Preclinical and clinical evidence for stem cell therapies as treatment for diabetic wounds

Chitosan based extruded nanofibrous bioscaffold for local delivery of mesenchymal stem cells to improve diabetic wound healing

BACKGROUND

Mesenchymal stem cells (MSCs)-based treatment strategy has shown promise in bolstering the healing process of chronic wounds in diabetic patients, who are at risk of amputation and mortality. To overcome the drawbacks of suboptimal cell retention and diminished cell viability at the injury site, a novel nanofibrous biomaterial-based scaffold was developed by using a controlled extrusion of a polymeric solution to deliver the cells (human adipose-derived MSCs (ADMSCs) and placenta-derived MSCs (PLMSCs)) locally to the animal model of diabetic ulcers.

METHODS

The physicochemical and biological properties of the nano-bioscaffold were characterized in terms of microscopic images, FTIR spectroscopy, tensile testing, degradation and swelling tests, contact angle measurements, MTT assay, and cell attachment evaluation. To evaluate the therapeutic efficacy, a study using an excisional wound model was conducted on diabetic rats.

RESULTS

The SEM and AFM images of scaffolds revealed a network of uniform nanofibers with narrow diameters between 100-130 nm and surface roughness less than 5 nm, respectively. ADMSCs and PLMSCs had a typical spindle-shaped or fibroblast-like morphology when attached to the scaffold. Desired characteristics in terms of swelling, hydrophilicity, biodegradation rate, and biocompatibility were achieved with the CS70 formulation. The wound healing process was accelerated according to wound closure rate assay upon treatment with MSCs loaded scaffold resulting in increased re-epithelialization, neovascularization, and less inflammatory reaction. Our findings unequivocally demonstrated that the cell-loaded nano-bioscaffold exhibited more efficacy compared with its acellular counterpart. In summation, our study underscores the potential of this innovative cellular scaffold as a viable solution for enhancing the healing of diabetic ulcers.

CONCLUSION

The utilization of MSCs in a nanofibrous biomaterial framework demonstrates significant promise, providing a novel avenue for advancing wound care and diabetic ulcer management.

The Angiogenic Repertoire of Stem Cell Extracellular Vesicles: Demystifying the Molecular Underpinnings for Wound Healing Applications

Stem cells-derived extracellular vesicles (SC-EVs) have emerged as promising therapeutic agents for wound repair, recapitulating the biological effects of parent cells while mitigating immunogenic and tumorigenic risks. These EVs orchestrate wound healing processes, notably through modulating angiogenesis-a critical event in tissue revascularization and regeneration. This study provides a comprehensive overview of the multifaceted mechanisms underpinning the pro-angiogenic capacity of EVs from various stem cell sources within the wound microenvironment. By elucidating the molecular intricacies governing their angiogenic prowess, we aim to unravel the mechanistic repertoire underlying their remarkable potential to accelerate wound healing. Additionally, methods to enhance the angiogenic effects of SC-EVs, current limitations, and future perspectives are highlighted, emphasizing the significant potential of this rapidly advancing field in revolutionizing wound healing strategies.

Upregulation of circ-IGF1R increased therapeutic effect of hypoxia-pretreated ADSC-derived extracellular vesicle by regulating miR-503-5p/HK2/VEGFA axis

Diabetes mellitus is a major cause of blindness and chronic ulcers in the working-age population worldwide. Wound healing is deeply dependent on neovascularization to restore blood flow. Former research has found that differentially expressed circular RNAs (circRNAs) are associated with hyperglycaemia-induced endothelial cell damage, and hypoxia-pretreated adipose-derived stem cells (ADSCs)-extracellular vesicle (HEV) transplants have a more therapeutic effect to enhance wound healing in diabetic mice by delivery circRNA. The current investigation employed high-throughput sequencing to identify circRNAs that are abnormally expressed between EV and HEV. The regulatory mechanism and predicted targets of one differentially expressed circRNA, circ-IGF1R, were investigated utilizing bioinformatics analyses, luciferase reporter assays, angiogenic differentiation assays, flow cytometric apoptosis analysis and RT-qPCR. Circ-IGF1R expression increased in HEV, and downregulation of circ-IGF1R suppressed and reversed the promotion effect of HEV on angiogenesis in ulcerated tissue. Bioinformatics analyses and luciferase reporter assays confirmed that miR-503-5p was the downstream target of circ-IGF1R, and inhibiting miR-503-5p restored the promotion effect of HEV on angiogenesis after circ-IGF1R silence. The study also found that miR-503-5p can interact with 3'-UTR of both HK2 and VEGFA. Overexpression of HK2 or VEGFA restored the promotion effect of HExo on angiogenesis after circ-IGF1R silence. Overexpression miR-503-5p or silence HK2/VEGFA reversed the protective effect of circ-IGF1R to MLMECs angiogenic differentiation. Overexpression of circ-IGF1R increased the protective effect of HEV on the promotion of wound healing in mice with diabetes. Circ-IGF1R promotes HIF-1α expression through miR-503-5p sponging. Our data demonstrate that circ-IGF1R overexpression EVs from ADSCs suppress high glucose-induced endothelial cell damage by regulating miR-503-5p/HK2/VEGFA axis.

