Wound Healing In Diabetic Mice Research Articles

Interference of sympathetic overactivation restores limbal stem/progenitor cells function and accelerates corneal epithelial wound healing in diabetic mice

Diabetic keratopathy (DK), the diabetic complication in the cornea, is characterized by the delayed epithelial regeneration and sensory nerve degeneration. The involvement of limbal stem/progenitor cells (LSPCs) dysfunction has been reported, however the pathogenic mechanisms remain unclear. Here, we confirmed the dysfunction of LSPCs in diabetic mouse and human corneas. The sympathetic nerve in the cornea was adjacent to LSPCs, and the sympathetic overactivation was found in diabetic mice. Surgical and pharmacological ablation of sympathetic nerves rescued the LSPCs function and promoted corneal epithelial regeneration in diabetic mice. In contrast, both topical norepinephrine (NE) application and chemogenetic sympathetic overactivation directly impaired the stemness and proliferation characteristics of LSPCs, as well as the normal epithelial regeneration. Moreover, we identified that β2-adrenoceptor (Adrb2) was the predominant adrenergic receptor expressed in LSPCs by corneal limbal single-cell sequencing and real time PCR (RT-PCR) analysis of sorted LSPCs. The Adrb2 knockout mice exhibited the enhancement of epithelial regeneration and LSPCs function, compared with the wild-type mice. Similarly, topical application of the Adrb2 specific antagonist ICI 118, 551 effectively accelerated diabetic corneal epithelial regeneration with the restored LSPCs function. Mechanistically, sonic hedgehog (Shh) activity mediated the downstream effects of NE-Adrb2 signaling pathway in regulating LSPCs and epithelial regeneration. Taken together, our data revealed the involvement of sympathetic overactivation in the impairment of diabetic LSPCs function and corneal epithelial regeneration through the NE-Adrb2-Shh signaling pathway. The interference of sympathetic overactivation may provide novel treatment strategies for diabetic keratopathy.

Topical combined Phyllanthus emblica Linn. and simvastatin improves wound healing in diabetic mice by enhancing angiogenesis and reducing neutrophil infiltration.

The present study aimed to investigate the effects of combined Phyllanthus emblica Linn. (PE) and simvastatin (SIM) on diabetic wounds in male BALB/C mice. Bilateral full thickness wound excisions were performed in the control and diabetic groups (45 mg/kg streptozotocin, intraperitoneally injected daily for 5 days). The diabetic mice received daily treatment with four different types of cream: Vehicle [diabetes mellitus (DM) + Vehicle group], 100% PE (DM + PE group), 5% SIM (DM + SIM group) and combined 100% PE + 5% SIM (DM + Combination group) for 4, 7 and 14 days. The tissue malondialdehyde (MDA) and IL-6 protein levels, the number of infiltrated neutrophils, and the percentages of wound closure (%WC), capillary vascularity (%CV) and re-epithelialization (%RE) were subsequently measured. The results indicated that in the DM + Combination group, %CV and %WC were significantly increased when compared with the DM + Vehicle group on days 7 and 14. The tissue MDA content on day 14, and the number of infiltrated neutrophils on days 4 and 7 were significantly reduced in the DM + Combination group compared with those in the DM + Vehicle group. Furthermore, a strong positive correlation was revealed between %CV and %WC in the five groups on day 7 (r=0.736; P=0.0003). These findings indicated that topical application of combined PE and SIM could enhance wound healing by upregulating angiogenesis and reducing neutrophil infiltration in mice with diabetic wounds.

Nitric oxide-releasing gel accelerates healing in a diabetic murine splinted excisional wound model.

