) for the first time as synergic photothermal agent was introduced into poly (ethylene glycol) diacrylate (PEGDA) to form Ag-SLS/PPy-PDA@PEGDA hydrogel. Thanks to the near-infrared light into heat conversion capacity of both Ag and PPy-PDA NPs, the formed hydrogel shows ultrahigh photothermal activity, and outstanding antibacterial activity to both Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria in vitro. Additionally, in vivo assay indicates that the hydrogel has outstanding long-term antibacterial effect due to the photothermal sterilization along with Ag ions release. Overall, the dual-synergic photothermal and antibacterial effects of the Ag-SLS/PPy-PDA@PEGDA hydrogel could highly accelerate infection wound healing, and thus has great potential to be used for tissue engineering.

Glucose/ROS cascade-responsive ceria nanozymes for diabetic wound healing

Diabetic wounds have an extremely complex microenvironment of hyperglycemia, hypoxia and high reactive oxygen species (ROS). Therefore, the regulation and management of this microenvironment may provide a new and improved treatment method for chronic diabetic wound healing. Herein, a glucose/ROS cascade-responsive nanozyme (CHA@GOx) was developed for diabetic wound treatment based on Ce-driven coassembly by a special dual ligand (alendronic acid and 2-methylimidazole) and glucose oxidase (GOx). It possesses superoxide dismutase and catalase mimic activities, which effectively remove excess ROS. In particular, it can catalyze excessive hydrogen peroxide generated by the glucose oxidation reaction to produce oxygen, regulate the oxygen balance of the wound, and reduce the toxic side effects of GOx, thus achieving the purpose of synergistically repairing diabetic wounds. In vitro experiments show that CHA@GOx assists mouse fibroblast migration and promotes human umbilical vein endothelial cell tube formation. In vivo, it can induce angiogenesis, collagen deposition, and re-epithelialization during wound healing in diabetic mice. Taken together, this study indicates that the coassembly of multifunctional nanozymes has implications in diabetic wound healing.

A review on contemporary nanomaterial-based therapeutics for the treatment of diabetic foot ulcers (DFUs) with special reference to the Indian scenario

Diabetes mellitus (DM) is a predominant chronic metabolic syndrome, resulting in various complications and high mortality associated with diabetic foot ulcers (DFUs). Approximately 15-30% of diabetic patients suffer from DFUs, which is expected to increase annually. The major challenges in treating DFUs are associated with wound infections, alterations to inflammatory responses, angiogenesis and lack of extracellular matrix (ECM) components. Furthermore, the lack of targeted therapy and efficient wound dressings for diabetic wounds often results in extended hospitalization and limb amputations. Hence, it is essential to develop and improve DFU-specific therapies. Nanomaterial-based innovative approaches have tremendous potential for preventing and treating wound infections of bacterial origin. They have greater benefits compared to traditional wound dressing approaches. In this approach, the physiochemical features of nanomaterials allow researchers to employ different methods for diabetic wound healing applications. In this review, the status and prevalence of diabetes mellitus (DM) and amputations due to DFUs in India, the pathophysiology of DFUs and their complications are discussed. Additionally, nanomaterial-based approaches such as the use of nanoemulsions, nanoparticles, nanoliposomes and nanofibers for the treatment of DFUs are studied. Besides, emerging therapeutics such as bioengineered skin substitutes and nanomaterial-based innovative approaches such as antibacterial hyperthermia therapy and gene therapy for the treatment of DFUs are highlighted. The present nanomaterial-based techniques provide a strong base for future therapeutic approaches for skin regeneration strategies in the treatment of diabetic wounds.

Hyaluronic acid-based glucose-responsive antioxidant hydrogel platform for enhanced diabetic wound repair

Hyaluronic acid (HA)-based antioxidant hydrogels have achieved remarkable results in diabetic wound repair. However, the realization of their glucose-responsive antioxidant functions remains a significant challenge. In this study, we modified hyaluronic acid methacrylate (HAMA) with phenylboronic acid (PBA) and developed a glucose-responsive HA derivative (HAMA-PBA). A glucose-responsive HAMA-PBA/catechin (HMPC) hydrogel platform was then fabricated by forming a borate ester bond between HAMA-PBA and catechin. The results showed that the HMPC hybrid hydrogel not only had a three-dimensional network structure and Young's modulus similar to those of skin tissue, but also possessed biocompatibility. The HMPC hydrogel also showed unique glucose-responsive catechin release behavior and remarkable antioxidant capability, which could effectively eliminate intracellular reactive oxygen species and protect cells from oxidative stress damage (increased superoxide dismutase activity, stabilized reduced glutathione/oxidized glutathione ratio, and reduced malondialdehyde content). Additionally, in vitro and in vivo experimental results showed that the HMPC hydrogel effectively promoted angiogenesis (enhanced VEGF and CD31 expression) and reduced inflammatory responses (decreased IL-6 level and increased IL-10 level), thus rapidly repairing diabetic wounds (within three weeks). This was a significant improvement as compared to that observed for the untreated control group and the HMP hydrogel group. These results indicated the potential for the application of the HMPC hydrogel for treating diabetic wounds. STATEMENT OF SIGNIFICANCE: At present, the delayed closure rate of diabetic chronic wounds caused by excessive reactive oxygen species (ROS) remains a worldwide challenge. Hyaluronic acid (HA)-based antioxidant hydrogels have made remarkable achievements in diabetic wound repair; however, the realization of their glucose-responsive antioxidant functions is a tough challenge. In this work, we developed a novel HA-based hydrogel platform with glucose-responsive antioxidant activity for rapid repair of diabetic wounds. In vitro and in vivo experimental results showed that the HMPC hydrogel could effectively promote angiogenesis (enhanced VEGF and CD31 expression) and reduce inflammatory response (decreased IL-6 level and increased IL-10 level), thus rapidly repairing diabetic wounds (within 3 weeks). These results indicated the potential of the HMPC hydrogel for application in diabetic wound treatment.

