Cellulose/Collagen Dressings for Diabetic Foot Ulcer: A Review

Bacterial cellulose: Is it really a promising biomedical material?

Bacterial cellulose (BC) is currently considered a promising biomaterial due to its specific structure and properties. However, despite extensive research, questions about its fundamental properties, especially biocompatibility, remain. Thus, the purpose of this review is to analyze the results of in vivo trials from different areas of biomedicine, including wound healing, tissue engineering, drug delivery, and biomedical implants. The primary question guiding our review was "Why is bacterial cellulose still not used in clinical practice?" Analysis of the literature has shown that the results of in vivo studies often contradict each other. For example, BC caused and did not cause an immune response in an equal number of reviewed articles. Its efficacy in pure form generally does not differ significantly from that of materials already on the market. Conversely, BC may prove to be a valuable material in the long term, not because of its efficacy, but rather because of its affordability and ease of use. Additionally, challenges associated with immune reactions, long-term biocompatibility, and the necessity for standardized experimental protocols must be addressed. We expect that this review will encourage a more thoughtful investigation of BC to bring it into practical medicine.

Intelligent hydrogel-based dressings for treatment of chronic diabetic wounds

Diabetic wounds represent a significant challenge in the medical field, significantly impacting patient quality of life and imposing a heavy burden on healthcare systems. Intelligent hydrogel dressings have attracted significant attention in diabetic wound treatment due to their unique properties. This review systematically explores the three main categories of intelligent hydrogels (natural, synthetic, and composite), dissecting their composition, structure, and the mechanisms that enable their intelligent responses. The crucial roles of these dressings in maintaining a moist wound environment, efficiently absorbing exudate, and precisely delivering drugs are expounded. Moreover, their application advantages in combating bacteria and infections, regulating inflammation and immunity, promoting angiogenesis and tissue regeneration, as well as enabling real-time monitoring and personalized treatment, are explored in depth. Additionally, we discuss future research directions and the prospects for personalized precision medicine in diabetic wound care, aiming to inspire innovation and provide a comprehensive theoretical basis for the development of next-generation intelligent dressings.

Novel highly flexible collagen-loaded latex dressing to treat diabetic foot ulcer: A pilot clinical trial

Diabetic Foot Ulcers (DFUs) are a common and severe complication of long-term, poorly managed type 2 diabetes. Among the 537 million people worldwide with type 2 diabetes, 19 % to 34 % are expected to develop a DFU in their lifetime. As life expectancy increases, so does the prevalence of DFUs, leading to complex and costly long-term care. This study introduces a novel, flexible dressing composed of natural rubber latex (NRL) infused with collagen (NRL-C), leveraging the natural healing properties of these biomaterials. The efficacy of NRL-C was validated through physicochemical characterization, in vitro and in vivo studies, and a pilot clinical trial. Results demonstrated that the NRL-C dressing promotes angiogenesis in endothelial cells, stimulates fibroblast and keratinocyte proliferation, accelerates wound closure, and exhibits biocompatibility in rodent models. Additionally, a pilot clinical study involving six diabetic patients revealed promising therapeutic outcomes, highlighting the potential of NRL-C as a cost-effective, safe, and sustainable strategy for DFU treatment.

Nanoparticle-Enhanced Collagen Hydrogels for Chronic Wound Management

Chronic wound infections present a persistent medical challenge; however, advancements in wound dressings and antimicrobial nanomaterials offer promising solutions for improving healing outcomes. This study introduces a hydrothermal synthesis approach for producing zinc oxide (ZnO) and copper oxide (CuO) nanoparticles, subsequently incorporated into PLGA microspheres and embedded within collagen hydrogels. The nanoparticles' physicochemical properties were characterized using X-ray diffraction (XRD) to confirm crystalline structure, scanning electron microscopy (SEM) for surface morphology, and Fourier-transform infrared spectroscopy (FT-IR) to verify functional groups and successful hydrogel integration. The hydrogels were tested for antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, which are key pathogens in chronic wounds. Biocompatibility was assessed using the human HaCat keratinocyte cell line. Both ZnO- and CuO-loaded hydrogels exhibited broad-spectrum antimicrobial efficacy. Cytocompatibility tests demonstrated that both ZnO- and CuO-loaded hydrogels sustain cell viability and proliferation, highlighting their biocompatibility and suitability for chronic wound healing applications, with superior biological performance of ZnO-loaded hydrogels. Furthermore, the distinct antimicrobial profiles of ZnO and CuO hydrogels suggest their tailored use based on wound microbial composition, with CuO hydrogels excelling in antibacterial applications and ZnO hydrogels showing potential for antifungal treatments. These results underscore the potential of nanoparticle-based collagen hydrogels as innovative therapeutic tools for managing chronic wounds.

