Effect of Oxidized Regenerated Cellulose/Collagen Matrix on Proteases in Wound Exudate of Patients With Diabetic Foot Ulcers

Extracellular matrix-inspired biomaterials for wound healing

Diabetic foot ulcers (DFU) are a debilitating and life-threatening complication of Diabetes Mellitus. Ulceration develops from a combination of associated diabetic complications, including neuropathy, circulatory dysfunction, and repetitive trauma, and they affect approximately 19-34% of patients as a result. The severity and chronic nature of diabetic foot ulcers stems from the disruption to normal wound healing, as a result of the molecular mechanisms which underly diabetic pathophysiology. The current standard-of-care is clinically insufficient to promote healing for many DFU patients, resulting in a high frequency of recurrence and limb amputations. Biomaterial dressings, and in particular those derived from the extracellular matrix (ECM), have emerged as a promising approach for the treatment of DFU. By providing a template for cell infiltration and skin regeneration, ECM-derived biomaterials offer great hope as a treatment for DFU. A range of approaches exist for the development of ECM-derived biomaterials, including the use of purified ECM components, decellularisation and processing of donor/ animal tissues, or the use of in vitro-deposited ECM. This review discusses the development and assessment of ECM-derived biomaterials for the treatment of chronic wounds, as well as the mechanisms of action through which ECM-derived biomaterials stimulate wound healing.

Comparative Effectiveness of Negative Pressure Wound Therapy with and Without Oxidized Regenerated Cellulose/Collagen/Silver-ORC Dressing

Objective: Negative pressure wound therapy (NPWT) and oxidized regenerated cellulose (ORC)/collagen/silver-ORC (OCSO) dressings have individually demonstrated effectiveness in supporting wound healing, but few studies have examined their combined use. This retrospective data analysis compared wound outcomes following outpatient NPWT with and without OCSO dressings. Approach: A search of deidentified records from the U.S. Wound Registry resulted in 485 cases of wounds managed with NPWT with OCSO dressings. A matched cohort of patients who received NPWT without any collagen dressing (n = 485) was created using propensity scoring. For patients in the NPWT + OCSO group, OCSO was applied topically on or after the day of NPWT initiation and stopped on or before the day of NPWT termination. Results: Wounds managed with NPWT + OCSO were significantly more likely to improve and/or heal compared with wounds that received NPWT alone (p = 0.00029). The relative wound area reduction was 40% for patients receiving NPWT + OCSO, compared with 9% for patients receiving only NPWT (p = 0.0099). The median time to achieve 75-100% granulation coverage with no measurable wound depth was shorter by 8 days with NPWT + OCSO in all wound types (p = 0.00034), and by 14 days in surgical wounds (p = 0.0010), than with NPWT alone. Innovation: This is the first study examining the clinical outcomes associated with the integration of NPWT and OCSO dressings compared with the use of NPWT alone. These data support the novel practice of applying NPWT concurrently with OCSO dressings. Conclusion: This retrospective comparative analysis using real-world data demonstrated improved healing outcomes with integrated use of NPWT with OCSO dressings versus NPWT alone.

A Multifunctional Polyethylene Glycol/Triethoxysilane-Modified Polyurethane Foam Dressing with High Absorbency and Antiadhesion Properties Promotes Diabetic Wound Healing

The delayed healing of chronic wounds, such as diabetic foot ulcers (DFUs), is a clinical problem. Few dressings can promote wound healing by satisfying the demands of chronic wound exudate management and tissue granulation. Therefore, the aim of this study was to prepare a high-absorption polyurethane (PU) foam dressing modified by polyethylene glycol (PEG) and triethoxysilane (APTES) to promote wound healing. PEG-modified (PUE) and PEG/APTES-modified (PUESi) dressings were prepared by self-foaming reactions. Gauze and PolyMem were used as controls. Next, Fourier transform-infrared spectroscopy, thermomechanical analyses, scanning electron microscopy and tensile strength, water absorption, anti-protein absorption, surface dryness and biocompatibility tests were performed for in vitro characterization. Wound healing effects were further investigated in nondiabetic (non-DM) and diabetes mellitus (DM) rat models. The PUE and PUESi groups exhibited better physicochemical properties than the gauze and PolyMem groups. Moreover, PUESi dressing showed better anti-adhesion properties and absorption capacity with deformation. Furthermore, the PUESi dressing shortened the inflammatory phase and enhanced collagen deposition in both the non-DM and DM animal models. To conclude, the PUESi dressing not only was fabricated with a simple and effective strategy but also enhanced wound healing via micronegative-pressure generation by its high absorption compacity with deformation.

