Negative pressure wound therapy is associated with up-regulation of bFGF and ERK1/2 in human diabetic foot wounds

Research progress on and molecular mechanism of vacuum sealing drainage in the treatment of diabetic foot ulcers

Diabetic foot ulcers (DFUs) are common chronic wounds and a common complication of diabetes. The foot is the main site of diabetic ulcers, which involve small and medium-sized arteries, peripheral nerves, and microcirculation, among others. DFUs are prone to coinfections and affect many diabetic patients. In recent years, interdisciplinary research combining medicine and material science has been increasing and has achieved significant clinical therapeutic effects, and the application of vacuum sealing drainage (VSD) in the treatment of DFUs is a typical representative of this progress, but the mechanism of action remains unclear. In this review, we integrated bioinformatics and literature and found that ferroptosis is an important signaling pathway through which VSD promotes the healing of DFUs and that System Xc-GSH-GPX4 and NAD(P)H-CoQ10-FSP1 are important axes in this signaling pathway, and we speculate that VSD is most likely to inhibit ferroptosis to promote DFU healing through the above axes. In addition, we found that some classical pathways, such as the TNF, NF-κB, and Wnt/β-catenin pathways, are also involved in the VSD-mediated promotion of DFU healing. We also compiled and reviewed the progress from clinical studies on VSD, and this information provides a reference for the study of VSD in the treatment of DFUs.

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.

The influence of negative pressure wound therapy on bacterial and fungal growth

BACKGROUND

The use of negative pressure wound therapy (NPWT) in superinfected wounds is controversial. The mechanism of action is unclear, but recent studies have shown lower atmospheric oxygen levels within the dressing. Therefore, different oxygen-favoring bacteria and fungi might benefit or face impaired thriving conditions. The aim of this in vitro study is to investigate the influence of NPWT on bacterial and fungal growth.

METHODS

Salmonella enterica subsp. enterica serovar Typhimurium, Pseudomonas aeruginosa and Candida albicans strains were cultured on concentrated agars and attached to a standard NPWT-device. After 48 hours, colonies were separately harvested from the agar and foam. Optical density (OD) was obtained in order to estimate bacterial loads.

RESULTS

For all tested microorganisms, no overall significant differences were found compared to controls. Subanalysis showed lower OD levels from the agar beneath the foam in the NPWT-group.

CONCLUSION

NPWT removed bacteria and fungi from the wound surface but accumulation is found within the foam. The use of NPWT showed no influence on bacterial or fungal growth selection. With superinfected wounds, the use of NPWT should thoroughly be evaluated as toxins and virulence factors may not fully be evacuated.

Molecular mechanisms of action of negative pressure wound therapy: a systematic review

Negative pressure wound therapy (NPWT) has significantly advanced wound care and continues to find new applications. Its effects at a molecular level however, remain a subject of debate. The aim of this systematic review is to summarize the current evidence regarding the molecular mechanisms of action of NPWT. Medline, Embase, EBSCO databases and clinical trial registries were searched from inception to January 2023. Clinical studies, animal models or in-vitro studies that quantitatively or semi-quantitatively evaluated the influence of NPWT on growth factors, cytokine or gene-expression in the circulation or wound-bed were included. Risk of Bias assessment was performed using the RoBANS tool for non-randomized studies, the COCHRANE's Risk of Bias 2(ROB-2) tool for randomized clinical studies, OHAT tool for in-vitro studies or the SYRCLE tool for animal model studies. A descriptive summary was collated and the aggregated data is presented as a narrative synthesis. This review included 19 clinical studies, 11 animal studies and 3 in-vitro studies. The effects of NPWT on 43 biomarkers and 17 gene expressions were studied across included studies. NPWT stimulates modulation of numerous local and circulating cytokines and growth factor expressions to promote an anti-inflammatory profile. This is most likely achieved by downregulation of TNFα, upregulation of VEGF, TGF-β and fibronectin.

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.

