The extracellular matrix in wound healing: a closer look at therapeutics for chronic wounds

Key extracellular proteins and TF-miRNA co-regulatory network in diabetic foot ulcer: Bioinformatics and experimental insights

BACKGROUND

Diabetic foot ulcers (DFUs), a serious complication of diabetes, are associated with abnormal extracellular protein (EP) metabolism. The identification of key EPs and their regulatory networks is crucial for the understanding of DFU formation and development of effective treatments. In this study, a large-scale bioinformatics analysis was conducted to identify potential therapeutic targets and experimental validation was performed to ensure the reliability and biological relevance of the findings.

METHODS

Due to the comprehensive profiling of DFU samples provided by the GSE80178 dataset, we initially selected it to derive differentially expressed genes (DEGs) associated with DFU. Subsequently, utilizing the UniProt database and annotated EP list from the Human Protein Atlas annotation database, we screened for extracellular protein-related differentially expressed genes (EP-DEGs) due to their crucial role in the pathogenesis and healing of DFU. We examined EP-DEG pathway enrichment and protein-protein interaction networks, analyzed paired full-thickness skin tissue samples from 24 patients with DFUs and healthy controls, and performed polymerase chain reaction (PCR) experiments to validate candidate genes. Ultimately, we constructed a transcription factor (TF)-microRNA (miRNA)-hub gene co-regulatory network to explore upstream and downstream regulatory connections based on validated DEGs.

RESULTS

Four crucial candidate genes (FMOD, LUM, VCAN, and S100A12) were identified and verified via PCR analysis. The TF-miRNA-hub EP-DEG regulatory network contained the pivotal TFs TRIM28 and STAT3 and the miRNAs hsa-mir-20a-5p, hsa-miR-21, and hsa-miR-203.

CONCLUSION

The findings of this study advance our understanding of the pathology of DFU by defining key roles of specific EPs and elucidating a comprehensive regulatory network. These insights pave the way for novel approaches to improve DFU treatment outcomes.

3D-printed electrospun fibres for wound healing

Wound management for acute and chronic wounds has become a serious clinical problem worldwide, placing considerable pressure on public health systems. Owing to the high-precision, adjustable pore structure, and repeatable manufacturing process, 3D-printed electrospun fibre (3DP-ESF) has attracted widespread attention for fabricating wound dressing. In addition, in comparison with 2D electrospun fibre membranes fabricated by traditional electrospinning, the 3D structures provide additional guidance on cell behaviour. In this perspective article, we first summarise the basic manufacturing principles and methods to fabricate 3DP-ESF. Then, we discuss the function of 3DP-ESF in manipulating the different stages of wound healing, including anti-bacteria, anti-inflammation, and promotion of cell migration and proliferation, as well as the construction of tissue-engineered scaffolds. In the end, we provide the current challenge faced by 3DP-ESF in the application of skin wound regeneration and its promising future directions.

Role of the mitochondrial protein cyclophilin D in skin wound healing and collagen secretion

Central for wound healing is the formation of granulation tissue, which largely consists of collagen and whose importance stretches past wound healing, including being implicated in both fibrosis and skin aging. Cyclophilin D (CyD) is a mitochondrial protein that regulates the permeability transition pore, known for its role in apoptosis and ischemia-reperfusion. To date, the role of CyD in human wound healing and collagen generation has been largely unexplored. Here, we show that CyD was upregulated in normal wounds and venous ulcers, likely adaptive as CyD inhibition impaired reepithelialization, granulation tissue formation, and wound closure in both human and pig models. Overexpression of CyD increased keratinocyte migration and fibroblast proliferation, while its inhibition reduced migration. Independent of wound healing, CyD inhibition in fibroblasts reduced collagen secretion and caused endoplasmic reticulum collagen accumulation, while its overexpression increased collagen secretion. This was confirmed in a Ppif-KO mouse model, which showed a reduction in skin collagen. Overall, this study revealed previously unreported roles of CyD in skin, with implications for wound healing and beyond.

Therapeutic Potential of Adipose-Derived Stem Cell-Conditioned Medium and Extracellular Vesicles in an In Vitro Radiation-Induced Skin Injury Model

Radiotherapy (RT) is one of three major treatments for malignant tumors, and one of its most common side effects is skin and soft tissue injury. However, the treatment of these remains challenging. Several studies have shown that mesenchymal stem cell (MSC) treatment enhances skin wound healing. In this study, we extracted human dermal fibroblasts (HDFs) and adipose-derived stem cells (ADSCs) from patients and generated an in vitro radiation-induced skin injury model with HDFs to verify the effect of conditioned medium derived from adipose-derived stem cells (ADSC-CM) and extracellular vesicles derived from adipose-derived stem cells (ADSC-EVs) on the healing of radiation-induced skin injury. The results showed that collagen synthesis was significantly increased in wounds treated with ADSC-CM or ADSC-EVs compared with the control group, which promoted the expression of collagen-related genes and suppressed the expression of inflammation-related genes. These findings indicated that treatment with ADSC-CM or ADSC-EVs suppressed inflammation and promoted extracellular matrix deposition; treatment with ADSC-EVs also promoted fibroblast proliferation. In conclusion, these results demonstrate the effectiveness of ADSC-CM and ADSC-EVs in the healing of radiation-induced skin injury.

Thermosensitive and antioxidant wound dressings capable of adaptively regulating TGFβ pathways promote diabetic wound healing

Various therapies have been utilized for treating diabetic wounds, yet current regiments do not simultaneously address the key intrinsic causes of slow wound healing, i.e., abnormal skin cell functions (particularly migration), delayed angiogenesis, and chronic inflammation. To address this clinical gap, we develop a wound dressing that contains a peptide-based TGFβ receptor II inhibitor (PTβR2I), and a thermosensitive and reactive oxygen species (ROS)-scavenging hydrogel. The wound dressing can quickly solidify on the diabetic wounds following administration. The released PTβR2I inhibits the TGFβ1/p38 pathway, leading to improved cell migration and angiogenesis, and decreased inflammation. Meanwhile, the PTβR2I does not interfere with the TGFβ1/Smad2/3 pathway that is required to regulate myofibroblasts, a critical cell type for wound healing. The hydrogel's ability to scavenge ROS in diabetic wounds further decreases inflammation. Single-dose application of the wound dressing significantly accelerates wound healing with complete wound closure after 14 days. Overall, using wound dressings capable of adaptively modulating TGFβ pathways provides a new strategy for diabetic wound treatment.

