Biomaterials and tissue engineering for scar management in wound care

Integration of Melt Electrowritten Polymeric Scaffolds and Bioprinting for Epithelial Healing via Localized Periostin Delivery

Management of skin injuries imposes a substantial financial burden on patients and hospitals, leading to diminished quality of life. Periostin (rhOSF), an extracellular matrix component, regulates cell function, including a proliferative healing phase, representing a key protein to promote wound healing. Despite its proven efficacy in vitro, there is a lack of scaffolds that facilitate the in situ delivery of rhOSF. In addition, there is a need for a scaffold to not only support cell growth, but also to resist the mechanical forces involved in wound healing. In this work, we synthesized rhOSF-loaded mesoporous nanoparticles (MSNs) and incorporated them into a cell-laden gelatin methacryloyl (GelMA) ink that was bioprinted into melt electrowritten poly(ε-caprolactone) (PCL) microfibrous (MF-PCL) meshes to develop mechanically competent constructs. Diffraction light scattering (DLS) analysis showed a narrow nanoparticle size distribution with an average size of 82.7 ± 13.2 nm. The rhOSF-loaded hydrogels showed a steady and controlled release of rhOSF over 16 days at a daily dose of ∼40 ng/mL. Compared with blank MSNs, the incorporation of rhOSF markedly augmented cell proliferation, underscoring its contribution to cellular performance. Our findings suggest a promising approach to address challenges such as prolonged healing, offering a potential solution for developing robust, biocompatible, and cell-laden grafts for burn wound healing applications.

Cocktail Cell-Reprogrammed Hydrogel Microspheres Achieving Scarless Hair Follicle Regeneration

The scar repair inevitably causes damage of skin function and loss of skin appendages such as hair follicles (HF). It is of great challenge in wound repair that how to intervene in scar formation while simultaneously remodeling HF niche and inducing in situ HF regeneration. Here, chemical reprogramming techniques are used to identify a clinically chemical cocktail (Tideglusib and Tamibarotene) that can drive fibroblasts toward dermal papilla cell (DPC) fate. Considering the advantage of biomaterials in tissue repair and their regulation in cell behavior that may contributes to cellular reprogramming, the artificial HF seeding (AHFS) hydrogel microspheres, inspired by the natural processes of "seeding and harvest", are constructed via using a combination of liposome nanoparticle drug delivery system, photoresponsive hydrogel shell, positively charged polyamide modification, microfluidic and photocrosslinking techniques. The identified chemical cocktail is as the core nucleus of AHFS. In vitro and in vivo studies show that AHFS can regulate fibroblast fate, induce fibroblast-to-DPC reprogramming by activating the PI3K/AKT pathway, finally promoting wound healing and in situ HF regeneration while inhibiting scar formation in a two-pronged translational approach. In conclusion, AHFS provides a new and effective strategy for functional repair of skin wounds.

A Printable Hydrogel Loaded with Medicinal Plant Extract for Promoting Wound Healing

How to promote wound healing is still a major challenge in the healthcare while macrophages are a critical component of the healing process. Compared to various bioactive drugs, many plants have been reported to facilitate the wound healing process by regulating the immune response of wounds. In this work, a Three-dimensional (3D) printed hydrogel scaffold loaded with natural Centella asiatica extract (CA extract) is developed for wound healing. This CA@3D scaffold uses gelatin (Gel) and sodium alginate (SA) with CA extract as bio-ink for 3D printing. The CA extract contains a variety of bioactive compounds that make the various active ingredients in Centella asiatica work in concert. The printed CA@3D scaffold can fit the shape of wound, orchestrate the macrophages and immune responses within the wound, and promote wound healing compared to commercial wound dressings. The underlying mechanism of promoting wound healing is also illuminated by applying multi-omic analyses. Moreover, the CA extract loaded 3D scaffold also showed great ability to promote wound healing in diabetic chronic wounds. Due to its ease of preparation, low-cost, biosafety, and therapeutic outcomes, this work proposes an effective strategy for promoting chronic wound healing.

Antifibrotic properties of hyaluronic acid crosslinked polyisocyanide hydrogels

Fibrosis is characterized by the formation of fibrous connective tissue in response to primary injury. As a result, an affected organ may lose part of its functionality due to chronic, organ-specific tissue damage. Since fibrosis is a leading cause of death worldwide, targeting fibrotic diseases with antifibrotic hydrogels can be a lifesaving therapeutic strategy. This study developed a novel hybrid antifibrotic hydrogel by combining the synthetic polyisocyanide (PIC) with hyaluronic acid (HA). Gels of PIC are highly tailorable, thermosensitive, and strongly biomimetic in architecture and mechanical properties, whereas HA is known to promote non-fibrotic fetal wound healing and inhibits inflammatory signaling. The developed HA-PIC hybrids were biocompatible with physical properties comparable to those of the PIC gels. The antifibrotic nature of the gels was assessed by 3D cultures of human foreskin fibroblasts in the presence (or absence as control) of TGFβ1 that promotes differentiation into myofibroblasts, a critical step in fibrosis. Proliferation and macroscopic contraction assays and studies on the formation of stress fibers and characteristic fibrosis markers all indicate a strong antifibrotic nature of HA-PIC hydrogel. We showed that these effects originate from both the lightly crosslinked architecture and the presence of HA itself. The hybrid displaying both these effects shows the strongest antifibrotic nature and is a promising candidate for use as in vivo treatment for skin fibrosis.