A Sustainable Solution to Skin Diseases: Ecofriendly Transdermal Patches

Skin is the largest epithelial surface of the human body, with a surface area of 2 m2 for the average adult human. Being an external organ, it is susceptible to more than 3000 potential skin diseases, including injury, inflammation, microbial and viral infections, and skin cancer. Due to its nature, it offers a large accessible site for administrating several medications against these diseases. The dermal and transdermal delivery of such medications are often ensured by utilizing dermal/transdermal patches or microneedles made of biocompatible and biodegradable materials. These tools provide controlled delivery of drugs to the site of action in a rapid and therapeutically effective manner with enhanced diffusivity and minimal side effects. Regrettably, they are usually fabricated using synthetic materials with possible harmful environmental effects. Manufacturing such tools using green synthesis routes and raw materials is hence essential for both ecological and economic sustainability. In this review, natural materials including chitosan/chitin, alginate, keratin, gelatin, cellulose, hyaluronic acid, pectin, and collagen utilized in designing ecofriendly patches will be explored. Their implementation in wound healing, skin cancer, inflammations, and infections will be discussed, and the significance of these studies will be evaluated with future perspectives.

A meta‐analysis examined the effect of oxidised regenerated cellulose/collagen dressing on the management of chronic skin wounds

To assess the impact of oxidised regenerated cellulose/collagen dressing on the management of chronic skin wounds, we conducted a meta-analysis. A thorough review of the literature up to September 2022 revealed that 1521 participants had chronic skin wounds at the start of the investigations; 763 of them used oxidised regenerated cellulose/collagen dressing, while 758 received control. Using dichotomous or contentious methods and a random or fixed-effect model, odds ratios (OR) and mean difference (MD) with 95% confidence intervals (CIs) were estimated to evaluate the impact of oxidised regenerated cellulose/collagen dressing on the management of chronic skin wounds. The oxidised regenerated cellulose/collagen dressing had significantly higher complete wound healing (OR, 1.74; 95% CI, 1.06-2.85; P = .03), higher wound relative reduction percent (MD, 13.50; 95% CI, 2.39-24.61; P = .02), and lower adverse events in wound healing (OR, 0.63; 95% CI, 0.41-0.98; P = .04) compared with control in chronic skin wounds. The oxidised regenerated cellulose/collagen dressing had significantly higher complete wound healing, higher wound relative reduction percent and lower adverse events in wound healing compared with control in chronic skin wounds. The low sample size of 8 out of 10 researches in the meta-analysis and the small number of studies in several comparisons calls for care when analysing the results.

Pullulan-Collagen Hydrogel Wound Dressing Promotes Dermal Remodeling and Wound Healing Compared to Commercially Available Collagen Dressings

Biological scaffolds such as hydrogels provide an ideal, physio‐mimetic of native extracellular matrix (ECM) that can improve wound healing outcomes after cutaneous injury. While most studies have focused on the benefits of hydrogels in accelerating wound healing, there are minimal data directly comparing different hydrogel material compositions. In this study, we utilized a splinted excisional wound model that recapitulates human‐like wound healing in mice and treated wounds with three different collagen hydrogel dressings. We assessed the feasibility of applying each dressing and performed histologic and histopathologic analysis on the explanted scar tissues to assess variations in collagen architecture and alignment, as well as the tissue response. Our data indicate that the material properties of hydrogel dressings can significantly influence healing time, cellular response, and resulting architecture of healed scars. Specifically, our pullulan‐collagen hydrogel dressing accelerated wound closure and promoted healed tissue with less dense, more randomly aligned, and shorter collagen fibres. Further understanding of how hydrogel properties affect the healing and resulting scar architecture of wounds may lead to novel insights and further optimization of the material properties of wound dressings.

Wound fluid sampling methods for proteomic studies: A scoping review

Understanding why some wounds are hard to heal is important for improving care and developing more effective treatments. The method of sample collection used is an integral step in the research process and thus may affect the results obtained. The primary objective of this study was to summarise and map the methods currently used to sample wound fluid for protein profiling and analysis. Eligible studies were those that used a sampling method to collect wound fluid from any human wound for analysis of proteins. A search for eligible studies was performed using MEDLINE, Embase and CINAHL Plus in May 2020. All references were screened for eligibility by one reviewer, followed by discussion and consensus with a second reviewer. Quantitative data were mapped and visualised using appropriate software and summarised via a narrative summary. After screening, 280 studies were included in this review. The most commonly used group of wound fluid collection methods were vacuum, drainage or use of other external devices, with surgical wounds being the most common sample source. Other frequently used collection methods were extraction from absorbent materials, collection beneath an occlusive dressing and direct collection of wound fluid. This scoping review highlights the variety of methods used for wound fluid collection. Many studies had small sample sizes and short sample collection periods; these weaknesses have hampered the discovery and validation of novel biomarkers. Future research should aim to assess the reproducibility and feasibility of sampling and analytical methods for use in larger longitudinal studies.

