Bioengineered Skin Substitutes: the Role of Extracellular Matrix and Vascularization in the Healing of Deep Wounds

Revealing the promising era of silk-based nanotherapeutics: a ray of hope for chronic wound healing treatment

Chronic wounds significantly contribute to disability and affect the mortality rate in diabetic patients. In addition, pressure ulcers, diabetic foot ulcers, arterial ulcers, and venous ulcers pose a significant health burden due to their associated morbidity and death. The complex healing process, environmental factors, and genetic factors have been identified as the rate-limiting stages of chronic wound healing. Changes in temperature, moisture content, mechanical strain, and genetics can result in slow wound healing, increased susceptibility to bacterial infections, and poor matrix remodelling. These obstacles can be addressed with natural biomaterials exhibiting antimicrobial, collagen synthesis, and granulation tissue formation properties. Recently, silk proteins have gained significant attention as a natural biomaterial owing to good biocompatibility, biodegradability, reduced immunogenicity, ease of sterilization, and promote the wound healing process. The silk components such as sericin and fibroin in combination with nano(platforms) effectively promote wound repair. This review emphasises the potential of sericin and fibroin when combined with nano(platforms) like nanoparticles, nanofibers, and nanoparticles-embedded films, membranes, gels, and nanofibers.

Optimizing Wound Healing in Radial Forearm Donor Sites: A Comparative Study of Ulnar-Based Flap and Split-Thickness Skin Grafting

Background: The radial forearm free flap (RFFF) is a common technique in head and neck reconstructive surgery. This study aimed to compare the clinical and biochemical outcomes of wound healing following ulnar-based transposition flap (UBTF) versus split-thickness skin grafting (STSG) for donor site closure, with a particular emphasis on tissue regeneration. Materials and Methods: A total of 24 patients (6 women, 18 men), underwent RFFF reconstruction. The donor site was closed using the UBTF technique in 10 cases, while STSG was performed in 14 cases. Postoperative complications-including necrosis, edema, hematoma, infection, and wound dehiscence-along with healing times were assessed daily during the first seven postoperative days and at monthly follow-ups over six months. Pre- and postoperative biochemical analyses included hemoglobin (HB), white blood cell count (WBC), platelets (PLT), albumin, and C-reactive protein (CRP) levels. An aesthetic evaluation of the flap was also performed. Results: The two groups were homogeneous. Postoperative complications occurred more frequently in the STSG group, which also demonstrated significantly longer healing times (p = 0.0004). In contrast, the UBTF group showed significantly better aesthetic outcomes in terms of skin color (p = 0.000021), skin texture (p = 0.000018), and flap stability (p = 0.0398). Additionally, pre- and postoperative PLT counts were significantly higher in the UBTF group (p = 0.001 and p = 0.043, respectively). Conclusions: While STSG remains a well-established method for forearm donor site closure following RFFF harvest, this study demonstrates that UBTF is a viable alternative associated with better clinical and aesthetic outcomes.

Application of novel strategies in chronic wound management with focusing on pressure ulcers: new perspective

Invading blood cells, extracellular tissue, and soluble mediators all play important roles in the wound-healing process. There is a substantial global burden of disease and mortality attributable to skin defects that do not heal. About 1% to 2% of the population in industrialized nations suffers from chronic wounds that don't heal, despite healthcare breakthroughs; this condition is very costly, costing about $25 billion each year in the US alone. Amputation, infection (affecting as many as 25% of chronic wounds), sepsis, and dermal replacements are all consequences of conventional therapeutic approaches like growth factor therapy and diabetic foot ulcers account for 85% of lower limb amputations. Despite these obstacles, scientists are constantly looking for new ways to speed healing and close wounds. The unique immunomodulatory capabilities and multipotency of mesenchymal stem cells (MSCs) have made them a potential therapeutic choice in tissue engineering and regenerative medicine. Animal models of wound healing have shown that MSCs can speed up the process by as much as 40% through enhancing angiogenesis, modulating inflammation, and promoting fibroblast migration. Clinical trials provide more evidence of their effectiveness; for instance, one RCT found that, after 12 weeks, patients treated with MSCs had a 72% smaller wound size than those in the control group. This review offers a thorough examination of MSCs by combining the latest research with preclinical evidence. Highlighting their potential to transform treatment paradigms, it delves into their biological properties, how they work during regeneration and healing, and therapeutic usefulness in controlling chronic wounds.

Advancements in bioengineered and autologous skin grafting techniques for skin reconstruction: a comprehensive review

The reconstruction of complex skin defects challenges clinical practice, with autologous skin grafts (ASGs) as the traditional choice due to their high graft take rate and patient compatibility. However, ASGs have limitations such as donor site morbidity, limited tissue availability, and the necessity for multiple surgeries in severe cases. Bioengineered skin grafts (BSGs) aim to address these drawbacks through advanced tissue engineering and biomaterial science. This study conducts a systematic review to describe the benefits and shortcomings of BSGs and ASGs across wound healing efficacy, tissue integration, immunogenicity, and functional outcomes focusing on wound re-epithelialization, graft survival, and overall aesthetic outcomes. Preliminary findings suggest ASGs show superior early results, while BSGs demonstrate comparable long-term outcomes with reduced donor site morbidity. This comparative analysis enhances understanding of bioengineered alternatives in skin reconstruction, potentially redefining best practices based on efficacy, safety, and patient-centric outcomes, highlighting the need for further innovation in bioengineered solutions.

The interplay of skin architecture and cellular dynamics in wound healing: Insights and innovations in care strategies

Wound healing involves complex interactions among skin layers: the epidermis, which epithelializes to cover wounds; the dermis, which supports granulation tissue and collagen production; and the hypodermis, which protects overall skin structure. Key factors include neutrophils, activated by platelet degranulation and cytokines, and fibroblasts, which aid in collagen production during proliferation. The healing process encompasses inflammation, proliferation, and remodeling, with angiogenesis, fibroplasia, and re-epithelialization crucial for wound closure. Angiogenesis is characterized by the creation of collateral veins, the proliferation of endothelial cells, and the recruitment of perivascular cells. Collagen is produced by fibroblasts in granulation tissue, aiding in the contraction of wounds. The immunological response is impacted by T cells and cytokines. External topical application of various formulations and dressings expedites healing and controls microbial contamination. Polymeric materials, both natural and synthetic, and advanced dressings enhance healing by providing biodegradability, biocompatibility, and infection control, thus addressing tissue regeneration challenges. Numerous dressings promote healing, including films, hydrocolloids, hydrogels, foams, alginates, and tissue-engineered substitutes. Wound dressings are treated with growth factors, particularly PDGF, and antibacterial drugs to prevent infection. The challenges of tissue regeneration and infection control are evolving along with the field of wound care.

Silver nanoparticles loaded with pomegranate peel extract and hyaluronic acid mediate recovery of cutaneous wounds infected with Candida albicans