Multifunctional and theranostic hydrogels for wound healing acceleration: An emphasis on diabetic-related chronic wounds

Hydrogels represent intricate three-dimensional polymeric structures, renowned for their compatibility with living systems and their ability to naturally degrade. These networks stand as promising and viable foundations for a range of biomedical uses. The practical feasibility of employing hydrogels in clinical trials has been well-demonstrated. Among the prevalent biomedical uses of hydrogels, a significant application arises in the context of wound healing. This intricate progression involves distinct phases of inflammation, proliferation, and remodeling, often triggered by trauma, skin injuries, and various diseases. Metabolic conditions like diabetes have the potential to give rise to persistent wounds, leading to delayed healing processes. This current review consolidates a collection of experiments focused on the utilization of hydrogels to expedite the recovery of wounds. Hydrogels have the capacity to improve the inflammatory conditions at the wound site, and they achieve this by diminishing levels of reactive oxygen species (ROS), thereby exhibiting antioxidant effects. Hydrogels have the potential to enhance the growth of fibroblasts and keratinocytes at the wound site. They also possess the capability to inhibit both Gram-positive and Gram-negative bacteria, effectively managing wounds infected by drug-resistant bacteria. Hydrogels can trigger angiogenesis and neovascularization processes, while also promoting the M2 polarization of macrophages, which in turn mitigates inflammation at the wound site. Intelligent and versatile hydrogels, encompassing features such as pH sensitivity, reactivity to reactive oxygen species (ROS), and responsiveness to light and temperature, have proven advantageous in expediting wound healing. Furthermore, hydrogels synthesized using environmentally friendly methods, characterized by high levels of biocompatibility and biodegradability, hold the potential for enhancing the wound healing process. Hydrogels can facilitate the controlled discharge of bioactive substances. More recently, there has been progress in the creation of conductive hydrogels, which, when subjected to electrical stimulation, contribute to the enhancement of wound healing. Diabetes mellitus, a metabolic disorder, leads to a slowdown in the wound healing process, often resulting in the formation of persistent wounds. Hydrogels have the capability to expedite the healing of diabetic wounds, facilitating the transition from the inflammatory phase to the proliferative stage. The current review sheds light on the biological functionalities of hydrogels, encompassing their role in modulating diverse mechanisms and cell types, including inflammation, oxidative stress, macrophages, and bacteriology. Additionally, this review emphasizes the significance of smart hydrogels with responsiveness to external stimuli, as well as conductive hydrogels for promoting wound healing. Lastly, the discussion delves into the advancement of environmentally friendly hydrogels with high biocompatibility, aimed at accelerating the wound healing process.

Electrospun Fibers Loaded with Pirfenidone: An Innovative Approach for Scar Modulation in Complex Wounds

Hypertrophic scars (HTSs) are pathological structures resulting from chronic inflammation during the wound healing process, particularly in complex injuries like burns. The aim of this work is to propose Biofiber PF (biodegradable fiber loaded with Pirfenidone 1.5 w/w), an electrospun advanced dressing, as a solution for HTSs treatment in complex wounds. Biofiber has a 3-day antifibrotic action to modulate the fibrotic process and enhance physiological healing. Its electrospun structure consists of regular well-interconnected Poly-L-lactide-co-poly-ε-caprolactone (PLA-PCL) fibers (size 2.83 ± 0.46 µm) loaded with Pirfenidone (PF, 1.5% w/w), an antifibrotic agent. The textured matrix promotes the exudate balance through mild hydrophobic wettability behavior (109.3 ± 2.3°), and an appropriate equilibrium between the absorbency % (610.2 ± 171.54%) and the moisture vapor transmission rate (0.027 ± 0.036 g/min). Through its finer mechanical properties, Biofiber PF is conformable to the wound area, promoting movement and tissue oxygenation. These features also enhance the excellent elongation (>500%) and tenacity, both in dry and wet conditions. The ancillary antifibrotic action of PF on hypertrophic scar fibroblast (HSF) for 3 days downregulates the cell proliferation over time and modulates the gene expression of transforming growth factor β1 (TGF-β1) and α-smooth muscle actin (α-SMA) at 48-72 h. After 6 days of treatment, a decrement of α-SMA protein levels was detected, proving the potential of biofiber as a valid therapeutic treatment for HTSs in an established wound healing process.

