Enhanced growth of endothelial precursor cells on PCG-matrix facilitates accelerated, fibrosis-free, wound healing: a diabetic mouse model

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.

Effects of dual-gene modification on biological characteristics of vascular endothelial cells and their significance as reserving cells for chronic wound repair

bFGF is a commonly used and reliable factor for improving chronic wound healing, and hSulf-1 expression is abundant in surrounding cells of chronic wound tissue and vascular endothelial cells, which can reverse the effect of bFGF and inhibit the signalling activity of cell proliferation. In this study, an adenovirus, Ad5F35ET1-bFGF-shSulf1, was designed for establishing the dual-gene modified vascular endothelial cells, which were used as the repair cells for skin chronic wound. Ad5F35ET1-bFGF-shSulf1 infected ECV304 cells in vitro and mediated the overexpression of bFGF and the knockdown of hSulf-1, which effectively activated the AKT and ERK signal transduction pathways, facilitate cell proliferation and migration, with the cell viability to 128.29% at 72 h after infection, compared to 66.65%, 73.74%, 87.63%, 103.14% in the blank control, Ad5F35ET1-EGFP-shNC, Ad5F35ET1-shSulf1, Ad5F35ET1-bFGF groups, respectively. In the rat ear skin injury model, the wound healing was significantly accelerated in the Ad5F35ET1-rbFGF-shrSulf1 group compared to the blank control group (p = 0.0046), Ad5F35ET1-EGFP-shNC group (p = 0.0245), Ad5F35ET1-shrSulf group (p = 0.0426), and Ad5F35ET1-rbFGF group (p = 0.2853). The results demonstrated that this strategy may be a candidate therapy for chronic injury repair.

Stimuli-responsive Polymeric nanosystems for therapeutic applications

BACKGROUND

Recent past decades have reported emerging of polymeric nanoparticles as a promising technique for controlled and targeted drug delivery. As nanocarriers, they have high drug loading and delivery to the specific site or targeted cells with an advantage of no drug leakage within en route and unloading of a drug in a sustained fashion at the site. These stimuli-responsive systems are functionalized in dendrimers, metallic nanoparticles, polymeric nanoparticles, liposomal nanoparticles, quantum dots.

PURPOSE OF REVIEW

The authors reviewed the potential of smart stimuli-responsive carriers for therapeutic application and their behavior in external or internal stimuli like pH, temperature, redox, light, and magnet. These stimuli-responsive drug delivery systems behave differently in In vitro and In vivo drug release patterns. Stimuli-responsive nanosystems include both hydrophilic and hydrophobic systems. This review highlights the recent development of the physical properties and their application in specific drug delivery.

CONCLUSION

The stimuli (smart, intelligent, programmed) drug delivery systems provide site-specific drug delivery with potential therapy for cancer, neurodegenerative, lifestyle disorders. As development and innovation, the stimuli-responsive based nanocarriers are moving at a fast pace and huge demand for biocompatible and biodegradable responsive polymers for effective and safe delivery.

Nanotechnology-based therapeutic applications: in vitro and in vivo clinical studies for diabetic wound healing

Diabetic wounds often indicate chronic complications that are difficult to treat. Unfortunately, existing conventional treatment modalities often cause unpremeditated side effects, given the need to develop alternative therapeutic phenotypes that are safe or have minimal side effects and risks. Nanotechnology-based platforms, including nanotherapeutics, nanoparticles (NPs), nanofibers, nanohydrogels, and nanoscaffolds, have garnered attention for their groundbreaking potential to decipher the biological environment and offer personalized treatment methods for wound healing. These nanotechnology-based platforms can successfully overcome the impediments posed by drug toxicity, existing treatment modalities, and the physiology and complexity of the wound sites. Furthermore, studies have shown that they play an essential role in influencing angiogenesis, collagen production, and extracellular matrix (ECM) synthesis, which are integral in skin repair mechanisms. In this review, we emphasized the importance of various nanotechnology-based platforms for healing diabetic wounds and report on the innovative preclinical and clinical outcomes of different nanotechnology-based platforms. This review also outlined the limitations of existing conventional treatment modalities and summarized the physiology of acute and chronic diabetic wounds.

