Advanced polymer hydrogels that promote diabetic ulcer healing: mechanisms, classifications, and medical applications

A multi-purpose dressing based on resveratrol-loaded ionic liquids/gelatin methacryloyl hydrogel for enhancing diabetic wound healing

Diabetic wound (DW) is a multifaceted challenge, characterized by persistent bacterial infections and compromised angiogenesis. To address these issues and enhance DW healing, we developed a novel strategy using a photo-crosslinked hydrogel system composed of ionic liquids (ILs) and gelatin methacryloyl (GelMA) loaded with resveratrol (Res). The ILs/GelMA hydrogel was fabricated via a simple photo-crosslinking process, resulting in desirable mechanical properties, biocompatibility, and controlled release kinetics. Res was incorporated into the hydrogel matrix (ILs/GelMA@Res) to ensure sustained release, facilitating angiogenesis and accelerating wound healing. In vitro studies demonstrated that the ILs/GelMA@Res hydrogel exhibited potent antibacterial activity against Staphylococcus aureus and Escherichia coli, inhibiting bacterial growth and biofilm formation. Furthermore, the sustained release of Res from the hydrogel promoted angiogenesis by activating the PI3K/AKT signaling pathways associated with VEGF and FGF, enhancing endothelial cell proliferation, migration, and tube formation. In a DW mice model, the ILs/GelMA@Res hydrogel demonstrated accelerated wound closure, reduced inflammation, and robust neovascularization. This multifunctional hydrogel-based delivery system holds considerable potential for clinical translation, offering a safe and effective treatment modality for diabetic patients with chronic wounds.

Trinitroglycerin-loaded chitosan nanogels accelerate angiogenesis in wound healing process

Trinitroglycerin (TNG) with remarkable angiogenic, antibacterial, and antioxidative activity is a promising candidate to govern wound healing capacity. However, its clinical administration is limited due to associated complications and NO short half-life. In the current study, TNG-loaded chitosan nanogels (TNG-Ngs) were examined in-vitro and in-vivo to gain insight into their clinical application. We prepared TNG-Ngs and characterized their physiochemical properties. The potential of TNG-Ngs was assessed using biocompatibility, scratch assay, and a full-thickness skin wounds model, followed by histopathological and immunohistochemistry examinations. TNG-Ngs particle size 96 ± 18 and definite size distribution histogram. The loading capacity (LC) and encapsulation efficiency (EE) of prepared TNG-Ngs were 70.2 % and 2.1 %, respectively. The TNG-Ngs samples showed enhanced migration of HUVECs with no apparent cytotoxicity. The topical use of TNG-Ngs200 on the wounds revealed a complete wound closure ratio, skin component formation, less scar width, remarkable granulation tissue, promoted collagen deposition, and enhanced the relative mean density of α-SMA and CD31. TNG-Ngs accelerated wound healing by promoting collagen deposition and angiogenic activity, as well as reducing inflammation. The findings indicated that TNG-Ngs is expected to be well vascularized in the wound area and to be more effective in topical therapy.

Waste-to-resource: Extraction and transformation of aquatic biomaterials for regenerative medicine

The fisheries and aquaculture industry are known for generating substantial waste or by-products, often underutilized, or relegated to low-value purposes. However, this overlooked segment harbors a rich repository of valuable bioactive materials of which have a broad-spectrum of high-value applications. As the blue economy gains momentum and fisheries expand, sustainable exploitation of these aquatic resources is increasingly prioritized. In this review, we present a comprehensive overview of technology-enabled methods for extracting and transforming aquatic waste into valuable biomaterials and their recent advances in regenerative medicine applications, focusing on marine collagen, chitin/chitosan, calcium phosphate and bioactive-peptides. We discuss the inherent bioactive qualities of these "waste-to-resource" aquatic biomaterials and identify opportunities for their use in regenerative medicine to advance healthcare while achieving the Sustainable Development Goals.