According to the American Diabetes Association (ADA), 9-12 million patients suffer from chronic ulceration each year, costing the healthcare system over USD $25 billion annually. There is a significant unmet need for new and efficacious therapies to accelerate closure of non-healing wounds. Nitric Oxide (NO) levels typically increase rapidly after skin injury in the inflammatory phase and gradually diminish as wound healing progresses. The effect of increased NO concentration on promoting re-epithelization and wound closure has yet to be described in the context of diabetic wound healing. In this study, we investigated the effects of local administration of an NO-releasing gel on excisional wound healing in diabetic mice. The excisional wounds of each mouse received either NO-releasing gel or a control phosphate-buffered saline (PBS)-releasing gel treatment twice daily until complete wound closure. Topical administration of NO-gel significantly accelerated the rate of wound healing as compared with PBS-gel-treated mice during the later stages of healing. The treatment also promoted a more regenerative ECM architecture resulting in shorter, less dense, and more randomly aligned collagen fibers within the healed scars, similar to that of unwounded skin. Wound healing promoting factors fibronectin, TGF-β1, CD31, and VEGF were significantly elevated in NO vs. PBS-gel-treated wounds. The results of this work may have important clinical implications for the management of patients with non-healing wounds.

Molecular Evolution of Acceptor–Donor–Acceptor‐type Conjugated Oligomer Nanoparticles for Efficient Photothermal Antimicrobial Therapy

AbstractInfectious diseases (such as wound infections) caused by pathogenic microorganisms can lead to serious consequences and even threaten life. The emergence of drug‐resistant bacteria has severely prevented the validity of traditional antibiotics. Therefore, developing novel antimicrobial strategies without drug‐resistant holds great promise for maximizing efficacy and minimizing the risk of drug‐resistance of resistant bacterial infections. Herein, near‐infrared (NIR)‐absorbing A–D–A type conjugated oligomers with a tunable backbone are designed and synthesized for regulating their photothermal conversion. After being assembled into nanoparticles, the conjugated oligomer CP‐F8P nanoparticles (NPs) containing a strong electron‐donating component show the strongest photothermal conversion efficiency of 81.6%. The low concentration of CP‐F8P NPs receive over 99% of antimicrobial efficiency against Ampr E. coli, S. aureus, and C. albicans upon NIR irradiation, and the phototherapy treatment of CP‐F8P NPs can effectively promote wound healing in diabetic mice with good biocompatibility. This work provides ideas for the design of efficient NIR‐activated antimicrobial reagents against drug‐resistant microbial infections.

Tumor tissue derived extracellular vesicles promote diabetic wound healing

The diabetic wound nowadays remains a major public health challenge, which is characterized by overproduced reactive oxygen species (ROS). However, the current therapy for diabetic wounds is limited for reliable data in the general application. The growth of tumors has been revealed to share parallels with wound healing. Extracellular vesicles (EVs) derived from breast cancer have been reported to promote cell proliferation, migration and angiogenesis. The tumor tissue-derived EVs (tTi-EVs) of breast cancer performance a feature inheritance from original tissue and might accelerate the diabetic wound healing. We wonder whether the tumor-derived EVs are able to accelerate diabetic wound healing. In this study, tTi-EVs were extracted from breast cancer tissue via ultracentrifugation and size exclusion. Subsequently, tTi-EVs reversed the H2O2-induced inhibition of fibroblast proliferation and migration. Moreover, tTi-EVs significantly accelerated wound closure, collagen deposition and neovascularization, and finally promoted wound healing in diabetic mice. The tTi-EVs also reduced the level of oxidative stress in vitro and in vivo. Besides, the biosafety of tTi-EVs were preliminarily confirmed by blood tests and morphological analysis of major organs. Collectively, the present study proves that tTi-EVs can suppress oxidative stress and facilitate diabetic wound healing, which puts forward a novel function of tTi-EVs and provides potential treatment for diabetic wounds.

STING Agonist-Induced Skin Inflammation Is Exacerbated with Prior Systemic Innate Immune Activation.

Activation of the Stimulator of Interferon Genes (STING) protein has paradoxical outcomes in skin disease. STING activation exacerbates psoriatic skin disease and delays wound healing in diabetic mice, yet it also facilitates wound healing in normal mice. To address the role of localized STING activation in the skin, mice were injected subcutaneously with a STING agonist, diamidobenzimidazole STING Agonist-1 (diAbZi). The effect of a prior inflammatory stimulus on STING activation was addressed by pre-treating mice intraperitoneally with poly (I:C). The skin at the injection site was evaluated for local inflammation, histopathology, immune cell infiltration, and gene expression. Serum cytokine levels were measured to assess systemic inflammatory responses. Localized diABZI injection induced severe skin inflammation with erythema, scaling, and induration. However, the lesions were self-limiting and resolved within 6 weeks. At the peak of inflammation, the skin showed epidermal thickening, hyperkeratosis, and dermal fibrosis. Neutrophils, CD3 T cells, and F4/80 macrophages were present in the dermis and subcutaneous layers. Gene expression was consistent with increased local interferon and cytokine signaling. Interestingly, the poly (I:C)-pre-treated mice showed higher serum cytokine responses and developed worse inflammation with delayed wound resolution. Our study demonstrates that prior systemic inflammation amplifies STING-mediated inflammatory responses and skin disease.