Smart innovative nanocomposites based on active ingredients and metallic nanoparticles with effective wound healing and antifungal properties are efficient in overcoming the limitations of traditional therapeutic products. Open wounds provide an ideal niche for colonization by Candida albicans (C. albicans) which poses substantial global health issues owing to delayed wound healing and disordered healing mechanisms. Therefore, proficient innovative therapies that control C. albicans infection and promote wound healing are of imperative importance for the management of wounds and prevention of infection and possible complications. This study aims to design a novel nanocarrier platform based on a hydrogel loaded with silver nanoparticles (AgNPs) and doped with pomegranate peel extract (PPE) and hyaluronic acid (HA), offering an unprecedented opportunity to achieve skin repair and manage C. albicans colonization with an efficient wound healing process. Sprague-Dawley rats (n=100) were assigned to 5 groups and infected with C. albicans and distributed as follows: control positive (untreated) and four cutaneous wound-healing model groups treated topically with commercial cream and PPE-HA-AgNPs at full, 50%, and 25% concentrations for 15 days, respectively. Our findings revealed that the severity of clinical signs, C. albicans burden, and the expression of biofilm-related genes ALS1, HYR1, and PLB1 were diminished following treatment with PPE-HA-AgNPsIII. Notably, the formulated nanocomposite was very effective in extending the release of PPE-HA-AgNPs in infected wounds with retention percentages of 65.4% for PPE-HA-AgNPsIII. Topical administration of PPE-HA-AgNPsIII successfully alleviated the extensive inflammatory response and healed wounded skin via downregulation of tumor necrosis factor-alpha (TNF-α), interleukin-6 and IL-1 beta, and nitric oxide synthase (NOS) levels as shown by enzyme-linked immunosorbent (ELISA) and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays. Interestingly, PPE-HA-AgNPsIII modulated angiogenic and wound healing markers as evidenced by the downregulation of MMP-9 and the upregulation of angiopoietin-1 (Ang-1), vascular endothelial growth factor (VEGF) (up to 10 days post-treatment), transforming growth factor-beta 1 (TGF-β1), bFGF, EGF, Ki-67, and collagen I and III with efficient wound closure capability. This was evidenced by the lessening of histopathological severity, which accelerated the healing of the infected skin wounds post-treatment with PPE-HA-AgNPs. Overall, our formulated PPE-HA-AgNPs provide an effective innovative therapeutic strategy for the treatment of cutaneous wounds infected with C. albicans with maximized wound healing efficacy, indicating their potential in clinical practice.

Safety evaluation of bi-layered allogenic keratinocyte and fibroblast skin substitute for diabetic foot ulcers-SAFESKIN-DFU: A Phase 1 clinical trial

AIM

To assess the safety and efficacy of a local skin substitute product in the treatment of chronic diabetic foot ulcers (DFUs).

MATERIALS AND METHODS

Five patients were evaluated over 6 months. Skin substitutes were applied twice at 2-week intervals. Patients were monitored for any possible adverse effects and wound improvement.

RESULTS

The results indicated the overall safety of the skin substitute, with only few adverse effects unrelated to this product. Significant reduction in wound size was observed in four patients during the initial 12-week treatment phase, with complete closure in two patients at 24 weeks.

CONCLUSIONS

The application of a bi-layered allogeneic keratinocyte and fibroblast skin substitute in patients with chronic DFU was safe and associated with favourable wound healing results. Adherence to standard treatment protocols, including optimal offloading, is essential to maximize the likelihood of successful wound healing.

Management of Acute Wounds-Expert Panel Consensus Statement

Significance: The Wound Healing Foundation recognized the need for consensus-based unbiased recommendations for the treatment of wounds. As a first step, a consensus on the treatment of chronic wounds was developed and published in 2022. The current publication on acute wounds represents the second step in this process. Acute wounds may result from any number of conditions, including burns, military and combat operations, and trauma to specific areas of the body. The management of acute wounds requires timely and evidence-driven intervention to achieve optimal clinical outcomes. This consensus statement provides the clinician with the necessary foundational approaches to the causes, diagnosis, and therapeutic management of acute wounds. Presented in a structured format, this is a useful guide for clinicians and learners in all patient care settings. Recent Advances: Recent advances in the management of acute wounds have centered on stabilization and treatment in the military and combat environment. Specifically, advancements in hemostasis, resuscitation, and the mitigation of infection risk through timely initiation of antibiotics and avoidance of high-pressure irrigation in contaminated soft tissue injury. Critical Issues: Critical issues include infection control, pain management, and the unique considerations for the management of acute wounds in pediatric patients. Future Directions: Future directions include new approaches to preventing the progression and conversion of burns through the use of specific gel formulations. Additionally, the use of three-dimensional bioprinting and photo-modulation for reconstruction is a promising area for continued discovery.

Silk Fibroin Nanofibers: Advancements in Bioactive Dressings through Electrospinning Technology for Diabetic Wound Healing

BACKGROUND

Non-healing diabetic wounds represent a significant clinical challenge globally, necessitating innovative approaches in drug delivery to enhance wound healing. Understanding the pathogenesis of these wounds is crucial for developing effective treatments. Bioactive dressings and polymeric nanofibers have emerged as promising modalities, with silk biomaterials gaining attention for their unique properties in diabetic wound healing.

PURPOSE OF REVIEW

The purpose of this review is to examine the challenges and innovations in treating non-healing diabetic wounds, emphasizing the global burden and the need for effective solutions. This review explores the complex mechanisms of wound healing in diabetes and evaluates the therapeutic potential of bioactive dressings and polymeric nanofibers. Special focus is given to the application of silk biomaterials, particularly silk fibroin, for wound healing, detailing their properties, mechanisms, and clinical translation. This review also describes various nanofiber fabrication methods, especially electrospinning technology, and presents existing evidence on the effectiveness of electrospun silk fibroin formulations.

RECENT FINDINGS

Recent advancements highlight the potential of silk biomaterials in diabetic wound healing, owing to their biocompatibility, mechanical strength, and controlled drug release properties. Electrospun silk fibroin-based formulations have shown promising results in preclinical and clinical studies, demonstrating accelerated wound closure and tissue regeneration.

SUMMARY

Non-healing diabetic wounds present a significant healthcare burden globally, necessitating innovative therapeutic strategies. Bioactive dressings and polymeric nanofibers, particularly silk-based formulations fabricated through electrospinning, offer promising avenues for enhancing diabetic wound healing. Further research is warranted to optimize formulation parameters and validate efficacy in larger clinical trials.

A Comparative Review of Meshed Versus Unmeshed Grafts in Split-Thickness Skin Grafting: Clinical Implications and Outcomes

Split-thickness skin grafting (STSG) is a cornerstone technique in reconstructive surgery, offering solutions for covering wounds, burns, and other skin defects. This review compares meshed versus unmeshed STSG, focusing on their clinical implications and outcomes. Meshed grafts, created by perforating the skin graft to form a mesh-like pattern, are frequently used for larger or irregularly shaped areas due to their ability to expand and conform to the underlying tissue. In contrast, unmeshed grafts are applied as whole sheets, making them suitable for smaller or cosmetically sensitive regions where appearance is paramount. This review examines various aspects of these graft types, including graft survival rates, aesthetic and functional results, healing times, and complications such as infection and graft contraction. This study aims to identify the relative advantages and drawbacks of meshed versus unmeshed grafts by analyzing data from clinical trials, meta-analyses, and systematic reviews. The findings highlight that while meshed grafts offer improved coverage and reduced risk of graft failure, unmeshed grafts are preferred for their superior cosmetic outcomes. Understanding these differences is crucial for optimizing surgical strategies and improving patient outcomes. The review also addresses patient-specific factors and recommends selecting the appropriate graft type based on clinical scenarios.

Rapid innervation and physiological epidermal regeneration by bioengineered dermis implanted in mouse

Tissue-engineered skin substitutes are promising tools to cover large and deep skin defects. However, the lack of a synergic and fast regeneration of the vascular network, nerves, and skin appendages limits complete skin healing and impairs functional recovery. It has been highlighted that an ideal skin substitute should mimic the structure of the native tissue to enhance clinical effectiveness. Here, we produced a pre-vascularized dermis (PVD) comprised of fibroblasts embedded in their own extracellular matrix (ECM) and a capillary-like network. Upon implantation in a mouse full-thickness skin defect model, we observed a very early innervation of the graft in 2 weeks. In addition, mouse capillaries and complete epithelialization were detectable as early as 1 week after implantation and, skin appendages developed in 2 weeks. These anatomical features underlie the interaction with the skin nerves, thus providing a further cue for reinnervation guidance. Further, the graft displays mechanical properties, collagen density, and assembly features very similar to the host tissue. Taken together our data show that the pre-existing ECM components of the PVD, physiologically organized and assembled similarly to the native tissue, support a rapid regeneration of dermal tissue. Therefore, our results suggest a promising potential for PVD in skin regeneration.