Teicoplanin-Decorated Reduced Graphene Oxide Incorporated Silk Protein Hybrid Hydrogel for Accelerating Infectious Diabetic Wound Healing and Preventing Diabetic Foot Osteomyelitis

Developing hybrid hydrogel dressings with anti-inflammatory, antioxidant, angiogenetic, and antibiofilm activities with higher bone tissue penetrability to accelerate diabetic wound healing and prevent diabetic foot osteomyelitis (DFO) is highly desirable in managing diabetic wounds. Herein, the glycopeptide teicoplanin is used for the first time as a green reductant to chemically reduce graphene oxide (GO). The resulting teicoplanin-decorated reduced graphene oxide (rGO) is incorporated into a mixture of silk proteins (SP) and crosslinked with genipin to yield a physicochemically crosslinked rGO-SP hybrid hydrogel. This hybrid hydrogel exhibits high porosity, self-healing, shear-induced thinning, increased cell proliferation and migration, and mechanical properties suitable for tissue engineering. Moreover, the hybrid hydrogel eradicates bacterial biofilms with a high penetrability index in agar and hydroxyapatite disks covered with biofilms, mimicking bone tissue. In vivo, the hybrid hydrogel accelerates the healing of noninfected wounds in a diabetic rat and infected wounds in a diabetic mouse by upregulating anti-inflammatory cytokines and downregulating matrix metalloproteinase-9, promoting M2 macrophage polarization and angiogenesis. The implantation of hybrid hydrogel into the infected site of mouse tibia improves bone regeneration. Hence, the rGO-SP hybrid hydrogel can be a promising wound dressing for treating infectious diabetic wounds, providing a further advantage in preventing DFO.

Insights of biopolymeric blended formulations for diabetic wound healing

Diabetic wounds (DWs) pose a significant health burden worldwide, with their management presenting numerous challenges. Biopolymeric formulations have recently gained attention as promising therapeutic approaches for diabetic wound healing. These formulations, composed of biocompatible and biodegradable polymers, offer unique properties such as controlled drug release, enhanced wound closure, and reduced scarring. In this review, we aim to provide a comprehensive overview of the current state of research and future prospects regarding the application of biopolymeric formulations for diabetic wound healing. The review begins by highlighting the underlying pathophysiology of DWs, including impaired angiogenesis, chronic inflammation, and compromised extracellular matrix (ECM) formation. It further explores the key characteristics of biopolymeric materials, such as their biocompatibility, biodegradability, and tunable physicochemical properties, which make them suitable for diabetic wound healing applications. The discussion further delves into the types of biopolymeric formulations utilized in the treatment of DWs. These include hydrogels, nanoparticles (NP), scaffolds, films, and dressings. Furthermore, the review addresses the challenges associated with biopolymeric formulations for diabetic wound healing. In conclusion, biopolymeric formulations present a promising avenue for diabetic wound healing. Their unique properties and versatility allow for tailored approaches to address the specific challenges associated with DWs. However, further research and developments are required to optimize their therapeutic efficacy, stability, manufacturing processes, and regulatory considerations. With continued advancements in biopolymeric formulations, the future holds great promise for improving the management and outcomes of DWs.

Injectable and self-healable nano-architectured hydrogel for NIR-light responsive chemo- and photothermal bacterial eradication

Hydrogels with multifunctional properties activated at specific times have gained significant attention in the biomedical field. As bacterial infections can cause severe complications that negatively impact wound repair, herein, we present the development of a stimuli-responsive, injectable, and in situ-forming hydrogel with antibacterial, self-healing, and drug-delivery properties. In this study, we prepared a Pluronic F-127 (PF127) and sodium alginate (SA)-based hydrogel that can be targeted to a specific tissue via injection. The PF127/SA hydrogel was incorporated with polymeric short-filaments (SFs) containing an anti-inflammatory drug - ketoprofen, and stimuli-responsive polydopamine (PDA) particles. The hydrogel, after injection, could be in situ gelated at the body temperature, showing great in vitro stability and self-healing ability after 4 h of incubation. The SFs and PDA improved the hydrogel injectability and compressive strength. The introduction of PDA significantly accelerated the KET release under near-infrared light exposure and extended its release validity period. The excellent composites' photo-thermal performance led to antibacterial activity against representative Gram-positive and Gram-negative bacteria, resulting in 99.9% E. coli and S. aureus eradication after 10 min of NIR light irradiation. In vitro, fibroblast L929 cell studies confirmed the materials' biocompatibility and paved the way toward further in vivo and clinical application of the system for chronic wound treatments.