Separable Microneedles with Photosynthesis-Driven Oxygen Manufactory for Diabetic Wound Healing

Oxygen plays an important role in diabetic chronic wound healing by regulating various life activities such as cell proliferation, migration, and angiogenesis. Therefore, oxygen-delivering systems have drawn much attention and evolved continuously. Here, we propose that an active Chlorella vulgaris (Cv)-loaded separable microneedle (MN) can be used to control oxygen delivery, which then promotes wound healing. The Cv-loaded microneedles (CvMN) consist of a polyvinyl acetate (PVA) substrate and gelatin methacryloyl (GelMA) tips with encapsulated Cv. Once CvMN is applied to diabetic wound, the PVA basal layer is rapidly dissolved in a short time, while the noncytotoxic and biocompatible GelMA tips remain in the skin. By taking advantage of the photosynthesis of Cv, oxygen would be continuously produced in a green way and released from CvMN in a controlled manner. Both in vitro and in vivo results showed that CvMN could promote cell proliferation, migration, and angiogenesis and enhance wound healing in diabetic mice effectively. The remarkable therapeutic effect is mainly attributed to the continuous generation of dissolved oxygen in CvMN and the presence of antioxidant vitamins, γ-linolenic acid, and linoleic acid in Cv. Thus, CvMN provides a promising strategy for diabetic wound healing with more possibility of clinical transformations.

Hypoxia-pretreated ADSC-derived exosome-embedded hydrogels promote angiogenesis and accelerate diabetic wound healing.

Accumulating reports indicate that adipose-derived stem cell (ADSC)-originating exosomes (ADSC-Exos) provide a potential strategy for diabetic wound repair. However, the disadvantages of exosomes, such as fast decrease of biological activity and unknown biological mechanisms, limit their clinical application. Herein, hypoxia-pretreated ADSC-Exo (ADSC-HExo)-embedded GelMA hydrogels (GelMA-HExo) were developed via non-covalent force and physical embedding. These materials rapidly converted into a gel state under illumination, thereby adapting to irregular diabetic wounds. The regulatory mechanism of circ-Snhg11 delivery by exosomes in accelerating diabetic wound healing was explored. In vitro, GelMA-HExo hydrogels had a loose porous structure, and a stable degradation and expansion rate. In vivo, GelMA-HExo hydrogels promoted wound healing in diabetic mice. In particular, ADSC-HExos had a good therapeutic effect, in which circ-Snhg11 expression was increased. Furthermore, circ-Snhg11-modified ADSC-Exos increased the migratory, proliferative and blood vessel regeneration potential of vascular endothelial cells (ECs). In addition, overexpression (OE) of NFE2L2-HIF1α or inhibition of miR-144-3p-both of which are members of the miR-144-3p/NFE2L2/HIF1α pathway downstream of circ-Snhg11-reversed the therapeutic effects of circ-Snhg11. In summary, this study explored the effects and downstream targets of hypoxic engineered exosome hydrogels in managing diabetic wound repair. These hydrogels are expected to serve as a new approach for clinical treatment and to have application possibilities in other disease areas. STATEMENT OF SIGNIFICANCE: ADSC-Exo treatment can accelerate diabetic wound healing via circRNA delivery. But how to reverse the problems such as poor mechanical properties, low biological activity, short duration of effect and high risk of sudden release of exosomes needs investigation. We constructed exosome-embedded GelMA (GelMA-Exo) hydrogels and found that GelMA-Exo treatment could significantly promote diabetic wound healing. Further study found that exosomes from hypoxia-pretreated ADSCs (ADSC-HExos) had an enhanced therapeutic effect than normal exosomes. The regulation mechanism study found that circ-Snhg11 delivery from GelMA-HExo incremented survival and maintained endothelial cell (EC) function, possibly via the activation of miR-144-3p/NFE2L2/HIF1α signaling. These findings suggest a new therapeutic strategy for patients with diabetic ulcer.