Comparing the traditional and emerging therapies for enhancing wound healing in diabetic patients: A pivotal examination

Chronic non-healing ulcers are common among diabetic patients, posing significant therapeutic challenges. This study compared traditional therapies (TT) and emerging therapies (ET) for enhancing diabetic patients' wound healing. A total of 150 diabetic patients with chronic ulcers, ages 30-65, were randomly assigned to one of two groups: TT (n = 75) or ET (n = 75). ET included growth factors, bioengineered skin substitutes, and hyperbaric oxygen therapy, while TT for wound healing predominantly included debridement, saline-moistened dressings, and off-loading techniques. The primary outcome was the percentage of lesions that healed within 12 weeks, which was assessed at intervals. Secondary outcomes included time to wound recovery, pain using Visual Analogue Scale (VAS), and life quality via Wound-QoL questionnaire. By the 12th week, the ET group had a repair rate of 81.33% compared to 57.33% in TT group (p < 0.05). ET exhibited superior pain reduction (VAS score: 4.7 ± 1.6 for ET vs. 6.2 ± 1.4 for TT, p < 0.05) and improved life quality (Wound-QoL score: 61.8 ± 9.1 for ET vs. 44.3 ± 10.3 for TT, p < 0.05). However, there were slightly more cases of cutaneous irritation and hematomas among ET patients. ET have demonstrated significant efficacy in accelerating wound healing in diabetic patients, surpassing traditional methods, with additional advantages in pain management and life quality. Due to the observed minor complications, however, caution is required.

Dermal Regeneration Template in the Management and Reconstruction of Burn Injuries and Complex Wounds: A Review

Background

Dermal scaffolds have created a paradigm shift for burn and wound management by providing improved healing and less scarring, while improving cosmesis and functionality. Dermal regeneration template (DRT) is a bilayer membrane for dermal regeneration developed by Yannas and Burke in the 1980s. The aim of this review is to summarize clinical evidence for dermal scaffolds focusing on DRT for the management and reconstruction of burn injuries and complex wounds.

Methods

A comprehensive search of PubMed was performed from the start of indexing through November 2022. Articles reporting on DRT use in patients with burns, limb salvage, and wound reconstruction were included with focus on high-level clinical evidence.

Results

DRT has become an established alternative option for the treatment of full-thickness and deep partial-thickness burns, with improved outcomes in areas where cosmesis and functionality are important. In the management of diabetic foot ulcers, use of DRT is associated with high rates of complete wound healing with a low risk of adverse outcomes. DRT has been successfully used in traumatic and surgical wounds, showing particular benefit in deep wounds and in the reconstruction of numerous anatomical sites.

Conclusions

Considerable clinical experience has accrued with the use of DRT beyond its original application for thermal injury. A growing body of evidence from clinical studies reports the successful use of DRT to improve clinical outcomes and quality of life across clinical indications at a number of anatomical sites.

3D bioprinting bioglass to construct vascularized full-thickness skin substitutes for wound healing

Constructing three-dimensional (3D) bioprinted skin tissues that accurately replicate the mechanical properties of native skin and provide adequate oxygen and nutrient support remains a formidable challenge. In this study, we incorporated phosphosilicate calcium bioglasses (PSCs), a type of bioactive glass (BG), into the bioinks used for 3D bioprinting. The resulting bioink exhibited mechanical properties and biocompatibility that closely resembled those of natural skin. Utilizing 3D bioprinting technology, we successfully fabricated full-thickness skin substitutes, which underwent comprehensive evaluation to assess their regenerative potential in treating full-thickness skin injuries in rats. Remarkably, the skin substitutes loaded with PSCs exhibited exceptional angiogenic activity, as evidenced by the upregulation of angiogenesis-related genes in vitro and the observation of enhanced vascularization in wound tissue sections in vivo. These findings conclusively demonstrated the outstanding efficacy of PSCs in promoting angiogenesis and facilitating the repair of full-thickness skin wounds. The insights garnered from this study provide a valuable reference strategy for the development of skin tissue grafts with potent angiogenesis-inducing capabilities.

The Use of Urinary Bladder Matrix for Reconstructing Avulsed Traumatic Soft Tissue Injuries to the Maxillofacial Region

INTRODUCTION

The purpose of the study was to provide an overview of our initial experience utilizing urinary bladder matrix (UBM) for reconstructing avulsed injuries resulting from trauma.

MATERIALS AND METHODS

This retrospective case series evaluated patients presented with avulsed soft tissue injuries to the head and neck who underwent reconstruction with UBM. Patients were treated by Oral and Maxillofacial Surgery Service in Louisiana State University Health Sciences Center (Baton Rouge, LA). Descriptive variables were collected. Descriptive statistics were calculated.

RESULTS

Eight patients (mean age 55.8 y) met our inclusion criteria. Wounds were located in the scalp (n=2, 25%), mandible (n=2, 25%), upper eyelid (n=1, 12.5%), cheek (n=1, 12.5%), nose (n=1, 12.5%), or neck (n=1, 12.5%). The depth of the wound extended from the skin to the subcutaneous tissue (n=1, 12.5%), muscle (n=2, 25%), bone (n=3, 37.5%), and/or cartilage (n=1, 12.5%). The mean wound diameter was 47.9 cm 2 (range 17-85 cm 2 ). Wounds were classified as acute (n=6, 75%) or chronic wounds (n=2, 25%). At 6 months, all patients had achieved complete healing with no need for additional surgical procedures (n=8, 100%) with a mean healing time of 36.5 days (range 14-90 d).

CONCLUSION

Urinary bladder matrix minimize donor-side morbidity, eliminates contraction, and offers a wide range of product sizes to cover a wide range of maxillofacial soft tissue defects in a single-stage manner.

FastSkin® Concept: A Novel Treatment for Complex Acute and Chronic Wound Management

Successful treatments for acute and chronic skin wounds remain challenging. The goal of this proof-of-concept study was to assess the technical feasibility and safety of a novel wound treatment solution, FastSkin®, in a pig model. FastSkin® was prepared from skin micrografts patterned in blood using acoustic waves. Upon coagulation, the graft was transferred on a silicone sheet and placed on wounds. Six full-thickness wounds were created at the back of two pigs and treated with either FastSkin®, split-thickness skin graft (positive control), a gauze coverage (negative control, NC1), or blood patterned without micrografts (negative control, NC2). Silicone sheets were removed after 7, 14, and 21 days. Wound healing was monitored for six weeks and evaluated macroscopically for re-epithelialization and morphometrically for residual wound area and wound contraction. Tissue regeneration was assessed with histology after six weeks. Re-epithelialization was faster in wounds covered with FastSkin® treatments compared to NC2 and in NC2 compared to NC1. Importantly, an enhanced collagen organization was observed in FastSkin® in contrast to NC treatments. In summary, two clinically approved skin wound treatments, namely micrografting and blood clot graft, were successfully merged with sound-induced patterning of micrografts to produce an autologous, simple, and biologically active wound treatment concept.

Copper-Epigallocatechin Gallate Enhances Therapeutic Effects of 3D-Printed Dermal Scaffolds in Mitigating Diabetic Wound Scarring

Morbid dermal templates, microangiopathy, and abnormal inflammation are the three most critical reasons for the scarred healing and the high recurrence rate of diabetic wounds. In this present study, a combination of a methacrylated decellularized extracellular matrix (ECMMA, aka EM)-based hydrogel system loaded with copper-epigallocatechin gallate (Cu-EGCG) capsules is proposed to fabricate bio-printed dermal scaffolds for diabetic wound treatment. Copper ions act as a bioactive element for promoting angiogenesis, and EGCG can inhibit inflammation on the wound site. In addition to the above activities, EM/Cu-EGCG (E/C) dermal scaffolds can also provide optimized templates and nutrient exchange space for guiding the orderly deposition and remodeling of ECM. In vitro experiments have shown that the E/C hydrogel can promote angiogenesis and inhibit the polarization of macrophages to the M1 pro-inflammatory phenotype. In the full-thickness skin defect model of diabetic rats, the E/C dermal scaffold combined with split-thickness skin graft transplantation can alleviate pathological scarring via promoting angiogenesis and driving macrophage polarization to the anti-inflammatory M2 phenotype. These may be attributed to the scaffold-actuated expression of angiogenesis-related genes in the HIF-1α/vascular endothelial growth factor pathway and decreased expression of inflammation-related genes in the TNF-α/NF-κB/MMP9 pathway. The results of this study show that the E/C dermal scaffold could serve as a promising artificial dermal analogue for solving the problems of delayed wound healing and reulceration of diabetic wounds.