The Role of Puerarin in Chronic Wounds: A Review of its Mechanism of Action and Potential Novel Applications

Chronic wounds have a high disease burden and significantly influence patient quality of life. The development of chronic wounds is multifactorial and thus adequate management and care is often difficult to achieve. Chronic diseases, malnutrition, smoking, immune dysregulation, and age contribute to chronic wound development. Treatment options include adequately addressing underlying conditions and selecting appropriate topical preparations which enhance and promote healing of different wounds based on an understanding of wound healing pathophysiology. Puerarin, a naturally occurring flavinoid, may offer therapeutic potential for addressing etiologies as well as managing wound beds due to its anti-inflammatory, anti-oxidative, pro-angiogenic, and anesthetic properties.

Efficacy of Oxidized Regenerated Cellulose/Collagen Dressing for Management of Skin Wounds: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of this study was to evaluate the wound healing efficacy of oxidized regenerated cellulose (ORC)/collagen dressing and ORC/collagen/silver-ORC dressings compared to standard of care or control in treatment of chronic skin wounds such as diabetic foot ulcers (DFUs), venous leg ulcers (VLUs), and pressure injuries sore ulcers (PISUs).

METHODS

An electronic search was carried out in four popular databases PubMed, Scopus, Embase, and CENTRAL to identify thirteen included studies, comparing the clinical efficacy of ORC/collagen dressings when compared to control in management of chronic skin wounds, especially DFUs, VLUs, and PISUs, and skin graft donor site wounds.

RESULTS

Consolidated data from thirteen comparative clinical studies undertaken for management of DFUs, VLUs, and PISUs showed favorable outcomes towards use of ORC/collagen compared to other traditional and hydrocolloid foam dressings in terms of wound healing rate (P=0.02) and percentage wound relative reduction (P=0.003). The time taken to achieve complete wound healing in the included studies did not show any statistical significant difference (P=0.24). There was no significant difference in adverse events between ORC/collagen-treated group and comparative group (P=0.19).

CONCLUSION

ORC/collagen wound dressings are beneficial in terms of improved wound healing rate and percentage wound relative reduction compared to already existing traditional standard of care with non-MMP, inhibiting biomaterials such as moistened gauze, autologous growth factors, hydrocolloid foam dressings, or ovine extracellular matrix.

Use of oxidised regenerated cellulose/collagen dressings versus standard of care over multiple wound types: A systematic review and meta-analysis

Oxidised regenerated cellulose (ORC)/collagen dressings help maintain physiologically moist wound environments conducive to wound healing. While evidence supporting ORC/collagen dressing use exists, comprehensive assessment is needed. This systematic review/meta-analysis evaluated the performance of ORC/collagen dressings compared with standard dressings. A systematic literature search was performed using PUBMED, EMBASE, and QUOSA Virtual Library. Published studies and conference abstracts were assessed between 1 January 1996 and 27 July 2020. Comparative studies in English completed by 31 December 2019, with a study population ≥10 were included. Patient demographics, wound healing, and protease concentrations were extracted. A random-effect model was used to assess the effect of ORC/collagen dressings. Twenty studies were included following removal of duplicates and articles not meeting inclusion criteria. A statistically significant effect in favour of ORC/collagen dressings was found for wound closure (P = 0.027) and percent wound area reduction (P = 0.006). Inconclusive evidence or limited reporting prevented assessment of time to complete healing, days of therapy, number of dressing applications, pain, matrix metalloproteinase, elastase, plasmin, and gelatinase concentration. Statistically significant increase in wound closure rates and percent wound area reduction were observed in patients receiving ORC/collagen dressings compared with standard dressings in this systematic review/meta-analysis.

Collagen membranes for skin wound repair: A systematic review

Membranes or skin dressing are common treatments for skin wound injuries, collagen being one the most effective materials for their manufacturing. Many different sources of collagen with diverse methods of extraction and processing have been used, with evidence of positive effects on the stimulation of skin wound healing. In spite of these factors, there is still limited understanding of the interaction between collagen membranes and biological tissues, especially due to the series of different types of collagen origin. In this context, this study aimed to conduct a systematic review of the available literature examining the effect of various collagen membranes for accelerating skin wound healing in experimental animal models and clinical trials. The present review was performed from March to May of 2020 searching in two databases (PubMed and Scopus). The following Medical Subject Headings (MeSH) descriptors were used: "collagen", "dressing", "membranes", "skin" and "wound". After the eligibility assessment, 16 studies were included and analyzed. The studies demonstrated that collagen was obtained predominantly from bovine and porcine sources, by acetic acid and/or enzyme dissolution. Additionally, most of the studies demonstrated that the membranes were processed mainly by freeze-drying or lyophilization methods. All the in vivo and clinical trial studies evidenced positive outcomes in the wound healing process, thus confirming that collagen membranes are one of the most efficient treatment for skin wounds, highlighting the enormous potential of this biomaterial to be used for skin tissue engineering purposes.