Effectiveness of most common adjuvant wound treatments (skin substitutes, negative pressure wound therapy, hyperbaric oxygen therapy, platelet-rich plasma/fibrin, and growth factors) for the management of hard-to-heal diabetic foot ulcers: a meta-analysis of randomized controlled trials for the development of the Italian Guidelines for the Treatment of Diabetic Foot Syndrome

AIM

To assess the effects of several adjuvant therapies (AT) commonly used in the treatment of diabetic foot ulcers (DFU). The present meta-analysis was designed to support the development of the Italian Guidelines for the Treatment of Diabetic Foot Syndrome.

METHODS

A Medline and Embase search were performed up to May 20th, 2024 collecting all RCTs including diabetic patients or reporting subgroup analyses on diabetic patients with DFU comparing AT with placebo/standard of care (SoC), with a duration of at least 12 weeks. Prespecified endpoints were: ulcer healing (principal), time-to-healing, major and minor amputation, serious adverse events (SAE), and all-cause mortality. AT assessed were: growth factors (GF), Platelet-rich plasma and fibrin (PRP/F), skin substitutes (SS), negative pressure wound therapy (NPWT), and hyperbaric oxygen therapy (HBOT). Mantel-Haenzel Odds ratios and 95% confidence intervals (MH-OR, 95% CIs) were either calculated or extracted directly from the publications. Weighted mean differences and 95% CIs were calculated for continuous variables.

RESULTS

Fifty-one studies fulfilled all inclusion criteria (3, 5, 27, 8, and 8 with GF, PRP/F, SS, NPWT, and HBOT, respectively). Participants treated with any of the explored AT had a significantly higher ulcer healing rate (MH-OR ranging from 2.17 to 4.18) and shorter time-to-healing in comparison with SoC/placebo. Only PRP/F and HBOT showed a significantly lower risk of major amputation (MH-OR: 0.32(0.11;0,93; p = 0.04 and 0.28(0.10;0,79; p = 0.02, respectively), despite a higher risk of SAE. No other significant effects on the above-reported prespecified endpoints were observed. For the primary endpoint, the quality of evidence was rated as "high" for all the AT, except for NPWT ("moderate").

CONCLUSIONS

In conclusion, AT can actively promote wound healing and shorten time-to-healing in patients with DFU. HBOT and PRP/F also showed a reduction of the risk of major amputation, despite a higher rate of SAE.

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.

Recent advances in the adjunctive management of diabetic foot ulcer: Focus on noninvasive technologies

Diabetic foot ulcer (DFU) is one of the most costly and serious complications of diabetes. Treatment of DFU is usually challenging and new approaches are required to improve the therapeutic efficiencies. This review aims to update new and upcoming adjunctive therapies with noninvasive characterization for DFU, focusing on bioactive dressings, bioengineered tissues, mesenchymal stem cell (MSC) based therapy, platelet and cytokine-based therapy, topical oxygen therapy, and some repurposed drugs such as hypoglycemic agents, blood pressure medications, phenytoin, vitamins, and magnesium. Although the mentioned therapies may contribute to the improvement of DFU to a certain extent, most of the evidence come from clinical trials with small sample size and inconsistent selections of DFU patients. Further studies with high design quality and adequate sample sizes are necessitated. In addition, no single approach would completely correct the complex pathogenesis of DFU. Reasonable selection and combination of these techniques should be considered.