Insights into the mechanisms of diabetic wounds: pathophysiology, molecular targets, and treatment strategies through conventional and alternative therapies

Diabetes mellitus is a prevalent cause of mortality worldwide and can lead to several secondary issues, including DWs, which are caused by hyperglycemia, diabetic neuropathy, anemia, and ischemia. Roughly 15% of diabetic patient's experience complications related to DWs, with 25% at risk of lower limb amputations. A conventional management protocol is currently used for treating diabetic foot syndrome, which involves therapy using various substances, such as bFGF, pDGF, VEGF, EGF, IGF-I, TGF-β, skin substitutes, cytokine stimulators, cytokine inhibitors, MMPs inhibitors, gene and stem cell therapies, ECM, and angiogenesis stimulators. The protocol also includes wound cleaning, laser therapy, antibiotics, skin substitutes, HOTC therapy, and removing dead tissue. It has been observed that treatment with numerous plants and their active constituents, including Globularia Arabica, Rhus coriaria L., Neolamarckia cadamba, Olea europaea, Salvia kronenburgii, Moringa oleifera, Syzygium aromaticum, Combretum molle, and Myrtus communis, has been found to promote wound healing, reduce inflammation, stimulate angiogenesis, and cytokines production, increase growth factors production, promote keratinocyte production, and encourage fibroblast proliferation. These therapies may also reduce the need for amputations. However, there is still limited information on how to prevent and manage DWs, and further research is needed to fully understand the role of alternative treatments in managing complications of DWs. The conventional management protocol for treating diabetic foot syndrome can be expensive and may cause adverse side effects. Alternative therapies, such as medicinal plants and green synthesis of nano-formulations, may provide efficient and affordable treatments for DWs.

Transplantation of Wharton's jelly mesenchymal stem cells encapsulated with Hydroactive® Gel promotes diabetic wound antifibrotic healing in type 2 diabetic rats

Diabetic cutaneous ulcers (DCU) are a complication for diabetes patients, mostly occurring in the foot and causing non-healing diabetic foot ulcers. Mesenchymal stem cell (MSC)-based therapy is currently being investigated as a therapeutic avenue for chronic diabetic ulcers. However, poor engraftment, short retention, and low survival still limit the treatment effectiveness. Hydroactive® Gel is a sterile transparent gel made of natural hydrocolloid, which has been widely used for wound management. Whether transplantation of Wharton's jelly mesenchymal stem cells (WJMSCs) encapsulated with Hydroactive® Gel is helpful to diabetic ulcers wound healing remains to be explored. The biocompatibility experiments showed that WJMSCs embedded in Hydroactive® Gel did not influence the cell viability, survival, proliferation, and apoptosis of WJMSCs in vitro. RNA-seq results also implied that Hydroactive® Gel + WJMSCs transplantation activated the "cytokine-cytokine receptor interaction", "mononuclear cell differentiation", "regulation of cell-cell adhesion", and "chemokine receptor activity" to accelerate the inflammatory reaction and epidermis regeneration in diabetic wounds. Histological analysis results demonstrated that Hydroactive® Gel encapsulated WJMSCs transplantation promoted diabetic wound healing and regeneration, indicating improved dermis regeneration, sebaceous gland formation, and type III collagen fiber deposition. Besides, immunohistochemical analysis results showed that Hydroactive® Gel + WJMSCs transplantation also facilitated the transformation of pro-inflammatory M1 macrophages to anti-inflammatory M2 macrophages, cell proliferation, and neovascularization at the wound site. Hydroactive® Gel encapsulation further prolonged the retention time of WJMSCs at the diabetic wound site. Above all, Hydroactive® Gel accelerates WJMSCs-mediated diabetic wound healing by promoting macrophage transformation, facilitating cell proliferation and angiogenesis, and prolonging cell retention time. Our findings may potentially provide a useful therapeutic strategy based on the combination of WJMSCs and biomedical materials for patients with diabetic cutaneous ulcers.

Stem Cell-Based Therapy for Diabetic Foot Ulcers

Diabetic foot ulcer has become a worldwide clinical medical challenge as traditional treatments are not effective enough to reduce the amputation rate. Therefore, it is of great social significance to deeply study the pathogenesis and biological characteristics of the diabetic foot, explore new treatment strategies and promote their application. Stem cell-based therapy holds tremendous promise in the field of regenerative medicine, and its mechanisms include promoting angiogenesis, ameliorating neuroischemia and inflammation, and promoting collagen deposition. Studying the specific molecular mechanisms of stem cell therapy for diabetic foot has an important role and practical clinical significance in maximizing the repair properties of stem cells. In addition, effective application modalities are also crucial in order to improve the survival and viability of stem cells at the wound site. In this paper, we reviewed the specific molecular mechanisms of stem cell therapy for diabetic foot and the extended applications of stem cells in recent years, with the aim of contributing to the development of stem cell-based therapy in the repair of diabetic foot ulcers.