Wound Pain and Wound Healing Biomarkers From Wound Exudate: A Scoping Review

PURPOSE

Effective management of wound pain is essential for optimal wound healing. Nevertheless, the outcomes of wound pain interventions are based on subjective measures, which can prove problematic in patients with cognitive impairment. Identification of biomarkers associated with wound pain and wound healing can be used to more objectively estimate wound pain and contribute to the development of precise management options to reduce wound pain and promote wound healing. This scoping review aimed to identify wound pain and wound healing biomarkers from wound exudates and to describe different wound collection methods to identify these biomarkers.

METHODS

We searched the literature (PROSPERO database registration number: CRD42018103843) via a scoping review.

SEARCH STRATEGY

The PubMed database was searched for articles that explored relationships between cutaneous wound pain, wound healing, and biomolecules. Inclusion criteria were articles that reported original data, used adult human samples, and were published in English.

FINDINGS

Twenty-one articles were retrieved: 17 investigated molecules from wound exudate associated with wound healing status, and 4 reported molecules associated with wound pain. The most frequently observed wound pain biomarkers were proinflammatory cytokines; the most frequently observed wound healing biomarkers were proteases including those in the matrix metalloproteinase family. Six wound exudate collection methods were identified to extract potential wound pain and wound healing biomarkers from wound exudate.

IMPLICATIONS

The results can guide future wound exudate research to validate these wound pain and wound healing biomarkers and to develop therapies targeting these biomarkers to reduce wound pain and promote wound healing.

Antibacterial-Integrated Collagen Wound Dressing for Diabetes-Related Foot Ulcers: An Evidence-Based Review of Clinical Studies

Diabetic foot ulcer (DFU) is a chronic wound frequently delayed from severe infection. Wound dressing provides an essential barrier between the ulcer and the external environment. This review aimed to analyse the effectiveness of antibacterial collagen-based dressing for DFU treatment in a clinical setting. An electronic search in four databases, namely, Scopus, PubMed, Ovid MEDLINE(R), and ISI Web of Science, was performed to obtain relevant articles published within the last ten years. The published studies were included if they reported evidence of (1) collagen-based antibacterial dressing or (2) wound healing for diabetic ulcers, and (3) were written in English. Both randomised and non-randomised clinical trials were included. The search for relevant clinical studies (n) identified eight related references discussing the effectiveness of collagen-based antibacterial wound dressings for DFU comprising collagen impregnated with polyhexamethylene biguanide (n = 2), gentamicin (n = 3), combined-cellulose and silver (n = 1), gentian violet/methylene blue mixed (n = 1), and silver (n = 1). The clinical data were limited by small sample sizes and multiple aetiologies of chronic wounds. The evidence was not robust enough for a conclusive statement, although most of the studies reported positive outcomes for the use of collagen dressings loaded with antibacterial properties for DFU wound healing. This study emphasises the importance of having standardised clinical trials, larger sample sizes, and accurate reporting for reliable statistical evidence confirming DFU treatment efficiency.

Cellulose/Collagen Dressings for Diabetic Foot Ulcer: A Review

Diabetic foot ulcer (DFU) is currently a global concern and it requires urgent attention, as the cost allocation by the government for DFU increases every year. This review was performed to provide scientific evidence on the advanced biomaterials that can be utilised as a first-line treatment for DFU patients. Cellulose/collagen dressings have a biological property on non-healing wounds, such as DFU. This review aims to analyse scientific-based evidence of cellulose/collagen dressing for DFU. It has been proven that the healing rate of cellulose/collagen dressing for DFU patients demonstrated a significant improvement in wound closure as compared to current standard or conventional dressings. It has been scientifically proven that cellulose/collagen dressing provides a positive effect on non-healing DFU. There is a high tendency for cellulose/collagen dressing to be used, as it highly promotes angiogenesis with a rapid re-epithelisation rate that has been proven effective in clinical trials.

Bioactive ECM Mimic Hyaluronic Acid Dressing via Sustained Releasing of bFGF for Enhancing Skin Wound Healing

Successful dermal wound regeneration requires the coordination of repair cells and cellular signals with the extracellular matrix (ECM), which serves as an indispensable mechanical and biological supporter for cell functions and communications with varied cytokines during healing processes. Here, we developed an injectable bioactive wound dressing, methacrylated hyaluronic acid (Me-HA)-based hydrogel loading with basic fibroblast growth factor (bFGF), endowing the dressing with the pleiotropic bioactivity to mimic natural ECM. This bFGF@Me-HA dressing was applied to a mouse with full-thickness excisional wounds to investigate its positive roles in wound repair owing to the complementary functions of HA with sustained release of bioactive bFGF. Compared with the single Me-HA and bFGF group, bFGF@Me-HA hydrogel dressings significantly enhanced wound healing with accelerated re-epithelialization, granulation formation, collagen, deposition and skin appendage regeneration. Further investigations showed significantly promoted cell proliferation and vascularization in the bFGF@Me-HA group, which was mediated by the upregulation of transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF) expressions. In conclusion, this bFGF@Me-HA hydrogel realized the optimization of simple ECM mimic dressing via introducing the bioactive effector, bFGF, and has the potential to be widely used as an effective bioactive ECM-based wound dressing in future wound care.