Polymeric Gel Scaffolds and Biomimetic Environments for Wound Healing

Infected wounds that do not heal are a worldwide problem that is worsening, with more people dying and more money being spent on care. For any disease to be managed effectively, its root cause must be addressed. Effective wound care becomes a bigger problem when various traditional wound healing methods and products may not only fail to promote good healing. Still, it may also hinder the healing process, causing wounds to stay open longer. Progress in tissue regeneration has led to developing three-dimensional scaffolds (3D) or constructs that can be leveraged to facilitate cell growth and regeneration while preventing infection and accelerating wound healing. Tissue regeneration uses natural and fabricated biomaterials that encourage the growth of tissues or organs. Even though the clinical need is urgent, the demand for polymer-based therapeutic techniques for skin tissue abnormalities has grown quickly. Hydrogel scaffolds have become one of the most imperative 3D cross-linked scaffolds for tissue regeneration because they can hold water perfectly and are porous, biocompatible, biodegradable, and biomimetic. For damaged organs or tissues to heal well, the porosity topography of the natural extracellular matrix (ECM) should be imitated. This review details the scaffolds that heal wounds and helps skin tissue to develop. After a brief overview of the bioactive and drug-loaded polymeric hydrogels, the discussion moves on to how the scaffolds are made and what they are made of. It highlights the present uses of in vitro and in-vivo employed biomimetic scaffolds. The prospects of how well bioactiveloaded hydrogels heal wounds and how nanotechnology assists in healing and regeneration have been discussed.

A long‐term follow‐up study of diabetic foot ulcer using micronized acellular dermal matrix

Treating a diabetic foot ulcer (DFU) extending to the tendon or bone can be a challenge for physicians. Recent studies have shown positive results of micronized acellular dermal matrix (ADM) treatment for treating DFU. However, studies on such ADM with a long-term follow-up are rare. Thus, the objective of this study was to retrospectively analyse patients treated with micronized ADM with a long-term follow-up to assess the effectiveness of the treatment and determine the recurrence rate. The rate of success of complete healing was 62.96% and the time of complete healing was 86.96 days in this study. The recurrence rate of DFUs was 41.17% in the overall group. However, it was only 23.52% in the micronized ADM group. The average duration of recurrence was 720.50 ± 505.12 days. The recurrence rate was 50% in weight bearing areas such as the plantar and heel. It was 12.5% in toes and non-weight bearing areas. In conclusion, micronized ADM can be used to effectively treat DFUs that have invaded ligaments or bones. A close follow-up of weight bearing area wounds will allow us to identify and treat recurrence early.

Human adipose-derived mesenchymal stem cells-derived exosomes encapsulated in pluronic F127 hydrogel promote wound healing and regeneration

Background

Large area skin trauma has always been a great challenge for both patients and clinicians. Exosomes originating from human adipose-derived mesenchymal stem cells (hADSCs) have been a novel promising cell-free treatment in cutaneous damage repair. Nevertheless, the low retention rate of exosomes post-transplantation in vivo remains a significant challenge in clinical applications. Herein, we purposed to explore the potential clinical application roles of hADSCs-Exos encapsulated in functional PF-127 hydrogel in wound healing.

Methods

hADSCs-Exos were isolated from human hADSCs by ultracentrifugation. An injectable, biocompatible, and thermo-sensitive hydrogel Pluronic F-127 hydrogel was employed to encapsulate allogeneic hADSCs-Exos, and this complex was topically applied to a full-thickness cutaneous wound in mice. On different days post-transplantation, the mice were sacrificed, and the skin tissue was excised for histological and immunohistochemical analysis.

Results

Compared with hADSCs-Exos or PF-127 only, PF-127/hADSCs-Exos complexes enhanced skin wound healing, promoted re-epithelialization, increased expression of Ki67, α-SMA, and CD31, facilitated collagen synthesis (Collagen I, Collagen III), up-regulated expression of skin barrier proteins (KRT1, AQP3), and reduced inflammation (IL-6, TNF-α, CD68, CD206). By using PF-127/hADSCs-Exos complexes, hADSCs-Exos can be administrated at lower doses frequency while maintaining the same therapeutic effects.

Conclusion

Administration of hADSCs-Exos in PF-127 improves the efficiency of exosome delivery, maintains the bioactivity of hADSCs-Exos, and optimizes the performance of hADSCs-Exos. Thus, this biomaterial-based exosome will be a promising treatment approach for the cutaneous rejuvenation of skin wounds.

Evaluation of Scar Quality after Treatment of Superficial Burns with Dressilk® and Suprathel®-In an Intraindividual Clinical Setting

Background: Various synthetic and biological wound dressings are available for the treatment of superficial burns, and standard care differs among hospitals. Nevertheless, the search for an ideal wound dressing offering a safe healing environment as well as optimal scar quality while being economically attractive is a continuing process. In recent years, Dressilk^®, which consists of pure silk, has become the standard of care for the treatment of superficial burns in our hospital. However, no long-term scar-evaluation studies have been performed to compare Dressilk^® with the often-used and more expensive Suprathel^® in the treatment of superficial burns. Methods: Subjective and objective scar evaluations were performed three, six, and twelve months after treatment in patients who received simultaneous treatment of 20 superficial burn wounds with both Suprathel^® and Dressilk^®. The evaluations were performed using the Vancouver Scar Scale, the Cutometer^®, Mexameter^®, Tewameter^®, and the O2C^®. Results: Both dressings showed mostly equivalent results in subjective scar evaluations. In the objective scar evaluations, the wounds treated with Dressilk^® showed a faster return to the qualities of non-injured skin. Wound areas treated with the two dressings showed no significant differences in elasticity and transepidermal water loss after 12 months. Only oxygen saturation was significantly lower in wound areas treated with Suprathel^® (p = 0.008). Subjectively, wound areas treated with Dressilk^® showed significantly higher pigmentation after six months, which was not apparent after 12 months. Conclusion: Both wound dressings led to esthetically satisfying scar recovery without significant differences from normal uninjured skin after 12 months. Therefore, Dressilk^® remains an economically and clinically interesting alternative to Suprathel^® for the treatment of superficial burns.

Transplantation of acellularized dermis matrix (ADM) plus fully covered metal stent to prevent stricture after circumferential endoscopic submucosal dissection of early esophageal cancer (with video)

Backgroud and study aims

Esophageal stricture is a serious adverse event occurring after circular endoscopic submucosal dissection (ESD) involving the whole esophagus. However, there is still a lack of effectively preventive methods. The main purpose of this study is to evaluate the efficacy of application of acellularized dermis matrix (ADM) for the prevention of post-ESD esophageal stricture. The main objective of this study was to evaluate the use of decellularized dermal matrix (ADM) in the prevention of post-esophageal ESD strictures.

Patients and methods

A pilot, single-center, prospective study was conducted. The study enrolled seven patients who had high-risks with extended resection of developing post-ESD esophageal stricture. After undergoing ESD, we attached different size of ADM patches to the mucosal defects using titanium clips then fixed with a metal mesh stent. The stent covered with metal mesh was removed at the median time of 27 days after the endoscopic procedure. Follow-up and repeated outpatient endoscopic screening were performed at appropriate scheduled times.

Results

The average longitudinal diameter of the resected specimens was 58.3 mm (range 38–90 mm). There were three patients developing strictures postoperatively at a mean time of 87 days (range 42–140). The median number of postoperative endoscopic balloon dilatation (EBD) in patients with stenosis was 2 (range 2–9). There were no deaths during a median follow-up period of 6 moths (range 1–12).