Chitosan-Based Biomaterial in Wound Healing: A Review

Wound healing is an evolving and intricate technique that is vital to the restoration of tissue integrity and function. Over the past few decades, chitosan a biopolymer derived from chitin, became known as an emerging biomaterial in the field of healing wounds due to its distinctive characteristics including biocompatibility, biodegradability, affinity to biomolecules, and wound-healing activity. This natural polymer exhibits excellent healing capabilities by accelerating the development of new skin cells, reducing inflammation, and preventing infections. Due to its distinct biochemical characteristics and innate antibacterial activity, chitosan has been extensively researched as an antibacterial wound dressing. Chronic wounds, such as diabetic ulcers and liver disease, are a growing medical problem. Chitosan-based biomaterials are a promising solution in the domain of wound care. The article analyzes the depth of chitosan-based biomaterials and their impact on wound healing and also the methods to enhance the advantages of chitosan by incorporating bioactive compounds. This literature review is aimed to improve the understanding and knowledge about biomaterials and their use in wound healing.

Comparison of healing effectiveness of different debridement approaches for diabetic foot ulcers: a network meta-analysis of randomized controlled trials

Objectives

The choice of the debridement method is very important for the healing of diabetic foot ulcers (DFUs), but the relative effectiveness of different debridement methods in the healing of DFUs remains unclear. This study conducted a network meta-analysis of the relative healing effectiveness of different debridement methods in patients with DFUs.

Methods

We performed a literature search in PubMed, Embase, and Cochrane Library from database inception up to 30 June 2023 for screening randomized controlled trials on the healing effectiveness of debridement in DFUs. Outcome measures included ulcer healing rate and ulcer area reduction rate. The Cochrane Risk Bias Tool, version 2.0, was used to assess the risk of bias in the included trials. R software was used for performing statistical analysis and GraphPad Prism was used for image plotting.

Results

A total of 19 randomized controlled trials were included, and 900 patients with DFUs were assessed in this analysis. The proteolytic fraction from the latex of Vasconcellea cundinamarcensis (P1G10) in enzymatic debridement showed the best ulcer healing rate (SURCA = 0.919) when compared with the standard of care (SOC) group, with a mean difference (MD) and 95% confidence interval (CI) of 1.40 (0.57, 2.36). Kiwifruit extract demonstrated the best effect on the ulcer area reduction rate (SURCA = 0.931), when compared with that in the SOC group, with an MD and 95% CI of 0.47 (0.27, 0.66).

Conclusion

Enzymatic debridement was superior to other debridement methods in terms of ulcer healing rate and ulcer area reduction rate in patients with DFUs. However, as the quality of the included trials is low, enzymatic debridement can be used as a candidate debridement method in addition to sharp-based debridement in clinical practice.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023441715.

Multifunctional and theranostic hydrogels for wound healing acceleration: An emphasis on diabetic-related chronic wounds

Hydrogels represent intricate three-dimensional polymeric structures, renowned for their compatibility with living systems and their ability to naturally degrade. These networks stand as promising and viable foundations for a range of biomedical uses. The practical feasibility of employing hydrogels in clinical trials has been well-demonstrated. Among the prevalent biomedical uses of hydrogels, a significant application arises in the context of wound healing. This intricate progression involves distinct phases of inflammation, proliferation, and remodeling, often triggered by trauma, skin injuries, and various diseases. Metabolic conditions like diabetes have the potential to give rise to persistent wounds, leading to delayed healing processes. This current review consolidates a collection of experiments focused on the utilization of hydrogels to expedite the recovery of wounds. Hydrogels have the capacity to improve the inflammatory conditions at the wound site, and they achieve this by diminishing levels of reactive oxygen species (ROS), thereby exhibiting antioxidant effects. Hydrogels have the potential to enhance the growth of fibroblasts and keratinocytes at the wound site. They also possess the capability to inhibit both Gram-positive and Gram-negative bacteria, effectively managing wounds infected by drug-resistant bacteria. Hydrogels can trigger angiogenesis and neovascularization processes, while also promoting the M2 polarization of macrophages, which in turn mitigates inflammation at the wound site. Intelligent and versatile hydrogels, encompassing features such as pH sensitivity, reactivity to reactive oxygen species (ROS), and responsiveness to light and temperature, have proven advantageous in expediting wound healing. Furthermore, hydrogels synthesized using environmentally friendly methods, characterized by high levels of biocompatibility and biodegradability, hold the potential for enhancing the wound healing process. Hydrogels can facilitate the controlled discharge of bioactive substances. More recently, there has been progress in the creation of conductive hydrogels, which, when subjected to electrical stimulation, contribute to the enhancement of wound healing. Diabetes mellitus, a metabolic disorder, leads to a slowdown in the wound healing process, often resulting in the formation of persistent wounds. Hydrogels have the capability to expedite the healing of diabetic wounds, facilitating the transition from the inflammatory phase to the proliferative stage. The current review sheds light on the biological functionalities of hydrogels, encompassing their role in modulating diverse mechanisms and cell types, including inflammation, oxidative stress, macrophages, and bacteriology. Additionally, this review emphasizes the significance of smart hydrogels with responsiveness to external stimuli, as well as conductive hydrogels for promoting wound healing. Lastly, the discussion delves into the advancement of environmentally friendly hydrogels with high biocompatibility, aimed at accelerating the wound healing process.