Fortified electrospun collagen utilizing biocompatible Poly Glycerol Sebacate prepolymer (PGSp) and zink oxide nanoparticles (ZnO NPs) for diabetics wound healing: Physical, biological and animal studies

Collagen, a naturally occurring fibrous protein, is a potential resource of biological materials for tissue engineering and regenerative medicine because it is structurally biocompatible, has low immunogenicity, is biodegradable, and is biomimetic. Numerous studies have documented in the literature how Collagen nanofibers exhibit limited cell adhesion, poor viscosity, and no interior fibril structure. The biomedical industry is using Poly Glycerol Sebacate prepolymer(PGSp), a biodegradable and biocompatible polyester with high adhesion and very viscous appearance, more often. Here, unique electrospun Collagen/PGSp/ZnO/NPs blend nanofibers for skin tissue application were developed and described with varied PGSp percent. Additionally, when ternary blends of Collagen, PGSp, and Zink Oxide Nanoparticles (ZnO NPs) are used, the antibacterial properties of the scaffolds are improved. The bead-free electrospun nanofibers were produced by raising the PGSp concentration to 30%w/w. SEM, EDS, tensile, MTT, FTIR, SDS-page, swelling test, contact-angle, antimicrobial, biodegradation, XRD, and cell attachment procedures were used to characterize the crosslinked nanofibers. The ternary blend nanofibers with a weight ratio of Collagen/PGSp 30%/ZnONPs 1% had higher stress/strain strength (0.25 mm/mm), porosity (563), cell survival, and degradation time. Moreover, after applying for wound healing in diabetic rats, Collagen/PGSp 30%/could be show improving wound healing significantly compared to other groups.

Current status and progress in research on dressing management for diabetic foot ulcer

Diabetic foot ulcer (DFU) is a major complication of diabetes and is associated with a high risk of lower limb amputation and mortality. During their lifetime, 19%-34% of patients with diabetes can develop DFU. It is estimated that 61% of DFU become infected and 15% of those with DFU require amputation. Furthermore, developing a DFU increases the risk of mortality by 50%-68% at 5 years, higher than some cancers. Current standard management of DFU includes surgical debridement, the use of topical dressings and wound decompression, vascular assessment, and glycemic control. Among these methods, local treatment with dressings builds a protective physical barrier, maintains a moist environment, and drains the exudate from DFU wounds. This review summarizes the development, pathophysiology, and healing mechanisms of DFU. The latest research progress and the main application of dressings in laboratory and clinical stage are also summarized. The dressings discussed in this review include traditional dressings (gauze, oil yarn, traditional Chinese medicine, and others), basic dressings (hydrogel, hydrocolloid, sponge, foam, film agents, and others), bacteriostatic dressings, composite dressings (collagen, nanomaterials, chitosan dressings, and others), bioactive dressings (scaffold dressings with stem cells, decellularized wound matrix, autologous platelet enrichment plasma, and others), and dressings that use modern technology (3D bioprinting, photothermal effects, bioelectric dressings, microneedle dressings, smart bandages, orthopedic prosthetics and regenerative medicine). The dressing management challenges and limitations are also summarized. The purpose of this review is to help readers understand the pathogenesis and healing mechanism of DFU, help physicians select dressings correctly, provide an updated overview of the potential of biomaterials and devices and their application in DFU management, and provide ideas for further exploration and development of dressings. Proper use of dressings can promote DFU healing, reduce the cost of treating DFU, and reduce patient pain.

Bacterial cellulose: Biopolymer with novel medical applications

Due to the growing importance of green chemistry, the search for alternatives to cellulose has begun, leading to the rediscovery of bacterial cellulose (BC). The material is produced by Gluconacetobacter and Acetobacter bacteria, mainly Komagataeibacter xylinus. It is a pure biopolymer, without lignin or hemicellulose, forming a three-dimensional mesh, showing much lower organization than its plant counterpart. Thanks to its design, it has proven itself in completely unprecedented applications - especially in the field of biomedical sciences. Coming in countless forms, it has found use in applications such as wound dressings, drug delivery systems, or tissue engineering. The review article focuses on discussing the main structural differences between plant and bacterial cellulose, methods of bacterial cellulose synthesis, and the latest trends in BC applications in biomedical sciences.