Polymer-Based Nanotherapeutics for Burn Wounds

Burn wounds are complex and intricate injuries that have become a common cause of trauma leading to significant mortality and morbidity every year. Dressings are applied to burn wounds with the aim of promoting wound healing, preventing burn infection and restoring skin function. The dressing protects the injury and contributes to recovery of dermal and epidermal tissues. Polymer-based nanotherapeutics are increasingly being exploited as burn wound dressings. Natural polymers such as cellulose, chitin, alginate, collagen, gelatin and synthetic polymers like poly (lactic-co-glycolic acid), polycaprolactone, polyethylene glycol, and polyvinyl alcohol are being obtained as nanofibers by nanotechnological approaches like electrospinning and have shown wound healing and re-epithelialization properties. Their biocompatibility, biodegradability, sound mechanical properties and unique structures provide optimal microenvironment for cell proliferation, differentiation, and migration contributing to burn wound healing. The polymeric nanofibers mimic collagen fibers present in extracellular matrix and their high porosity and surface area to volume ratio enable increased interaction and sustained release of therapeutics at the site of thermal injury. This review is an attempt to compile all recent advances in the use of polymer-based nanotherapeutics for burn wounds. The various natural and synthetic polymers used have been discussed comprehensively and approaches being employed have been reported. With immense research effort that is currently being invested in this field and development of proper characterization and regulatory framework, future progress in burn treatment is expected to occur. Moreover, appropriate preclinical and clinical research will provide evidence for the great potential that polymer-based nanotherapeutics hold in the management of burn wounds.

Electrospun and co-electrospun biopolymer nanofibers for skin wounds on diabetic patients: an overview

Wound healing treatment in diabetic patients worldwide represents around 2.1 trillion dollars to global health sectors. This is because of the complications presented in the wound healing process of skin ulcers, such as a lack of macrophage and fibroblast growth factors (TGF-β1 and PDGF, respectively) that are both needed for extracellular matrix (ECM) synthesis. Therefore, there is a need for research on new and cost-effective materials to enable ECM synthesis. Such materials include co-electrospun nanofibers used as wound dressings, since they have a similar morphology to the ECM, and therefore, possess the advantage of using different materials to accelerate the wound healing process. Co-electrospun nanofibers have a unique structural configuration, formed by a core and a shell. This configuration allows the protection and gradual liberation of healing agent compounds, which could be included in the core. Some of the materials used in nanofibers are polymers, including natural compounds, such as chitosan (which has been proven to possess antimicrobial and therapeutic activity) and gelatin (for its cell growth, adhesion, and organisational capacity in the wound healing process). Synthetics such as polyvinyl-alcohol (PVA) (mainly as a co-spinning agent to chitosan) can also be used. Another bioactive compound that can be used to enhance the wound healing process is eugenol, a terpenoid present in different medicinal plant tissues that have scarring properties. Therefore, the present review analyses the potential use of co-electrospun nanofibers, with chitosan-PVA-eugenol in the core and gelatin in the shell as a wound dressing for diabetic skin ulcers.

Effects of a Catechol-Functionalized Hyaluronic Acid Patch Combined with Human Adipose-Derived Stem Cells in Diabetic Wound Healing

Introduction: Chronic inflammation and impaired neovascularization play critical roles in delayed wound healing in diabetic patients. To overcome the limitations of current diabetic wound (DBW) management interventions, we investigated the effects of a catechol-functionalized hyaluronic acid (HA-CA) patch combined with adipose-derived mesenchymal stem cells (ADSCs) in DBW mouse models. Methods: Diabetes in mice (C57BL/6, male) was induced by streptozotocin (50 mg/kg, >250 mg/dL). Mice were divided into four groups: control (DBW) group, ADSCs group, HA-CA group, and HA-CA + ADSCs group (n = 10 per group). Fluorescently labeled ADSCs (5 × 10⁵ cells/100 µL) were transplanted into healthy tissues at the wound boundary or deposited at the HA-CA patch at the wound site. The wound area was visually examined. Collagen content, granulation tissue thickness and vascularity, cell apoptosis, and re-epithelialization were assessed. Angiogenesis was evaluated by immunohistochemistry, quantitative real-time polymerase chain reaction, and Western blot. Results: DBW size was significantly smaller in the HA-CA + ADSCs group (8% ± 2%) compared with the control (16% ± 5%, p < 0.01) and ADSCs (24% ± 17%, p < 0.05) groups. In mice treated with HA-CA + ADSCs, the epidermis was regenerated, and skin thickness was restored. CD31 and von Willebrand factor-positive vessels were detected in mice treated with HA-CA + ADSCs. The mRNA and protein levels of VEGF, IGF-1, FGF-2, ANG-1, PIK, and AKT in the HA-CA + ADSCs group were the highest among all groups, although the Spred1 and ERK expression levels remained unchanged. Conclusions: The combination of HA-CA and ADSCs provided synergistic wound healing effects by maximizing paracrine signaling and angiogenesis via the PI3K/AKT pathway. Therefore, ADSC-loaded HA-CA might represent a novel strategy for the treatment of DBW.