Adipose Stem Cell-Based Treatments for Wound Healing

Wound healing is one of the most complex physiological regulation mechanisms of the human body. Stem cell technology has had a significant impact on regenerative medicine. Adipose stem cells (ASCs) have many advantages, including their ease of harvesting and high yield, rich content of cell components and cytokines, and strong practicability. They have rapidly become a favored tool in regenerative medicine. Here, we summarize the mechanism and clinical therapeutic potential of ASCs in wound repair.

Autologous Stem Cell Therapy for Chronic Lower Extremity Wounds: A Meta-Analysis of Randomized Controlled Trials

Lower extremity chronic wounds (LECWs) commonly occur in patients with diabetes mellitus (DM) and peripheral arterial disease (PAD). Autologous stem cell therapy (ASCT) has emerged as a promising alternative treatment for those who suffered from LECWs. The purpose of this study was to assess the effects of ASCT on LECWs. Two authors searched three core databases, and independently identified evidence according to predefined criteria. They also individually assessed the quality of the included randomized controlled trials (RCTs), and extracted data on complete healing rate, amputation rate, and outcomes regarding peripheral circulation. The extracted data were pooled using a random-effects model due to clinical heterogeneity among the included RCTs. A subgroup analysis was further performed according to etiology, source of stem cells, follow-up time, and cell markers. A total of 28 RCTs (n = 1096) were eligible for this study. The pooled results showed that patients receiving ASCT had significantly higher complete healing rates (risk ratio (RR) = 1.67, 95% confidence interval (CI) 1.28-2.19) as compared with those without ASCT. In the CD34+ subgroup, ASCT significantly led to a higher complete healing rate (RR = 2.70, 95% CI 1.50-4.86), but there was no significant difference in the CD34- subgroup. ASCT through intramuscular injection can significantly improve wound healing in patients with LECWs caused by either DM or critical limb ischemia. Lastly, CD34+ is an important cell marker for potential wound healing. However, more extensive scale and well-designed studies are necessary to explore the details of ASCT and chronic wound healing.

Wound Healing and Antioxidant Evaluations of Alginate from Sargassum ilicifolium and Mangosteen Rind Combination Extracts on Diabetic Mice Model

A diabetic foot ulcer is an open wound that can become sore and frequently occurs in diabetic patients. Alginate has the ability to form a hydrophilic gel when in contact with a wound surface in diabetic patients. Xanthones are the main compounds of mangosteen rind and have antibacterial and anti-inflammatory properties. The purpose of this research was to evaluate the wound healing and antioxidants assay with a combination of alginate from S. ilicifolium and mangosteen rind combination extracts on a diabetic mice model. The characterization of alginate was carried out by size exclusion chromatography with multiple angle laser light scattering (SEC-MALLS) and thermogravimetric analysis (TGA). The M/G ratio of alginate was calculated by using proton nuclear magnetic resonance (1H NMR). The antioxidant activity of mangosteen rind and the combination extracts was determined using the DPPH method. The observed parameters were wound width, number of neutrophils, macrophages, fibrocytes, fibroblasts, and collagen densities. The 36 male mice were divided into 12 groups including non-diabetic control (NC), diabetes alginate (DA), alginate–mangosteen (DAM), and diabetes control (DC) groups in three different groups by a histopathology test on skin tissue. The treatment was carried out for 14 days and mice were evaluated on Days 3, 7, and 14. The SEC-MALLS results showed that the molecular weight and dispersity index (Ð) of alginate were 2.77 × 104 Dalton and 1.73, respectively. The M/G ratio of alginate was 0.77 and described as single-stage decomposition based on TGA. Alginate, mangosteen rind extract, and their combination were divided into weak, medium, and strong antioxidant, respectively. The treatment of the DA and DAM groups showed a decrease in wound width and an increase in the number of fibrocytes, fibroblasts, and macrophages. The number of neutrophils decreased while the percentage of collagen densities increased for all the considered groups.

Stem cell transplantation therapy for diabetic foot ulcer: a narrative review

Diabetes mellitus is a chronic metabolic disease associated with high cardiovascular risk. A vascular complication of diabetes is foot ulcers. Diabetic foot ulcers are prevalent and substantially reduce the quality of life of patients who have them. Currently, diabetic foot ulcer is a major problem for wound care specialists, and its treatment requires considerable health care resources. So far, various therapeutic modalities have been proposed to treat diabetic foot ulcers and one of them is stem cell-based therapy. Stem cell-based therapy has shown great promise for the treatment of diabetic foot ulcers. This strategy has been shown to be safe and effective in both preclinical and clinical trials. In this review, we provide an overview of the stem cell types and possible beneficial effects of stem cell transplantation therapy for diabetic foot ulcers, and an overview of the current status of stem cell research in both preclinical and clinical trial stages of treatment strategies for diabetic foot ulcers.