Smart and versatile biomaterials for cutaneous wound healing

The global increase of cutaneous wounds imposes huge health and financial burdens on patients and society. Despite improved wound healing outcomes, conventional wound dressings are far from ideal, owing to the complex healing process. Smart wound dressings, which are sensitive to or interact with changes in wound condition or environment, have been proposed as appealing therapeutic platforms to effectively facilitate wound healing. In this review, the wound healing processes and features of existing biomaterials are firstly introduced, followed by summarizing the mechanisms of smart responsive materials. Afterwards, recent advances and designs in smart and versatile materials of extensive applications for cutaneous wound healing were submarined. Finally, clinical progresses, challenges and future perspectives of the smart wound dressing are discussed. Overall, by mapping the composition and intrinsic structure of smart responsive materials to their individual needs of cutaneous wounds, with particular attention to the responsive mechanisms, this review is promising to advance further progress in designing smart responsive materials for wounds and drive clinical translation.

Efficient Decellularization of the Full-Thickness Rat-Derived Abdominal Wall to Produce Acellular Biologic Scaffolds for Tissue Reconstruction: Promising Evidence Acquired from In Vitro Results

BACKGROUND

Functional restoration of abdominal wall defects represents one of the fundamental challenges of reconstructive surgery. Synthetic grafts or crosslinked animal-derived biological grafts are characterized by significant adverse reactions, which are mostly observed after their implantation. The aim of this study was to evaluate the efficacy of the decellularization protocol to produce a completely acellular full-thickness abdominal wall scaffold.

METHODS

Full-thickness abdominal wall samples were harvested from Wistar rats and submitted to a three-cycle decellularization process. Histological, biochemical, and DNA quantification analyses were applied to evaluate the effect of the decellularization protocol. Mechanical testing and immunogenicity assessment were also performed.

RESULTS

Histological, biochemical, and DNA analysis results showed efficient decellularization of the abdominal wall samples after the third cycle. Decellularized abdominal wall scaffolds were characterized by good biochemical and mechanical properties.

CONCLUSION

The data presented herein confirm the effective production of a rat-derived full-thickness abdominal wall scaffold. Expanding this approach will allow the exploitation of the capacity of the proposed decellularization protocol in producing acellular abdominal wall scaffolds from larger animal models or human cadaveric donors. In this way, the utility of biological scaffolds with preserved in vivo remodeling properties may be one step closer to its application in clinical studies.

In Vitro Cell Proliferation and Migration Properties of Oral Mucosal Fibroblasts: A Comparative Study on the Effects of Cord Blood- and Peripheral Blood-Platelet Lysate

Cord blood-platelet lysate (CB-PL), containing growth factors such as a platelet-derived growth factor, has a similar efficacy to peripheral blood-platelet lysate (PB-PL) in initiating cell growth and differentiation, which makes it a unique alternative to be implemented into oral ulceration healing. This research study aimed to compare the effectiveness of CB-PL and PB-PL in promoting oral wound closure in vitro. Alamar blue assay was used to determine the optimal concentration of CB-PL and PB-PL in enhancing the proliferation of human oral mucosal fibroblasts (HOMF). The percentage of wound closure was measured using the wound-healing assay for CB-PL and PB-PL at the optimal concentration of 1.25% and 0.3125%, respectively. The gene expressions of cell phenotypic makers (Col. I, Col. III, elastin and fibronectin) were determined via qRT-PCR. The concentrations of PDGF-BB were quantified using ELISA. We found that CB-PL was as effective as PB-PL in promoting wound-healing and both PL were more effective compared to the control (CTRL) group in accelerating the cell migration in the wound-healing assay. The gene expressions of Col. III and fibronectin were significantly higher in PB-PL compared to CB-PL. The PDGF-BB concentration of PB-PL was the highest and it decreased after the wound closed on day 3. Therefore, we concluded that PL from both sources can be a beneficial treatment for wound-healing, but PB-PL showed the most promising wound-healing properties in this study.

New insights into balancing wound healing and scarless skin repair

Scars caused by skin injuries after burns, wounds, abrasions and operations have serious physical and psychological effects on patients. In recent years, the research of scar free wound repair has been greatly expanded. However, understanding the complex mechanisms of wound healing, in which various cells, cytokines and mechanical force interact, is critical to developing a treatment that can achieve scarless wound healing. Therefore, this paper reviews the types of wounds, the mechanism of scar formation in the healing process, and the current research progress on the dual consideration of wound healing and scar prevention, and some strategies for the treatment of scar free wound repair.

Advanced Multifunctional Wound Dressing Hydrogels as Drug Carriers

Skin injuries, especially chronic wounds, remain a significant healthcare system problem. The number of burns, diabetic patients, pressure ulcers, and other damages is also growing, particularly in elderly populations. Several investigations are pursued in designing more effective therapeutics for treating different wound injuries. These efforts have resulted in developing multifunctional wound dressings to improve wound repair. For this, preparing multifunctional dressings using various methods has provided a new attitude to support effective skin regeneration. This review focuses on the recent developments in designing multifunctional hydrogel dressings with hemostasis, adhesiveness, antibacterial, and antioxidant properties.