Nanotechnology-driven advances in the treatment of diabetic wounds

Diabetic foot ulcers (DFUs) are chronic severe complications of diabetes disease and remain a worldwide clinical challenge with social and economic consequences. Diabetic wounds can cause infection, amputation of lower extremities, and even death. Several factors including impaired angiogenesis, vascular insufficiency, and bacterial infections result in a delayed process of wound healing in diabetic patients. Treatment of wound infections using traditional antibiotics has become a critical status. Thus, finding new therapeutic strategies to manage diabetic wounds is urgently needed. Nanotechnology has emerged as an efficient approach for this purpose. This review aimed to summarize recent advances using nanotechnology for the treatment of diabetic wounds.

Electrospun nanofibers as a wound dressing for treating diabetic foot ulcer

Diabetes is one of the most prevalent diseases in the world with high-mortality and complex complications including diabetic foot ulcer (DFU). It has been reported that the difficulties in repairing the wound related to DFU has much relationship with the wound infection, change of inflammatory responses, lack of extracellular matrix (ECM), and the failure of angiogenesis. Following the development of medical materials and pharmaceutical technology, nanofibers has been developed by electrospinning with huge porosity, excellent humidity absorption, a better oxygen exchange rate, and some antibacterial activities. That is to say, as a potential material, nanofibers must be a wonderful candidate for the DFU treatment with so many benefits. Careful selection of polymers from natural resource and synthetic resource can widen the nanofibrous application. Popular methods applied for the nanofibrous fabrication consist of uniaxial electrospinning and coaxial electrospinning. Furthermore, nanofibers loading chemical, biochemical active pharmaceutical ingredient (API) or even stem cells can be wonderful dosage forms for the treatment of DFU. This review summarizes the present techniques applied in the fabrication of nanofibrous dressing (ND) that utilizes a variety of materials and active agents to offer a better health care for the patients suffering from DFU.

Matrix-entrapped cellular secretome rescues diabetes-induced EPC dysfunction and accelerates wound healing in diabetic mice

Cellular secretory products have infinite potential, which is only recently explored for research and therapeutic applications. The present study elaborated on the formation of a unique matrix-entrapped cellular secretome (MCS), a hydrogel-like secretome produced by bone marrow-derived mononuclear cells when cultured on a three-dimensional electrospun nanofiber matrix under specific conditions. These culture conditions support the growth of a mixed population predominantly comprising of endothelial precursor cells (EPCs), along with mesenchymal stromal cells and pericytes. Interestingly, such secretome is not formed in a pure culture of EPCs on the similarly formulated matrix, suggesting that a heterotypic cell-cell interaction is essential for the formation of MCS. In addition, the specific composition of the matrix was found to be a critical necessity for the formation of MCS. Furthermore, the application of the MCS as a substrate promotes the growth of EPCs in culture. It also rescues the diabetes-induced EPC dysfunction as assessed based on the parameters, such as viability, proliferation, colony formation, cellular adhesion, chemotactic migration, and tubule formation. MCS augments the levels of eNOS-specific mRNA (Nos3) and also promotes the restoration of the SDF1/CXCR4 axis in diabetic EPCs. Notably, a topical application of MCS on diabetic wounds leads to an accelerated wound closure. Thus, the current data showed that MCS forms an excellent cell-free biomaterial in the treatment of diabetic wounds and non-healing ulcers.

Nanopharmaceuticals for wound healing - Lost in translation?

Today, many of the newly developed pharmaceuticals and medical devices take advantage of nanotechnology and with a rising incidence of chronic diseases such as diabetes and cardiovascular disease, the number of patients afflicted globally with non-healing wounds is growing. This has created a requirement for improved therapies and wound care. However, converting the strategies applied in early research into new products is still challenging. Many of them fail to comply with the market requirements. This review discusses the legal and scientific challenges in the design of nanomedicines for wound healing. Are they lost in translation or is there a new generation of therapeutics in the pipeline?