The bone marrow-derived mesenchymal stem cells (BMSCs) alleviate diabetic peripheral neuropathy induced by STZ via activating GSK-3β/β-catenin signaling pathway

BACKGROUND

Diabetic peripheral neuropathy, a common complication of diabetic mellitus, has brought a threaten on patients' health. The bone marrow-derived mesenchymal stem cells (BMSCs) were reported to play an important role in diverse diseases. Nevertheless, the specific function of BMSCs in diabetic peripheral neuropathy remained uncharacterized.

METHODS

A wide range of experiments including RT-qPCR, western blot, H&E staining, oxidative stress assessment, measurement of thermal sensitivity, ELISA, urine protein and CCK-8 assays were implemented to explore the function and mechanism of BMSCs in vivo and vitro.

RESULTS

The experimental results displayed that BMSCs improve STZ-induced diabetes symptoms in rats by decreasing blood glucose and urinary protein. Functionally, BMSCs ameliorate oxidative stress, painful diabetic neuropathy, neurotrophic status and angiogenesis in STZ-induced rats. Moreover, BMSCs participate in the regulation of sciatic neuro morphology in diabetic neuropathy rat model. In mechanism, BMSCs alleviate diabetic peripheral neuropathy via activating GSK-3β/β-catenin signaling pathway in rats and improve Schwann's cells viability by activating GSK-3β/β-catenin signaling pathway under high glucose.

CONCLUSIONS

We verified that BMSCs alleviate diabetic peripheral neuropathy of rats induced by STZ via activating GSK-3β/β-catenin signaling pathway, which implied a novel biomarker for diabetic peripheral neuropathy treatment.

The role of Smad7 in cutaneous wound healing

Chronic refractory wounds are generally caused by local tissue defects and necrosis, and they are characterized by delayed wound healing as well as high recurrence, which seriously affects life quality. However, effective therapeutics to treat wounds are currently unavailable. Therapy primarily aims to accelerate generation of granulation tissue and decrease recurrence. The pathogenesis of chronic refractory wounds is closely related to multiple complex signaling pathways and a series of cytokines. Among these signaling pathways, TGF-β/Smad7 axis plays a critical role. Specifically, Smad7 is an antagonist of TGF-β that inhibits activation of TGF-β. Moreover, Smad7 promotes wound healing by regulating cytokines and controlling growth, differentiation and apoptosis of cells, which may be exploited to cure the disease. This review aims to reveal the exact functions and mechanisms of Smad7 in regulation of wound healing.

Characterization of Alginate from Sargassum duplicatum and the Antioxidant Effect of Alginate–Okra Fruit Extracts Combination for Wound Healing on Diabetic Mice

Diabetes mellitus is a group of metabolic disorders characterized by high blood-glucose levels over a prolonged period that causes complications when an open wound is present. Alginate is an antioxidant and a good absorbent of exudates. Okra fruit contains flavonoids that can act as antioxidants. The antioxidant properties of extracts combination reduce blood-glucose levels significantly to accelerate the activities of wound-healing processes on diabetic mice. Alginate was characterized by Size Exclusion Chromatography-Multiple Angle Laser Light Scattering (SEC-MALLS), thermal stability and Proton Nuclear Magnetic Resonance (1H-NMR). The evaluation of wound healing on 36 male mice were divided into 12 groups including normal control (NC), diabetics control (DC), alginate (DA) and alginate–okra (DAO) groups in three different times by histopathology test on skin tissue. The results of SEC-MALLS analysis showed that alginate as single and homogeneous polysaccharide. The 1H-NMR spectrum showed that the mannuronate/guluronate ratio of the used alginate was 0.91. Alginate, okra fruit extract and their combination were classified as moderate and strong antioxidants. The numbers of fibrocytes, fibroblasts, collagen densities had significantly increased from three to seven days. In contrast, wound width, neutrophil, macrophages had significantly decreased at 14 days. The administration of extracts combination increased the re-epithelization of the wound area and wound-healing process on diabetic mice.

Tetrahedral framework nucleic acids promote scarless healing of cutaneous wounds via the AKT-signaling pathway

While the skin is considered the first line of defense in the human body, there are some vulnerabilities that render it susceptible to certain threats, which is an issue that is recognized by both patients and doctors. Cutaneous wound healing is a series of complex processes that involve many types of cells, such as fibroblasts and keratinocytes. This study showed that tetrahedral framework nucleic acids (tFNAs), a type of self-assembled nucleic-acid material, have the ability to promote keratinocyte(HaCaT cell line) and fibroblast(HSF cell line) proliferation and migration in vitro. In addition, tFNAs increased the secretion of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in HSF cells and reduced the production of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in HaCaT cells by activating the AKT-signaling pathway. During in vivo experiments, tFNA treatments accelerated the healing process in skin wounds and decreased the development of scars, compared with the control treatment that did not use tFNAs. This is the first study to demonstrate that nanophase materials with the biological features of nucleic acids accelerate the healing of cutaneous wounds and reduce scarring, which indicates the potential application of tFNAs in skin tissue regeneration.