Rotary Jet Spinning (RJS): A Key Process to Produce Biopolymeric Wound Dressings

Wounds result from different causes (e.g., trauma, surgeries, and diabetic ulcers), requiring even extended periods of intensive care for healing, according to the patient's organism and treatment. Currently, wound dressings generated by polymeric fibers at micro and nanometric scales are promising for healing the injured area. They offer great surface area and porosity, mimicking the fibrous extracellular matrix structure, facilitating cell adhesion, migration, and proliferation, and accelerating the wound healing process. Such properties resulted in countless applications of these materials in biomedical and tissue engineering, also as drug delivery systems for bioactive molecules to help tissue regeneration. The techniques used to engineer these fibers include spinning methods (electro-, rotary jet-), airbrushing, and 3D printing. These techniques have important advantages, such as easy-handle procedure and process parameters variability (type of polymer), but encounter some scalability problems. RJS is described as a simple and low-cost technique resulting in high efficiency and yield for fiber production, also capable of bioactive agents' incorporation to improve the healing potential of RJS wound dressings. This review addresses the use of RJS to produce polymeric fibers, describing the concept, type of configuration, comparison to other spinning techniques, most commonly used polymers, and the relevant parameters that influence the manufacture of the fibers, for the ultimate use in the development of wound dressings.

Decorin mediated biomimetic PCL-gelatin nano-framework to impede scarring

Scars occur as a result of fibrosis after tissue damage or surgery and reports suggest that excessive Transforming growth factor-β (TGF-β) activity during the process of wound healing leads to progressive fibrosis. Decorin is an extracellular matrix (ECM) protein which regulates collagen fibrillogenesis. However, targeted delivery and effective protein therapy remains a challenge owing to degradation byproteases. Hence, we aimed to deliver Decorin in a sustainable mode for the reduction of TGF-β levels and subsequent scar formation. Herein, we have fabricated PCL-Gelatin bio-mimetic scaffolds to optimize the bio-activity and provide localized delivery of recombinant Decorin. The degradation and drug release patterns reveals that this biomaterial is biodegradable and offers sustained release of the recombinant Decorin. Decorin loaded nanofiber displayed lower adhesion and proliferation rates in in-vitro conditions. Moreover, Decorin loaded scaffolds demonstrated morphological changes in cells, specifically targeting the myofibroblast. The expression of TGF-β was also scrutinized to understand the effect of Decorin loaded nanofibers. Besides, in the in-vitro fibrotic model, Decorin loaded nanofibers efficiently reduced the expression of ECM related proteins. Therefore, we report the sustained delivery of the recombinant Decorin from nanofiber dressing to potentially obstruct scar formation during the process of wound healing.

In Vivo Sensing of pH in Tomato Plants Using a Low-Cost and Open-Source Device for Precision Agriculture

The development of sensing devices for precision agriculture is crucial to boost crop yields and limit shortages in food productions due to the growing population. However, current approaches cannot provide direct information about the physiological status of the plants, reducing sensing accuracy. The development of implanted devices for plant monitoring represents a step forward in this field, enabling the direct assessment of key biomarkers in plants. However, available devices are expensive and cannot be used for long-term applications. The current work presents the application of ruthenium oxide-based nanofilms for the in vivo monitoring of pH in plants. The sensors were manufactured using the low-cost electrodeposition of RuO2 films, and the final device could be successfully incorporated for the monitoring of xylem sap pH for at least 10 h. RuO2 nanoparticles were chosen as the sensing material due to its biocompatibility and chemical stability. To reduce the noise rates and drift of the sensors, a protective layer consisting of a cellulose/PDMS hybrid material was deposited by an aerosol method (>GBP 50), involving off-the-shelf devices, leading to a good control of film thickness. Nanometrically thin films with a thickness of 80 nm and roughness below 3 nm were fabricated. This film led to a seven-fold decrease in drift while preserving the selectivity of the sensors towards H+ ions. The sensing devices were tested in vivo by implantation inside a tomato plant. Environmental parameters such as humidity and temperature were additionally monitored using a low-cost Wio Terminal device, and the data were sent wirelessly to an online server. The interactions between plant tissues and metal oxide-based sensors were finally studied, evidencing the formation of a lignified layer between the sensing film and xylem. Thus, this work reports for the first time a low-cost electrochemical sensor that can be used for the continuous monitoring of pH in xylem sap. This device can be easily modified to improve the long-term performance when implanted inside plant tissues, representing a step forward in the development of precision agriculture technologies.