Dressings, Topical Therapy, and Negative Pressure Wound Therapy

The current epidemic of diabetes has created a high demand for skilled wound-care professionals. Wound-care treatment begins with an appreciation of the cause of the ulceration and an adherence to the fundamental pillars of wound care. Also critical in the wound management paradigm is the optimization of the wound environment to facilitate the progression through the stages of healing. This can be accomplished through the use of different topical therapies and wound dressings to generate a favorable condition conducive to healing. This article summarizes the updated literature and best practices related to this topic.

Instructive microenvironments in skin wound healing: Biomaterials as signal releasing platforms

Skin wound healing aims to repair and restore tissue through a multistage process that involves different cells and signalling molecules that regulate the cellular response and the dynamic remodelling of the extracellular matrix. Nowadays, several therapies that combine biomolecule signals (growth factors and cytokines) and cells are being proposed. However, a lack of reliable evidence of their efficacy, together with associated issues such as high costs, a lack of standardization, no scalable processes, and storage and regulatory issues, are hampering their application. In situ tissue regeneration appears to be a feasible strategy that uses the body's own capacity for regeneration by mobilizing host endogenous stem cells or tissue-specific progenitor cells to the wound site to promote repair and regeneration. The aim is to engineer instructive systems to regulate the spatio-temporal delivery of proper signalling based on the biological mechanisms of the different events that occur in the host microenvironment. This review describes the current state of the different signal cues used in wound healing and skin regeneration, and their combination with biomaterial supports to create instructive microenvironments for wound healing.

Selenium-loaded cellulose film derived from Styela clava tunic accelerates the healing process of cutaneous wounds in streptozotocin-induced diabetic Sprague-Dawley rats

PURPOSE

Aims of this study is to evaluate the therapeutic effects and toxicity of Se-loaded cellulose film originated from Styela clava tunic (SeSCTF) on cutaneous wounds during diabetic conditions.

MATERIALS AND METHODS

Alterations in skin regeneration, angiogenesis and toxicity were examined using streptozotocine (STZ)-induced diabetic Sprague Dawley^® (SD) rats with surgical skin wounds after application of SeSCTF for 12 days.

RESULTS

SCTF showed high tensile strength (1.64 MPa), low elongation (28.59%), low water vapor transmission rate (WVTR) and outstanding porous structure. Although SeSCTF application did not induce any significant alterations in glucose concentration or toxicity, wound morphology was rapidly recovered in the SeSCTF treated group relative to the gauze (GZ) and SCTF treated group. Moreover, recovery of re-epithelization, wound contraction and number of blood vessel was observed in SeSCTF treated groups when compared with all other groups. Furthermore, the SeSCTF treated group showed complete recovery of key protein expressions of the downstream signaling pathway of vascular endothelial growth factor (VEGF), angiopoietin-2/1 (Ang-2/1), the signaling pathway of insulin receptors and anti-oxidative status.

CONCLUSIONS

Overall, the results of this study suggest that SeSCTF accelerates the healing process of cutaneous wounds in STZ-induced diabetic SD rats through stimulation of angiogenesis and the glucose receptor signaling pathway.

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.

Biology and Biomarkers for Wound Healing

BACKGROUND

As the population grows older, the incidence and prevalence of conditions that lead to a predisposition for poor wound healing also increase. Ultimately, this increase in nonhealing wounds has led to significant morbidity and mortality with subsequent huge economic ramifications. Therefore, understanding specific molecular mechanisms underlying aberrant wound healing is of great importance. It has and will continue to be the leading pathway to the discovery of therapeutic targets, as well as diagnostic molecular biomarkers. Biomarkers may help identify and stratify subsets of nonhealing patients for whom biomarker-guided approaches may aid in healing.

METHODS

A series of literature searches were performed using Medline, PubMed, Cochrane Library, and Internet searches.

RESULTS

Currently, biomarkers are being identified using biomaterials sourced locally from human wounds and/or systemically using high-throughput "omics" modalities (genomic, proteomic, lipidomic, and metabolomic analysis). In this review, we highlight the current status of clinically applicable biomarkers and propose multiple steps in validation and implementation spectrum, including those measured in tissue specimens, for example, β-catenin and c-myc, wound fluid, matrix metalloproteinases and interleukins, swabs, wound microbiota, and serum, for example, procalcitonin and matrix metalloproteinases.

CONCLUSIONS

Identification of numerous potential biomarkers using different avenues of sample collection and molecular approaches is currently underway. A focus on simplicity and consistent implementation of these biomarkers, as well as an emphasis on efficacious follow-up therapeutics, is necessary for transition of this technology to clinically feasible point-of-care applications.