Polyphenol-driven facile assembly of a nanosized acid fibroblast growth factor-containing coacervate accelerates the healing of diabetic wounds.

Diabetic wounds are challenging to heal due to complex pathogenic abnormalities. Routine treatment with acid fibroblast growth factor (aFGF) is widely used for diabetic wounds but hardly offers a satisfying outcome due to its instability. Despite the emergence of various nanoparticle-based protein delivery approaches, it remains challenging to engineer a versatile delivery system capable of enhancing protein stability without the need for complex preparation. Herein, a polyphenol-driven facile assembly of nanosized coacervates (AE-NPs) composed of aFGF and Epigallocatechin-3-gallate (EGCG) was constructed and applied in the healing of diabetic wounds. First, the binding patterns of EGCG and aFGF were predicted by molecular docking analysis. Then, the characterizations demonstrated that AE-NPs displayed higher stability in hostile conditions than free aFGF by enhancing the binding activity of aFGF to cell surface receptors. Meanwhile, the AE-NPs also had a powerful ability to scavenge reactive oxygen species (ROS) and promote angiogenesis, which significantly accelerated full-thickness excisional wound healing in diabetic mice. Besides, the AE-NPs suppressed the early scar formation by improving collagen remodeling and the mechanism was associated with the TGF-β/Smad signaling pathway. Conclusively, AE-NPs might be a potential and facile strategy for stabilizing protein drugs and achieving the scar-free healing of diabetic wounds. STATEMENT OF SIGNIFICANCE: Diabetic chronic wound is among the serious complications of diabetes that eventually cause the amputation of limbs. Herein, a polyphenol-driven facile assembly of nanosized coacervates (AE-NPs) composed of aFGF and EGCG was constructed. The EGCG not only acted as a carrier but also possessed a therapeutic effect of ROS scavenging. The AE-NPs enhanced the binding activity of aFGF to cell surface receptors on the cell surface, which improved the stability of aFGF in hostile conditions. Moreover, AE-NPs significantly accelerated wound healing and improved collagen remodeling by regulating the TGF-β/Smad signaling pathway. Our results bring new insights into the field of polyphenol-containing nanoparticles, showing their potential as drug delivery systems of macromolecules to treat diabetic wounds.

Neutralization of excessive CCL28 improves wound healing in diabetic mice.

Introduction: Chronic, non-healing skin wounds such as diabetic foot ulcers (DFUs) are common in patients with type 2 diabetes mellitus (T2DM) and often result in limb amputation and even death. However, mechanisms by which T2DM and inflammation negatively impact skin wound healing remains poorly understood. Here we investigate a mechanism by which an excessive level of chemokine CCL28, through its receptor CCR10, impairs wound healing in patients and mice with T2DM. Methods & Results: Firstly, a higher level of CCL28 was observed in skin and plasma in both patients with T2DM, and in obesity-induced type 2 diabetic db/db mice. Compared with WT mice, adipose tissue from db/db mice released 50% more CCL28, as well as 2- to 3-fold more IL-1β, IL-6, and TNF-α, and less VEGF, as determined by ELISA measurements. Secondly, overexpression of CCL28 with adenovirus (Adv-CCL28) caused elevation of proinflammatory cytokines as well as CCR10 expression and also reduced eNOS expression in the dorsal skin of WT mice as compared with control Adv. Thirdly, topical application of neutralizing anti-CCL28 Ab dose-dependently accelerated wound closure and eNOS expression, and decreased IL-6 level, with an optimal dose of 1 μg/wound. In addition, mRNA levels of eNOS and anti-inflammatory cytokine IL-4 were increased as shown by real-time RT-PCR. The interaction between eNOS and CCR10 was significantly reduced in diabetic mouse wounds following application of the optimal dose of anti-CCL28 Ab, and eNOS expression increased. Finally, enhanced VEGF production and increased subdermal vessel density as indicated by CD31 immunostaining were also observed with anti-CCL28 Ab. Discussion: Taken together, topical application of neutralizing anti-CCL28 Ab improved dorsal skin wound healing by reducing CCR10 activation and inflammation in part by preventing eNOS downregulation, increasing VEGF production, and restoring angiogenesis. These results indicate anti-CCL28 Ab has significant potential as a therapeutic strategy for treatment of chronic non-healing diabetic skin wounds such as DFUs.