Use of Adipose Stem Cells Against Hypertrophic Scarring or Keloid

Hypertrophic scars or keloid form as part of the wound healing reaction process, and its formation mechanism is complex and diverse, involving multi-stage synergistic action of multiple cells and factors. Adipose stem cells (ASCs) have become an emerging approach for the treatment of many diseases, including hypertrophic scarring or keloid, owing to their various advantages and potential. Herein, we analyzed the molecular mechanism of hypertrophic scar or keloid formation and explored the role and prospects of stem cell therapy, in the treatment of this condition.

Immunomodulation of Skin Repair: Cell-Based Therapeutic Strategies for Skin Replacement (A Comprehensive Review)

The immune system has a crucial role in skin wound healing and the application of specific cell-laden immunomodulating biomaterials emerged as a possible treatment option to drive skin tissue regeneration. Cell-laden tissue-engineered skin substitutes have the ability to activate immune pathways, even in the absence of other immune-stimulating signals. In particular, mesenchymal stem cells with their immunomodulatory properties can create a specific immune microenvironment to reduce inflammation, scarring, and support skin regeneration. This review presents an overview of current wound care techniques including skin tissue engineering and biomaterials as a novel and promising approach. We highlight the plasticity and different roles of immune cells, in particular macrophages during various stages of skin wound healing. These aspects are pivotal to promote the regeneration of nonhealing wounds such as ulcers in diabetic patients. We believe that a better understanding of the intrinsic immunomodulatory features of stem cells in implantable skin substitutes will lead to new translational opportunities. This, in turn, will improve skin tissue engineering and regenerative medicine applications.

Wound Healing: From Passive to Smart Dressings

The universal increase in the number of patients with nonhealing skin wounds imposes a huge social and economic burden on the patients and healthcare systems. Although, the application of traditional wound dressings contributes to an effective wound healing outcome, yet, the complexity of the healing process remains a major health challenge. Recent advances in materials and fabrication technologies have led to the fabrication of dressings that provide proper conditions for effective wound healing. The 3D-printed wound dressings, biomolecule-loaded dressings, as well as smart and flexible bandages are among the recent alternatives that have been developed to accelerate wound healing. Additionally, the new generation of wound dressings contains a variety of microelectronic sensors for real-time monitoring of the wound environment and is able to apply required actions to support the healing progress. Moreover, advances in manufacturing flexible microelectronic sensors enable the development of the next generation of wound dressing substrates, known as electronic skin, for real-time monitoring of the whole physiochemical markers in the wound environment in a single platform. The current study reviews the importance of smart wound dressings as an emerging strategy for wound care management and highlights different types of smart dressings for promoting the wound healing process.

Engineering immune-responsive biomaterials for skin regeneration

The progress of biomaterials and tissue engineering has led to significant advances in wound healing, but the clinical therapy to regenerate perfect skin remains a great challenge. The implantation of biomaterial scaffolds to heal wounds inevitably leads to a host immune response. Many recent studies revealed that the immune system plays a significant role in both the healing process and the outcome. Immunomodulation or immuno-engineering has thus become a promising approach to develop pro-regenerative scaffolds for perfect skin regeneration. In this paper, we will review recent advancements in immunomodulating biomaterials in the field of skin repair and regeneration, and discuss strategies to modulate the immune response by tailoring the chemical, physical and biological properties of the biomaterials. Understanding the important role of immune responses and manipulating the inherent properties of biomaterials to regulate the immune reaction are approaches to overcome the current bottleneck of skin repair and regeneration.

Serum cytokine profile during subcutaneous implantation of the decellularized esophagus matrix in rats

AIM

to study non-specific immune response characteristics (serum cytokine profile) in rats after subcutaneous implantation of the decellularized esophagus matrix.

METHODS

Data were obtained in Wistar rats. The rats underwent subcutaneous implantation of decellularized esophagus (DE) and native allogeneic esophagus (NE). Explantation of sampling were carried out on the 7th, 14th and 21st day of the experiment. Explanted NEs and DEs were processed for histologic examination. The content of IL1α, IL2, IL4, IL17А, TNFα, IFNγ and GM-CSF in serum samples were tested by ELISA.

RESULTS

In rat serum with DEs on the 7th day of the experiment it was significant increase in IL1α level in comparison with control group, IL2, TNFα, IL4 levels did not differ from the control group levels that indicates the stabilization of inflammation. The content of IL17A, IFNγ and GM-CSF significantly decreased compared to control. On the 14th day, IL17A concentration analysis showed a sharp decrease in comparison with the the 7th experimental day. We found decrease in IL1α level vs control group and decrease in IFNγ level vs 7th day. On the 21st experimental day was shown a significant decrease in the IL17A, IFNγ and IL1α content in DE rats.

CONCLUSIONS

It was found dynamic change in studied rat cytokine concentrations that correspond to favourable clinical picture in DE group in comparison with an active inflammatory reaction in NE group. IL1α, IL4, IL17A and IFNγ concentrations reflect positive dynamics of the wound healing process and the absence of local inflammation and rejection of decellularized matrices.