Exudate collection using wound sponges-An easy, non-invasive and reliable method to explore protease activities in ulcers

Proteases are important for wound healing, but in excessive amounts or left uncontrolled, they may cause healing impairment or other severe wound complications. Point-of-care testing for protease activities in wounds may be useful for monitoring the effectiveness of treatment, and for early identification of wounds that potentially fail to heal. Here we describe an easy, noninvasive method to collect wound fluid for evaluating the protease milieu of wounds. Wound fluids were collected using sterile sponges applied between wound surface and normal wound dressing. Wound fluid could be easily squeezed or centrifuged out of the sponges and was tested for gelatinase (MMP-2 and MMP-9) activities by gel zymography. In addition, we measured polymorphonuclear granulocyte elastase levels by ELISA. Both gelatinases were remarkably stable in sponge derived fluids, as no significant loss was observed even when samples were stored for 3 days at room temperature. Protease levels were highly diverse amongst patients and, in some cases, showed substantial variations in the course of the treatment. The here described wound sponge approach represents a patient-friendly and reliable method to collect wound fluid for evaluating wound healing relevant biomarkers, such as matrix metalloproteinases.

Effects of different cellulose membranes regenerated from Styela clava tunics on wound healing

The aim of this study was to investigate the therapeutic effects of three different cellulose membranes (CMs) manufactured from Styela clava tunics (SCTs) on the healing of cutaneous wounds. We examined the physical properties and therapeutic effects of three CMs regenerated from SCTs (referred to as SCT- CMs), including normal CM (SCT-CM), freeze-dried SCT-CM (FSCT-CM) and sodium alginate-supplemented SCT-CM (ASCT-CM) on skin regeneration and angiogenesis using Sprague-Dawley (SD) rats. FSCT-CM exhibited an outstanding interlayered structure, a high tensile strength (1.64 MPa), low elongation (28.59%) and a low water vapor transmission rate (WVTR) compared with the other SCT-CMs, although the fluid uptake rate was maintained at a medium level. In the SD rats with surgically wounded skin, the wound area and score of wound edge were lower in the FSCT-CM-treated group than in the gauze (GZ)-treated group on days 3–6 and 12–14. In addition, a significant attenuation in the histopathological changes was observed in the FSCT-CM-treated group. Furthermore, the expression level of collagen-1 and the signaling pathway of transforming growth factor (TGF)-β1 were significantly stimulated by the topical application of FSCT-CM. However, no signs of toxicity were detected in the livers or kidneys of the three SCT-CM-treated groups. Overall, our data indicate that the FSCT-CM may accelerate the process of wound healing in the surgically wounded skin of SD rats through the regulation of angiogenesis and connective tissue formation without inducing any specific toxicity.

Reinforced collagen with oxidized microcrystalline cellulose shows improved hemostatic effects

Sponges composed of different levels of composite collagen/oxidized microcrystalline cellulose (collagen/OMCC), denoted M1-M4, were studied to improve the hemostatic effect of single-collagen sponges. Surface morphological observations showed that structural combinations and intermolecular interactions occurred between collagen and OMCC in the composites. M2 presented the best physical properties and platelet activation and was thus selected for the investigations of the in vitro coagulation time and hemostatic and biological effects on animals. The results illustrated that M2 could reduce the length of the activated partial thromboplastin time (APTT) and thrombin time (TT) and presented rapid hemostatic efficiency in the two injury models (P<0.05). These findings were used to evaluate the hemostatic mechanism of M2, which can promote blood absorption and platelet activation and could be directly involved in the intrinsic coagulation pathway to accelerate hemostasis. Furthermore, M2 was not cytotoxic and was completely biodegraded in subcutaneous tissue within 28days.

Reactive oxygen species and bacterial biofilms in diabetic wound healing

Chronic wounds are a common and debilitating complication for the diabetic population. It is challenging to study the development of chronic wounds in human patients; by the time it is clear that a wound is chronic, the early phases of wound healing have passed and can no longer be studied. Because of this limitation, mouse models have been employed to better understand the early phases of chronic wound formation. In the past few years, a series of reports have highlighted the importance of reactive oxygen species and bacterial biofilms in the development of chronic wounds in diabetics. We review these recent findings and discuss mouse models that are being utilized to enhance our understanding of these potentially important contributors to chronic wound formation in diabetic patients.