Conclusions

This study was performed to assess the efficacy and safe method of relieving the severity of esophageal stricture after ESD through transplantation of ADM.

Extracellular Matrix-Based Biomaterials for Cardiovascular Tissue Engineering

Regenerative medicine and tissue engineering strategies have made remarkable progress in remodeling, replacing, and regenerating damaged cardiovascular tissues. The design of three-dimensional (3D) scaffolds with appropriate biochemical and mechanical characteristics is critical for engineering tissue-engineered replacements. The extracellular matrix (ECM) is a dynamic scaffolding structure characterized by tissue-specific biochemical, biophysical, and mechanical properties that modulates cellular behavior and activates highly regulated signaling pathways. In light of technological advancements, biomaterial-based scaffolds have been developed that better mimic physiological ECM properties, provide signaling cues that modulate cellular behavior, and form functional tissues and organs. In this review, we summarize the in vitro, pre-clinical, and clinical research models that have been employed in the design of ECM-based biomaterials for cardiovascular regenerative medicine. We highlight the research advancements in the incorporation of ECM components into biomaterial-based scaffolds, the engineering of increasingly complex structures using biofabrication and spatial patterning techniques, the regulation of ECMs on vascular differentiation and function, and the translation of ECM-based scaffolds for vascular graft applications. Finally, we discuss the challenges, future perspectives, and directions in the design of next-generation ECM-based biomaterials for cardiovascular tissue engineering and clinical translation.

Development of an in-situ forming, self-healing scaffold for dermal wound healing: in-vitro and in-vivo studies

The importance of the extra-cellular matrix (ECM) for wound healing has been extensively researched. Understanding its importance, multiple ECM mimetic scaffolds have been developed. However, the majority of such scaffolds are prefabricated. Due to their stiffness, prefabricated scaffolds cannot come into direct contact with the basal skin cells at the wound bed, limiting their efficacy. We have developed a unique wound dressing, using chitosan (CH) and chondroitin sulfate (CS), that can form a porous scaffold (CH-CS PEC) in-situ, at the wound site, by simple mixing of the polymer solutions. As CH is positively and CS is negatively charged, mixing these two polymer solutions would lead to electrostatic cross-linking between the polymers, converting them to a porous, viscoelastic scaffold. Owing to the in-situ formation, the scaffold can come in direct contact with the cells at the wound bed, supporting their proliferation and biofunction. In the present study, we confirmed the cross-linked scaffold formation by solid-state NMR, XRD, and TGA analysis. We have demonstrated that the scaffold had a high viscoelastic property, with self-healing capability. Both keratinocyte and fibroblast cells exhibited significantly increased migration and functional markers expression when grown on this scaffold. In the rat skin-excisional wound model, treatment with the in-situ forming CH-CS PEC exhibited enhanced wound healing efficacy. Altogether, this study demonstrated that mixing CH and CS solutions lead to the spontaneous formation of a highly viscoelastic, porous scaffold, which can support epidermal and dermal cell proliferation and bio-function, with an enhanced in-vivo wound healing efficacy.

Wound dressings: curbing inflammation in chronic wound healing

Chronic wounds represent an economic burden to healthcare systems worldwide and a societal burden to patients, deeply impacting their quality of life. The incidence of recalcitrant wounds has been steadily increasing since the population more susceptible, the elderly and diabetic, are rapidly growing. Chronic wounds are characterised by a delayed wound healing process that takes longer to heal under standard of care than acute (i.e. healthy) wounds. Two of the most common problems associated with chronic wounds are inflammation and infection, with the latter usually exacerbating the former. With this in mind, researchers and wound care companies have developed and marketed a wide variety of wound dressings presenting different compositions but all aimed at promoting healing. This makes it harder for physicians to choose the correct therapy, especially given a lack of public quantitative data to support the manufacturers’ claims. This review aims at giving a brief introduction to the clinical need for chronic wound dressings, focusing on inflammation and evaluating how bio-derived and synthetic dressings may control excess inflammation and promote healing.

A clinical comparison of pure knitted silk and a complex synthetic skin substitute for the treatment of partial thickness burns

Currently, many dressings are commercially available for the treatment of burn wounds. Some of these wound dressings remain on the wound, prevent painful dressing changes, and reduce tissue scarring. Nevertheless, still a wound dressing that is cost-effective, produces good wound healing properties, and has a high patient satisfaction is needed. Standard care of superficial burn wounds differs between burn centres. This study aimed to determine a dressing with easy appliance, accurate pain control, favourable outcome, and cost-effectiveness. Therefore, we compared the widely used but expensive Suprathel with the rather new but much cheaper Dressilk in the clinical setting. In a prospective clinical study, the healing of partial thickness burn wounds after simultaneous treatment with Suprathel and Dressilk was examined in 20 patients intra-individually. During wound healing, pain, infection, exudation, and bleeding were evaluated. A subjective scar evaluation was performed using the Patient and Observer Scar Scale. Both dressings were easy to apply, remained on the wound in place, and were gradually cut back as reepithelisation proceeded and showed similar times to wound closure. Dressing changes were not necessary, and neither infections nor bleeding was detected. Overall exudation and pain were highest in the beginning but declined during the wound-healing phase without significant differences. In the follow-up scar evaluation after 12 months, patients reported overall high satisfaction. Overall, the modern dressings Suprathel and Dressilk (solely made out of pure silk) led to safe wound healing without infection and rapidly reduced pain. There was no need for dressing changes, and they had similar clinical outcomes in scar evaluation. Therefore, both dressings seem to be ideal for the treatment of superficial burns. Because acquisition costs remain one of the main factors in the treatment of burns, Dressilk, which is ~20 times cheaper than Suprathel, remains a good option for the treatment of partial thickness burns.

A Human Cellular Model for Colorectal Anastomotic Repair: The Effect of Localization and Transforming Growth Factor-β1 Treatment on Collagen Deposition and Biomarkers

Anastomotic leakage (AL) is a devastating complication after colorectal surgery, possibly due to the loss of stabilizing collagen fibers in the submucosa. Our aim was to assess the formation of collagen in the colon versus the rectum with or without transforming growth factor (TGF)-β1 exposure in a human cellular model of colorectal repair. Primary fibroblasts were isolated by an explant procedure from clinically resected tissue rings during anastomosis construction in 19 consecutive colorectal patients who underwent laparoscopy. The cells, identified as fibroblasts by morphologic characteristics and flow cytometry analysis (CD90⁺), were cultured for 8 days and in 12 patients in the presence of 1 ng/mL TGF-β1. Total collagen deposition was measured colorimetrically after Sirius red staining of fixed cell layers, and type I, III, and VI collagen biosynthesis and degradation were specifically determined by the biomarkers PINP, PRO-C3, PRO-C6, and C3M in conditioned media by competitive enzyme-linked immunosorbent assays. Total collagen deposition by fibroblasts from the colon and rectum did not significantly differ. TGF-β1 treatment increased PINP, PRO-C6, and total collagen deposition. Mechanistically, TGF-β1 treatment increased COL1A1 and ACTA2 (encoding α-smooth muscle actin), and decreased COL6A1 and MMP2 mRNA levels in colorectal fibroblasts. In conclusion, we found no effect of anatomic localization on collagen production by fibroblasts derived from the large intestine. TGF-β1 represents a potential therapeutic agent for the prevention of AL by increasing type I collagen synthesis and collagen deposition.