Hyperosmolar potassium inhibits myofibroblast conversion and reduces scar tissue formation

Scar formation is a natural result of almost all wound healing in adult mammals. Unfortunately, scarring disrupts normal tissue function and can cause significant physical and psychological distress. In addition to improving surgical techniques to limit scar formation, several therapies are under development towards the same goal. Many of these treatments aim to disrupt transforming growth factor β1 (TGFβ1) signaling, as this is a critical control point for fibroblast differentiation into myofibroblasts; a contractile cell that organizes synthesized collagen fibrils into scar tissue. The present study aimed to examine the role of hyperosmolar potassium gluconate (KGluc) on fibroblast function in skin repair. KGluc was first determined to negatively regulate fibroblast proliferation, metabolism, and migration in a dose-dependent manner in vitro. Increasing concentrations of KGluc also inhibited differentiation into myofibroblasts, suggesting that local KGluc treatment might reduce fibrosis. KGluc delivery was confirmed via loading into collagen hydrogels and used to treat a full thickness skin wound in mice. KGluc qualitatively slowed initial closure of the wounds and resulted in tissue that more closely resembled mature, healthy skin (epidermal thickness and dermal-epidermal morphology) when compared to unloaded collagen hydrogels. KGluc treatment significantly reduced the number of myofibroblasts within the dermis while upregulated blood vessel density with respect to unloaded hydrogels, likely a result of disruption of TGFβ1 signaling. Taken together, these data demonstrate the effectiveness of KGluc treatment on skin wound healing and suggest that this may be an efficient treatment to limit scar formation.

Current and upcoming therapies to modulate skin scarring and fibrosis

Skin is the largest organ of the human body. Being the interface between the body and the outer environment, makes it susceptible to physical injury. To maintain life, nature has endowed skin with a fast healing response that invariably ends in the formation of scar at the wounded dermal area. In many cases, skin remodelling may be impaired, leading to local hypertrophic scars or keloids. One should also consider that the scarring process is part of the wound healing response, which always starts with inflammation. Thus, scarring can also be induced in the dermis, in the absence of an actual wound, during chronic inflammatory processes. Considering the significant portion of the population that is subject to abnormal scarring, this review critically discusses the state-of-the-art and upcoming therapies in skin scarring and fibrosis.

Re-Epithelialization Appraisal of Skin Wound in a Porcine Model Using a Salmon-Gelatin Based Biomaterial as Wound Dressing

The design of new functional materials for skin tissue engineering is an area of constant research. In this work, a novel wound-dressing biomaterial with a porous structure, previously formulated using salmon-gelatin as main component (called salmon-gelatin biomaterial (SGB)), was tested in vivo using pigs as skin wound models. Four weeks after cutaneous excision and implantation in the animals, the healing process did not show apparent symptoms of inflammation or infection. Interestingly, the temporal evolution of wound size from 100% to around 10% would indicate a faster recovery when SGB was compared against a commercial control. Histological analysis established that wounds treated with SGB presented similar healing and epithelialization profiles with respect to the commercial control. Moreover, vascularized granulation tissue and epithelialization stages were clearly identified, indicating a proliferation phase. These results showed that SGB formulation allows cell viability to be maintained. The latter foresees the development of therapeutic alternatives for skin repair based on SGB fabricated using low cost production protocols.

Modulation of Hypertrophic Scar Formation Using Amniotic Membrane/Electrospun Silk Fibroin Bilayer Membrane in a Rabbit Ear Model

Hypertrophic scarring is a dermal disorder resulting from collagen and other extra cellular matrix protein depositions following the deep trauma, severe burn injury, and surgery incisions. A variety of therapeutic procedures are currently available, however, achieving an ideal treatment method remains a challenge. In our recently published report, a 3D bilayered decellularized human amniotic membrane/electrospun silk fibroin membrane was fabricated and characterized for regenerative medical applications. To obtain a solid bind between two layers, the samples were immersed in 70% ethanol. In this study, the effects of amniotic membrane/electrospun silk fibroin on minimizing the postinjury hypertrophic scar formation were determined in the rabbit ear model. In vivo experiments were carried out to assess the bilayer membrane characteristics on full thickness hypertrophic scar at days 28 and 50 postimplantations. A significant decrease in collagen deposition and expression and increased expression and deposition of MMP1 in the wound bed were observed on the wounds dressed with bilayered membrane when compared to the amniotic membrane alone and controls (wound with no implant). The current study shows that our fabricated construct has potential as an efficient antiscarring wound dressing material and may also serve for the subsequent soft tissue engineering needs.

Physicochemical properties and in vivo evaluation of Pt/TiO2-SiO2 nanopowders

AIM

Sol-gel is a suitable and advantageous method to synthesize mixed oxide nanomaterials with unique physicochemical and biological properties.