Progress in hydrogels for skin wound repair

As the first defensive line between the human body and the outside world, the skin is vulnerable to damage from the external environment. Skin wounds can be divided into acute wounds (mechanical injuries, chemical injuries and surgical wounds, etc.) and chronic wounds (burns, infections, diabetes, etc.). In order to manage skin wound, a variety of wound dressings have been developed, including gauze, films, foams, nanofibers, hydrocolloids and hydrogels. Recently, hydrogels have received much attention because of their natural extracellular matrix (ECM)-mimik structure, tunable mechanical properties, and facile bioactive substance delivery capability. They show great potential application in skin wound repair. This paper first introduces the anatomy and function of the skin, the process of wound healing and conventional wound dressings, and then introduces the composition and construction methods of hydrogels. Next, this paper introduces the necessary properties of hydrogels in skin wound repair and the latest research progress of hydrogel dressings for skin wound repair. Finally, the future development goals of hydrogel materials in the field of wound healing are proposed. This article is protected by copyright. All rights reserved.

Smart Hydrogels for Advanced Drug Delivery Systems

Since the last few decades, the development of smart hydrogels, which can respond to stimuli and adapt their responses based on external cues from their environments, has become a thriving research frontier in the biomedical engineering field. Nowadays, drug delivery systems have received great attention and smart hydrogels can be potentially used in these systems due to their high stability, physicochemical properties, and biocompatibility. Smart hydrogels can change their hydrophilicity, swelling ability, physical properties, and molecules permeability, influenced by external stimuli such as pH, temperature, electrical and magnetic fields, light, and the biomolecules' concentration, thus resulting in the controlled release of the loaded drugs. Herein, this review encompasses the latest investigations in the field of stimuli-responsive drug-loaded hydrogels and our contribution to this matter.

Bacillus subtilis WB800N alleviates diabetic wounds in mice by regulating gut microbiota homeostasis and TLR2

OBJECTIVE

This study aims to investigate the effect of Bacillus subtilis WB800N on diabetic wounds.

METHODS

Hematoxylin & eosin (H&E) staining was used to observe the healing of skin wounds. Collagen deposition was assessed by Masson staining. Western blotting and qRT-PCR were used to detect vascular endothelial-related factors (VWF), CD31, TLR2, NLRP3, ASC, and Caspase-1 expression. 16S rDNA sequencing detected microbiota distribution. The concentrations of IL-1β and IL-37 were measured by ELISA. Apoptosis was measured by the TUNEL assay.

RESULTS

Compared with the control group, the wound healing was delayed in diabetic mice. The wound area in the Bacillus subtilis group decreased more significantly than the diabetic wounds group. H&E staining showed that Bacillus subtilis WB800N promoted wound healing and increased re-epithelialization. Masson staining showed that Bacillus subtilis WB800N increased collagen deposition in diabetic wounds mice. Bacillus subtilis WB800N upregulated VWF and CD31 protein expression in diabetic wounds mice. The 16S rDNA results showed that Bacillus subtilis WB800N reduced the diversity of the gut microbiota of diabetic wounds mice and regulated the microbial composition. At the genus level, Bacillus subtilis WB800N reduced the relative abundance of Muribaculaceae and CG-005 in diabetic wounds mice, while increasing the relative abundance of Lactobacillus. Bacillus subtilis WB800N increased the expression of TLR2, NLRP3, ASC, and Caspase-1. Bacillus subtilis WB800N increased the concentrations of IL-1β and IL-37 in serum. Bacillus subtilis WB800N upregulated cell apoptosis. The TLR2 antagonist Sparstolonin B (SsnB) reduced the expression of TLR2, NLRP3, ASC, Caspase-1, IL-1β, and IL-37 and the apoptosis in diabetic wounds mice, while the combined intervention of Bacillus subtilis and SsnB reversed the effect of SsnB treatment alone.

CONCLUSION

Bacillus subtilis WB800N alleviated diabetic wounds healing by regulating gut microbiota homeostasis and TLR2.

SIGNIFICANCE AND IMPACT OF RESEARCH

Our findings might provide potential therapeutic targets for diabetic wounds.