ECM-inspired mechanically robust hydrogels for diabetic wound regeneration

Diabetic wounds are often chronic in nature, and issues like elevated blood sugar, bacterial infections, oxidative stress and persistent inflammation impede the healing process. To ensure the appropriate healing of wounds, scaffolds should promote complete tissue regeneration in wounds, both functionally and structurally. However, the available scaffolds lack the explicit architecture and functionality that could match those of native skin, thus failing to carry out the scar-free skin regeneration in diabetic wounds. This study deals with the synthesis of a bi-layered nanofibrous scaffold mimicking the native skin architecture in terms of porosity and hydrophobic-hydrophilic gradients. In addition, herbal extracts of Aloe vera and litchi honey were added in consecutive layers to manage the high blood glucose level, inflammation, and increased ROS level associated with diabetic wounds. In vitro studies confirmed that the prepared scaffold with herbal extracts showed enhanced proliferation of skin cells with good mechanical strength, degradability, anti-bacterial and anti-diabetic properties. The scaffold also demonstrated superior wound healing in vivo with quicker scar-free wound recovery and appropriate skin regeneration, compared to conventional treatment. Altogether, the synthesized herbal extract loaded bi-layered nanofibrous scaffold can be used as a regenerative template for hard-to-heal diabetic wounds, offering a new strategy for the management of chronic wounds.

Exosome laden oxygen releasing antioxidant and antibacterial cryogel wound dressing OxOBand alleviate diabetic and infectious wound healing

A highly stretchable, adhesive, and antibacterial hydrogel with chitosan and tobramycin as dynamic cross-linkers for treating the infected diabetic wound

Microneedle dressing incorporating deferoxamine-loaded silk fibroin nanoparticles for diabetic wound therapy.

Purpose: There is an urgent need of effective drug/formulation to speed up the healing process in diabetic wounds. In our earlier studies, quercetin has accelerated the healing of nondiabetic wounds. So, we investigated the wound-healing potentials of quercetin in diabetic rats. Materials and methods: A square-shaped cutaneous wound (≈400 mm2) was created on the back of nondiabetic and diabetic rats. They were divided into three groups, viz. healthy control (nondiabetic), diabetic control and diabetic-treated group. Ointment base was topically applied for 21 days in healthy and diabetic control groups. Quercetin (0.3%) ointment was similarly applied in third group. Effects of quercetin on repair and regenerations of diabetic wounds in terms of wound closure, inflammation, angiogenesis, fibroblast proliferation, collagen synthesis, epithelialization, axonal regeneration etc was studied. Results: Quercetin accelerated the wound closure and increased the expressions of IL-10, VEGF and TGF-β1 in granulation/healing tissue of diabetic wound. However, quercetin decreased the expression of TNF-α, IL-1β, and MMP-9. Histopathological evaluation revealed amelioration of persistence of inflammatory cells by quercetin in diabetic wounds. There was good quality of granulation tissue, marked fibroblast proliferation, well organized collagen deposition, early regeneration of epithelial layer etc. in the quercetin treated diabetic wounds in comparison to diabetic control group. Results of immunohistochemistry showed more angiogenesis, faster phenotypic switching of fibroblast to myofibroblasts and increased GAP-43 positive nerve fibers in quercetin-treated diabetic wounds. Conclusion: Quercetin ointment at 0.3% w/w concentration modulates cytokines, growth factors and protease, thereby improved repair and regenerations of cutaneous diabetic wounds in rats.

Effective regulation and reconstruction of the microenvironment are critical for the regeneration of chronic wounds. Diabetic wounds, in particular, pose a significant clinical challenge due to increased oxidative stress and dysfunctional healing processes. In this study, a novel therapeutic strategy is developed using 3D copper‐magnesium bimetallic antioxidant nano‐enzymes (Cu/Mg‐MOF) to mitigate reactive oxygen species (ROS) and restore redox balance through electron transfer. To optimize delivery, a thermo‐sensitive hydrogel composed of chitosan (CS) and ε‐polylysine (PL) is designed, serving as an efficient carrier for the nano‐enzymes. This Cu/Mg‐MOF@CS/PL hydrogel exhibits excellent physical properties, including injectability, softness, and biocompatibility, making it ideal for application in diabetic wounds. In a diabetic wound model, treatment with Cu/Mg‐MOF@CS/PL hydrogel significantly accelerated wound healing, with a closure rate of 90.6% by day 14, compared to just 55.4% in the untreated group. The hydrogel effectively promoted key aspects of wound healing, such as collagen deposition, re‐epithelialization, angiogenesis, and immunomodulation. These findings underscore the potential of the Cu/Mg‐MOF@CS/PL hydrogel as a promising therapeutic system for enhancing the healing of diabetic wounds.