Vascular precursor cells in tissue injury repair

Vascular precursor cells include stem cells and progenitor cells giving rise to all mature cell types in the wall of blood vessels. When tissue injury occurs, local hypoxia and inflammation result in the generation of vasculogenic mediators which orchestrate migration of vascular precursor cells from their niche environment to the site of tissue injury. The intricate crosstalk among signaling pathways coordinates vascular precursor cell proliferation and differentiation during neovascularization. Establishment of normal blood perfusion plays an essential role in the effective repair of the injured tissue. In recent years, studies on molecular mechanisms underlying the regulation of vascular precursor cell function have achieved substantial progress, which promotes exploration of vascular precursor cell-based approaches to treat chronic wounds and ischemic diseases in vital organ systems. Verification of safety and establishment of specific guidelines for the clinical application of vascular precursor cell-based therapy remain major challenges in the field.

Eicosanoids: Emerging contributors in stem cell-mediated wound healing

Eicosanoids are bioactive lipid products primarily derived from the oxidation of arachidonic acid (AA). The individual contributions of eicosanoids and stem cells to wound healing have been of great interest. This review focuses on how stem cells work in concert with eicosanoids to create a beneficial environment in the wound bed and in the promotion of wound healing. Stem cells contribute to wound healing through modulating inflammation, differentiating into skin cells or endothelial cells, and exerting paracrine effects by releasing various potent growth factors. Eicosanoids have been shown to stimulate proliferation, migration, homing, and differentiation of stem cells, all of which contribute to the process of wound healing. Increasing evidence has shown that eicosanoids improve wound healing through increasing stem cell densities, stimulating differentiation, and enhancing the angiogenic properties of stem cells. Chronic wounds have become a major problem in health care. Therefore, research regarding the effects of stem cells and eicosanoids in the promotion wound healing is of great importance.

Hemostatic Efficacy of Nanofibrous Matrix in Rat Liver Injury Model

This present study examined the hemostatic efficacy of nanofibrous matrix in a rat liver model. The nanofibrous matrix comprising gelatin and polycaprolactone was prepared by electrospinning method. Twelve animals underwent surgery and were followed-up for a month. Time taken to cease bleeding, activated partial thromboplastin time, prothrombin time, and fibrinogen concentration were measured. Histopathological examination of liver was also done of treated and control animals. All test animals showed very rapid hemostasis after application of electrospun sheet. Histopathological study showed quick recovery of liver wound in the test group as compared to the control group. The nanofibrous matrix has proven to be not only safe and effective as hemostat but has also shown its potential for liver regeneration.

A nano zinc oxide doped electrospun scaffold improves wound healing in a rodent model

Development of new and effective wound dressing materials continues to be an area of intense research in wound care management. ​Fabricated ZnO doped nanofibrous scaffold exhibited proficiency in EPCs enrichment and wound healing.

A highly infectious chimeric adenovirus expressing basic fibroblast growth factor exerts potent targeted therapy for rabbit ear chronic ischemic wounds

BACKGROUND

Poor angiogenesis and impaired proliferation of cells responsible for the repair of chronic ischemic wounds result in impaired wound healing. The continuous and efficient expression of therapeutic factors by means of gene transfection is an ideal adjuvant treatment method to promote cell proliferation and angiogenesis.

METHODS

A chimeric recombinant adenoviral vector, Ad5F35ET1-bFGF, was constructed that carried the basic fibroblast growth factor (bFGF) gene and used the endothelin-1 promoter to control the targeted expression of bFGF in endothelial cells and fibroblasts. Thus, the authors established a targeted gene therapy for chronic ischemic wounds.

RESULTS

The chimeric adenovirus Ad5F35ET1-bFGF efficiently infected the endothelin-1-positive endothelial cells and fibroblasts, specifically expressed bFGF, and promoted cell proliferation. In the rabbit wound healing model, the chimeric recombinant adenovirus expressed a high level of bFGF in wound tissues, which continuously promoted angiogenesis and cell proliferation and thus accelerated wound healing.

CONCLUSION

Targeted gene therapy that uses bFGF as a therapeutic gene provides an effective candidate strategy for the treatment of chronic ischemic wounds.