Ex vivo antioxidant preconditioning improves the survival rate of bone marrow stem cells in the presence of wound fluid

The advancement of autologous mesenchymal stem cell (MSC) therapy for the treatment of non-healing diabetic wounds is hampered by endogenous MSC dysfunction and limited viability of cells post-transplantation into the pathological wound environment. The development of effective strategies to restore the functional capabilities of these impaired MSCs prior to transplantation may be a key to their ultimate success as wound repair mediators. The current study therefore investigated whether antioxidant preconditioning [7.5 mM N-acetylcysteine (NAC) + 0.6 mM ascorbic 2-phosphate (AAP)] could restore the growth rate, migration ability and viability of impaired MSCs and whether this restored state is maintained in the presence of diabetic wound fluid (DWF). Healthy control (source: wild type, C57BL/6J mice) (n = 12) and impaired/diabetic MSCs (source: obese prediabetic, B6.Cg-Lepob/J mice) (n = 12) were isolated from the bone marrow of mice. Treatment groups post-isolation were as follow: (a) No treatment (baseline phenotype): MSCs expanded in standard growth media (SGM) (±8 days) and only exposed to growth media. (b) DWF (baseline response): MSCs expanded in SGM (±8 days) followed by exposure to DWF (24 hours, 48 hours, 96 hours). (c) Antioxidant preconditioning (preconditioned phenotype): MSCs expanded in the presence of NAC/AAP (±8 days). (d) Antioxidant preconditioning + DWF (preconditioned response): MSCs expanded in the presence of NAC/AAP (±8 days) followed by exposure to DWF (24 hours, 48 hours, 96 hours). The results demonstrated that expansion of MSCs (both healthy control and impaired diabetic) in the presence of combined NAC/AAP treatment improved ex vivo MSC viability and protected MSCs in the presence of DWF. Despite improved viability, AAP/NAC could however not rescue the reduced proliferation and migration capacity of impaired diabetic MSCs. The protective effect of NAC/AAP preconditioning against the toxicity of DWF could however be a potential strategy to improve cell number post-transplantation.

Combination of leflunomide and benazepril reduces renal injury of diabetic nephropathy rats and inhibits high-glucose induced cell apoptosis through regulation of NF-κB, TGF-β and TRPC6

Objective: To investigate effects of combination use of leflunomide and benazepril on diabetic nephropathy (DN) both in vivo and in vitro.

Methods: The streptozotocin (STZ) induced Sprague-Dawley rats were treated with leflunomide (15 mg/kg/d), benazepril (15 mg/kg/d) or both the two drugs. Fasting blood glucose (FBG) and renal function indexes including blood urea nitrogen (BUN), serum creatinine (Scr), and proteinuria and kidney/body weight ratio (KW/BW) were measured. HE staining was used for histological analysis. The rat glomerular mesangial cells (RMCs) were treated with high-glucose (150 mg/ml) and the leflunomide and benazepril with both concentrations of 50 μmol/l were used to treat the high-glucose induced cells. TUNEL assay was used for measurement of cell apoptosis. Western blotting was conducted to determine expression of nuclear factor Kappa B (NF-κB), transforming growth factor-β (TGF-β) and transient receptor potential canonical 6 (TRPC6).

Results: The body weight was significantly lower and all indexes of FBG, BUN, Scr, proteinuria and KW/BW ratio, GFR, as well as inflammatory factors TNF-α and IL-6 were significantly increased in the DN group after STZ treatment for 4 weeks. The treatment with leflunomide, benazepril or the both dramatically reduced the above effects induced by STZ, and the alteration was the most significant in the combination group. Treatment of leflunomide and benazepril significantly reduced expression levels of NF-κB, TGF-β and TRPC6 in renal tissues of DN rats as well as in high-glucose induced RMCs. It was also observed leflunomide and benazepril reduced high-glucose induced cell apoptosis of RMCs.

Conclusion: The combination use of leflunomide and benazepril could improve the renal function and reduce the renal injury of DN rats and could reduce the levels of NF-κb, TGF-β and TRPC6 in both DN rats and high-glucose induced RMCs.

Using a modified Delphi methodology to gain consensus on the use of dressings in chronic wounds management

OBJECTIVE

Managing chronic wounds is associated with a burden to patients, caregivers, health services and society and there is a lack of clarity regarding the role of dressings in improving outcomes. This study aimed to provide understanding on a range of topics, including: the definition of chronicity in wounds, the burden of illness, clinical outcomes of reducing healing time and the impact of early interventions on clinical and economic outcomes and the role of matrix metalloproteinases (MMPs) in wound healing.