Engineered Biopolymeric Scaffolds for Chronic Wound Healing

Skin regeneration requires the coordinated integration of concomitant biological and molecular events in the extracellular wound environment during overlapping phases of inflammation, proliferation, and matrix remodeling. This process is highly efficient during normal wound healing. However, chronic wounds fail to progress through the ordered and reparative wound healing process and are unable to heal, requiring long-term treatment at high costs. There are many advanced skin substitutes, which mostly comprise bioactive dressings containing mammalian derived matrix components, and/or human cells, in clinical use. However, it is presently hypothesized that no treatment significantly outperforms the others. To address this unmet challenge, recent research has focused on developing innovative acellular biopolymeric scaffolds as more efficacious wound healing therapies. These biomaterial-based skin substitutes are precisely engineered and fine-tuned to recapitulate aspects of the wound healing milieu and target specific events in the wound healing cascade to facilitate complete skin repair with restored function and tissue integrity. This mini-review will provide a brief overview of chronic wound healing and current skin substitute treatment strategies while focusing on recent engineering approaches that regenerate skin using synthetic, biopolymeric scaffolds. We discuss key polymeric scaffold design criteria, including degradation, biocompatibility, and microstructure, and how they translate to inductive microenvironments that stimulate cell infiltration and vascularization to enhance chronic wound healing. As healthcare moves toward precision medicine-based strategies, the potential and therapeutic implications of synthetic, biopolymeric scaffolds as tunable treatment modalities for chronic wounds will be considered.

Topical Collagen-Based Biomaterials for Chronic Wounds: Rationale and Clinical Application

Significance: The extracellular matrix (ECM) is known to be deficient in chronic wounds. Collagen is the major protein in the ECM. Many claims are made while extolling the virtues of collagen-based biomaterials in promoting cell growth and modulating matrix metalloproteinases. This review will explore the rationale for using topical collagen or ECM as an interface for healing. Recent Advances: Rapid improvements in electrospinning and nanotechnology have resulted in the creation of third-generation biomaterials that mimic the native ECM, stimulate cellular and genetic responses in the target tissue, and provide a platform for controlled release of bioactive molecules and live cells. Although the major focus is currently on development of artificial tissues and organ regeneration, better understanding of the mechanisms that stimulate wound healing can be applied to specific deficits in the chronic wound. Critical Issues: When choosing between the various advanced wound-care products and dressings, the clinician is challenged to select the most appropriate material at the right time. Understanding how the ECM components promote tissue regeneration and modulate the wound microenvironment will facilitate those choices. Laboratory discoveries of biomolecular and cellular strategies that promote skin regeneration rather than repair should be demonstrated to translate to deficits in the chronic wound. Future Directions: Cost-effective production of materials that utilize non-mammalian sources of collagen or ECM components combined with synthetic scaffolding will provide an optimal structure for cellular ingrowth and modulation of the chronic wound microenvironment to facilitate healing. These bioengineered materials will be customizable to provide time-released delivery of bioactive molecules or drugs based on the degradation rate of the scaffold or specific signals from the wound.

A clinical trial of Integra Template for diabetic foot ulcer treatment

Individuals with diabetes mellitus are at an increased risk of developing a diabetic foot ulcer (DFU). This study evaluated the safety and efficacy of Integra Dermal Regeneration Template (IDRT) for the treatment of nonhealing DFUs. The Foot Ulcer New Dermal Replacement Study was a multicenter, randomized, controlled, parallel group clinical trial conducted under an Investigational Device Exemption. Thirty-two sites enrolled and randomized 307 subjects with at least one DFU. Consented patients were entered into the 14-day run-in phase where they were treated with the standard of care (0.9% sodium chloride gel) plus a secondary dressing and an offloading/protective device. Patients with less than 30% reepithelialization of the study ulcer after the run-in phase were randomized into the treatment phase. The subjects were randomized to the control treatment group (0.9% sodium chloride gel; n = 153) or the active treatment group (IDRT, n = 154). The treatment phase was 16 weeks or until confirmation of complete wound closure (100% reepithelialization of the wound surface), whichever occurred first. Following the treatment phase, all subjects were followed for 12 weeks. Complete DFU closure during the treatment phase was significantly greater with IDRT treatment (51%) than control treatment (32%; p = 0.001) at sixteen weeks. The median time to complete DFU closure was 43 days for IDRT subjects and 78 days for control subjects in wounds that healed. The rate of wound size reduction was 7.2% per week for IDRT subjects vs. 4.8% per week for control subjects (p = 0.012). For the treatment of chronic DFUs, IDRT treatment decreased the time to complete wound closure, increased the rate of wound closure, improved components of quality of life and had less adverse events compared with the standard of care treatment. IDRT could greatly enhance the treatment of nonhealing DFUs.

Prospective and randomised evaluation of the protease-modulating effect of oxidised regenerated cellulose/collagen matrix treatment in pressure sore ulcers