MATERIALS & METHODS

In this work, TiO₂-SiO₂ nanopowders cogeled with platinum acetylacetonate were developed and studied in the perspective of nanomedicine. The physicochemical properties of the Pt/TiO₂-SiO₂ nanopowders, named NanoRa²-Pt, were evaluated in detail by means of complementary spectroscopic and microscopic tools. The nanopowder's biocatalytic efficiency in wound healing was evaluated in a Type I diabetes animal model.

RESULTS

These are TiO₂-SiO₂ submicron mesoporous particles with variable size and shape containing ultra-small platinum nanoparticles with catalytic properties.

CONCLUSION

The use of NanoRa²-Pt catalyzes the natural healing processes with a faster remodeling stage. These sols, which we call nanobiocatalysts, belong to an emerging and very promising research field known as catalytic nanomedicine.

Scar free healing mediated by the release of aloe vera and manuka honey from dextran bionanocomposite wound dressings

Scar preventive dextran based bionanocomposite dressings containing aloe vera (AV) and manuka honey (MH) were developed as wound care devices. This work was a challenge to fabricate herbal dressing that promotes healing, which at the same time is biocompatible, non-toxic, biodegradable, and cost effective in terms of the simplicity of application in complex chronic wound situations. With this aim, we synthesized in-situ crosslinked dextran/nanosoy/glycerol/chitosan (DNG/Ch) nanocomposite membranes via solvent casting technique followed by subsequent addition of AV and MH to obtain DNG/Ch/AV and DNG/Ch/MH herbal dressings. The drug release kinetics of the bionanocomposite dressings indicated an initial burst release of AV and MH, followed by controlled release when examined in-vitro using non-fickian and quasi-fickian model. Antibacterial studies confirmed >99% antibacterial activity against both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and bacterial adherence test demonstrated its efficacy for arresting microbial invasion. Wound healing analysis conducted in-vivo showed enhanced epithelialization in the terms scar prevention and aesthetics with absolute wound contraction for the mice treated with AV loaded dressings after 14th post wounding day. Histological features displayed ordered deposition of collagen with a thin epidermis layer. Hence, the present herbal dressing could function without many cytotoxicity and biocompatibility issues.

Immune Regulation of Skin Wound Healing: Mechanisms and Novel Therapeutic Targets

Significance: The immune system plays a central role in orchestrating the tissue healing process. Hence, controlling the immune system to promote tissue repair and regeneration is an attractive approach when designing regenerative strategies. This review discusses the pathophysiology of both acute and chronic wounds and possible strategies to control the immune system to accelerate chronic wound closure and promote skin regeneration (scar-less healing) of acute wounds. Recent Advances: Recent studies have revealed the key roles of various immune cells and immune mediators in skin repair. Thus, immune components have been targeted to promote chronic wound repair or skin regeneration and several growth factors, cytokines, and biomaterials have shown promising results in animal models. However, these novel strategies are often struggling to meet efficacy standards in clinical trials, partly due to inadequate drug delivery systems and safety concerns. Critical Issues: Excess inflammation is a major culprit in the dysregulation of normal wound healing, and further limiting inflammation effectively reduces scarring. However, current knowledge is insufficient to efficiently control inflammation and specific immune cells. This is further complicated by inadequate drug delivery methods. Future Directions: Improving our understanding of the molecular pathways through which the immune system controls the wound healing process could facilitate the design of novel regenerative therapies. Additionally, better delivery systems may make current and future therapies more effective. To promote the entry of current regenerative strategies into clinical trials, more evidence on their safety, efficacy, and cost-effectiveness is also needed.

Leprosy-associated Chronic Wound Management Using Biomaterials

Background:

Deformities and neuropathic chronic ulcers are the common features associated with leprosy-cured individuals that impact their quality of life and impair rehabilitation efforts. The challenging aspects for treatment of chronic wounds are the factors that inhibit healing. We reasoned that limited success of various therapeutic interventions could be due to the fact that leprosy-cured individual's physiology gets acclimatized to having a chronic wound that any therapeutic intervention is counterbalanced to maintain status quo at the wound site. Therefore, an alternative strategy would be to use biomaterials that gradually alter the wound site allowing the individual's physiology to participate in the healing process.

Aims:

Developing the human amnion (Amn)-derived biomaterial scaffolds and evaluating its use to heal chronic wounds in leprosy-cured but deformed persons (LCDPs).

Materials and Methods:

Using an enzymatic protocol, we have developed a rapid method to generate biomaterial scaffolds from discarded human Amn. A clinical trial on 26 LCDPs was performed with the biomaterial, and its wound-healing potential was then compared with LCDPs undergoing standard treatment procedure.

Results:

Biomaterial-based treatment of chronic wounds on LCDP displayed a higher efficiency in healing when compared to standard treatment.

Conclusions:

This study exemplifies that biomaterial-based treatment of leprosy-wounds offers an excellent affordable alternative for wound management. This study underlines the importance of involving both local wound environment and systemic effects for healing. In addition, we highlight wound healing as a necessity for successful rehabilitation and reintegration of leprosy-cured person into the society.