Mussel-inspired collagen-hyaluronic acid composite scaffold with excellent antioxidant properties and sustained release of a growth factor for enhancing diabetic wound healing.

Self-healing and shape-adaptive nanocomposite hydrogels with anti-inflammatory, antioxidant, antibacterial activities and hemostasis for real-time visual regeneration of diabetic wounds

Extracellular matrix (ECM) hydrogel can create a favorable regenerative microenvironment and act as a promising dressing for accelerating the healing of diabetic wound. In this study, a simple and effective decellularization technique was developed and optimized to obtain acellular extracellular matrix (aECM) from porcine skin. It was found that decellularization at 30% formic acid for 72 h effectively decellularized porcine skin while retaining >75% collagen and ~37% GAG in the aECM with no presence of nuclei of cellular remnants. aECM hydrogel was fabricated by digesting aECM with pepsin in various acidic solutions (0.1 N HCl, glycolic acid (GA) and 2-pyrrolidone-5-carboxylic acid (PCA)) and then treated with a pH-controlled neutralization and temperature-controlled gelation procedure. Based on physical characterizations, including SDS-PAGE, rheological analysis and SEM analysis, aECMHCl hydrogels fabricated at 25 mg/mL in 0.1 N HCl were selected. Four polymeric ECM-mimic hydrogels, including sacchachitin (SC), hyaluronic acid (HA) and chitosan (CS) and three composite hydrogels of combining SC either with aECMHCl,25 (aECMHCl/SC), HA (HA/SC) or CS (SC/CS) were prepared and evaluated for WS-1 cell viability and wound-healing effectiveness. Cell viability study confirmed that no hydrogel dressings possessed any toxicity at all concentrations examined and ECMHCl, HA and ECMHCl/SC at higher concentrations (>0.05%) induced statistically significant proliferation. Diabetic wound healing study and histological examinations revealed that ECMHCl/SC hydrogel was observed to synergistically accelerate wound healing and ultimately stimulated the growth of hair follicles and sweat glands in the healing wound indicating the wound had healed as functional tissues. The results support the great potential of this newly produced ECMHCl/SC composite hydrogel for healing and regeneration of diabetic wounds.

More than 70,000 diabetic patients have amputations annually due to wound care complications. Poor circulation and hyperglycemia-related nerve damage, which are complications of diabetes, prevent natural wound-healing processes. The purpose of this investigation is to develop a hydrogel to aid skin regeneration by creating an extracellular matrix for fibroblast growth with antibacterial and infection-detection properties. We developed two natural hydrogels based on pectin and potato peels and characterized the gels for fibroblast compatibility through rheology, scanning electron microscopy, swelling, degradation, and cell cytotoxicity assays. All five assays indicated that potato peel starch and citrus pectin were capable of mimicking natural skin, with a relevant pore diameter and stiffness. Both groups were able to absorb 40 times their weight before naturally degrading and supported upwards of 500% NIH 3T3 fibroblast proliferation. Additionally, anthocyanin, a pigmented flavonoid, was encapsulated in hydrogels and used as an infection biomarker and preventative agent. We conducted a pH responsivity test and time-to-kill antibacterial assay, validating the ability of anthocyanin to noticeably change colors in hydrogels and assert bactericidal effects even at low concentrations. A concentration of 200 milligrams could prevent bacteria growth and showed no effect on fibroblast growth. Overall, this experiment fabricated various hydrogels capable of acting as skin substitutes and counteracting infections to facilitate wound healing. Following further testing and validation, these hydrogels could help alleviate the 13-billion-dollar financial burden of foot ulcer treatment.

A single-component photocurable chitosan hydrogel mitigates inflammation and promotes angiogenesis and neurogenesis for diabetic wound healing.