Poly(l-lactic acid) Scaffold Releasing an α4β1 Integrin Agonist Promotes Nonfibrotic Skin Wound Healing in Diabetic Mice.

Skin wound healing is a highly complex process that continues to represent a major medical problem, due to chronic nonhealing wounds in several classes of patients and to possible fibrotic complications, which compromise the function of the dermis. Integrins are transmembrane receptors that play key roles in this process and that offer a recognized druggable target. Our group recently synthesized GM18, a specific agonist for α4β1, an integrin that plays a role in skin immunity and in the migration of neutrophils, also regulating the differentiated state of fibroblasts. GM18 can be combined with poly(l-lactic acid) (PLLA) nanofibers to provide a controlled release of this agonist, resulting in a medication particularly suitable for skin wounds. In this study, we first optimized a GM18-PLLA nanofiber combination with a 7-day sustained release for use as skin wound medication. When tested in an experimental pressure ulcer in diabetic mice, a model for chronic nonhealing wounds, both soluble and GM18-PLLA formulations accelerated wound healing, as well as regulated extracellular matrix synthesis toward a nonfibrotic molecular signature. In vitro experiments using the adhesion test showed fibroblasts to be a principal GM18 cellular target, which we then used as an in vitro model to explore possible mechanisms of GM18 action. Our results suggest that the observed antifibrotic behavior of GM18 may exert a dual action on fibroblasts at the α4β1 binding site and that GM18 may prevent profibrotic EDA-fibronectin-α4β1 binding and activate outside-in signaling of the ERK1/2 pathways, a critical component of the wound healing process.

Sex difference on fibroblast growth factors (FGFs) expression in skin and wound of streptozotocin(STZ)-induced type 1 diabetic mice.

Fibroblast growth factors (FGFs) are key factors affecting diabetic wound healing. However, the FGF family's expression patterns in skin and wounds influenced by both diabetes and sex are still unknown. In this study, normal and Streptozotocin (STZ)-induced type 1 diabetic C57BL/6J male and female mice were used to study the FGF family's expression in non-wound skin and wounds. We found that the expression patterns of Fgfs were affected by sex in both normal and diabetic animals during wound healing. In normal control mice, sex difference had a limited effect on basal skin Fgf expressions. However, it significantly influenced Fgfexpressions in wounds. Type 1 diabetes reduced basal and wound-induced skin Fgf expressions. Female mice had far lower wound-induced skin Fgf expressions in diabetic mice. In addition, sex differently influenced Fibroblast growth factors receptor (Fgfr) expression patterns of non-wound skin and wounds in both normal and diabetic mice. Moreover, female mice had a lower relative level of Fibronectin leucine-rich repeat transmembrane protein 2 (FLRT2) - a FGFR activation marker gene - in wound and blood plasma. Correspondingly, the wound areas of female animals were larger than that of male animals in the early stage of wound healing (less than 3-day injury). Our research shows that the FGF family have different expression patterns in normal and diabetic wound healing in mice of different sex. Additionally, we also provide the signatures of individual FGFs in diabetic wound healing, which deserve further investigation.

EGFL7 affects the migration of epidermal stem cells in refractory diabetic wounds by regulating Notch signaling pathway.