Successful use of minimal invasive debridement plus negative pressure wound therapy under skin flap and axillary region for refractory postmastectomy seroma: A STROBE-compliant retrospective study

Seroma is the most common wound complication due to dead space remaining after mastectomy and axillary dissection. Seroma formation, which causes pain and tension, together with the limitations of shoulder and arm movements, can cause wound healing problems that can progress to wound dehiscence and flap necrosis. The aim of our study was to investigate the effects of continuous drainage and negative pressure wound therapy (NPWT) in breast cancer patients with refractory postmastectomy seroma. This retrospectively designed study was conducted with 27 patients who were referred to our center between 2018 and 2021 due to refractory seroma after mastectomy. The inclusion criteria of the study were the cases who were planned minimally invasive debridement and NPWT due to having refractory seroma formation with at least 200 cc and having interventions more than 1 month after modified radical mastectomy (MRM), despite conventional treatment methods. All patients' demographics, disease stage, history of possible neoadjuvant therapy, comorbidities, body mass index (BMI), number of wound dressings with NPWT, and total amount of NPWT accumulation were enrolled and compared statistically. Twenty-seven patients included in the study underwent continuous drainage after debridement, and 5 (3-9) dressings were treated with NPWT. None of the patients experienced complications after debridement and NPWT administration. In refractory seroma cases seen after postmastectomy, NPWT especially for the management of debridement and dead space can be evaluated as an appropriate treatment method in patients with high flow rate seroma.

Gene set enrichment analysis and ingenuity pathway analysis to identify biomarkers in Sheng-ji Hua-yu formula treated diabetic ulcers

ETHNOPHARMACOLOGICAL RELEVANCE

Sheng-ji Hua-yu (SJHY) formula is a Chinese herbal prescription for diabetic ulcers (DUs) treatment, which can accelerate wound reconstruction and shorten the healing time. However, its mechanism role maintains unclear.

AIM OF THE STUDY

To elucidate the molecular mechanisms of SJHY application on DUs.

MATERIALS AND METHODS

To begin with, transcriptome sequencing was adopted to identified differentially expression mRNAs among normal ulcers, DUs, and DUs + SJHY treatment in vivo. Liquid chromatography-tandem mass spectrometry was applied for the quality control of SJHY formula. GO and KEGG enrichment analysis were used to identify the mechanisms underlying the therapeutic effect of SJHY formula, and then gene set enrichment analysis and ingenuity pathway analysis were conducted for functional analysis. Further, qPCR detection was performed in vivo for validation.

RESULTS

SJHY administration could regulate the glucose metabolic process, AMPK and HIF-1 pathway to accelerate healing processes of DUs. Besides, CRHR1, SHH, and GAL were identified as the critical targets, and SLC6A3, GRP, FGF23, and CYP27B1 were considered as the upstream genes of SJHY treatment. Combined with animal experiments, the prediction results were validated in DUs mice model.

CONCLUSIONS

This study used modular pharmacology analysis to identify the biomarkers of SJHY formula and provide the potential therapeutic targets for DUs treatment as well.

The progress and challenges of circRNA for diabetic foot ulcers: A mini-review

Since the Human Genome Project was successfully completed, humanity has entered a post-genome era, and the second-generation sequencing technology has gradually progressed and become more accurate. Meanwhile, circRNAs plays a crucial role in the regulation of diseases and potential clinical applications has gradually attracted the attention of physicians. However, the mechanisms of circRNAs regulation at the cellular and molecular level of diabetic foot ulcer (DFU) is still not well-understood. With the deepening of research, there have been many recent studies conducted to explore the effect of circRNAs on DFU. In this mini-review, we discuss the potential role of circRNAs as therapeutic targets and diagnostic markers for DFU in order to gain a better understanding of the molecular mechanisms that underlie the development of DFU and to establish a theoretical basis for accurate treatment and effective prevention.

Consensus on the application of negative pressure wound therapy of diabetic foot wounds

Because China is becoming an aging society, the incidence of diabetes and diabetic foot have been increasing. Diabetic foot has become one of the main health-related killers due to its high disability and mortality rates. Negative pressure wound therapy (NPWT) is one of the most effective techniques for the treatment of diabetic foot wounds and great progress, both in terms of research and its clinical application, has been made in the last 20 years of its development. However, due to the complex pathogenesis and management of diabetic foot, irregular application of NPWT often leads to complications, such as infection, bleeding and necrosis, that seriously affect its treatment outcomes. In 2020, under the leadership of Burns, Trauma and Tissue Repair Committee of the Cross-Straits Medicine Exchange Association, the writing group for ‘Consensus on the application of negative pressure wound therapy of diabetic foot wounds’ was established with the participation of scholars from the specialized areas of burns, endocrinology, vascular surgery, orthopedics and wound repair. Drawing on evidence-based practice suggested by the latest clinical research, this consensus proposes the best clinical practice guidelines for the application and prognostic evaluation of NPWT for diabetic foot. The consensus aims to support the formation of standardized treatment schemes that clinicians can refer to when treating cases of diabetic foot.