METHOD

A systematic review of the literature was carried out on the role of dressings in diabetic foot ulcer (DFU), and venous leg ulcer (VLU) management strategies, their effectiveness, associated resource use/cost, and quality of life (QoL) impact on patients. From this evidence-base statements were written regarding chronicity in wounds, burden of illness, healing time, and the role of MMPs, early interventions and dressings. A modified Delphi methodology involving two iterations of email questionnaires followed by a face-to-face meeting was used to validate the statements, in order to arrive at a consensus for each. Clinical experts were selected, representing nurses, surgeons, podiatrists, academics, and policy experts.

RESULTS

In the first round, 38/47 statements reached or exceeded the consensus threshold of 80% and none were rejected. According to the protocol, any statement not confirmed or rejected had to be modified using the comments from participants and resubmitted. In the second round, 5/9 remaining statements were confirmed and none rejected, leaving 4 to discuss at the meeting. All final statements were confirmed with at least 80% consensus.

CONCLUSION

This modified Delphi panel sought to gain clarity from clinical experts surrounding the use of dressings in the management of chronic wounds. A full consensus statement was developed to help clinicians and policy makers improve the management of patients with these conditions.

Mechanistic insight into diabetic wounds: Pathogenesis, molecular targets and treatment strategies to pace wound healing

Wound management in diabetic patient is of an extreme clinical and social concern. The delayed and impaired healing makes it more critical for research focus. The research on impaired healing process is proceeding hastily evident by new therapeutic approaches other than conventional such as single growth factor, dual growth factor, skin substitutes, cytokine stimulators, cytokine inhibitors, matrix metalloproteinase inhibitors, gene and stem cell therapy, extracellular matrix and angiogenesis stimulators. Although numerous studies are available that support delayed wound healing in diabetes but detailed mechanistic insight including factors involved and their role still needs to be revealed. This review mainly focuses on the molecular cascades of cytokines (with growth factors) and erstwhile factors responsible for delayed wound healing, molecular targets and recent advancements in complete healing and its cure. Present article briefed recent pioneering information on possible molecular targets and treatment strategies including clinical trials to clinicians and researchers working in similar area.

Microvesicles from human adipose stem cells promote wound healing by optimizing cellular functions via AKT and ERK signaling pathways

BACKGROUND

Human adipose stem cells (ASCs) have emerged as a promising treatment paradigm for skin wounds. Recent works demonstrate that the therapeutic effect of stem cells is partially mediated by extracellular vesicles, which comprise exosomes and microvesicles. In this study, we investigate the regenerative effects of isolated microvesicles from ASCs and evaluate the mechanisms how ASC microvesicles promote wound healing.

METHODS

Adipose stem cell-derived microvesicles (ASC-MVs) were isolated by differential ultracentrifugation, stained by PKH26, and characterized by electron microscopy and dynamic light scattering (DLS). We examined ASC-MV effects on proliferation, migration, and angiogenesis of keratinocytes, fibroblasts, and endothelial cells both in vitro and in vivo. Next, we explored the underlying mechanisms by gene expression analysis and the activation levels of AKT and ERK signaling pathways in all three kinds of cells after ASC-MV stimulation. We then assessed the effect of ASC-MVs on collagen deposition, neovascularization, and re-epithelialization in an in vivo skin injury model.

RESULTS

ASC-MVs could be readily internalized by human umbilical vein endothelial cells (HUVECs), HaCAT, and fibroblasts and significantly promoted the proliferation, migration, and angiogenesis of these cells both in vitro and in vivo. The gene expression of proliferative markers (cyclin D1, cyclin D2, cyclin A1, cyclin A2) and growth factors (VEGFA, PDGFA, EGF, FGF2) was significantly upregulated after ASC-MV treatment. Importantly, ASC-MVs stimulated the activation of AKT and ERK signaling pathways in those cells. The local injection of ASC-MVs at wound sites significantly increased the re-epithelialization, collagen deposition, and neovascularization and led to accelerated wound closure.

CONCLUSIONS

Our data suggest that ASC-MVs can stimulate HUVEC, HaCAT, and fibroblast functions. ASC-MV therapy significantly accelerates wound healing, and the benefits of ASC-MVs may due to the involvement of AKT and ERK signaling pathways. This illustrates the therapeutic potential of ASC-MVs which may become a novel treatment paradigm for cutaneous wound healing.

Mesenchymal Stem Cells Coated by the Extracellular Matrix Promote Wound Healing in Diabetic Rats

OBJECTIVE

To investigate the effects of mesenchymal stem cells (MSCs) coated by the extracellular matrix (ECM) on wound healing in diabetic rats.

METHODS

Mesenchymal stem cells were cocultured with ECM. Cell viabilities were evaluated using MTT assay. The diabetes model was established using both STZ and high-glucose/fat methods in SD rats. A wound area was made on the middle of the rats' back. MSCs or ECM-MSCs were used to treat the rats. HE staining and CD31 immunohistochemistry were used to detect the skin thickness and angiogenesis. Western blotting and qRT-PCR were conducted to determine the level of VEGF-α, PDGF, and EGF.