Nanofibrous Scaffolds for Diabetic Wound Healing

Chronic wounds are one of the secondary health complications that develop in individuals who have poorly managed diabetes mellitus. This is often associated with delays in the wound healing process, resulting from long-term uncontrolled blood glucose levels. As such, an appropriate therapeutic approach would be maintaining blood glucose concentration within normal ranges, but this can be quite challenging to achieve. Consequently, diabetic ulcers usually require special medical care to prevent complications such as sepsis, amputation, and deformities, which often develop in these patients. Although several conventional wound dressings, such as hydrogels, gauze, films, and foams, are employed in the treatment of such chronic wounds, nanofibrous scaffolds have gained the attention of researchers because of their flexibility, ability to load a variety of bioactive compounds as single entities or combinations, and large surface area to volume ratio, which provides a biomimetic environment for cell proliferation relative to conventional dressings. Here, we present the current trends on the versatility of nanofibrous scaffolds as novel platforms for the incorporation of bioactive agents suitable for the enhancement of diabetic wound healing.

Therapeutic Efficacy of Polymeric Biomaterials in Treating Diabetic Wounds-An Upcoming Wound Healing Technology

Diabetic wounds are one of the serious, non-healing, chronic health issues faced by individuals suffering from diabetic mellitus. The distinct phases of wound healing are either prolonged or obstructed, resulting in the improper healing of diabetic wounds. These injuries require persistent wound care and appropriate treatment to prevent deleterious effects such as lower limb amputation. Although there are several treatment strategies, diabetic wounds continue to be a major threat for healthcare professionals and patients. The different types of diabetic wound dressings that are currently used differ in their properties of absorbing wound exudates and may also cause maceration to surrounding tissues. Current research is focused on developing novel wound dressings incorporated with biological agents that aid in a faster rate of wound closure. An ideal wound dressing material must absorb wound exudates, aid in the appropriate exchange of gas, and protect from microbial infections. It must support the synthesis of biochemical mediators such as cytokines, and growth factors that are crucial for faster healing of wounds. This review highlights the recent advances in polymeric biomaterial-based wound dressings, novel therapeutic regimes, and their efficacy in treating diabetic wounds. The role of polymeric wound dressings loaded with bioactive compounds, and their in vitro and in vivo performance in diabetic wound treatment are also reviewed.

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.

Emerging Antimicrobial and Immunomodulatory Fiber-Based Scaffolding Systems for Treating Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are one of the main complications of diabetes and are characterized by their complexity and severity, which are frequently aggravated by overexpressed inflammatory factors and polymicrobial infections. Most dressing systems offer a passive action in the treatment of DFUs, being frequently combined with antibiotic or immunomodulatory therapies. However, in many instances due to these combined therapies' inability to properly fight microbial presence, and provide a suitable, breathable and moist environment that is also capable of protecting the site from secondary microbial invasions or further harm, aggravation of the wound state is unavoidable and lower limb amputations are necessary. Considering these limitations and knowing of the urgent demand for new and more effective therapeutic systems for DFU care that will guarantee the quality of life for patients, research in this field has boomed in the last few years. In this review, the emerging innovations in DFU dressing systems via fiber-based scaffolds modified with bioactive compounds have been compiled; data focused on the innovations introduced in the last five years (2017-2022). A generalized overview of the classifications and constraints associated with DFUs healing and the bioactive agents, both antimicrobial and immunomodulatory, that can contribute actively to surpass such issues, has also been provided.

A Net Meta-Analysis of the Effectiveness of Different Types of Dressings in the Treatment of Diabetic Foot

Objective

This is an analysis of the impact of a new dressing commonly used to treat diabetic foot (DFU).

Methods

Chinese and English databases were searched to collect clinical randomized controlled studies (RCTs) of various types of dressings for the treatment of DFU, and the healing rates of the different dressings were combined by reticulation meta-analysis.

Results

The aggregate of the 36 RCTs included in this study analysed the healing rates of nine dressings: conventional dressing, alginate dressing, chitosan dressing, hyaluronic acid dressing, platelet-rich plasma dressing, amniotic membrane dressing, honey dressing, human recombinant growth factor dressing, and silver ionomer dressing.

Conclusion

Hyaluronic acid dressing, amniotic membrane dressing, honey dressing, and platelet-rich plasma dressing are the ideal materials for topical treatment of DFU.