Identification of potential circRNAs and circRNA-miRNA-mRNA regulatory network in the development of diabetic foot ulcers by integrated bioinformatics analysis

We aimed to explore the mechanism of circular RNAs (circRNAs) and provide potential biomarkers for molecular therapy of diabetic foot ulcers (DFU). Gene expression profile of GSE114248, including five normal samples and five DFU samples, was downloaded from GEO database. Differentially expressed circRNAs (DEcircRNAs) between two groups were identified. Then, DEcircRNA‐miRNA and miRNA‐mRNA interaction was revealed, followed by the circRNA‐miRNA‐mRNA network construction. Moreover, functional and pathway analysis were performed based on mRNAs, followed by the DM‐related pathway exploration. Specific binding sites for key circRNAs and associated miRNAs were under investigation. Finally, RT‐qPCR was used to verify the candidate the relative expression level of circRNA between normal tissues and DFU. Totally, 65 DEcircRNAs were revealed between two groups, followed by 113 circRNA‐miRNA‐mRNA interactions explored. The mRNAs in these interactions were mainly assembled in functions like cell proliferation and pathways. Moreover, a total of 11 DM‐related pathways were revealed. Finally, circRNA‐miRNA specific binding‐site analysis revealed two key circRNAs, for example, circRNA_072697 and circRNA_405463, corresponding to their miRNAs. These two circRNAs were novel biomarkers for DFU. circRNA_072697 acted as a sponge of miR‐3150a‐3p in the progression of DFU via regulating KRAS. MAPK signaling pathway might contribute to the development of DFU.

The effectiveness of negative pressure wound therapy as a novel management of diabetic foot ulcers: an overview of systematic reviews

Background

Diabetic foot ulcer (DFU) is one the serious disabling conditions in patients with diabetes. Several approaches are available to manage DFU including Negative Pressure Wound Therapy (NPWT). The objective of this overview is systematically reviewing the related reviews about the effectiveness, safety, and cost benefits of NPWT interventions.

Methods

In October 2018, electronic databases including Medline, Embase, Scopous, Web of Science, the Cochrane Library and Google scholar were searched for systematic reviews about the NPWT's effectiveness and safety in DFUs. The Assessment of Multiple Systematic Reviews 2 (AMSTAR2) checklist was used for the appraisal of the systematic reviews. According to this checklist the studies were categorized as high, moderate, low and critically low quality.

Results

The electronic searches yielded 6889 studies. After excluding duplicates and those not fellfield the inclusion criteria, 23 systematic reviews were considered. The sample size of the reviews ranged between 20 and 2800 patients published since 2004 to 2018. Twenty systematic reviews (86.95%) included only randomized clinical trials (RCT). Regarding the AMSTAR-2 checklist, 7 studies were assigned to high quality, 8 were categorized as low quality and 8 studies belonged to the critically low quality groups. Accordingly, three, two and one out of seven high quality studies approved the effectiveness, safety and cost benefit of the NPWT therapy, respectively. However, some of them declared that there is some flaws in RCTs designing.

Conclusion

This overview illustrated that either systematic reviews or the included RCTs had wide variety of quality and heterogeneity in order to provide high level of evidence. Hence, well-designed RCTs as well as meta-analysis are required to shade the light on different aspects of NPWT.

Effects of Pulsed 810 nm Al-Ga-As Diode Laser on Wound Healing Under Immunosuppression: A Molecular Insight

BACKGROUND AND OBJECTIVES

Dysregulated inflammation is one of the major contributing factors for the prevalence of non-healing chronic wound in immunosuppressed subjects. Photobiomodulation (PBM) has emerged as a potential non-thermal, light-based therapeutic healing intervention for the treatment of impaired wounds.