Personalised burn treatment: bedside electrospun nanofibre scaffold with cultured autologous keratinocytes: a case study

Nearly four decades after cultured epidermal autografts (CEA) were first used for the treatment of extensive burn wounds, the current gold standard treatment remains grafting healthy autologous skin from a donor site to the damaged areas, with current skin substitutes limited in their clinical use. We propose a novel treatment approach, using an electrospun polymer nanofibrous matrix (EPNM) applied on-site directly on the CEA-grafted areas. In addition, we propose a personalised treatment on hard-to-heal areas, in which we spray suspended autologous keratinocytes integrated with 3D EPNM applied on-site, directly onto the wound bed. This method enables the coverage of larger wound areas than possible with CEA. We present the case of a 26-year-old male patient with full-thickness burns covering 98% of his total body surface area (TBSA). We were able to show that this treatment approach resulted in good re-epithelialisation, seen as early as seven days post CEA grafting, with complete wound closure within three weeks, and to a lesser extent in areas treated with cell spraying. Moreover, in vitro experiments confirmed the feasibility of using keratinocytes embedded within the EPNM: cell and culture viability, identity, purity and potency were determined. These experiments show that the skin cells are viable and can proliferate within the EPNM. The results presented are of a promising novel strategy for the development of personalised wound treatment, integrating on-the-spot 'printed' EPNM with autologous skin cells, which will be applied at the bedside, over deep dermal wounds, to accelerate healing time and wound closure.

The use of xenogenic dermal matrices in the context of open extremity wounds: where and when to consider?

Optimal treatment of orthopaedic extremity trauma includes meticulous care of both bony and soft tissue injuries. Historically, clinical scenarios involving soft tissue defects necessitated the assistance of a plastic surgeon. While their expertise in coverage options and microvascular repair is invaluable, barriers preventing collaboration are common. Acellular dermal matrices represent a promising and versatile tool for orthopaedic trauma surgeons to keep in their toolbox. These biological scaffolds are each unique in how they are used and promote healing. This review explores some commercial products and offers guidance for selection in different clinical scenarios involving traumatic wounds.

Statistical study of clinical trials with stem cells and their function in skin wound

Mesenchymal stem cells (MSCs) have been known as a reliable and effective source to repair damaged tissues. The differentiation and self-renewal ability, easy access, immune system modulation capability, and important role in the process of repairing wounds have caused using these cells extensively in wound healing. In this review study, the role of MSCs is debated about different diseases especially in repairing skin wounds. This review article was obtained from 75 basic and trial articles on the PubMed, Google Scholar, and Clinical Trials databases between 2000 and 2022. MSCs are capable of migrating to the wound site and are effective in all stages of wound healing. These cells differentiate into skin cells and also inhibit inflammatory responses, proliferation, and differentiation cells through paracrine messages. They stimulate locally resident precursors, leading to angiogenesis, epithelial regeneration, and granular tissue formation. During maturation stages, these cells decrease fibrosis tissue formation and wound contraction and increase collagen expression and wound tensile strength. The molecular factors of the lesion site change function of these cells and cause MSCs to create a wound healing microenvironment instead of a fibrotic microenvironment. Currently, significant advances have been achieved in the delivery of MSCs to wound sites. These cells are injected intravenously or intradermally, with or without a scaffold. They are also used in the form of spray or hydrogels. Furthermore, the extracellular vesicles and the synergistic environment of these cells alone are effective. Forthcoming studies could lead to more effective treatment strategies for the use of MSCs in wound healing.

Functionalised-biomatrix for wound healing and cutaneous regeneration: future impactful medical products in clinical translation and precision medicine

Skin tissue engineering possesses great promise in providing successful wound injury and tissue loss treatments that current methods cannot treat or achieve a satisfactory clinical outcome. A major field direction is exploring bioscaffolds with multifunctional properties to enhance biological performance and expedite complex skin tissue regeneration. Multifunctional bioscaffolds are three-dimensional (3D) constructs manufactured from natural and synthetic biomaterials using cutting-edge tissue fabrication techniques incorporated with cells, growth factors, secretomes, antibacterial compounds, and bioactive molecules. It offers a physical, chemical, and biological environment with a biomimetic framework to direct cells toward higher-order tissue regeneration during wound healing. Multifunctional bioscaffolds are a promising possibility for skin regeneration because of the variety of structures they provide and the capacity to customise the chemistry of their surfaces, which allows for the regulated distribution of bioactive chemicals or cells. Meanwhile, the current gap is through advanced fabrication techniques such as computational designing, electrospinning, and 3D bioprinting to fabricate multifunctional scaffolds with long-term safety. This review stipulates the wound healing processes used by commercially available engineered skin replacements (ESS), highlighting the demand for a multifunctional, and next-generation ESS replacement as the goals and significance study in tissue engineering and regenerative medicine (TERM). This work also scrutinise the use of multifunctional bioscaffolds in wound healing applications, demonstrating successful biological performance in the in vitro and in vivo animal models. Further, we also provided a comprehensive review in requiring new viewpoints and technological innovations for the clinical application of multifunctional bioscaffolds for wound healing that have been found in the literature in the last 5 years.

Engineering Immunomodulatory Biomaterials to Drive Skin Wounds toward Regenerative Healing

The healing of human skin wounds is designed for a rapid fibroproliferative response at the expense of tissue complexity and is therefore prone to scar formation. Moreover, wound healing often goes awry when excessive inflammation leads to chronic nonhealing wounds or when excessive repair results in uncontrolled tissue fibrosis. The immune system plays a central role in orchestrating wound healing, and, thus, controlling immune cell activities holds great potential for reducing scars and enhancing regeneration. Biomaterial dressings directly interact with immune cells in the wound and have been shown to improve the repair process. A few studies have even shown that biomaterials can induce complete regeneration through mechanisms involving immune cells. Here, we review the role of the immune system in skin repair and regeneration and describe how advances in biomaterial research may uncover immunomodulatory elements to enhance fully functional skin regeneration.

Single-stage transplantation combined with epidermal stem cells promotes the survival of tissue-engineered skin by inducing early angiogenesis

BACKGROUND

The composite transplantation of a split-thickness skin graft (STSG) combined with an acellular dermal matrix (ADM) is a promising repair method for full-thickness skin defects. Due to delayed vascularization of the ADM, no currently available engineered skin tissue is able to permanently cover full-thickness skin defects via a single-stage procedure. Epidermal stem cells (EpSCs) have been found to promote angiogenesis in the wound bed. Whether EpSCs can induce early angiogenesis of dermal substitutes and promote the survival of single-stage tissue-engineered skin transplantation needs to be further studied.

METHODS

In vitro, rat vascular endothelial cells (RVECs) were treated with the supernatant of EpSCs cultured in ADM and stimulated for 48 h. RVECs were analysed by RNA sequencing and tube formation assays. For the in vivo experiment, 75 rats were randomly divided into five groups: ADM, ADM + EpSCs (AE), STSG, ADM + STSG (AS), and ADM + STSG + EpSCs (ASE) groups. The quality of wound healing was estimated by general observation and H&E and Masson staining. The blood perfusion volume was evaluated using the LDPI system, and the expression of vascular markers was determined by immunohistochemistry (IHC).