In diabetic wounds, hyperglycemia-induced cytotoxicity and impaired immune microenvironment plasticity directly hinder the wound healing process. Regulation of the hyperglycemic microenvironment and remodeling of the immune microenvironment are crucial. Here, we developed a nanozymatic functionalized regenerative microenvironmental regulator (AHAMA/CS-GOx@Zn-POM) for the effective repair of diabetic wounds. This novel construct integrated an aldehyde and methacrylic anhydride-modified hyaluronic acid hydrogel (AHAMA) and chitosan nanoparticles (CS NPs) encapsulating zinc-based polymetallic oxonate nanozyme (Zn-POM) and glucose oxidase (GOx), facilitating a sustained release of release of both enzymes. The GOx catalyzed glucose to gluconic acid and (H₂O₂), thereby alleviating the effects of the hyperglycemic microenvironment on wound healing. Zn-POM exhibited catalase and superoxide dismutase activities to scavenge reactive oxygen species and H₂O₂, a by-product of glucose degradation. Additionally, Zn-POM induced M1 macrophage reprogramming to the M2 phenotype by inhibiting the MAPK/IL-17 signaling diminishing pro-inflammatory cytokines, and upregulating the expression of anti-inflammatory mediators, thus remodeling the immune microenvironment and enhancing angiogenesis and collagen regeneration within wounds. In a rat diabetic wound model, the application of AHAMA/CS-GOx@Zn-POM enhanced neovascularization and collagen deposition, accelerating the wound healing process. Therefore, the regenerative microenvironment regulator AHAMA/CS-GOx@Zn-POM can achieve the effective conversion of a pathological microenvironment to regenerative microenvironment through integrated control of the hyperglycemic-immune microenvironment, offering a novel strategy for the treatment of diabetic wounds.

Currently, diabetic infectious wound treatments remain a significant challenge for regenerative medicine due to the unicity of clinical dressings, which lack systemic multifunctional wound dressings with high absorbability, customizable shape, rapid self‐healing, guiding tissue regeneration, and restoring physiological functions. Here, a multifunctional DNA hydrogel is conveniently obtained through grafting DNA units and polyethyleneimine dynamic cross‐linking and doped heating function black phosphorus quantum dots. The obtained DNA hydrogel features excellent exudate absorption performance, adjustable heating ability, mechanical behavior, self‐healing ability, writability, tissue adhesion, and antibacterial properties. The incorporation of procyanidin B2 (OPC B2) endows the DNA hydrogels with renowned scavenging free radicals and antioxidant properties. Furthermore, the DNA hydrogel dressing can promote the transformation of macrophages from pro‐inflammatory M1 into repairing M2 phenotype, keeping the wound in a stable remodeled state. Astonishingly, the DNA hydrogel dressing can activate neurons to transform into a repair state, accelerating skin nerve regeneration and angiogenesis. Beyond that, it can recruit myeloid cells to activate the adaptive immune response, enhancing the ability of DNA hydrogel dressing to promote tissue regeneration, thereby promoting hair follicle and hair regeneration. Therefore, this advanced collaborative strategy provides an effective method for cascade management of clinical guided tissue regeneration.

Delayed wound healing process is one of the most important concerns in diabetes. Healing of wounds has four phases, namely, hemostasis, inflammation, proliferation, and remodeling. For a successful repair, all four factors must occur properly. Hence, we aimed to evaluate the healing effects of Hypericum perforatum (HP) on full-thickness diabetic skin wounds by using stereological methods. Forty-eight female diabetic rats were randomly divided into four groups (n = 12): gel base treated group, HP 5% gel treated group, HP 10% gel treated group, and the control group which received no treatment. A circular 1 cm2 full-thickness wound was created on the animal's neck and wound area was measured every three days. After sacrificing the animals, skin samples were fixed and prepared for stereological evaluations. Based on the results, HP treated group showed faster wound closure rate in comparison with control and vehicle groups (P < 0.05). In addition, numerical density of fibroblasts, volume density of collagen bundles, and mean diameter and volume densities of the vessels in HP group were significantly higher than control and vehicle groups. The results of this study showed that HP has the ability to improve tissue regeneration by enhancing fibroblast proliferation, collagen bundle synthesis, and revascularization.

A photothermal-enhanced thermoelectric nanosheet incorporated with zwitterionic hydrogels for wound repair and bioelectronics.