STUDY DESIGN/MATERIALS AND METHODS

The present study delineates the underlying molecular mechanisms of PBM 810 nm laser-induced full-thickness cutaneous wound repair in immunosuppressed rats at continuous and pulsed wave-mode with power-density of 40 mW/cm ² , fluence 22.6 J/cm ² for 10 minutes daily for 7 post-wounding days. Molecular markers were assessed using biochemical, enzyme-linked immunosorbent assay quantification, enzyme kinetics and immunoblots analyses pertaining to inflammation, oxidative stress, cell survival, calcium signaling, and proliferation cascades.

RESULTS

Results distinctly revealed that pulsed 810 nm (10 Hz) PBM potentially influenced the cell survival and proliferation signaling pathway by significantly upregulated phospho-protein kinase B(phospho-Akt), phospho-extracellular-signal-regulated kinase 1 (ERK1), transient receptor potential vanilloid-3 (TRPV3), Ca²⁺ , calmodulin, transforming growth factor-β1 (TGF-β1), TGF-βR3, and Na ⁺ /K ⁺ -ATPase pump levels. PBM treatment resulted in reduction of exaggerated inflammatory responses evident by significantly repressed levels of interleukin-1β (IL-1β), IL-6, cyclooxygenase 2 (COX-2), and substance-P receptor (SPR), as well as inhibited apoptotic cell death by decreasing p53, cytochrome C, and caspase 3 levels (P < 0.05), which, in turn, effectively augment the wound repair in immunosuppressed rats. PBM treatment also lowered 4-hydroxynoneal (HNE) adduct level and NADP/NADPH ratio and upregulated the GRP78 expression, which might culminate into reduced oxidative stress and maintained the redox homeostasis.

CONCLUSIONS

Taken together, these findings would be helpful in better understanding of the molecular aspects involved in pulsed 810 nm laser-mediated dermal wound healing in immunosuppressed rats through regulation of cell survival and proliferation via Ca²⁺ -calmodulin, Akt, ERK, and redox signaling. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Tannic Acid Accelerates Cutaneous Wound Healing in Rats Via Activation of the ERK 1/2 Signaling Pathways

Objective: This study was aimed to evaluate the effect of tannic acid (TA), a natural plant polyphenol astringent, on wound healing in vitro and in vivo, and to elucidate the underlying molecular signaling pathway in the wound healing. Approach: Cutaneous skin wounds were created in rats and then treated until closure with purified TA, serum or tissue samples were collected to test the concentration of factors by enzyme-linked immunosorbent assay (ELISA), and the expression in gene or protein was measured by quantitative real-time polymerase chain reaction or Western blot. We explored the cell-/dose-specific responses of TA (0.1-0.4 μg/mL) on proliferation and gene and protein expression of fibroblast NIH 3T3 cells. Results: The wounds on rats treated by TA got healed faster than those in the untreated group. The histopathology study showed that TA accelerated re-epithelialization and increase in hair follicles could be detected. The levels of growth factors including basic fibroblast growth factor (bFGF), transforming growth factor-beta, and vascular endothelial growth factor in TA-treated groups were all increased, and the content of interleukin-1 (IL-1) and IL-6 was decreased significantly when compared with that of the untreated group. The NIH 3T3 cells grow faster in 6 h at concentration of 0.1 μg/mL, and the expression of bFGF in gene and protein was increased significantly in the 0.1 μg/mL TA group. Further study revealed that the protein levels of bFGF, extracellular signal regulated kinase (Erk) 1/2, and P-Erk 1/2 in Erk 1/2 pathway were increased after TA treatment. Innovation: The role of TA in wound healing efficacy is unclear; this study, therefore, assesses the effects of TA on wound healing in different periods and the underlying molecular mechanisms. Conclusion: These results suggested that TA could accelerate wound healing through modulation of inflammatory cytokines and growth factors and activate Erk 1/2 pathway. In conclusion, TA may be a potential agent in promoting wound healing.

The Role of Negative-Pressure Wound Therapy in Lower-Limb Reconstruction

Negative-pressure wound therapy (NPWT) has gained increasing popularity among clinicians since its introduction in 1997 as a potential aid to wound healing. Multiple benefits of NPWT have since been proven in studies, including increase in granulation tissue formation, decrease in bacterial load, and the improved survival of flaps. With our increasing use and greater understanding of the tissue and cellular changes that occur in a wound treated with NPWT, our lower-limb reconstructive practice has also evolved. Although controversial, the definite timing for lower-limb reconstruction has stretched from 72 hours to longer than 2 weeks as NPWT contains the wound within a sterile, closed system. It has also shown to decrease the rate of infection in open tibia fractures. Previously, a large number of critical defects of the lower limb would require free tissue transfer for definitive reconstruction. NPWT has reduced this rate by more than 50% and has allowed for less complicated resurfacing procedures to be performed instead.