Delivery systems of current biologicals for the treatment of chronic cutaneous wounds and severe burns

While wound therapy remains a clinical challenge in current medical practice, much effort has focused on developing biological therapeutic approaches. This paper presents a comprehensive review of delivery systems for current biologicals for the treatment of chronic wounds and severe burns. The biologicals discussed here include proteins such as growth factors and gene modifying molecules, which may be delivered to wounds free, encapsulated, or released from living systems (cells, skin grafts or skin equivalents) or biomaterials. Advances in biomaterial science and technologies have enabled the synthesis of delivery systems such as scaffolds, hydrogels and nanoparticles, designed to not only allow spatially and temporally controlled release of biologicals, but to also emulate the natural extracellular matrix microenvironment. These technologies represent an attractive field for regenerative wound therapy, by offering more personalised and effective treatments.

Long-term follow-up comparison of two different bi-layer dermal substitutes in tissue regeneration: Clinical outcomes and histological findings

Double layer dermal substitute (DS) consist of a 3‐dimensional collagen structures and a superficial silicon layer that are positioned within the defect provide to promote tissue regeneration in skin wounds. DS often have unique physical characteristics due to differences in manufacturing techniques. The aim of this study is the clinical and histological comparison of Nevelia and Integra double layer DSs in patients with post‐traumatic injury wounds. Thirty patients with post‐traumatic wounds localised on the inferior limbs were randomised in 2 groups Nevelia or Integra, followed by autologous dermal epidermal graft (DEG). Clinical results were evaluated through the healing time; Manchester Scar Scale (MSS) and Visual Analog Scale (VAS) at 1, 2, and 3 weeks and after 1 and 3 years. Histological and immunohistochemical evaluation were performed at 0, 2, and 3 weeks. The difference in healing time between groups (P = .467, log‐rank test), pain and self‐estimation was not statistically significant after 35, 42, and 49 days and at 1‐year follow up. Histological data showed evident healing of wound after 2 weeks compared with preoperative with both DSs. At 3 weeks reepithelialisation and dermal regeneration were evident with both substitutes; however Nevelia showed early regenerative properties in terms of epidermal proliferation and dermal renewal compared with Integra. Nevelia showed also a more evident angiogenesis vs Integra evaluated as α‐SMA immunohistochemistry. Differences in the MSS score were statistically significant at 3 years follow up in favour of Nevelia group (P = .001). At long‐term follow up, Nevelia showed a better clinical outcome measured as MSS score vs Integra measured as MSS. Histological and immunohistochemistry data showed that Nevelia allows faster neoangiogenesis and tissue regeneration with neoformed tissue architecture closer to the physiology of the skin.

A gene-activating skin substitute comprising PLLA/POSS nanofibers and plasmid DNA encoding ANG and bFGF promotes in vivo revascularization and epidermalization

A gene-activated porous nanofibrous scaffold for effectively promoting vascularization, epidermalization and dermal wound healing by sustained release of dual plasmid DNAs.

Phenotypic Screening Identifies Synergistically Acting Natural Product Enhancing the Performance of Biomaterial Based Wound Healing

The potential of multifunctional wound heal biomaterial relies on the optimal content of therapeutic constituents as well as the desirable physical, chemical, and biological properties to accelerate the healing process. Formulating biomaterials such as amnion or collagen based scaffolds with natural products offer an affordable strategy to develop dressing material with high efficiency in healing wounds. Using image based phenotyping and quantification, we screened natural product derived bioactive compounds for modulators of types I and III collagen production from human foreskin derived fibroblast cells. The identified hit was then formulated with amnion to develop a biomaterial, and its biophysical properties, in vitro and in vivo effects were characterized. In addition, we performed functional profiling analyses by PCR array to understand the effect of individual components of these materials on various genes such as inflammatory mediators including chemokines and cytokines, growth factors, fibroblast stimulating markers for collagen secretion, matrix metalloproteinases, etc., associated with wound healing. FACS based cell cycle analyses were carried out to evaluate the potential of biomaterials for induction of proliferation of fibroblasts. Western blot analyses was done to examine the effect of biomaterial on collagen synthesis by cells and compared to cells grown in the presence of growth factors. This work demonstrated an uncomplicated way of identifying components that synergistically promote healing. Besides, we demonstrated that modulating local wound environment using biomaterials with bioactive compounds could enhance healing. This study finds that the developed biomaterials offer immense scope for healing wounds by means of their skin regenerative features such as anti-inflammatory, fibroblast stimulation for collagen secretion as well as inhibition of enzymes and markers impeding the healing, hydrodynamic properties complemented with other features including non-toxicity, biocompatibility, and safety.

Mussel-inspired hydrogel tissue adhesives for wound closure

Tissue adhesives have been introduced as a promising alternative for the traditional wound closure method of suturing.