In chronic wounds, excess levels and activity of proteases such as elastase and plasmin have been detected. Oxidised regenerated cellulose/collagen matrix (ORC/collagen matrix) has been reported to ameliorate the wound microenvironment by binding and inactivating excess proteases in wound exudates. In this study, the levels and activity of elastase and plasmin in wound exudates of pressure sore ulcers were measured to determine the beneficial effect of ORC/collagen matrix treatment compared with control treatment with a foam dressing. A total of 33 patients with pressure sores were enrolled in the study and were followed up for 12 weeks after treatment. Ten control patients were treated with a foam hydropolymer dressing (TIELLE^® , Systagenix), and the remaining 23 patients were treated with ORC/collagen matrix plus the foam dressing (TIELLE^® , Systagenix) on top. Wound assessments were carried out over 12 weeks on a weekly basis, with dressing changes twice a week. Ulcers were photographed and wound exudates were collected on admission and at days 5, 14 and then every 14 days to provide a visual record of any changes in appearance of the ulcer and healing rate and for biochemical analysis of the wound. The levels and activity of elastase and plasmin were measured in wound exudates. Statistical analysis was performed using ANOVA and Bonferroni's post hoc test with P-values <0·05 considered to be significant. Compared with controls, ORC/collagen matrix-treated pressure sore wounds showed a significant faster healing rate, which positively correlated with a decreased activity of elastase and plasmin in wound exudates. No signs of infection or intolerance to the ORC/collagen matrix were observed.

Development of a Novel Technique to Collect Proteases from Chronic Wounds

Proteases play an essential role in normal wound healing. However, chronic wounds are characterized by abnormally high levels of proteases, in particular, the matrix metalloproteases (MMPs) and neutrophil elastase. In 2010, an international consensus panel identified elevated MMPs and human neutrophil elastase (HNE) as strong candidates for biomarkers for nonhealing wounds. A cooperative group of wound healing centers (SerenaGroup, Inc., Cambridge, MA and Systagenix, Inc., Gargrave, England) collaborated to conduct a series of laboratory and clinical trials to develop the first point-of-care diagnostic in wound healing. The first challenge was that detecting an elevated protease activity required an accurate specimen collection technique. The Levine technique utilized in the collection of bacteria for culture, using a cotton swab, failed to gather consistent levels of proteases. Extensive experimentation with collection methods and swab types finally led to the optimal procedure, The Serena Technique©. Laboratory measurements for MMPs and HNE confirmed the reliability and repeatability of the procedure. This article describes a novel method for collecting wound proteases (The Serena Technique^©).

Recent advances on the development of wound dressings for diabetic foot ulcer treatment--a review

Diabetic foot ulcers (DFUs) are a chronic, non-healing complication of diabetes that lead to high hospital costs and, in extreme cases, to amputation. Diabetic neuropathy, peripheral vascular disease, abnormal cellular and cytokine/chemokine activity are among the main factors that hinder diabetic wound repair. DFUs represent a current and important challenge in the development of novel and efficient wound dressings. In general, an ideal wound dressing should provide a moist wound environment, offer protection from secondary infections, remove wound exudate and promote tissue regeneration. However, no existing dressing fulfills all the requirements associated with DFU treatment and the choice of the correct dressing depends on the wound type and stage, injury extension, patient condition and the tissues involved. Currently, there are different types of commercially available wound dressings that can be used for DFU treatment which differ on their application modes, materials, shape and on the methods employed for production. Dressing materials can include natural, modified and synthetic polymers, as well as their mixtures or combinations, processed in the form of films, foams, hydrocolloids and hydrogels. Moreover, wound dressings may be employed as medicated systems, through the delivery of healing enhancers and therapeutic substances (drugs, growth factors, peptides, stem cells and/or other bioactive substances). This work reviews the state of the art and the most recent advances in the development of wound dressings for DFU treatment. Special emphasis is given to systems employing new polymeric biomaterials, and to the latest and innovative therapeutic strategies and delivery approaches.

Collagen-based wound dressings for the treatment of diabetes-related foot ulcers: a systematic review

BACKGROUND

Diabetic foot ulcers are a major source of morbidity, limb loss, and mortality. A prolonged inflammatory response, extracellular matrix degradation irregularities, and increased bacteria presence have all been hypothesized as major contributing factors in the delayed healing of diabetic wounds. Collagen components such as fibroblast and keratinocytes are fundamental to the process of wound healing and skin formation. Wound dressings that contain collagen products create a biological scaffold matrix that supports the regulation of extracellular components and promotes wound healing.

METHODS

A systematic review of studies reporting collagen wound dressings used in the treatment of Diabetic foot ulcers was conducted. Comprehensive searches were run in Ovid MEDLINE, PubMed, EMBASE, and ISI Web of Science to capture citations pertaining to the use of collagen wound dressings in the treatment of diabetic foot ulcers. The searches were limited to human studies reported in English.

RESULTS

Using our search strategy, 26 papers were discussed, and included 13 randomized designs, twelve prospective cohorts, and one retrospective cohort, representing 2386 patients with diabetic foot ulcers. Our design was not a formal meta-analysis. In those studies where complete epithelialization, 58% of collagen-treated wounds completely healed (weighted mean 67%). Only 23% of studies reported control group healing with 29% healing (weighted mean 11%) described for controls.

CONCLUSION

Collagen-based wound dressings can be an effective tool in the healing of diabetic foot wounds. The current studies show an overall increase in healing rates despite limitations in study designs. This study suggests that future works focus on biofilms and extracellular regulation, and include high risk patients.