Negative pressure wound therapy use in diabetic foot syndrome-from mechanisms of action to clinical practice

BACKGROUND

Diabetes and its complications constitute a rising medical challenge. Special attention should be given to diabetic foot syndrome (DFS) due to its high rate of associated amputation and mortality. Negative pressure wound therapy (NPWT) is a frequently used supportive modality in a diabetic foot with ulcerations (DFUs).

DESIGN

Here, we reviewed the current knowledge concerning the tissue and molecular mechanisms of NPWT action with an emphasis on diabetes research followed by a summary of clinical DFU studies and practice guidelines.

RESULTS

Negative pressure wound therapy action results in two types of tissue deformations-macrodeformation, such as wound contraction, and microdeformation occurring at microscopic level. Both of them stimulate a wound healing cascade including tissue granulation promotion, vessel proliferation, neoangiogenesis, epithelialization and excess extracellular fluid removal. On the molecular level, NPWT results in an alteration towards more pro-angiogenic and anti-inflammatory conditions. It increases expression of several key growth factors, including vascular endothelial growth factor and fibroblast growth factor 2, while expression of inflammatory cytokinesis reduced. The NPWT application also alters the presence and function of matrix metalloproteinases. Clinical studies in DFU patients showed a superiority of NPWT over standard therapy in terms of efficacy outcomes, primarily wound healing and amputation rate, without a rise in adverse events. International guidelines point to NPWT as an important adjuvant therapy in DFU whose use is expected to increase.

CONCLUSIONS

This current knowledge improves our understanding of NPWT action and its tailoring for application in diabetic patients. It may inform the development of new treatments for DFU.

Negative pressure wound therapy in the treatment of diabetic foot ulcers may be mediated through differential gene expression

AIMS

Negative pressure wound therapy (NPWT) has been successfully used as a treatment for diabetic foot ulceration (DFU). Its mechanism of action on the molecular level, however, is not fully understood. We assessed the effect of NPWT on gene expression in patients with type 2 diabetes (T2DM) and DFU.

METHODS

We included two cohorts of patients-individuals treated with either NPWT or standard therapy. The assignment to NWPT was non-randomized and based on wound characteristics. Differential gene expression profiling was performed using Illumina gene expression arrays and R Bioconductor pipelines based on the 'limma' package.

RESULTS

The final cohort encompassed 21 patients treated with NPWT and 8 with standard therapy. The groups were similar in terms of age (69.0 versus 67.5 years) and duration of T2DM (14.5 versus 14.4 years). We identified four genes differentially expressed between the two study arms post-treatment, but not pre-treatment: GFRA2 (GDNF family receptor alpha-2), C1QBP (complement C1q binding protein), RAB35 (member of RAS oncogene family) and SYNJ1 (synaptic inositol 1,4,5-trisphosphate 5-phosphatase 1). Interestingly, all four genes seemed to be functionally involved in wound healing by influencing re-epithelialization and angiogenesis. Subsequently, we utilized co-expression analysis in publicly available RNA-seq data to reveal the molecular functions of GFRA2 and C1QBP, which appeared to be through direct protein-protein interactions.

CONCLUSIONS

We found initial evidence that the NPWT effect on DFUs may be mediated through differential gene expression. A discovery of the specific molecular mechanisms of NPWT is potentially valuable for its clinical application and development of new therapies.