Progress of esophageal stricture prevention after endoscopic submucosal dissection by regenerative medicine and tissue engineering

Endoscopic submucosal dissection (ESD) has been widely accepted as an effective treatment for early esophageal cancer. However, post-ESD esophageal stricture remains a thorny issue. We herein review many strategies for preventing post-ESD esophageal stricture, as well as discuss their strengths and weaknesses. These strategies include pharmacological prophylaxis, esophageal stent and tissue engineering and regenerative medicine treatment. In this review, we summarize these studies and discuss the underlying progress and future directions of tissue engineering and regenerative medicine treatment.

The inhibitory effects of isolated constituents from Plantago major subsp. major L. on collagenase, elastase and hyaluronidase enzymes: Potential wound healer

Plantago major L. which is a medicinal plant with important biological activities, commonly used as traditional medicine. Potential inhibitory activities of the aqueous extract and three isolated constituents calceorioside B (1), homoplantaginin (hispidulin-7-O-glucoside) (2) and plantamajoside (3) from the aerial parts of Plantago major subsp. major L. (Plantaginaceae) have been tested against hyaluronidase, collagenase, and elastase, which play critical roles in wound pathogenesis. Even though, the extract (27.04%), and among the isolated compounds, calceorioside B (41.16%) exerted significant inhibition against hyaluronidase enzyme, homoplantaginin and plantamajoside were found to be inactive. Similar results were obtained from collagenase enzyme inhibition test. The extract (21.92%) and calceorioside B (28.34%) also caused notable inhibition in this test. However, no remarkable inhibition was observed in the presence of elastase enzyme. The experimental data revealed that P. major subsp. major displayed remarkable inhibitory activity against hyaluronidase and collagenase enzymes. In vitro enzyme activity of P. major subsp. major is reported for the first time in the current study.

Uncontrolled gelatin degradation in non-healing chronic wounds

OBJECTIVE

To compare matrix metalloproteinase (MMP)-9 and the antiproteinase tissue inhibitor of metalloproteinases (TIMP)-1 in wound fluids and sera from patients with chronic non-healing or acute healing wounds. In addition, the functional consequences on MMP-9 activity and general gelatinase activity were assessed.

METHOD

In this observational study, samples were collected from patients with venous leg ulcers (VLUs), patients with type 2 diabetes with neuropathic foot ulcers (DFUs), and from another cohort of VLU patients with sterile split-thickness skin graft donor sites after autologous skin grafting, serving as healing control wounds. MMP-9 and TIMP-1 concentrations were determined by enzyme-linked immunosorbent assays. MMP-9 and gelatinase activities were determined in wound fluids in subsets of the patients.

RESULTS

A total of 24 patients took part in the study. No significant differences in MMP-9 wound fluid levels were found among the three groups. TIMP-1 levels were markedly and significantly lower in the two chronic wound groups resulting in a severely unbalanced MMP-9/TIMP-1 ratio, especially notable in the VLU group and possibly in the elevated endogenous MMP-9 activity (p<0.01) compared with the acute wound fluids. At least 20% of the chronic wound fluids displayed atypical patterns on gelatin zymography and showed high general gelatinase activity that was not inhibited by either TIMP-1 or by a gelatinase inhibitor (AG3340). MMP-9 levels were higher in the sera of the patients with type 2 diabetes.

CONCLUSION

We hypothesise that non-MMP proteinases contribute to matrix destruction in a significant number of chronic wounds. Blocking the excessive MMP-9 activity may be insufficient to normalise wound healing. The reasons and effects of the very low TIMP-1 levels in chronic wounds need further clarification.

The significance of collagen dressings in wound management: a review

Clinical experience and research has improved our understanding of wound healing which, in turn, has enabled health professionals to aid wound healing and manufacturers to develop modern wound dressings. The significant role of collagen in wound healing has led to the development of numerous products on the basis of this biological material. The main focus of this review is to provide a critical appraisal of publications about collagen and acellular collagen dressings with a fleece-like or spongy structure. It is intended for clinicians and researchers, and aims to keep them up-to-date in the complex field of interactive, collagen-based wound dressings, including their manufacture, combination possibilities, mechanisms of action, performance in the promotion of wound healing and indications. Despite the small number of clinical studies, the importance of acellular collagen dressings with a fleece- or sponge-like structure is likely to increase in the future. As there is no ideal wound dressing, the knowledge attained is meant to support health professionals in selecting the right product, and pave the way for new applications and clinical studies.

Scarless wound healing: From development to senescence

An essential element of tissue homeostasis is the response to injuries, cutaneous wound healing being the most studied example. In the adults, wound healing aims at quickly restoring the barrier function of the skin, leading however to scar, a dysfunctional fibrotic tissue. On the other hand, in fetuses a scarless tissue regeneration takes place. During ageing, the wound healing capacity declines; however, in the absence of comorbidities a higher quality in tissue repair is observed. Senescent cells have been found to accumulate in chronic unhealed wounds, but more recent reports indicate that their transient presence may be beneficial for tissue repair. In this review data on skin wound healing and scarring are presented, covering the whole spectrum from early embryonic development to adulthood, and furthermore until ageing of the organism.

MicroRNA 155 Downregulation by Vitamin C–Loaded Human Serum Albumin Nanoparticles During Cutaneous Wound Healing in Mice

This study focused on potential of vitamin C loaded human serum albumin (HSA) nanoparticles for treatment of wound. Nanocarrier were prepared and assessed for their effect on growth of 3T3 fibroblast cells, cell migration, wound healing rate and expression of miR-155, TGF-β1 and SMAD 1,2 genes. Wound healing assay was done and wounds were treated with vitamin C loaded HSA nanoparticles. Nanoparticles were prepared with size and zeta potential of 180±6 and -29 mV, respectively. Vitamin C loaded HSA nanoparticles showed controlled release of vitamin C into the buffer solution. Also, yield and encapsulation efficacy of loaded nanoparticles were obtained as 70.6 and 52.1 %, respectively. MTT results showed that the growth of 3T3 fibroblast cells was promoted in culture medium with 20 µg/ml of vitamin C loaded HSA nanoparticles. Cell migration assay indicated the positive effect of loaded nanoparticles on wound healing. The in-vivo results showed that the rate of wound healing was increased after treatment with 20 µg/ml of vitamin C loaded HSA nanoparticles. The wounds were healed faster when treated with vitamin C loaded HSA nanoparticles in comparison with control group. The expression of miR-155 was downregulated after treatment. Furthermore, expression of TGF-β1 and SMAD 1,2 were increased while the wounds were treated with these nanoparticles. In conclusion, these results showed for the first time that wounds were healed after treatment with albumin nanocarrier loaded with vitamin C. This nanocarrier changed expression of miR-155 and TGF-β1 towards faster healing of wounds.