Active Potential of Bacterial Cellulose-Based Wound Dressing: Analysis of Its Potential for Dermal Lesion Treatment

The use of innate products for the fast and efficient promotion of healing process has been one of the biomedical sector's main bets for lesion treatment modernization process. The aim of this study was to develop and characterize bacterial cellulose-based (BC) wound dressings incorporated with green and red propolis extract (2 to 4%) and the active compounds p-coumaric acid and biochanin A (8 to 16 mg). The characterization of the nine developed samples (one control and eight active wound dressings) evidenced that the mechanics, physics, morphological, and barrier properties depended not only on the type of active principle incorporated onto the cellulosic matrix, but also on its concentration. Of note were the results found for transparency (28.59-110.62T₆₀₀ mm^-1), thickness (0.023-0.046 mm), swelling index (48.93-405.55%), water vapor permeability rate (7.86-38.11 g m² day^-1), elongation (99.13-262.39%), and antioxidant capacity (21.23-86.76 μg mL^-1). The wound dressing based on BC and red propolis was the only one that presented antimicrobial activity. The permeation and retention test revealed that the wound dressing containing propolis extract presented the most corneal stratum when compared with viable skin. Overall, the developed wound dressing showed potential to be used for treatment against different types of dermal lesions, according to its determined proprieties.

Diabetic foot ulcer, antimicrobial remedies and emerging strategies for the treatment

According to the International Diabetes Federation's 2015 study, diabetes affects over 415 million people globally (5 million of whom die each year), and the incidence of diabetes is expected to climb to over 640 million (1 in 10) by 2040. (IDF 2015). Diabetes foot ulcers (DFU) are one of the most significant diabetic health consequences. Antimicrobial treatments, such as dressings, topical therapies, medicines, drugs, debridement procedures, molecular, cellular, and gene therapies, plant extracts, antimicrobial peptides, growth factors, devices, ozone, and energy-based therapies, would be the focus of this study. Scopus, Web of Science, Bentham Science, Science Direct, and Google Scholar were among the sources used to compile the English-language publications on DFU. DFU treatment requires a multidisciplinary approach that includes the use of proper diagnostic tools, competence, and experience. To prevent amputations, this starts with patient education and the use of new categories to steer treatment. New diagnostic methods, such as the 16S ribosomal DNA sequence in bacteria, should become available to acquire a better knowledge of the microbiota in DFUs. 

Biocompatible and Antimicrobial Cellulose Acetate-Collagen Films Containing MWCNTs Decorated with TiO2 Nanoparticles for Potential Biomedical Applications

This research focuses on the synthesis of multi-walled carbon nanotubes (MWCNTs) decorated with TiO₂ nanoparticles (NPs) and incorporated in cellulose acetate-collagen film in order to obtain a new biomaterial with potential biomedical applications and improved antimicrobial activity. The successful decoration of the MWCNTs with TiO₂ NPs was confirmed by several structural and morphological analysis, such as Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction and transmission electron microscopy. The obtained nanocomposites were further incorporated into cellulose acetate-collagen films, at different concentrations and absorption kinetics, antimicrobial activity and in vitro biocompatibility of the obtained films was investigated. The antimicrobial tests sustained that the presence of the nanocomposites into the polymeric matrix is an important aspect in increasing and maintaining the antimicrobial activity of the polymeric wound dressings over time. The biocompatibility and cytotoxicity of the obtained films was evaluated using cellular viability/proliferation assay and fluorescent microscopy which revealed the ability of the obtained materials as potential wound dressing biomaterial.

Zebrafish as a Model System to Study the Mechanism of Cutaneous Wound Healing and Drug Discovery: Advantages and Challenges

In humans, cutaneous wounds may heal without scars during embryogenesis. However, in the adult phase, the similar wound may undergo a few events such as homeostasis, blood clotting, inflammation, vascularization, and the formation of granulation tissue, which may leave a scar at the injury site. In consideration of this, research evolves daily to improve the healing mechanism in which the wound may heal without scarring. In regard to this, zebrafish (Danio rerio) serves as an ideal model to study the underlying signaling mechanism of wound healing. This is an important factor in determining a relevant drug formulation for wound healing. This review scrutinizes the biology of zebrafish and how this favors the cutaneous wound healing relevant to the in vivo evidence. This review aimed to provide the current insights on drug discovery for cutaneous wound healing based on the zebrafish model. The advantages and challenges in utilizing the zebrafish model for cutaneous wound healing are discussed in this review. This review is expected to provide an idea to formulate an appropriate drug for cutaneous wound healing relevant to the underlying signaling mechanism. Therefore, this narrative review recapitulates current evidence from in vivo studies on the cutaneous wound healing mechanism, which favours the discovery of new drugs. This article concludes with the need for zebrafish as an investigation model for biomedical research in the future to ensure that drug repositions are well suited for human skin.