Aim: This study aimed to explore the role of EGFL7 in the healing process of refractory diabetic wounds. Methods: Epidermal stem cells (ESCs) were isolated from healthy mice and diabetic mice, identified by immunofluorescence, transfected with EGFL7 overexpression and silencing lentiviral vectors, and treated with Notch pathway inhibitor (DAPT). Results: SiEGFL7 significantly inhibited the proliferation, invasion and migration of ESCs of healthy mice. DAPT prominently inhibited the expressions of Notch1, Notch2, Hes1 and Jag1 in ESCs of healthy mice induced by overexpressed EGFL7. Overexpressed EGFL7 promoted wound healing in diabetic mice with refractory wounds. Conclusion: EGFL7 affects the proliferation and migration of ESCs in refractory diabetic wounds by regulating the Notch signaling pathway.

Recombinant Expression of Human IL-33 Protein and Its Effect on Skin Wound Healing in Diabetic Mice.

Chronic refractory wounds are one of the complications of diabetes mellitus that require effective therapy. The dermal-wound-healing property of IL-33 in diabetics is little understood. Therefore, this study aimed to express recombinant humanized mature IL-33 (rhmatIL-33) in Escherichia coli BL21 (DE3) and demonstrate its efficacy on dermal wounds in streptozotocin (STZ)-induced diabetic and nondiabetic mice by the dorsal incisional skin wound model. Results revealed that the rhmatIL-33 accelerated the scratch-healing of keratinocytes and fibroblasts at the cellular level. The wounds of diabetic mice (DM) showed more severe ulceration and inflammation than wild-type mice (WT), and the exogenous administration of rhmatIL-33 increased wound healing in both diabetic and wild-type mice. Compared with the up-regulation of endogenous IL-33 mRNA after injury in WT mice, the IL-33 mRNA decreased after injury in DM mice. Exogenous IL-33 administration increased the endogenous IL-33 mRNA in the DM group but decreased the IL-33 mRNA expression level of the WT group, indicating that IL-33 plays a balancing role in wound healing. IL-33 administration also elevated ILC2 cells in the wounds of diabetic and non-diabetic mice and improve the transcript levels of YM1, a marker of M2 macrophages. In conclusion, Hyperglycemia in diabetic mice inhibited the expression of IL-33 in the dermal wound. Exogenous addition of recombinant IL-33 promoted wound healing in diabetic mice by effectively increasing the level of IL-33 in wound tissue, increasing ILC2 cells, and accelerating the transformation of macrophage M1 to M2 phenotype.

Selective inhibition of PKR by C16 accelerates diabetic wound healing by inhibiting NALP3 expression in mice.

To understand the expression of dsRNA-dependent protein kinase R (PKR) in impaired diabetic wounds, hyperglycemia was induced in C57/BL6 mice with streptozotocin. Murine macrophage cell line, Raw 264.7, stimulated with high glucose and LPS was used to mimic diabetic wound environment in in-vitro. Macrophages stimulated with HG + LPS, in presence and absence of PKR inhibitor (C16) and wound tissue samples from topically treated mice with C16, were analyzed for the expression of PKR, NALP3, active caspase-1, mature IL-1β and phosphorylation of PKR and eIF2α. Wounds tissues were also analyzed for inflammatory cell infiltration by immunohistochemistry, angiogenesis by CD31 staining, collagen expression by western blotting, expression of CD206+ macrophages by flow cytometry and wound strength by texture analyzer. PKR and NALP3 were found to be upregulated in macrophages stimulated with HG + LPS as well as in impaired diabetic wounds. PKR inhibition using C16 ameliorated expression of NALP3, caspase-1, IL-1β and phosphorylation of PKR and eIF2α, in macrophages and also in diabetic wounds. Treatment with C16 promoted the wound healing in diabetic mice by increasing collagen synthesis, reducing infiltration of F4/80+ macrophages and MPO+ neutrophil cells, increased angiogenesis, and increased number of M2 macrophages. PKR inhibition using C16 accelerates the wound healing process in diabetic mice by decreasing NALP3-mediated IL-1β maturation.

Effects of exosomes from hepatocyte growth factor-modified human adipose mesenchymal stem cells on full-thickness skin defect in diabetic mice

Effects of exosomes from hepatocyte growth factor-modified human adipose mesenchymal stem cells on full-thickness skin defect in diabetic mice

GDF11 promotes wound healing in diabetic mice via stimulating HIF-1ɑ-VEGF/SDF-1ɑ-mediated endothelial progenitor cell mobilization and neovascularization.