RESULTS

It was observed that treatment of ECM had no significant effects on the cell viability of ECM-MSCs. Wound area assay showed that both MSCs and ECM-MSCs could enhance the wound healing of diabetic rats and ECM-MSCs could further promote the effects. Both MSCs and ECM-MSCs could enhance angiogenesis and epithelialization of the wounds, as well as the expression of VEGF-α, PDGF, and EGF in wound tissues, while ECM-MSC treatment showed more obvious effects.

CONCLUSION

Mesenchymal stem cells coated by the extracellular matrix could promote wound healing in diabetic rats. Our study may offer a novel therapeutic method for impaired diabetic wound healing.

Antioxidant Preconditioning Improves the Paracrine Responsiveness of Mouse Bone Marrow Mesenchymal Stem Cells to Diabetic Wound Fluid

Mesenchymal stem cells (MSCs) are a promising therapeutic tool for the treatment of nonhealing diabetic wounds. The pathological nature of the niche microenvironment limits the use of autologous cell therapy in diabetic patients. Prolonged exposure of endogenous MSCs to a pathological microenvironment in vivo reduces their ability to respond to environmental cues. This study investigated the effectiveness of ex vivo antioxidant treatment [N-acetylcysteine (7.5 mM NAC) and Ascorbic acid 2-phosphate (0.6 mM AAP)] to restore the paracrine function of diabetic MSCs. Healthy control [bone marrow stem cells derived from wild-type mice (SC^WT)] (source: wild-type C57BL/6J mice) (n = 12) and impaired/dysfunctional [bone marrow stem cells derived from ob/ob mice (SC^ob)] (source: obese diabetic, B6.Cg-Lep^ob/J mice) (n = 12) MSCs were isolated. Ex vivo treatment groups (SC^WT vs. SC^ob) were as follows: (1) no treatment (baseline phenotype), (2) stimulated with diabetic wound fluid (DWF) (baseline response), (3) antioxidant preconditioning (preconditioned phenotype), and (4) antioxidant preconditioned with subsequent stimulation with DWF (preconditioned response). The paracrine responsiveness on both the molecular (mRNA expression of 80 cytokines and receptors, quantitative polymerase chain reaction microarray) and protein (23-plex bead-array Luminex assay) level was assessed. At baseline, 31 genes were overexpressed (> × 2-fold) and 39 genes were underexpressed (> × 2-fold) in SC^ob versus SC^WT. In conditioned media, significant differences (P < 0.05) were detected at baseline for two proinflammatory cytokines [tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ)], four chemokines [keratinocyte chemoattractant (KC), granulocyte colony-stimulating factor (GCSF), Eotaxin, and macrophage chemoattractant protein (MCP1)], and one anti-inflammatory cytokine [interleukin 10 (IL10)]. Following stimulation with DWF, significant differences (P < 0.05) were detected in the secretion of two chemokines [granulocyte macrophage colony-stimulating factor (GMCSF) and Eotaxin], three proinflammatory cytokines (TNFα, IFNγ, and IL9), and four anti-inflammatory cytokines (IL10, IL4, IL13, and IL3). Antioxidant preconditioning significantly dampened the excessive TNFα response observed in SC^ob and improved the secretion of IL10. Taken together these data suggest that the combined ex vivo treatment of autologous stem cells with NAC and AAP could potentially be an effective strategy to restore the paracrine function of impaired diabetic MSCs before transplantation.

Efficiency of stem cell based therapy in the treatment of diabetic foot ulcer: a meta-analysis

Diabetic foot ulcer is a chronic, refractory, frequent complication in diabetic patient. Its treatment often requires multidisciplinary joint efforts, diverse strategies have been adopted to address this annoying issue, including stem cell-based therapy/acellular dermal matrix/negative pressure wound therapy etc. However, consensus has not been reached. To assess the current evidence regarding the efficiency and potential advantages of stem cell-based therapy compared with conventional standard treatment and/or placebo in the treatment of diabetic foot ulcer. A comprehensive search in PubMed, EmBase, Cochrane Central and Web of Science databases was conducted during December 2016 and a systematic review and meta-analysis of all relevant studies were performed. A total of 7 studies that involved 224 diabetic foot patients, classified as Wagner grades 1-5, were analyzed. The pooled results confirmed the benefits of using the stem cell treatment. Partial and/or complete healing were significantly higher in the stem cell group compared with the control group (77.4% vs. 31.9%; RR: 2.22; 95% CI, 1.65-2.98). Subgroup analysis on ABI and TCP02 also confirmed the results. The present meta-analysis indicates that stem cell-based therapy can enhance the healing of diabetic foot ulcers and is associated with lesser pain, lower amputation rate and improved prognosis compared with normal treatment. Well-designed randomized controlled trials are required in the future in order to confirm and update these findings.

Evaluation of negative-pressure wound therapy for patients with diabetic foot ulcers: systematic review and meta-analysis

Objectives

The aim of this study was to perform an updated systematic review and meta-analysis to assess the clinical efficacy, safety, and cost-effectiveness of negative-pressure wound therapy (NPWT) in the treatment of diabetic foot ulcers (DFUs).