MnSOD is implicated in accelerated wound healing upon Negative Pressure Wound Therapy (NPWT): A case in point for MnSOD mimetics as adjuvants for wound management

Negative Pressure Wound Therapy (NPWT), a widely used modality in the management of surgical and trauma wounds, offers clear benefits over conventional wound healing strategies. Despite the wide-ranging effects ascribed to NPWT, the precise molecular mechanisms underlying the accelerated healing supported by NPWT remains poorly understood. Notably, cellular redox status-a product of the balance between cellular reactive oxygen species (ROS) production and anti-oxidant defense systems-plays an important role in wound healing and dysregulation of redox homeostasis has a profound effect on wound healing. Here we investigated potential links between the use of NPWT and the regulation of antioxidant mechanisms. Using patient samples and a rodent model of acute injury, we observed a significant accumulation of MnSOD protein as well as higher enzymatic activity in tissues upon NPWT. As a proof of concept and to outline the important role of SOD activity in wound healing, we replaced NPWT by the topical application of a MnSOD mimetic, Mn(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP5+, MnE, BMX-010, AEOl10113) in the rodent model. We observed that MnE is a potent wound healing enhancer as it appears to facilitate the formation of new tissue within the wound bed and consequently advances wound closure by two days, compared to the non-treated animals. Taken together, these results show for the first time a link between NPWT and regulation of antioxidant mechanism through the maintenance of MnSOD activity. Additionally this discovery outlined the potential role of MnSOD mimetics as topical agents enhancing wound healing.

Negative pressure wound therapy for treating foot wounds in people with diabetes mellitus

BACKGROUND

Foot wounds in people with diabetes mellitus (DM) are a common and serious global health issue. People with DM are prone to developing foot ulcers and, if these do not heal, they may also undergo foot amputation surgery resulting in postoperative wounds. Negative pressure wound therapy (NPWT) is a technology that is currently used widely in wound care. NPWT involves the application of a wound dressing attached to a vacuum suction machine. A carefully controlled negative pressure (or vacuum) sucks wound and tissue fluid away from the treated area into a canister. A clear and current overview of current evidence is required to facilitate decision-making regarding its use.

OBJECTIVES

To assess the effects of negative pressure wound therapy compared with standard care or other therapies in the treatment of foot wounds in people with DM in any care setting.

SEARCH METHODS

In January 2018, for this first update of this review, we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies, reviews, meta-analyses and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication or study setting. We identified six additional studies for inclusion in the review.

SELECTION CRITERIA

Published or unpublished randomised controlled trials (RCTs) that evaluated the effects of any brand of NPWT in the treatment of foot wounds in people with DM, irrespective of date or language of publication. Particular effort was made to identify unpublished studies.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, risk of bias assessment and data extraction. Initial disagreements were resolved by discussion, or by including a third review author when necessary. We presented and analysed data separately for foot ulcers and postoperative wounds.

MAIN RESULTS

Eleven RCTs (972 participants) met the inclusion criteria. Study sample sizes ranged from 15 to 341 participants. One study had three arms, which were all included in the review. The remaining 10 studies had two arms. Two studies focused on postamputation wounds and all other studies included foot ulcers in people with DM. Ten studies compared NPWT with dressings; and one study compared NPWT delivered at 75 mmHg with NPWT delivered at 125 mmHg. Our primary outcome measures were the number of wounds healed and time to wound healing.NPWT compared with dressings for postoperative woundsTwo studies (292 participants) compared NPWT with moist wound dressings in postoperative wounds (postamputation wounds). Only one study specified a follow-up time, which was 16 weeks. This study (162 participants) reported an increased number of healed wounds in the NPWT group compared with the dressings group (risk ratio (RR) 1.44, 95% confidence interval (CI) 1.03 to 2.01; low-certainty evidence, downgraded for risk of bias and imprecision). This study also reported that median time to healing was 21 days shorter with NPWT compared with moist dressings (hazard ratio (HR) calculated by review authors 1.91, 95% CI 1.21 to 2.99; low-certainty evidence, downgraded for risk of bias and imprecision). Data from the two studies suggest that it is uncertain whether there is a difference between groups in amputation risk (RR 0.38, 95% CI 0.14 to 1.02; 292 participants; very low-certainty evidence, downgraded once for risk of bias and twice for imprecision).NPWT compared with dressings for foot ulcersThere were eight studies (640 participants) in this analysis and follow-up times varied between studies. Six studies (513 participants) reported the proportion of wounds healed and data could be pooled for five studies. Pooled data (486 participants) suggest that NPWT may increase the number of healed wounds compared with dressings (RR 1.40, 95% CI 1.14 to 1.72; I² = 0%; low-certainty evidence, downgraded once for risk of bias and once for imprecision). Three studies assessed time to healing, but only one study reported usable data. This study reported that NPWT reduced the time to healing compared with dressings (hazard ratio (HR) calculated by review authors 1.82, 95% CI 1.27 to 2.60; 341 participants; low-certainty evidence, downgraded once for risk of bias and once for imprecision).Data from three studies (441 participants) suggest that people allocated to NPWT may be at reduced risk of amputation compared with people allocated to dressings (RR 0.33, 95% CI 0.15 to 0.70; I² = 0%; low-certainty evidence; downgraded once for risk of bias and once for imprecision).Low-pressure compared with high-pressure NPWT for foot ulcersOne study (40 participants) compared NPWT 75 mmHg and NPWT 125 mmHg. Follow-up time was four weeks. There were no data on primary outcomes. There was no clear difference in the number of wounds closed or covered with surgery between groups (RR 0.83, 95% CI 0.47 to 1.47; very low-certainty evidence, downgraded once for risk of bias and twice for serious imprecision) and adverse events (RR 1.50, 95% CI 0.28 to 8.04; very low-certainty evidence, downgraded once for risk of bias and twice for serious imprecision).