Non-healing diabetic wounds (DW) are a serious clinical problem that remained poorly understood. We recently found that topical application of growth differentiation factor 11 (GDF11) accelerated skin wound healing in both Type 1 DM (T1DM) and genetically engineered Type 2 diabetic db/db (T2DM) mice. In the present study, we elucidated the cellular and molecular mechanisms underlying the action of GDF11 on healing of small skin wound. Single round-shape full-thickness wound of 5-mm diameter with muscle and bone exposed was made on mouse dorsum using a sterile punch biopsy 7 days following the onset of DM. Recombinant human GDF11 (rGDF11, 50 ng/mL, 10 μL) was topically applied onto the wound area twice a day until epidermal closure (maximum 14 days). Digital images of wound were obtained once a day from D0 to D14 post-wounding. We showed that topical application of GDF11 accelerated the healing of full-thickness skin wounds in both type 1 and type 2 diabetic mice, even after GDF8 (a muscle growth factor) had been silenced. At the cellular level, GDF11 significantly facilitated neovascularization to enhance regeneration of skin tissues by stimulating mobilization, migration and homing of endothelial progenitor cells (EPCs) to the wounded area. At the molecular level, GDF11 greatly increased HIF-1ɑ expression to enhance the activities of VEGF and SDF-1ɑ, thereby neovascularization. We found that endogenous GDF11 level was robustly decreased in skin tissue of diabetic wounds. The specific antibody against GDF11 or silence of GDF11 by siRNA in healthy mice mimicked the non-healing property of diabetic wound. Thus, we demonstrate that GDF11 promotes diabetic wound healing via stimulating endothelial progenitor cells mobilization and neovascularization mediated by HIF-1ɑ-VEGF/SDF-1ɑ pathway. Our results support the potential of GDF11 as a therapeutic agent for non-healing DW.

Therapeutic Applications of Garlic and Turmeric for the Diabetic Wound Healing in Mice.

Diabetes is involved in delayed wound healing that can be cured by natural products such as garlic, turmeric, and fibroin extracts. Alloxan monohydrate is used for inducing diabetes in mice. The percent wound contraction of garlic (150 mg/ml), turmeric (100 mg/ml), and fibroin (50 mg/ml), individually and in combinations garlic (150 mg/ml) + fibroin (50 mg/ml), turmeric (100 mg/ml) + fibroin (50 mg/ml), garlic (150 mg/ml) + turmeric (100 mg/ml), and garlic (150 mg/ml) + turmeric (100 mg/ml) + fibroin (50 mg/ml) was checked by evaluating the healing time, % wound contraction and histological analysis. The serum level of MMPs (MMP 2, MMP7, MMP 9), pro-inflammatory cytokines (TNF-α, IL-6, IL-8), and TIMPs were evaluated. With the combination of three extracts (Ga+Tu+Fi) garlic (150 mg/ml), turmeric (100 mg/ml) and fibroin (50 mg/ml), wounds healed in 12 days and had 97.3 ± 2.2% wound contraction. While the positive control (polyfax) and diabetic control (saline) wounds healed in 17- and 19-days with wound contraction of 96.7 ± 1.4% and 96.3 ± 1.1%, respectively. Histological analysis showed that the combination of Ga+Tu+Fi exhibited an increase in the growth of collagen fibers, fibroblasts number, and keratinocytes, and lessened inflammation of blood vessels. The combination of Ga+Tu+Fi significantly alleviated the serum concentration of TNF-α (14.2 ± 0.7 pg/ml), IL-6 (10.0 ± 1.0 pg/ml), IL-8 (16.0 ± 1.5 pg/ml), MMP2 (228.0 ± 18.1 pg/ml), MMP7 (271.0 ± 9.9 pg/ml), and MMP9 (141.0 ± 5.3 pg/ml) to diabetic control. The level of TIMPs (193.0 ± 9.1 pg/ml) was increased significantly with respect to diabetic control. We conclude that the combination of these biomaterials possessed high regenerative and healing capabilities and can be an effective remedy in the healing of chronic wounds in diabetic patients.