Methods

We searched the Cochrane Library, MEDLINE, EMBASE, Ovid, and Chinese Biological Medicine databases up to June 30, 2016. We also manually searched the articles from reference lists of the retrieved articles, which used the NPWT system in studies of vacuum-assisted closure therapy. Studies were identified and selected, and two independent reviewers extracted data from the studies.

Results

A total of eleven randomized controlled trials, which included a total of 1,044 patients, were selected from 691 identified studies. Compared with standard dressing changes, NPWT had a higher rate of complete healing of ulcers (relative risk, 1.48; 95% confidence interval [CI]: 1.24–1.76; P<0.001), shorter healing time (mean difference, −8.07; 95% CI: −13.70– −2.45; P=0.005), greater reduction in ulcer area (mean difference, 12.18; 95% CI: 8.50–15.86; P<0.00001), greater reduction in ulcer depth (mean difference, 40.82; 95% CI: 35.97–45.67; P<0.00001), fewer amputations (relative risk, 0.31; 95% CI: 0.15–0.62; P=0.001), and no effect on the incidence of treatment-related adverse effects (relative risk, 1.12; 95% CI: 0.66–1.89; P=0.68). Meanwhile, many analyses showed that the NPWT was more cost-effective than standard dressing changes.

Conclusion

These results indicate that NPWT is efficacious, safe, and cost-effective in treating DFUs.

Stem Cell-Containing Hyaluronic Acid-Based Spongy Hydrogels for Integrated Diabetic Wound Healing

The detailed pathophysiology of diabetic foot ulcers is yet to be established and improved treatments are still required. We propose a strategy that directs inflammation, neovascularization, and neoinnervation of diabetic wounds. Aiming to potentiate a relevant secretome for nerve regeneration, stem cells were precultured in hyaluronic acid-based spongy hydrogels under neurogenic/standard media before transplantation into diabetic mice full-thickness wounds. Acellular spongy hydrogels and empty wounds were used as controls. Re-epithelialization was attained 4 weeks after transplantation independently of the test groups, whereas a thicker and more differentiated epidermis was observed for the cellular spongy hydrogels. A switch from the inflammatory to the proliferative phase of wound healing was revealed for all the experimental groups 2 weeks after injury, but a significantly higher M2(CD163⁺)/M1(CD86⁺) subtype ratio was observed in the neurogenic preconditioned group that also failed to promote neoinnervation. A higher number of intraepidermal nerve fibers were observed for the unconditioned group probably due to a more controlled transition from the inflammatory to the proliferative phase. Overall, stem cell-containing spongy hydrogels represent a promising approach to enhance diabetic wound healing by positively impacting re-epithelialization and by modulating the inflammatory response to promote a successful neoinnervation.

Biomaterials and Nanotherapeutics for Enhancing Skin Wound Healing

Wound healing is an intricate process that requires complex coordination between many cell types and an appropriate extracellular microenvironment. Chronic wounds often suffer from high protease activity, persistent infection, excess inflammation, and hypoxia. While there has been intense investigation to find new methods to improve cutaneous wound care, the management of chronic wounds, burns, and skin wound infection remain challenging clinical problems. Ideally, advanced wound dressings can provide enhanced healing and bridge the gaps in the healing processes that prevent chronic wounds from healing. These technologies have great potential for improving outcomes in patients with poorly healing wounds but face significant barriers in addressing the heterogeneity and clinical complexity of chronic or severe wounds. Active wound dressings aim to enhance the natural healing process and work to counter many aspects that plague poorly healing wounds, including excessive inflammation, ischemia, scarring, and wound infection. This review paper discusses recent advances in the development of biomaterials and nanoparticle therapeutics to enhance wound healing. In particular, this review focuses on the novel cutaneous wound treatments that have undergone significant preclinical development or are currently used in clinical practice.

Stem Cells in Skin Regeneration, Wound Healing, and Their Clinical Applications

The skin is the largest organ of the body and has an array of functions. Skin compartments, epidermis, and hair follicles house stem cells that are indispensable for skin homeostasis and regeneration. These stem cells also contribute to wound repair, resulting in restoration of tissue integrity and function of damaged tissue. Unsuccessful wound healing processes often lead to non-healing wounds. Chronic wounds are caused by depletion of stem cells and a variety of other cellular and molecular mechanisms, many of which are still poorly understood. Current chronic wound therapies are limited, so the search to develop better therapeutic strategies is ongoing. Adult stem cells are gaining recognition as potential candidates for numerous skin pathologies. In this review, we will discuss epidermal and other stem cells present in the skin, and highlight some of the therapeutic applications of epidermal stem cells and other adult stem cells as tools for cell/scaffold-based therapies for non-healing wounds and other skin disorders. We will also discuss emerging concepts and offer some perspectives on how skin tissue-engineered products can be optimized to provide efficacious therapy in cutaneous repair and regeneration.