Vasculogenic Chronic Ulcer: Tissue Regeneration with an Innovative Dermal Substitute

The healing of venous and arterial ulcers is slow, and in some cases, they may not heal at all. This study aims to demonstrate the clinical advantage of Nevelia®, an innovative collagen dermal template substitute (DS) in venous and arterial chronic ulcers treatment. 35 patients affected by chronic vascular ulcers with a mean area of 35.1 ± 31.8 cm2 were treated with DS followed by autologous dermal epidermal graft (DEG). Follow-up was performed at 7-14-21 and 28 days after DS implant and 7-14-21 and 28 days after DEG. At 28 days after DEG, the mean values of Manchester Scar Scale was of 1.8 ± 0.7 for skin color, 1.6 ± 0.7 for skin contour, 1.7 ± 0.7 for distortion, and 1.7 ± 0.7 for skin texture, whereas skin was matte in 27 patients (77%) and shiny in the remaining eight cases (23%). Histological findings correlate with the clinical result showing a regenerated skin with reactive epidermal hyperplasia and dermal granulation tissue after two weeks (T1), and after three weeks (T2) a re-epithelialization and a formed new tissue architecture analogue to normal skin physiology. These data suggest that Nevelia® could be useful to treat chronic venous and arterial ulcers.

Acellular Fish Skin Grafts and Pig Urinary Bladder Matrix Assessed in the Collagen-Induced Arthritis Mouse Model

It is vital that cellular- and tissue-based products (CTPs) used for wound treatment do not provoke autoimmunity. In this study, the immunogenic response to extracts of 2 CTPs of piscine and porcine origin was assessed in the collagen-induced arthritis model. Male DBA/1J mice were divided into 4 groups, each composed of 7 to 9 animals. Each animal was injected with one of following to assess their immune responses: (1) bovine type II collagen (100 µg) in Freund's adjuvant, (2) extract of piscine skin (100 µg) in Freund's adjuvant, (3) extract of porcine urinary bladder matrix (100 µg) in Freund's adjuvant, or (4) Freund's adjuvant alone (control) at the beginning of the experiment and 3 weeks later. Clinical signs of arthritis were assessed from week 5 onwards, and anti-type II and anti-type I collagen antibody immunoglobulin G (IgG) serum levels were measured before injections and 8 weeks after exposure using enzyme-linked immunosorbent assays. Only the mice exposed to bovine type II collagen developed clinical arthritis accompanied by very high anti-type II collagen IgG serum levels. Anti-type II collagen IgG serum levels were also detected in the porcine group but were undetectable in the piscine skin and control groups after 8 weeks. There were no significant differences in anti-type I collagen IgG serum levels among the groups. The results showed that piscine skin did not provoke systemic autoimmunity against type II collagens in DBA/1J mice.

Understanding the Impact of Preservation Methods on the Integrity and Functionality of Placental Allografts

INTRODUCTION

Human placental membranes (hPMs) have a long history in treating burns and wounds. The composition of hPMs includes structural matrix, growth factors, and neonatal cells, all of which contribute to their regenerative potential. However, most hPM products are devitalized after dehydration and irradiation. We compared the functionality of single-layer viable cryopreserved human amniotic membrane (vCHAM) with multilayer devitalized dehydrated human amnion/chorion membrane (dHACM) in wound-relevant models to determine the effect of different processing methods on hPMs.

METHODS

Viable cryopreserved human amniotic membrane and dHACM were compared with fresh hPM for structural integrity and viability. Viable cell persistence in vCHAM over time was evaluated in vitro and in vivo in a diabetic chronic wound mouse model. Proliferation of cells within fresh hPM and vCHAM was evaluated with bromodeoxyuridine and Ki-67 staining, and proliferation of isolated cells in culture was evaluated. Growth factor release over time and in vitro response to chronic wound stimuli (tumor necrosis factor α, lipopolysaccharide, and hypoxia) were used to compare the functionality of vCHAM and dHACM.

RESULTS

The structure and thickness of fresh hPM were retained in vCHAM but were compromised in dHACM. Similar to fresh hPM, vCHAM contained viable cells, whereas dHACM did not. Cells in vCHAM remained viable after 4 and 7 days in culture and in an in vitro chronic wound environment and after 4 and 8 days in vivo after application to a mouse chronic wound. Staining for bromodeoxyuridine and Ki-67 did not reveal proliferative cells within fresh hPM and vCHAM. However, isolated cells proliferated in culture. Viable cryopreserved human amniotic membrane increased platelet-derived growth factor BB, hepatocyte growth factor, and epidermal growth factor levels over time and responded to chronic wound stimuli in vitro by significantly increasing levels of vascular endothelial growth factor and prostaglandin E2. Dehydrated human amnion/chorion membrane showed no significant accumulation of growth factors and did not respond to chronic wound stimuli.

CONCLUSIONS

These results indicate that vCHAM retains intact, native matrix, and viable, active cells and responds to chronic wound stimuli in vitro. The inclusion of multiple layers of hPM does not compensate for structural degradation and loss of viability caused by dehydration as evidenced by a lack of functional response by dHACM. The clinical significance of these results remains to be answered.

Effectiveness of extracellular matrix dressings and topical agents in the treatment of leg ulcers: a systematic review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this review is to synthesize the best available evidence on the effectiveness of the application of extracellular matrix products as dressings or in topical form as treatment for venous, arterial and mixed leg ulcers, compared to compression therapy alone, any type of dressings and topical agents, or placebos in adults over 18 years in any care setting.

Photobiomodulation alters matrix protein activity in stressed fibroblast cells in vitro

A balance is maintained between matrix synthesis and degradation, and a prolonged increase in matrix metalloproteinases (MMPs) affects healing. Photobiomodulation (PBM) speeds up healing and alters wound environment. The study aimed to determine changes in protein and gene expression of collagen type 1 (Col-I), MMP-3 and -9 and TIMP-1 in fibroblasts irradiated at 660 or 830 nm. Commercially purchased human skin fibroblast cells were modeled into five groups namely, normal, normal wounded, diabetic wounded, hypoxic wounded and diabetic hypoxic wounded. Control cells were sham irradiated. Laser irradiation was conducted at 660 or 830 nm (108/or 94 mW, 9.1 cm² , 420/or 483 s) with 5 J/cm² . Forty-eight hours post-irradiation, protein expression of TIMP-1, MMP-3, -9 and Col-I was determined by flow cytometry and immunofluorescence, and gene expression by real-time RT-PCR. There was an increase in TIMP-1 and Col-I, and a decrease in MMP-3 and -9, as well as an alteration in mRNA expression of MMP3, MMP9, TIMP1 and COL1A1 in irradiated cells. Due to the responsiveness of the diabetic hypoxic wounded model, the findings propose this model as appropriate for wound healing studies and suggest that PBM promotes the remodeling phase of wound healing by decreasing matrix degradation and upregulating synthesis.