RESULTS

The active substances secreted by EpSCs cultured in ADM promoted angiogenesis, as shown by tube formation experiments and RNA-seq. EpSCs promoted epithelialization of the ADM and vascularization of the ADM implant. The ASE group showed significantly increased skin graft survival, reduced skin contraction, and an improved cosmetic appearance compared with the AS group and the STSG control group.

CONCLUSIONS

In summary, our findings suggest that EpSCs promote the formation of new blood vessels in dermal substitutes and support one-step transplantation of tissue-engineered skin, and thereby provide new ideas for clinical application.

Engineered multi-functional, pro-angiogenic collagen-based scaffolds loaded with endothelial cells promote large deep burn wound healing

The lack of vascularization associated with deep burns delays the construction of wound beds, increases the risks of infection, and leads to the formation of hypertrophic scars or disfigurement. To address this challenge, we have fabricated a multi-functional pro-angiogenic molecule by grafting integrin αvβ3 ligand LXW7 and collagen-binding peptide (SILY) to a dermatan sulfate (DS) glycosaminoglycan backbone, named LXW7-DS-SILY (LDS), and further employed this to functionalize collagen-based Integra scaffolds. Using a large deep burn wound model in C57/BLK6 mice (8-10 weeks old, 26-32g, n = 39), we demonstrated that LDS-modified collagen-based Integra scaffolds loaded with endothelial cells (ECs) accelerate wound healing rate, re-epithelialization, vascularization, and collagen deposition. Specifically, a 2 cm × 3 cm full-thickness skin burn wound was created 48 h after the burn, and then wounds were treated with four groups of different dressing scaffolds, including Integra + ECs, Integra + LDS, and Integra + LDS + ECs with Integra-only as the control. Digital photos were taken for wound healing measurement on post-treatment days 1, 7, 14, 21, 28, and 35. Post-treatment photos revealed that treatment with the Intgera + LDS + ECs scaffold exhibited a higher wound healing rate in the proliferation phase. Histology results showed significantly increased re-epithelialization, increased collagen deposition, increased thin and mixed collagen fiber content, increased angiogenesis, and shorter wound length within the Integra + LDS + ECs group at Day 35. On Day 14, the Integra + LDS + ECs group showed the same trend. The relative proportions of collagen changed from Day 14 to Day 35 in the Integra + LDS + ECs and Integra + ECs groups demonstrated decreased thick collagen fiber deposition and greater thin and mixed collagen fiber deposition. LDS-modified Integra scaffolds represent a promising novel treatment to accelerate deep burn wound healing, thereby potentially reducing the morbidity associated with open burn wounds. These scaffolds can also potentially reduce the need for autografting and morbidity in patients with already limited areas of harvestable skin.

Tissue Engineering-Based Strategies for Diabetic Foot Ulcer Management

Significance: Diabetic foot ulcers (DFU) are a mounting problem with the increasingly frail population. Injuries that would otherwise heal are kept open by risk factors such as diabetes, obesity, and age-related conditions, which interferes with the natural wound healing processes. Recent Advances: This review summarizes recent advancements in the field of tissue engineering for the treatment of DFUs. FDA-approved approaches, including signaling-based therapies, stem cell therapies, and skin substitutes are summarized and cutting-edge experimental technologies that have the potential to manage chronic wounds, such as skin printing, skin organogenesis, skin self-assembly, and prevascularization, are discussed. Critical Issues: The standard of care for chronic wounds involves wound debridement, wound dressings, and resolving the underlying cause such as lowering the glycemic index and reducing wound pressure. Current DFU treatments are limited by low wound closure rates and poor regrown skin quality. New adjuvant therapies that facilitate wound closure in place of or in conjunction with standard care are critically needed. Future Directions: Tissue engineering strategies are limited by the plasticity of adult human cells. In addition to traditional techniques, genetic modification, although currently an emerging technology, has the potential to unlock human regeneration and can be incorporated in future therapeutics.

Preparation of laser microporous porcine acellular dermal matrix and observation of wound transplantation

To prepare a new type of porcine acellular dermis matrix (PADM) with the new laser microporous technique and verify its safety and feasibility. A novel porcine acellular dermis matrix (ADM) was prepared by using sequential combined decellularization of trypsin, neutral protease and SDS solution method and fully rinsed with ultrasonic wave. Specific laser microporous technology was used to prepare the laser micropore porcine acellular dermal matrix (LPADM). SD rats were chose as the animal models and autologous skin was transplanted by one-step method to observe and detect the graft activity, immunogenicity and vascularization degree of the novel PADM. A porcelain white, shiny, soft and elastic dermal matrix was prepared in this study, the results showed low DNA residue and low cytotoxicity. HE staining and SEM observation revealed that the PADM had neither residual cells nor cell fragments, while the collagen bundles were intact and orderly arranged. All the SD rats survived. No infection or skin allergy was found after surgery. None of the animals lost weight. Histological examination showed that the LPADM was fully vascularized with little tissue destruction in the experiment group. Immunohistochemical staining for CD31 showed ideal vascularization in the experiment group, and immunohistochemical staining for TNF-α showed there were no statistical significance of inflammatory reaction in both groups. This study demonstrated that the novel PADM prepared by sequential combined decellularization of trypsin, neutral protease and SDS solution method and new laser microporous technique was effective and safe in animal transplantation.

Biomaterials Based on Chitosan and Polyvinyl Alcohol as a Drug Delivery System with Wound-Healing Effects

The excellent biological properties of chitosan (CS) together with the increased oxygen permeability of polyvinyl alcohol (PVA) were the prerequisites for the creation of a wound healing dressing that would also function as a system for L-arginine (L-arg) and caffeine (Caff) delivery. Using the freezing/thawing method, 12 hydrogels were obtained in PVA:CS polymer ratios of 90:10, 75:25, and 60:40, and all were loaded with L-arg, Caff, and the mixture of L-arg and Caff, respectively. Afterwards, an inorganic material (zeolite-Z) was added to the best polymeric ratio (75:25) and loaded with active substances. The interactions between the constituents of the hydrogels were analyzed by FTIR spectroscopy, the uniformity of the network was highlighted by the SEM technique, and the dynamic water vapor sorption capacity was evaluated. In the presence of the inorganic material, the release profile of the active substances is delayed, and in vitro permeation kinetics proves that the equilibrium state is not reached even after four hours. The synergy of the constituents in the polymer network recommends that they be used in medical applications, such as wound healing dressings.

Influence of advanced wound matrices on observed vacuum pressure during simulated negative pressure wound therapy

Biomaterials and negative pressure wound therapy (NPWT) are treatment modalities regularly used together to accelerate soft-tissue regeneration. This study evaluated the impact of the design and composition of commercially available collagen-based matrices on the observed vacuum pressure delivered under NPWT using a custom test apparatus. Specifically, testing compared the effect of the commercial products; ovine forestomach matrix (OFM), collagen/oxidized regenerated cellulose (collagen/ORC) and a collagen-based dressing (CWD) on the observed vacuum pressure. OFM resulted in an ∼50% reduction in the observed target vacuum pressure at 75 mmHg and 125 mmHg, however, this effect was mitigated to a ∼0% reduction when fenestrations were introduced into the matrix. Both collagen/ORC and CWD reduced the observed vacuum pressure at 125 mmHg (∼15% and ∼50%, respectively), and this was more dramatic when a lower vacuum pressure of 75 mmHg was delivered (∼20% and ∼75%, respectively). The reduced performance of the reconstituted collagen products is thought to result from the gelling properties of these products that may cause occlusion of the delivered vacuum to the wound bed. These findings highlight the importance of in vitro testing to establish the impact of adjunctive therapies on NPWT, where effective delivery of vacuum pressure is paramount to the efficacy of this therapy.