Current Insights into Collagen Type I

Collagen type I (Col-I) is unique due to its high biocompatibility in human tissue. Despite its availability from various sources, Col-I naturally mimics the extracellular matrix (ECM) and generally makes up the larger protein component (90%) in vasculature, skin, tendon bone, and other tissue. The acceptable physicochemical properties of native Col-I further enhance the incorporation of Col-I in various fields, including pharmaceutical, cosmeceutical, regenerative medicine, and clinical. This review aims to discuss Col-I, covering the structure, various sources of availability, native collagen synthesis, current extraction methods, physicochemical characteristics, applications in various fields, and biomarkers. The review is intended to provide specific information on Col-I currently available, going back five years. This is expected to provide a helping hand for researchers who are concerned about any development on collagen-based products particularly for therapeutic fields.

Pre-Formulation Studies: Physicochemical Characteristics and In Vitro Release Kinetics of Insulin from Selected Hydrogels

Insulin loaded to the polymer network of hydrogels may affect the speed and the quality of wound healing in diabetic patients. The aim of our research was to develop a formulation of insulin that could be applied to the skin. We chose hydrogels commonly used for pharmaceutical compounding, which can provide a form of therapy available to every patient. We prepared different gel formulations using Carbopol^® Ultrez^TM 10, Carbopol^® Ultrez^TM 30, methyl cellulose, and glycerin ointment. The hormone concentration was 1 mg/g of the hydrogel. We assessed the influence of model hydrogels on the pharmaceutical availability of insulin in vitro, and we examined the rheological and the texture parameters of the prepared formulations. Based on spectroscopic methods, we evaluated the influence of model hydrogels on secondary and tertiary structures of insulin. The analysis of rheograms showed that hydrogels are typical of shear-thinning non-Newtonian thixotropic fluids. Insulin release from the formulations occurs in a prolonged manner, providing a longer duration of action of the hormone. The stability of insulin in hydrogels was confirmed. The presence of model hydrogel carriers affects the secondary and the tertiary structures of insulin. The obtained results indicate that hydrogels are promising carriers in the treatment of diabetic foot ulcers. The most effective treatment can be achieved with a methyl cellulose-based insulin preparation.

Natural-Based Biomaterial for Skin Wound Healing (Gelatin vs. Collagen): Expert Review

Collagen (Col) and gelatin are most extensively used in various fields, particularly in pharmaceuticals and therapeutics. Numerous researchers have proven that they are highly biocompatible to human tissues, exhibit low antigenicity and are easy to degrade. Despite their different sources both Col and gelatin have almost the same effects when it comes to wound healing mechanisms. Considering this, the bioactivity and biological effects of both Col and gelatin have been, and are being, constantly investigated through in vitro and in vivo assays to obtain maximum outcomes in the future. With regard to their proven nutritional values as sources of protein, Col and gelatin products exert various possible biological activities on cells in the extracellular matrix (ECM). In addition, a vast number of novel Col and gelatin applications have been discovered. This review compared Col and gelatin in terms of their structures, sources of derivatives, physicochemical properties, results of in vitro and in vivo studies, their roles in wound healing and the current challenges in wound healing. Thus, this review provides the current insights and the latest discoveries on both Col and gelatin in their wound healing mechanisms.

Lower Extremity Ulcers

Lower extremity ulcerations contribute to significant morbidity and economic burden globally. Chronic wounds, or those that do not progress through healing in a timely manner, are estimated to affect 6.5 million people in the United States alone causing, significant morbidity and economic burden of at least an estimated $25 billion annually. Owing to the aging population and increasing rates of obesity and diabetes mellitus globally, chronic lower extremity ulcers are predicted to increase. Here, we explore the pathophysiology, diagnosis, and management of the most (and least) commonly seen lower extremity ulcers.