Adipose Tissue-Derived Stromal Cells for Wound Healing

Skin as the outer layer covers the body. Wounds can affect this vital organ negatively and disrupt its functions. Wound healing as a biological process is initiated immediately after an injury. This process consists of three stages: inflammation, proliferation, remodeling. Generally, these three stages occur continuously and timely. However, some factors such as infection, obesity and diabetes mellitus can interfere with these stages and impede the normal healing process which results in chronic wounds. Financial burden on both patients and health care systems, negative biologic effect on the patient's general health status and reduction in quality of life are a number of issues which make chronic wounds as a considerable challenge. During recent years, along with advances in the biomedical sciences, various surgical and non-surgical therapeutic methods have been suggested. All of these suggested treatments have their own advantages and disadvantages. Recently, cell-based therapies and regenerative medicine represent promising approaches to wound healing. Accordingly, several types of mesenchymal stem cells have been used in both preclinical and clinical settings for the treatment of wounds. Adipose-derived stromal cells are a cost-effective source of mesenchymal stem cells in wound management which can be easily harvest from adipose tissues through the less invasive processes with high yield rates. In addition, their ability to secrete multiple cytokines and growth factors, and differentiation into skin cells make them an ideal cell type to use in wound treatment. This is a concise overview on the application of adipose-derived stromal cells in wound healing and their role in the treatment of chronic wounds.

Oxidized Regenerated Cellulose/Collagen Dressings: Review of Evidence and Recommendations

OBJECTIVE

Healthcare systems are being challenged to manage increasing numbers of nonhealing wounds. Wound dressings are one of the first lines of defense in wound management, and numerous options exist. The oxidized regenerated cellulose (ORC)/collagen dressing may offer healthcare providers a robust and cost-effective tool for use in a variety of wounds.

DESIGN

A multidisciplinary panel meeting was convened to discuss the use of ORC/collagen dressings in wound care and provide practice recommendations. A literature search was conducted to provide a brief review of the peer-reviewed studies published between January 2000 and March 2016 to inform the meeting.

SETTING

A 2-day panel meeting convened in February 2017.

PARTICIPANTS

Healthcare providers with experience using ORC/collagen dressings. This multidisciplinary panel of 15 experts in wound healing included podiatrists, wound care specialists (doctors, certified wound care nurses, and research scientists), and an orthopedist.

RESULTS

The literature search identified 58 articles, a majority of which were low levels of evidence (69.3% were level 3 or lower). Panel members identified wound types, such as abrasions, burns, stalled wounds, diabetic foot ulcers, and pressure injuries, where ORC/collagen dressing use could be beneficial. Panel members then provided recommendations and technical pearls for the use of ORC/collagen dressings in practice. Barriers to ORC/collagen dressing use were discussed, and potential resolutions were offered.

CONCLUSIONS

An ORC/collagen dressing can be a critical tool for clinicians to help manage a variety of wounds. Clinical and economic studies comparing standard-of-care dressings and plain collagen dressings to ORC/collagen dressings are needed.

Redox Signaling in Diabetic Wound Healing Regulates Extracellular Matrix Deposition

SIGNIFICANCE

Impaired wound healing is a major complication of diabetes, and can lead to development of chronic foot ulcers in a significant number of patients. Despite the danger posed by poor healing, very few specific therapies exist, leaving patients at risk of hospitalization, amputation, and further decline in overall health. Recent Advances: Redox signaling is a key regulator of wound healing, especially through its influence on the extracellular matrix (ECM). Normal redox signaling is disrupted in diabetes leading to several pathological mechanisms that alter the balance between reactive oxygen species (ROS) generation and scavenging. Importantly, pathological oxidative stress can alter ECM structure and function.

CRITICAL ISSUES

There is limited understanding of the specific role of altered redox signaling in the diabetic wound, although there is evidence that ROS are involved in the underlying pathology.

FUTURE DIRECTIONS

Preclinical studies of antioxidant-based therapies for diabetic wound healing have yielded promising results. Redox-based therapeutics constitute a novel approach for the treatment of wounds in diabetes patients that deserve further investigation. Antioxid. Redox Signal. 27, 823-838.

Opposing effects of in vitro differentiated macrophages sub-type on epithelial wound healing

Inappropriate repair responses to pulmonary epithelial injury have been linked to perturbation of epithelial barrier function and airway remodelling in a number of respiratory diseases, including chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. We developed an in vitro mechanical scratch injury model in air-liquid interface differentiated primary human small airway epithelial cells that recapitulates many of the characteristics observed during epithelial wound injury in both human tissue and small animal models. Wound closure was initially associated with de-differentiation of the differentiated apical cells and rapid migration into the wound site, followed by proliferation of apical cells behind the wound edge, together with increases in FAK expression, fibronectin and reduction in PAI-1 which collectively facilitate cell motility and extracellular matrix deposition. Macrophages are intimately involved in wound repair so we sought to investigate the role of macrophage sub-types on this process in a novel primary human co-culture model. M₁ macrophages promoted FAK expression and both M₁ and M₂ macrophages promoted epithelial de-differentiation. Interestingly, M_2a macrophages inhibited both proliferation and fibronectin expression, possibly via the retinoic acid pathway, whereas M_2b and M_2c macrophages prevented fibronectin deposition, possibly via MMP expression. Collectively these data highlight the complex nature of epithelial wound closure, the differential impact of macrophage sub-types on this process, and the heterogenic and non-delineated function of these macrophages.

Extracellular matrix remodeling and matrix metalloproteinases (ajMMP-2 like and ajMMP-16 like) characterization during intestine regeneration of sea cucumber Apostichopus japonicus

Remodeling of extracellular matrix (ECM) regulated by matrix metalloproteinases (MMPs) is essential for tissue regeneration. In the present study, we used immunohistochemistry (IHC) techniques against ECM components to reveal changes of ECM during intestine regeneration of Apostichopus japonicus. The expression of collagen I and laminin reduced apparently from the eviscerated intestine, while fibronectin exhibited continuous expression in all regeneration stages observed. Meanwhile, we cloned two MMP genes from A. japonicus by RACE PCR. The full-length cDNA of ajMMP-2 like is 2733bp and contains a predicted open reading frame (ORF) of 1716bp encoding 572 amino acids. The full-length cDNA of ajMMP-16 like is 2705bp and contains an ORF of 1452bp encoding 484 amino acids. The predicted protein sequences of each MMP contain two conserved domains, ZnMc_MMP and HX. Homology and phylogenetic analysis revealed that ajMMP-2 like and ajMMP-16 like share high sequence similarity with MMP-2 and MMP-16 from Strongylocentrotus purpuratus, respectively. Then we investigated spatio-temporal expression of ajMMP-2 like and ajMMP-16 like during different regeneration stages by qRT-PCR and IHC. The expression pattern of them showed a roughly opposite trend from that of ECM components. According to our results, a fibronectin-dominate temporary matrix is created in intestine regeneration, and it might provide structural integrity for matrix and promote cell movement. We also hypothesize that ajMMP-2 like and ajMMP-16 like could accelerate cell migration and regulate interaction between ECM components and growth factors. This work provides new evidence of ECM and MMPs involvement in sea cucumber regeneration.