A Comprehensive Review on Bio-Based Materials for Chronic Diabetic Wounds

Globally, millions of people suffer from poor wound healing, which is associated with higher mortality rates and higher healthcare costs. There are several factors that can complicate the healing process of wounds, including inadequate conditions for cell migration, proliferation, and angiogenesis, microbial infections, and prolonged inflammatory responses. Current therapeutic methods have not yet been able to resolve several primary problems; therefore, their effectiveness is limited. As a result of their remarkable properties, bio-based materials have been demonstrated to have a significant impact on wound healing in recent years. In the wound microenvironment, bio-based materials can stimulate numerous cellular and molecular processes that may enhance healing by inhibiting the growth of pathogens, preventing inflammation, and stimulating angiogenesis, potentially converting a non-healing environment to an appropriately healing one. The aim of this present review article is to provide an overview of the mechanisms underlying wound healing and its pathophysiology. The development of bio-based nanomaterials for chronic diabetic wounds as well as novel methodologies for stimulating wound healing mechanisms are also discussed.

Burn Wound Bed Management

Critical to the success of modern burn care is the management of the burn wound. Timely and complete removal of nonviable tissue is complicated by the irreplaceable nature of the tissue lost either through the burn injury or as "collateral damage" as part of the treatment. Challenges in distinguishing between viable and nonviable tissue and "replacing the irreplaceable" are discussed alongside potential disruptive technologies which could fundamentally change how burn care is delivered. Advances in burn wound bed management forms the foundation on which the goal of zero preventable death and disability after burn injury can be achieved.

A critical review on starch-based electrospun nanofibrous scaffolds for wound healing application

Starch-based nanofibrous scaffolds exhibit a potential wound healing processes as they are cost-effective, flexible, and biocompatible. Recently, natural polymers have received greater importance in regenerative medicine, mainly in the process of healing wounds and burns due to their unique properties which also include safety, biocompatibility, and biodegradability. In this respect, starch is considered to be one of the reliable natural polymers to promote the process of wound healing at a significantly faster rate. Starch and starch-based electrospun nanofibrous scaffolds have been used for the wound healing process which includes the process of adhesion, proliferation, differentiation, and regeneration of cells. It also possesses significant activity to encapsulate and deliver biomaterials at a specific site which persuades the wound healing process at an increased rate. As the aforementioned scaffolds mimic the native extracellular matrix more closely, may help in the acceleration of wound closure, which in turn may lead to the promotion of tissue reorganization and remodeling. In-depth knowledge in understanding the properties of nanofibrous scaffolds paves a way to unfold novel methods and therapies, also to overcome challenges associated with wound healing. This review is intended to provide comprehensive information and recent advances in starch-based electrospun nanofibrous scaffolds for wound healing.

Nrf2 Mediated Heme Oxygenase-1 Activation Contributes to Diabetic Wound Healing - an Overview

Diabetic wound healing is a complicated procedure because hyperglycemia changes the various stages of wound healing. In type 2 diabetes mellitus (T2DM), oxidative stress is proven to be a critical factor in causing non-healing wounds and aggravating the inflammatory phase, resulting in the amputation of lower limbs in T2DM patients. This makes scientists figure out how to control oxidative stress and chronic inflammation at the molecular level. Nuclear factor erythroid 2- related factor 2 (Nrf2) releases antioxidant proteins to suppress reactive oxygen species (ROS) activation and inflammation. The current review discusses the role of Nrf2 in improving diabetic wound healing by reducing the production of ROS and thus reducing oxidative stress, as well as inhibiting nuclear factor kappa B (NF-kB) dissociation and nuclear translocation, which prevents the release of inflammatory mediators and increases antioxidant protein levels, thereby improving diabetic wound healing. As a result, the researcher will be able to find a more effective diabetic wound healing therapy.

Comparison of three different skin substitutes in promoting wound healing in an ovine model

Skin substitutes are designed dressings intended to promote wound closure. In previous in vitro and in vivo studies on small animal, an acellular skin patch made of collagen hydrogel with dermal fibroblast conditioned medium (Col-DFCM), a collagen sponge scaffold with freshly harvested skin cells (OTC), and a platelet-rich-plasma gel with freshly harvested skin cells (PRP) have been developed and tested for immediate treatment of full-thickness wound. However, to determine the safety and efficacy of these skin patches for clinical applications, further study in a large animal model is needed. The aim of this study is to evaluate the potential of Col-DFCM, OTC and PRP in treating full-thickness wound in an ovine model via histological analysis and immunohistochemistry staining were performed, with the untreated (NT) group serving as the control. Gross examination was conducted on day 7, 14 and 21 to determine the wound closure rate. The findings of percentage of wound size reduction showed that the wound healed fastest in the presence of Col-DFCM (91.34 ± 23.35%) followed by OTC (84.49 ± 23.13%), PRP (77.73 ± 20.9%) and NT group (73.94 ± 23.71%). Histological evaluation with Hematoxylin & Eosin (H & E) and Masson's trichrome staining was used to study the structure of the wound area. The results showed that OTC treated wound was more mature as indicated by the presence of a thinner epidermis followed by the Col-DFCM, PRP and NT group. Immunohistochemistry analysis also confirmed the integrity and maturity of the regenerated skin, with positive expression of cytokeratin 10 (CK10) and involucrin in the epidermal layer. In conclusion, Col-DFCM, OTC and PRP treatments promote healing of full-thickness wound and have the potential to be used clinically for rapid treatment of full-thickness wound.

The degradation of gelatin/alginate/fibrin hydrogels is cell type dependent and can be modulated by targeting fibrinolysis

In tissue engineering, cell origin is important to ensure outcome quality. However, the impact of the cell type chosen for seeding in a biocompatible matrix has been less investigated. Here, we investigated the capacity of primary and immortalized fibroblasts of distinct origins to degrade a gelatin/alginate/fibrin (GAF)-based biomaterial. We further established that fibrin was targeted by degradative fibroblasts through the secretion of fibrinolytic matrix-metalloproteinases (MMPs) and urokinase, two types of serine protease. Finally, we demonstrated that besides aprotinin, specific targeting of fibrinolytic MMPs and urokinase led to cell-laden GAF stability for at least forty-eight hours. These results support the use of specific strategies to tune fibrin-based biomaterials degradation over time. It emphasizes the need to choose the right cell type and further bring targeted solutions to avoid the degradation of fibrin-containing hydrogels or bioinks.

Design of 3D Hybrid Plant Extract/Marine and Bovine Collagen Matrixes as Potential Dermal Scaffolds for Skin Wound Healing

Tissue engineering involves the use of smart biomimetic hybrid matrices to reinforce the cellular interaction with the matrix and restore native properties after regeneration. In this study, we highlight the potential of 3D collagen sponges soaked with bioactive extract, to enhance the wound healing process in vivo. Acid-soluble collagen from two sources, marine and bovine, were extracted and characterized physiochemically using Fourier transform infrared spectroscopy (FTIR) and SDS-PAGE. Our results confirmed that the extracted collagens were mainly composed of collagen type I with slight molecular structure differences. Both collagens present two different α chains (α1 and α2) and one β chain. Highly interconnected 3D scaffolds from collagen from the skin are designed and added by the widely known healing plants Pistacia lentiscus and Calendula officinalis. The resulting 3D collagen matrices possess fine biocompatibility with skin cells, Hacat (keratinocytes), and 3T3-L1 (fibroblasts) cells. To evaluate the potential wound healing effect, a collagen sponge soaked with the bioactive extract was tested on BALB/c mice. Our findings confirmed that sponges significantly improve animal re-epithelialization by increasing wound closure. Consequently, spongy collagen scaffolds loaded with Pistacia lentiscus and Calendula officinalis could be used as potential wound dressing material.