The role of neutrophils in diabetic ulcers and targeting therapeutic strategies

Diabetic ulcers (DUs) are a common complication of diabetes with high morbidity, poor prognosis, and a high socio-economic burden. The main pathological manifestations of DUs are chronic inflammation, impaired re-epithelialization, and impaired angiogenesis. During the inflammatory phase, neutrophils are one of the main DU cell types and act by releasing neutrophil extracellular traps (NETs), leading to poor healing in DUs. This review summarizes the role of neutrophils in the pathology and treatment of DUs, with a view to potential novel therapies and therapeutic targets.

An Immunomodulatory Hydrogel by Hyperthermia-Assisted Self-Cascade Glucose Depletion and ROS Scavenging for Diabetic Foot Ulcer Wound Therapeutics

Current therapeutic protocols for diabetic foot ulcers (DFUs), a severe and rapidly growing chronic complication in diabetic patients, remain nonspecific. Hyperglycemia-caused inflammation and excessive reactive oxygen species (ROS) are common obstacles encountered in DFU wound healing, often leading to impaired recovery. These two effects reinforce each other, forming an endless loop. However, adequate and inclusive methods are still lacking to target these two aspects and break the vicious cycle. This study proposes a novel approach for treating DFU wounds, utilizing an immunomodulatory hydrogel to achieve self-cascade glucose depletion and ROS scavenging to regulate the diabetic microenvironment. Specifically, AuPt@melanin-incorporated (GHM3) hydrogel dressing is developed to facilitate efficient hyperthermia-enhanced local glucose depletion and ROS scavenging. Mechanistically, in vitro/vivo experiments and RNA sequencing analysis demonstrate that GHM3 disrupts the ROS-inflammation cascade cycle and downregulates the ratio of M1/M2 macrophages, consequently improving the therapeutic outcomes for dorsal skin and DFU wounds in diabetic rats. In conclusion, this proposed approach offers a facile, safe, and highly efficient treatment modality for DFUs.

Natural Polymeric Hydrogels Encapsulating Small Molecules for Diabetic Wound Healing

Diabetes is a condition correlated with a high number of diagnosed chronic wounds as a result of a complex pathophysiological mechanism. Diabetic chronic wounds are characterized by disorganized and longer stages, compared to normal wound healing. Natural polymer hydrogels can act as good wound dressings due to their versatile physicochemical properties, represented mainly by high water content and good biocompatibility. Natural bioactive hydrogels are polymers loaded with bioactive compounds providing antibacterial and antioxidant properties, modulation of inflammation and adherence to wounded tissue, compared to traditional dressings, which enables promising future applications for diabetic wound healing. Natural bioactive compounds, such as polyphenols, polysaccharides and proteins have great advantages in promoting chronic wound healing in diabetes due to their antioxidant, anti-inflammatory, antimicrobial, anti-allergic and wound healing properties. The present paper aims to review the wound healing mechanisms underlining the main issues of chronic wounds and those specifically occurring in diabetes. Also, the review highlights the recent state of the art related to the effect of hydrogels enriched with natural bioactive compounds developed as biocompatible functional materials for improving diabetic-related chronic wound healing and providing novel therapeutic strategies that could prevent limb amputation and increase the quality of life in diabetic patients.