The Insights of Microbes' Roles in Wound Healing: A Comprehensive Review

A diverse range of normal flora populates the human skin and numbers are relatively different between individuals and parts of the skin. Humans and normal flora have formed a symbiotic relationship over a period of time. With numerous disease processes, the interaction between the host and normal flora can be interrupted. Unlike normal wound healing, which is complex and crucial to sustaining the skin’s physical barrier, chronic wounds, especially in diabetes, are wounds that fail to heal in a timely manner. The conditions become favorable for microbes to colonize and establish infections within the skin. These include secretions of various kinds of molecules, substances or even trigger the immune system to attack other cells required for wound healing. Additionally, the healing process can be slowed down by prolonging the inflammatory phase and delaying the wound repair process, which causes further destruction to the tissue. Antibiotics and wound dressings become the targeted therapy to treat chronic wounds. Though healing rates are improved, prolonged usage of these treatments could become ineffective or microbes may become resistant to the treatments. Considering all these factors, more studies are needed to comprehensively elucidate the role of human skin normal flora at the cellular and molecular level in a chronic injury. This article will review wound healing physiology and discuss the role of normal flora in the skin and chronic wounds.

Synergistic Effect of Biomaterial and Stem Cell for Skin Tissue Engineering in Cutaneous Wound Healing: A Concise Review

Skin tissue engineering has made remarkable progress in wound healing treatment with the advent of newer fabrication strategies using natural/synthetic polymers and stem cells. Stem cell therapy is used to treat a wide range of injuries and degenerative diseases of the skin. Nevertheless, many related studies demonstrated modest improvement in organ functions due to the low survival rate of transplanted cells at the targeted injured area. Thus, incorporating stem cells into biomaterial offer niches to transplanted stem cells, enhancing their delivery and therapeutic effects. Currently, through the skin tissue engineering approach, many attempts have employed biomaterials as a platform to improve the engraftment of implanted cells and facilitate the function of exogenous cells by mimicking the tissue microenvironment. This review aims to identify the limitations of stem cell therapy in wound healing treatment and potentially highlight how the use of various biomaterials can enhance the therapeutic efficiency of stem cells in tissue regeneration post-implantation. Moreover, the review discusses the combined effects of stem cells and biomaterials in in vitro and in vivo settings followed by identifying the key factors contributing to the treatment outcomes. Apart from stem cells and biomaterials, the role of growth factors and other cellular substitutes used in effective wound healing treatment has been mentioned. In conclusion, the synergistic effect of biomaterials and stem cells provided significant effectiveness in therapeutic outcomes mainly in wound healing improvement.

Collagen in Wound Healing

Normal wound healing progresses through inflammatory, proliferative and remodeling phases in response to tissue injury. Collagen, a key component of the extracellular matrix, plays critical roles in the regulation of the phases of wound healing either in its native, fibrillar conformation or as soluble components in the wound milieu. Impairments in any of these phases stall the wound in a chronic, non-healing state that typically requires some form of intervention to guide the process back to completion. Key factors in the hostile environment of a chronic wound are persistent inflammation, increased destruction of ECM components caused by elevated metalloproteinases and other enzymes and improper activation of soluble mediators of the wound healing process. Collagen, being central in the regulation of several of these processes, has been utilized as an adjunct wound therapy to promote healing. In this work the significance of collagen in different biological processes relevant to wound healing are reviewed and a summary of the current literature on the use of collagen-based products in wound care is provided.

Injectable Hydrogels for Chronic Skin Wound Management: A Concise Review

Diabetic foot ulcers (DFU) are a predominant impediment among diabetic patients, increasing morbidity and wound care costs. There are various strategies including using biomaterials have been explored for the management of DFU. This paper will review the injectable hydrogel application as the most studied polymer-based hydrogel based on published journals and articles. The main key factors that will be discussed in chronic wounds focusing on diabetic ulcers include the socioeconomic burden of chronic wounds, biomaterials implicated by the government for DFU management, commercial hydrogel product, mechanism of injectable hydrogel, the current study of novel injectable hydrogel and the future perspectives of injectable hydrogel for the management of DFU.