Fabricating a Novel Three-Dimensional Skin Model Using Silica Nonwoven Fabrics (SNF)

Silica nonwoven fabrics (SNF) prepared using electrospinning have high biocompatibility, thermal stability, and porosity that allows growing three-dimensional culture of cells. In this study, we used SNF to construct a three-dimensional artificial skin model consisting of epidermal and dermal layers with immortalized and primary human cell lines, creating a novel model that minimizes tissue shrinkage. As a result, SNF dermal/epidermal models have enhanced functions in the basement membrane, whereas Collagen dermal/epidermal models have advantages in keratinization and barrier functions. The SNF dermal/epidermal model with mechanical strength formed a basement membrane mimicking structure, suggesting the construction of a stable skin model. Next, we constructed three-dimensional skin models consisting of SNF and collagen. In the combination models, the expression of genes in the basement membrane was significantly increased compared with that in the Collagen dermal/epidermal model, and the gene for keratinization was increased compared with that in the SNF dermal/epidermal model. We believe that the combination model can be a biomimetic model that takes advantage of both SNF and collagen and can be applied to various basic research. Our new skin model is expected to be an alternative method for skin testing to improve the shrinkage of the collagen matrix gel.

Bioengineered Wound Healing Skin Models: The Role of Immune Response and Endogenous ECM to Fully Replicate the Dynamic of Scar Tissue Formation In Vitro

The healing of deep skin wounds is a complex phenomenon evolving according with a fine spatiotemporal regulation of different biological events (hemostasis, inflammation, proliferation, remodeling). Due to the spontaneous evolution of damaged human dermis toward a fibrotic scar, the treatment of deep wounds still represents a clinical concern. Bioengineered full-thickness skin models may play a crucial role in this direction by providing a deep understanding of the process that leads to the formation of fibrotic scars. This will allow (i) to identify new drugs and targets/biomarkers, (ii) to test new therapeutic approaches, and (iii) to develop more accurate in silico models, with the final aim to guide the closure process toward a scar-free closure and, in a more general sense, (iv) to understand the mechanisms involved in the intrinsic and extrinsic aging of the skin. In this work, the complex dynamic of events underlaying the closure of deep skin wound is presented and the engineered models that aim at replicating such complex phenomenon are reviewed. Despite the complexity of the cellular and extracellular events occurring during the skin wound healing the gold standard assay used to replicate such a process is still represented by planar in vitro models that have been largely used to identify the key factors regulating the involved cellular processes. However, the lack of the main constituents of the extracellular matrix (ECM) makes these over-simplistic 2D models unable to predict the complexity of the closure process. Three-dimensional bioengineered models, which aim at recreating the closure dynamics of the human dermis by using exogenous biomaterials, have been developed to fill such a gap. Although interesting mechanistic effects have been figured out, the effect of the inflammatory response on the ECM remodelling is not replicated yet. We discuss how more faithful wound healing models can be obtained by creating immunocompetent 3D dermis models featuring an endogenous ECM.

Polydopamine modified acellular dermal matrix sponge scaffold loaded with a-FGF: Promoting wound healing of autologous skin grafts

Despite increasing potentials as a skin regeneration template (DRT) to guide tissue healing, acellular dermal matrix (ADM) is still challenged by issues (like dense architecture, low cellular adhesion and poor vascularization), contributing to necrosis and shedding of upper transplanted skins. Modified with polydopamine (PDA), a novel and porous DRT capable of drug delivery was designed using porcine-derived ADM (PADMS) gels, termed PDA-PADMS. However, it was unclear whether it could efficiently deliver human acidic fibroblast growth factor (a-FGF) and regenerate skin defects. Herein, after being fabricated and optimized with PADMS gels in different ratios (1:6, 1:7, 1:8), PDA-PADMS loading a-FGF (PDA-PADMS-FGF) was evaluated by the morphology, physical& chemical properties, drug release and in-vitro biological evaluations, followed by full-thickness skin defects implanted with PDA-PADMS-FGF covered by transplanted skins. Apart from containing abundant collagen and elastin, porous PADMS (with a loose and uniform structure) was demonstrated to possess controlled release of a-FGF and biocompatibility attributed to PDA coating. Consistent with augmented cellular migration and proliferation in vitro, PDA-PADMS-FGF also accelerated wound healing and reduced scarring, improving collagen arrangement and neovascularization. In conclusion, PDA-PADMS-FGF has a good potential and application prospect as a matrix material for wound repair.

Managing Wound Healing with a High-Risk Patient: A Case Report

Wound healing is a complex, multi-step process. This process begins immediately after skin damage. The outcome of wound healing depends on the quality of each stage of this process: a normal or pathological scar. Violation of wound healing entails a decrease in the function of scar tissue as well as aesthetic dissatisfaction with the patient. This problem is especially important in aesthetic surgery. Patients who have come for beauty feel frustration, obtaining pathological scars. We have been dealing with the problem of wound healing after plastic surgery for about 10 years. Our approach includes the assessment of the risk of pathological wound healing and the treatment of high-risk patients. The risk assessment includes historical data on wound healing, signs of connective tissue dysfunction (especially patients with connective tissue dysplasia), and genetic polymorphisms of genes responsible for the structure of the components of the extracellular matrix of the skin. In the future, patients with a high risk of pathological scarring can be prescribed treatment after surgery. This article presents a clinical case in which we demonstrate our approach.

Clinical applications of acellular dermal matrices: A review

INTRODUCTION

The extracellular matrix (ECM) plays an integral role in wound healing. It provides both structure and growth factors that allow for the organised cell proliferation. Large or complex tissue defects may compromise host ECM, creating an environment that is unfavourable for the recovery of anatomical function and appearance. Acellular dermal matrices (ADMs) have been developed from a variety of sources, including human (HADM), porcine (PADM) and bovine (BADM), with multiple different processing protocols. The objective of this report is to provide an overview of current literature assessing the clinical utility of ADMs across a broad spectrum of applications.

METHODS

PubMed, MEDLINE, EMBASE, Scopus, Cochrane and Web of Science were searched using keywords 'acellular dermal matrix', 'acellular dermal matrices' and brand names for commercially available ADMs. Our search was limited to English language articles published from 1999 to 2020 and focused on clinical data.

RESULTS

A total of 2443 records underwent screening. After removing non-clinical studies and correspondence, 222 were assessed for eligibility. Of these, 170 were included in our synthesis of the literature. While the earliest ADMs were used in severe burn injuries, usage has expanded to a number of surgical subspecialties and procedures, including orthopaedic surgery (e.g. tendon and ligament reconstructions), otolaryngology, oral surgery (e.g. treating gingival recession), abdominal wall surgery (e.g. hernia repair), plastic surgery (e.g. breast reconstruction and penile augmentation), and chronic wounds (e.g. diabetic ulcers).

CONCLUSION

Our understanding of ADM's clinical utility continues to evolve. More research is needed to determine which ADM has the best outcomes for each clinical scenario.

LAY SUMMARY

Large or complex wounds present unique reconstructive and healing challenges. In normal healing, the extracellular matrix (ECM) provides both structural and growth factors that allow tissue to regenerate in an organised fashion to close the wound. In difficult or large soft-tissue defects, however, the ECM is often compromised. Acellular dermal matrix (ADM) products have been developed to mimic the benefits of host ECM, allowing for improved outcomes in a variety of clinical scenarios. This review summarises the current clinical evidence regarding commercially available ADMs in a wide variety of clinical contexts.

The Role of Extracellular Matrix in Skin Wound Healing

Impaired wound healing is one of the unsolved problems of modern medicine, affecting patients’ quality of life and causing serious economic losses. Impaired wound healing can manifest itself in the form of chronic skin wounds or hypertrophic scars. Research on the biology and physiology of skin wound healing disorders is actively continuing, but, unfortunately, a single understanding has not been developed. The attention of clinicians to the biological and physiological aspects of wound healing in the skin is necessary for the search for new and effective methods of prevention and treatment of its consequences. In addition, it is important to update knowledge about genetic and non-genetic factors predisposing to impaired wound healing in order to identify risk levels and develop personalized strategies for managing such patients. Wound healing is a very complex process involving several overlapping stages and involving many factors. This thematic review focuses on the extracellular matrix of the skin, in particular its role in wound healing. The authors analyzed the results of fundamental research in recent years, finding promising potential for their transition into real clinical practice.