A composite hydrogel containing resveratrol-laden nanoparticles and platelet-derived extracellular vesicles promotes wound healing in diabetic mice

Diabetic wounds are difficult to heal because of persistent inflammation and limited angiogenesis. Resveratrol (RES) is an anti-inflammatory and antioxidant agent. Platelet-derived extracellular vesicles (PDEVs) are rich in growth factors and cytokines, which promote proliferation and angiogenesis. However, single drug treatment has limited efficacy and delivery efficiency. Bioengineering can improve the limited effect of single drugs by combining drugs and materials to obtain complementary or cooperative bioengineered drugs. In this study, gelatin methacrylate (GelMA) and silk fibroin glycidyl methacrylate (SFMA) were used to synthesize GelMA/SFMA composite hydrogels with suitable mechanical properties, swelling ratio and biodegradability. The composite hydrogel was used as a wound dressing for sustained drug release. RES was loaded into mesoporous silica nanoparticles (MSNs) to synthesize MSN-RES to enhance the release dynamic, and MSN-RES and PDEVs were combined with the composite hydrogels to form GelMA/SFMA/MSN-RES/PDEVs hydrogels. The GelMA/SFMA/MSN-RES/PDEVs had low cytotoxicity and good biocompatibility, inhibited macrophage iNOS expression, and promoted the tube formation by human umbilical vein endothelial cells (HUVECs) in vitro. In a diabetic mouse wound model, the GelMA/SFMA/MSN-RES/PDEVs hydrogels decreased the expression of pro-inflammatory factors TNF-α and iNOS, increased the expression of anti-inflammatory factors TGF-β1 and Arg-1, promoted angiogenesis, and accelerated wound healing. Interestingly, the GelMA/SFMA/MSN-RES/PDEVs hydrogels promoted the expression of extracellular purinergic signaling pathway-related CD73 and adenosine 2A receptor (A2A-R). Therefore, the GelMA/SFMA/MSN-RES/PDEVs hydrogels could be used as wound dressings to regulate the inflammation and angiogenesis of diabetic wounds and accelerate wound healing. Statement of significanceDrugs often fail to function because of a continuous oxidative stress microenvironment and inflammation. Here, a GelMA/SFMA hydrogel, with enhanced mechanical properties and liquid absorption ability, is proposed for sustained release of drugs. In addition to carrying platelet-derived extracellular vesicles (PDEVs) with pro-angiogenic effects, the hydrogels were also loaded with nanoparticle-encapsulated resveratrol with anti-inflammatory activities, aiming to reduce inflammation and oxidative stress in the wound microenvironment, such that the wound could receive proliferative repair signals to achieve sequential treatment and heal quickly. We also experimentally predicted that the regulatory mechanism of the GelMA/SFMA/MSN-RES/PDEVs in wound healing might be related to the extracellular purinergic signaling pathway.

Inhibition of TGFβ1/Smad pathway by NF-κB induces inflammation leading to poor wound healing in high glucose

This study mainly analyzed the relationship between nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and transforming growth factor-β (TGFβ1)/Smad under high glucose environment and its influence on wound healing. Fibroblast NIH-3T3 was used to analyze the effect of high concentration glucose (20 nmol/mL) on cell viability, migration ability, inflammation level and NF-κB pathway. Pyrrolidinedithiocarbamate (PDTC) was used to inhibit NF-κB for rescue experiments. Diabetic mice were used to construct wound healing models. Recombinant TGF-β1 was used to promote wound healing in diabetic mice. FSL-1 was applied to activate NF-κB to verify the mechanism. High glucose inhibited cell viability and migration ability, promoted the expression of TNF-α, IL-6 and IL-1β, induced the activation of NF-κB pathway in fibroblasts. Inhibition of NF-κB not only blocked the decrease in cell viability and migration ability induced by high glucose, but also relieved the release of inflammatory factors. TGF-β1 activated the TGF-β1/Smad pathway and promoted wound healing in diabetic mice. Activating the NF-κB pathway not only inhibited the activation of the TGF-β1/Smad pathway, but also alleviated the promoting effect of TGF-β1 on wound healing. In a high glucose environment, the activation of NF-κB may inhibit the function of fibroblasts by inhibiting the TGF-β1/Smad pathway, resulting in poor wound healing.