The Effect of a Synthetic Heparan Sulfate on the Healing of Colonic Anastomoses

Background

The mimetic compound OTR4120 may replace endogenous-degraded heparan sulfates that normally maintain the bioactivity of growth factors that are important for tissue repair. Herein, we investigated the effect of OTR4120 on the healing of normal colonic anastomoses.

Methods

We evaluated the following two treatment groups of male Sprague Dawley rats (220–256 g): control-treated colonic anastomoses (n = 25) and OTR4120-treated colonic anastomoses (n = 25). We resected 10 mm of the left colon and then applied either saline alone (control) or OTR4120 (100 μg/mL) in saline to the colonic ends before an end-to-end single-layer anastomosis was constructed and again on the anastomosis before the abdomen and skin were closed.

Results

On postoperative day 3, the anastomotic breaking strengths were 1.47 ± 0.32 N (mean ± SD) in the control group and 1.52 ± 0.27 N in the OTR4120-treated animals (P = 0.622). We also found that the hydroxyproline concentration (indicator of collagen) in the anastomotic wounds did not differ (P = 0.571) between the two groups.

Conclusions

Our data demonstrate that a single local application of OTR4120 intraoperatively did not increase the biomechanical strength of colonic anastomoses at the critical postoperative day 3 when the anastomoses are the weakest.

Fabrication of Hybrid Collagen Aerogels Reinforced with Wheat Grass Bioactives as Instructive Scaffolds for Collagen Turnover and Angiogenesis for Wound Healing Applications

The present study illustrates the progress of the wheat grass bioactive-reinforced collagen-based aerogel system as an instructive scaffold for collagen turnover and angiogenesis for wound healing applications. The reinforcement of wheat grass bioactives in collagen resulted in the design and development of aerogels with enhanced physicochemical and biomechanical properties due to the intermolecular interaction between the active growth factors of wheat grass and collagen fibril. Differential scanning calorimetry analysis revealed an enhanced denaturation temperature when compared to those of native collagen aerogels. Fourier transform infrared spectroscopy analysis confirmed that the reinforcement of bioactives in the wheat grass did not affect the structural integrity of the collagen molecule. Additionally, the reinforced biomaterial with a systematic absorptive morphology resulted in a three-dimensional (3D) sponge-like aerogel exhibiting a potent highly oriented 3D structural assembly that showed increased water retention ability and substance permeability that would enable the passage of nutrients and gaseous components for cellular growth. Furthermore, the cumulative effect of the growth factors in wheat grass and the collagen molecule augments the angiogenic ability and collagen production of the aerogel by restoration of the damaged tissue thereby making it a potential 3D wound dressing scaffold. The results were confirmed by in vivo wound healing assays. This study shows the possibility for progress of a biocompatible, biodegradable, and nonadhesive nutraceutical-reinforced collagen aerogel as an instructive scaffold with good antimicrobial properties for collagen turnover and angiogenic response for wound healing applications.

The role of biophysical properties of provisional matrix proteins in wound repair

Wound healing is a complex, dynamic process required for maintaining homeostasis in an organism. Along with being controlled biochemically, wound healing is also controlled through the transduction of biophysical stimuli through cell interactions with the extracellular matrix (ECM). This review provides an overview of the ECM's role in the wound healing process and subsequently expands on the variety of roles biophysical phenomenon play.

Integrin-mediated regulation of epidermal wound functions

During cutaneous wound healing, keratinocyte proliferation and migration are critical for re-epithelialization. In addition the epidermis secretes growth factors, cytokines, proteases, and matricellular proteins into the wound microenvironment that modify the extracellular matrix and stimulate other wound cells that control the inflammatory response, promote angiogenesis and facilitate tissue contraction and remodeling. Wound keratinocytes express at least seven different integrins-the major cell adhesion receptors for the extracellular matrix-that collectively control essential cell-autonomous functions to ensure proper re-epithelialization, including migration, proliferation, survival and basement membrane assembly. Moreover, it has become evident in recent years that some integrins can regulate paracrine signals from wound epidermis that stimulate other wound cells involved in angiogenesis, contraction and inflammation. Importantly, it is likely that abnormal integrin expression or function in the epidermis contributes to wound pathologies such as over-exuberant healing (e.g., hypertrophic scar formation) or diminished healing (e.g., chronic wounds). In this review, we discuss current knowledge of integrin function in the epidermis, which implicates them as attractive therapeutic targets to promote wound healing or treat wound pathologies. We also discuss challenges that arise from the complex roles that multiple integrins play in wound epidermis, which may be regulated through extracellular matrix remodeling that determines ligand availability. Indeed, understanding how different integrin functions are temporally coordinated in wound epidermis and which integrin functions go awry in pathological wounds, will be important to determine how best to target them clinically to achieve maximum therapeutic benefit. Graphical abstract In addition to their well-characterized roles in keratinocyte adhesion, migration and wound re-epithelialization, epidermal integrins play important roles in modifying the wound microenvironment by regulating the expression and secretion of growth factors, extracellular proteases, and matricellular proteins that stimulate other wound cells, including vascular endothelial cells and fibroblasts/myofibroblasts.

Therapeutic Applications of Extracellular Matrix

Chronic and hard-to-heal wounds are a tremendous burden on our healthcare system and impair the quality of life for millions of people. An emerging focus of regenerative medicine is the development of natural biomaterials that can stimulate tissue formation or repair by recreating the functional and structural properties of proteins and polysaccharides found within the extracellular matrix (ECM). Promising new developments include the fabrication of novel ECM-based biologics to selectively deliver drugs or growth factors to wounds; new classes of bioactive tissue sealants, scaffolds, and hydrogels; as well as inductive wound dressings derived from decellularized tissues. The advances highlighted in this forum issue provide an exciting glimpse into the growing potential of ECM-based wound therapeutics.

Extracellular Matrix-Inspired Growth Factor Delivery Systems for Skin Wound Healing

Significance: Growth factors are very promising molecules for the treatment of skin wounds. However, their translation to clinical use has been seriously limited, facing issues related to safety and cost-effectiveness. These problems may derive from the fact that growth factors are used at vastly supra-physiological levels without optimized delivery systems. Recent Advances: The extracellular matrix (ECM) plays a fundamental role in coordinating growth factor signaling. Therefore, understanding the mechanisms by which the ECM modulates growth factor activity is key for designing efficient growth factor-based therapies. Recently, several growth factor-binding domains have been discovered within various ECM proteins, and growth factor delivery systems integrating these ECM growth factor-binding domains showed promising results in animal models of skin wound healing. Moreover, a novel strategy consisting of engineering growth factors to target endogenous ECM could substantially enhance their efficacy, even when used at low doses. Critical Issues: Optimal delivery of growth factors often requires complex engineered biomaterial matrices, which can face regulatory issues for clinical translation. To simplify delivery systems and render strategies more applicable, growth factors can be engineered to optimally function with clinically approved biomaterials or with endogenous ECM present at the delivery site. Future Directions: Further development and clinical trials will reveal whether growth factor-based therapies can be used as main therapeutic approaches for skin wound healing. The future impact of these therapies will depend on our capacity to deliver growth factors more precisely, to improve efficacy, safety, and cost-effectiveness.