An overview on the manufacturing of functional and mature cellular skin substitutes

There are different types of skin diseases due to chronic injuries that impede the natural healing process of the skin. Tissue engineering (TE) has focused on the development of bioengineered skin or skin substitutes that cover the wound, providing the necessary care to restore the functionality of injured skin. There are two types of substitutes: acellular skin substitutes (ASSs), which offer a low response of the body, and cellular skin substitutes (CSSs), which incorporate living cells and appear as a great alternative in the treatment of skin injuries due to them presenting a greater interaction and integration with the rest of the body. For the development of a CSS, it is necessary to select the most suitable biomaterials, cell components, and methodology of biofabrication for the wound to be treated. Moreover, these CSSs are immature substitutes that must undergo a maturing process in specific bioreactors, guaranteeing their functionality. The bioreactor simulates the natural state of maturation of the skin by controlling parameters such as temperature, pressure, or humidity, allowing a homogeneous maturation of the CSSs in an aseptic environment. The use of bioreactors not only contributes to the maturation of the CSSs, but also offers a new way of obtaining large sections of skin substitutes or natural skin from small portions acquired from the patient, donor, or substitute. Based on the innovation of this technology and the need to develop efficient CSSs, this work offers an update on bioreactor technology in the field of skin regeneration.

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.

Evaluation of a novel tilapia-skin acellular dermis matrix rationally processed for enhanced wound healing

Acellular Dermal Matrix (ADM) is mainly made with human or porcine skins and has the risk of zoonotic virus transmission. The fish skin-derived ADM could overcome the shortcoming. Fish skin acellular matrix has been used as wound dressing, but there is few systematic studies on tilapia-skin acellular dermal matrix (TS-ADM). In the present study, a novel TS-ADM was made by an alkaline decellularization process and γ-irradiation. The physical properties, biocompatibility, pre-clinical safety and wound healing activity of TS-ADM were systematically evaluated for its value as a functionally bioactive wound dressing. Histopathological analysis (hematoxylin and eosin staining, 4,6-diamidino-2-phenylindole (DAPI) staining) and DNA quantification both proved that the nuclear components of tilapia skin were removed sufficiently in TS-ADM. Compared to the commercial porcine acellular dermal matrix (DC-ADM), TS-ADM has distinctive features in morphology, thermal stability, degradability and water vapor transmission. TS-ADM was more readily degradable than DC-ADM in vitro and in vivo. In both rat and mini-pig skin wound healing experiments, TS-ADM was shown to significantly promote granulation growth, collagen deposition, angiogenesis and re-epithelialization, which may be attributed to the high expression of transforming growth factor-beta 1 (TGF-β1), alpha-smooth muscle actin (α-SMA) and CD31. Herein, the novel TS-ADM, used as a low-cost bioactive dressing, could form a microenvironment conducive to wound healing.

A Prototype Skin Substitute, Made of Recycled Marine Collagen, Improves the Skin Regeneration of Sheep

Simple Summary

Marine ecosystems are a huge source of unexplored “blue” materials for different applications. The edible part of sea urchin is limited, and the vast majority of the product ends up as waste. Our studies intend to fully recycle wastes from the food industry and reconvert them in high added-value products, as innovative biocompatible skin substitutes for tissue regeneration. The aim of the present work is to apply the pioneering skin substitute in in vivo experimental wounds to test its regenerative potential and compare it, in a future study, to the available commercial membranes produced with collagen of bovine, porcine, and equine origin. Results are encouraging since the skin substitute made with marine collagen reduced inflammation, promoted the deposition of granulation tissue, and enhanced a proper re-epithelialization with the adequate development of skin appendages. In summary, our findings might be of great interest for processing industries and biotech companies which transform waste materials in high-valuable and innovative products for Veterinary advanced applications.

Abstract

Skin wound healing is a complex and dynamic process that aims to restore lesioned tissues. Collagen-based skin substitutes are a promising treatment to promote wound healing by mimicking the native skin structure. Recently, collagen from marine organisms has gained interest as a source for producing biomaterials for skin regenerative strategies. This preliminary study aimed to describe the application of a collagen-based skin-like scaffold (CBSS), manufactured with collagen extracted from sea urchin food waste, to treat experimental skin wounds in a large animal. The wound-healing process was assessed over different time points by the means of clinical, histopathological, and molecular analysis. The CBSS treatment improved wound re-epithelialization along with cell proliferation, gene expression of growth factors (VEGF-A), and development of skin adnexa throughout the healing process. Furthermore, it regulated the gene expression of collagen type I and III, thus enhancing the maturation of the granulation tissue into a mature dermis without any signs of scarring as observed in untreated wounds. The observed results (reduced inflammation, better re-epithelialization, proper development of mature dermis and skin adnexa) suggest that sea urchin-derived CBSS is a promising biomaterial for skin wound healing in a “blue biotechnologies” perspective for animals of Veterinary interest.

Recent Advances in the Design of Three-Dimensional and Bioprinted Scaffolds for Full-Thickness Wound Healing

Three-dimensional (3D) printed scaffolds have recently emerged as an innovative treatment option for patients with critical-sized skin wounds. Current approaches to managing life-threatening wounds include skin grafting and application of commercially sourced skin substitutes. However, these approaches are not without several challenges. Limited donor tissue and donor site morbidity remain a concern for tissue grafting, while engineered skin substitutes fail to fully recapitulate the complex native environment required for wound healing. The implementation of 3D printed dermal scaffolds offers a potential solution for these shortcomings. Spatial control over scaffold structure, the ability to incorporate multiple materials and bioactive ingredients, enables the creation of conditions specifically optimized for wound healing. Three-dimensional bioprinting, a subset of 3D printing, allows for the replacement of lost cell populations and secreted active compounds that contribute to tissue repair and recovery. The replacement of damaged and lost cells delivers beneficial effects directly, or synergistically, supporting injured tissue to recover its native state. Despite encouraging results, the promise of 3D printed scaffolds has yet to be realized. Further improvements to current material formulations and scaffold designs are required to achieve the goal of clinical adoption. Herein, we provide an overview of 3D printing techniques and discuss several strategies for healing of full-thickness wounds by using 3D printed acellular scaffolds or bioprinted cellular scaffolds, aimed at translating this technology to the clinical management of skin lesions. We identify the challenges associated with designing and optimizing printed tissue replacements, and discuss the future perspectives of this emerging option for managing patients who present with critical-sized life-threatening cutaneous wounds.

Combined adipose mesenchymal stromal cell advanced therapy resolved a recalcitrant leg ulcer in an 85-year-old patient

Venous leg ulcers (VLU) represent an uphill economic, health and social burden, aggravated in the elderly. Best-practice care interventions are often insufficient and alternative therapies need to be explored. Herein, we have treated for the first time a chronic VLU in an elderly patient by combining cell therapy and tissue engineering in the context of a compassionate use. The administration of allogeneic adipose-derived mesenchymal stromal cells (MSCs) embedded in a plasma-based bioengineered dermis covering the ulcer bed and also injected into the ulcer margins led to the complete closure of a 10-year recalcitrant VLU in an 85-year-old patient. Regenerative properties of MSCs might be boosted by the use of bioengineered matrices for their delivery.

Scar-Free Healing: Current Concepts and Future Perspectives

Every year, millions of people develop scars due to skin injuries after trauma, surgery, or skin burns. From the beginning of wound healing development, scar hyperplasia, and prolonged healing time in wound healing have been severe problems. Based on the difference between adult and fetal wound healing processes, many promising therapies have been developed to decrease scar formation in skin wounds. Currently, there is no good or reliable therapy to cure or prevent scar formation. This work briefly reviews the engineering methods of scarless wound healing, focusing on regenerative biomaterials and different cytokines, growth factors, and extracellular components in regenerative wound healing to minimize skin damage cell types, and scar formation.