AUTHORS' CONCLUSIONS

There is low-certainty evidence to suggest that NPWT, when compared with wound dressings, may increase the proportion of wounds healed and reduce the time to healing for postoperative foot wounds and ulcers of the foot in people with DM. For the comparisons of different pressures of NPWT for treating foot ulcers in people with DM, it is uncertain whether there is a difference in the number of wounds closed or covered with surgery, and adverse events. None of the included studies provided evidence on time to closure or coverage surgery, health-related quality of life or cost-effectiveness. The limitations in current RCT evidence suggest that further trials are required to reduce uncertainty around decision-making regarding the use of NPWT to treat foot wounds in people with DM.

The role of TrkA in the promoting wounding-healing effect of CD271 on epidermal stem cells

CD271, a receptor of nerve growth factor (NGF), affects the biological properties of epidermal stem cells (eSCs) which are essential for skin wound closure. Tropomyosin-receptor kinase A (TrkA), another receptor of NGF, combined with CD271 has been involved with nervous system and skin keratinocytes. However, the exact role of TrkA combined with CD271 in eSCs during skin wound closure is still unclear. This study aimed to reveal the role of TrkA in the promoting wounding-healing effect of CD271 on eSCs. We obtained CD271-vo (over-expression of CD271) eSCs by lentiviral infection. K252a was used to inhibit TrkA expression. Full-thickness skin mouse wound closure model (5 mm in diameter) was used to detect the ability of CD271 over-expressed/TrkA-deficient during wound healing. The biological characteristics of eSCs and their proliferation and apoptosis were detected using immunohistochemistry and western blot. The expressions of protein kinase B (pAkt)/Akt, phosphorylated extracellular-signal-related kinase (pERK)/ERK1/2, and c-Jun N-terminal kinase (pJNK)/JNK were also detected by western blot. We found that over-expression of CD271 promoted the biological functions of eSCs. Interestingly, over-expression of CD271 in the absence of TrkA neither promoted eSCs' migration and proliferation nor promoted wound healing in a mouse model. In addition, we observed the reduced expression of pAkt/Akt and pERK/ERK1/2 following TrkA inhibition in vitro. Our studies demonstrated that the role of TrkA in the promoting wounding-healing effect of CD271 on eSCs.

Effect of negative pressure wound therapy on molecular markers in diabetic foot ulcers

Diabetic foot ulcers are one of the most common complications of diabetes with high morbidity and mortality. Negative pressure wound therapy (NPWT) is one of the treatment modalities that facilitates the wound healing process; however, its molecular mechanism remains unclear. The aim of this study was to investigate the mechanism of action of NPWT in the treatment of diabetic foot ulcers via measuring the tissue expression of genes related to the wound healing process. The study included 40 patients with diabetic foot ulceration, 20 of them received NPWT and the other 20 were a control group treated with advanced moist therapy. Granulation tissue biopsies were obtained before and 10 days after treatment in both groups and subjected to real-time polymerase chain reaction to measure the mRNA expression of TGF-β1, VEGF, TNF-α, IL-1β, MMP-1, MMP-9 and TIMP-1 which are involved in the wound healing pathway. After 10 days of treatment with NPWT, the mRNA levels of IL-1β, TNF-α, MMP-1, and MMP-9 were significantly downregulated, while the levels of VEGF, TGF-β1 and TIMP-1 were significantly increased. Our study demonstrated that NPWT promotes wound healing in diabetic foot ulcers possibly by affecting growth factors, inflammatory cytokines, and matrix metalloproteinases.