Diverse Roles of Heparan Sulfate and Heparin in Wound Repair

Heparan sulfate (HS) and heparin (Hp) are linear polysaccharide chains composed of repeating (1→4) linked pyrosulfuric acid and 2-amino-2-deoxy glucopyranose (glucosamine) residue. Mentioned glycosaminoglycans chains are covalently O-linked to serine residues within the core proteins creating heparan sulfate/heparin proteoglycans (HSPG). The latter ones participate in many physiological and pathological phenomena impacting both the plethora of ligands such as cytokines, growth factors, and adhesion molecules and the variety of the ECM constituents. Moreover, HS/Hp determine the effective wound healing process. Initial growth of HS and Hp amount is pivotal during the early phase of tissue repair; however heparan sulfate and heparin also participate in further stages of tissue regeneration.

Using Copper to Improve the Well-Being of the Skin

Copper has two key properties that are being exploited in consumer and medical device products in the last decade. On the one hand, copper has potent biocidal properties. On the other hand, copper is involved in numerous physiological and metabolic processes critical for the appropriate functioning of almost all tissues in the human body. In the skin, copper is involved in the synthesis and stabilization of extracellular matrix skin proteins and angiogenesis. This manuscript reviews clinical studies that show that the use of textile consumer and medical device products, embedded with microscopic copper oxide particles, improve the well-being of the skin. These include studies showing a) cure of athlete’s foot infections and improvement in skin elasticity, especially important for individuals suffering from diabetes; b) reduction of facial fine line and wrinkles; and c) enhancement of wound healing; by copper oxide embedded socks, pillowcases and wound dressings, respectively. The manuscript also reviews and discusses the mechanisms by which the presence of copper in these products improves skin well-being.

Provisional Matrix Deposition in Hemostasis and Venous Insufficiency: Tissue Preconditioning for Nonhealing Venous Ulcers

Significance: Chronic wounds represent a major burden on global healthcare systems and reduce the quality of life of those affected. Significant advances have been made in our understanding of the biochemistry of wound healing progression. However, knowledge regarding the specific molecular processes influencing chronic wound formation and persistence remains limited. Recent Advances: Generally, healing of acute wounds begins with hemostasis and the deposition of a plasma-derived provisional matrix into the wound. The deposition of plasma matrix proteins is known to occur around the microvasculature of the lower limb as a result of venous insufficiency. This appears to alter limb cutaneous tissue physiology and consequently drives the tissue into a 'preconditioned' state that negatively influences the response to wounding. Critical Issues: Processes, such as oxygen and nutrient suppression, edema, inflammatory cell trapping/extravasation, diffuse inflammation, and tissue necrosis are thought to contribute to the advent of a chronic wound. Healing of the wound then becomes difficult in the context of an internally injured limb. Thus, interventions and therapies for promoting healing of the limb is a growing area of interest. For venous ulcers, treatment using compression bandaging encourages venous return and improves healing processes within the limb, critically however, once treatment concludes ulcers often reoccur. Future Directions: Improved understanding of the composition and role of pericapillary matrix deposits in facilitating internal limb injury and subsequent development of chronic wounds will be critical for informing and enhancing current best practice therapies and preventative action in the wound care field.

Comparison of cryopreserved amniotic membrane and umbilical cord tissue with dehydrated amniotic membrane/chorion tissue

OBJECTIVE

To evaluate how the different processing methods cryopreservation and dehydration affect the structural integrity and biological composition of key signalling molecules within amniotic membrane and umbilical cord tissues.

METHOD

We directly compared cryopreserved amniotic membrane (AM) and umbilical cord (UC) tissues with dehydrated amniotic membrane/chorion (dHACM) tissue using biochemical and functional assays including histological and histochemical staining, BCA, agarose gel electrophoresis, western blot, ELISA, and proliferation and cell death assays.

RESULTS

Cryopreservation retains the native architecture of the AM/UC extracellular matrix and maintains the quantity and activity of key biological signals present in fresh AM/UC, including high molecular weight hyaluronic acid, heavy chain-HA complex, and pentraxin 3. In contrast, dehydrated tissues were structurally compromised and almost completely lacked these crucial components.

CONCLUSION

The results presented here indicate that cryopreservation better preserves the structural and biological signaling molecules of foetal tissues.

An algorithmic approach for managing orthopaedic surgical wounds of the foot and ankle

BACKGROUND

Wound breakdown after orthopaedic foot and ankle surgery may necessitate secondary soft tissue coverage. The foot and ankle region is challenging to reconstruct for orthopaedic and plastic surgeons owing to its complex bony anatomy and unique functional demands. Therefore, identifying strategies for plastic surgery of these wounds may help guide surgeons in defining the best treatment plan.

QUESTIONS/PURPOSES

We evaluated our current algorithmic approach for managing orthopaedic surgical wounds of the foot and ankle with respect to whether (1) prophylactic or simultaneous soft tissue coverage affected wound-healing complications (secondary plastic surgery, orthopaedic hardware removal, malunion, further orthopaedic surgery, ultimate failure) and (2) postoperative referral for soft tissue management was associated with wound location, size, and orthopaedic procedure.

METHODS

We retrospectively reviewed 112 patients who underwent elective orthopaedic foot or ankle surgery and required concomitant plastic surgery at our institution. Study end points included secondary plastic surgery procedures, hardware removal for infection, foot or ankle malunion, further orthopaedic surgery, and wound-healing failure as defined by a chronic nonhealing wound or need for amputation. Minimum followup was 0.6 months (mean, 24.9 months; range, 0.6-197 months). Four patients were lost to complete followup. We developed an algorithm that centers on two critical points of care: preoperative evaluation by the orthopaedic surgeon and evaluation and treatment by the plastic surgeon after referral.

RESULTS

Compared with postoperative intervention, prophylactic or simultaneous soft tissue coverage did not lead to differences in frequency of secondary plastic surgery procedures (p = 0.55), hardware removal procedures (p = 0.13), malunions (p = 0.47), further orthopaedic surgery (p = 0.48), and ultimate failure (p = 0.27). Patients referred postoperatively for soft tissue management most frequently had dorsal ankle wounds (p < 0.001) of smaller size (p = 0.03), most commonly associated with total ankle arthroplasty (p = 0.004).

CONCLUSIONS

Using our algorithmic approach, prophylactic or simultaneous soft tissue coverage did not improve the study end points. In addition, unexpected postoperative wound breakdown necessitating a plastic surgery consultation most commonly occurred on the dorsal ankle after total ankle arthroplasty. Our algorithm facilitates early identification of skin instability and enables prompt soft tissue coverage before or concurrently with orthopaedic procedures. The effect of prophylactic or simultaneous soft tissue coverage on postoperative wound healing requires further investigation.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Instructions for Authors for a complete description of levels of evidence.