Effect of Negative Pressure Wound Therapy on Cellular Fibronectin and Transforming Growth Factor-β1 Expression in Diabetic Foot Wounds

BACKGROUND

Chronic diabetic foot wounds are a leading cause of amputation, morbidity, and hospitalization for patients with diabetes. Negative-pressure wound therapy (NPWT) can putatively facilitate wound healing, but the underlying mechanisms remain unclear. Cellular fibronectin (cFN) and transforming growth factor-β1 (TGF-β1) play an important role in wound healing. This prospective randomized controlled trial evaluated the effects of NPWT on the production of cFN and the expression of TGF-β1 in diabetic foot wounds of patients.

METHODS

From January 2012 to January 2015, 40 patients with diabetic foot wounds were randomly and equally apportioned to receive either NPWT or advanced moist wound therapy (control) for 7 days. Granulation tissue was harvested before and after treatment. Immunohistochemistry and Western blot were performed to evaluate protein levels of cFN and TGF-β1, and real-time polymerase chain reaction (PCR) to measure corresponding mRNA expressions.

RESULTS

NPWT facilitated the expression of cFN and TGF-β1 in diabetic foot wounds. Immunohistochemical analysis revealed higher levels of cFN and TGF-β1 in the NPWT group than in the control group. Western blot and real-time PCR analysis further showed that protein and mRNA levels of cFN or TGF-β1 were higher in the NPWT group than that in the control group ( P < .01, both).

CONCLUSION

Our results showed that NPWT facilitated the production of cFN and the expression of TGF-β1 in granulation tissue in diabetic foot ulcers.

LEVEL OF EVIDENCE

Level I, randomized controlled study.

The effectiveness of negative pressure therapy on infected wounds: preliminary results

Vacuum-assisted closure (VAC) therapy is a sophisticated system that maintains a closed, humid, sterile and isolated environment. Wound infection is considered a relative contraindication. The objective of this study is to extend the indications for VAC therapy to include infected wounds by demonstrating its ability to increase the antibiotic concentration in the damaged and infected tissues. Patients who presented with ulcers infected with daptomycin-sensitive bacteria were eligible to be enrolled in this prospective study. They were given antibiotic therapy with daptomycin with a specific protocol. A biopsy of the lesion was carried out to detect tissue concentration of the drug at time 0. Afterwards, the patients were subjected to VAC therapy. At the end of VAC therapy, a second lesion biopsy was performed and analysed to detect tissue concentration of the drug at time 1. A control group was enrolled in which patients followed the same protocol, but they were treated with traditional dressings. Fisher's exact test was used to compare the two groups. The results highlighted a significant increase in the concentration of antibiotics in the study group tissue; the improvement was sensibly lower in the control group. Statistical differences were not found between the two groups. The preliminary analysis of the data showed an important increase of antibiotic concentration in the tissue after VAC therapy. Despite the encouraging data, it is necessary to broaden the sample of patients and perform the same study with other antibiotics.

Deconstructing negative pressure wound therapy

Since its introduction 20 years ago for the treatment of chronic wounds, negative pressure wound therapy use has expanded to a variety of other wound types. Various mechanisms of action for its efficacy in wound healing have been postulated, but no unifying theory exists. Proposed mechanisms include induction of perfusion changes, microdeformation, macrodeformation, exudate control and decreasing the bacterial load in the wound. We surmise that these different mechanisms have varying levels of dominance in each wound type. Specifically, negative pressure wound therapy is beneficial to acute open wounds because it induces perfusion changes and formation of granulation tissue. Post-surgical incisional wounds are positively affected by perfusion changes and exudate control. In the context of chronic wounds, negative pressure wound therapy removes harmful and corrosive substances within the wounds to affect healing. When skin grafts and dermal substitutes are used to close a wound, negative pressure wound therapy is effective in promoting granulation tissue formation, controlling exudate and decreasing the bacterial load in the wound. In this review, we elucidate some of the mechanisms behind the positive wound healing effects of negative pressure wound therapy, providing possible explanations for these effects in different wound types.