Effects of bilayer nanofibrillar scaffolds containing epidermal growth factor on full‐thickness wound healing

A photocrosslinkable and hemostatic bilayer wound dressing based on gelatin methacrylate hydrogel and polyvinyl alcohol foam for skin regeneration

The enormous potential of multifunctional bilayer wound dressings in various medical interventions for wound healing has led to decades of exploration into this field of medicine. However, it is usually difficult to synthesize a single hydrogel with all the required capabilities simultaneously. This paper proposes a bilayer model with an outer layer intended for hydrogel wound treatment. By adding gelatin methacrylate (GelMA) and tannic acid (TA) to the hydrogel composition and using polyvinyl alcohol-carboxymethyl chitosan (PVA-CMCs) foam layer as supports, a photocrosslinkable hydrogel with an optimal formulation was created. The hydrogels were then examined using a range of analytical procedures, including mechanical testing, rheology, chemical characterization, and in vitro and in vivo tests. The resulting bilayer wound dressing has many desirable properties, namely uniform adhesion and quick crosslinking by UV light. When used against Gram-positive and Gram-negative bacterial strains, bilayer wound dressings demonstrated broad antibacterial efficacy. In bilayer wound dressings with GelMA and TA, better wound healing was observed. Those without these elements showed less effectiveness in healing wounds. Additionally, encouraging collagen production and reducing wound infection has a major therapeutic impact on wounds. The results of this study could have a significant impact on the development of better-performing wound dressings.

Examining the wound healing potential of curcumin-infused electrospun nanofibers from polyglutamic acid and gum arabic

Advancements in medicine have led to continuous enhancements and innovations in wound dressing materials, making them pivotal in medical care. We used natural biological macromolecules, γ-polyglutamic acid and gum arabic as primary raw materials to create nanofibers laden with curcumin by blending electrostatic spinning technology in the current investigation. These nanofibers were meticulously characterized using fluorescence microscopy, scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Our comprehensive analyses confirmed the successful encapsulation of curcumin within the nanofiber carrier and it has uniform diameter, good water absorption and mechanical properties. Subsequently, we evaluated the antimicrobial effects of these curcumin-loaded nanofibers against Staphylococcus aureus through an oscillating flask method. We created a mouse model with acute full-thickness skin defects to further investigate the wound healing potential. We conducted various biochemical assays to elucidate the mechanism of action. The results revealed that curcumin nanofibers profoundly impacted wound healing. They bolstered the expression of TGF-β1 and VEGF and reduced the expression of inflammatory factors, leading to an accelerated re-epithelialization process, enhanced wound contraction, and increased regeneration of new blood vessels and hair follicles. Furthermore, these nanofibers positively influenced the proportion of three different collagen types. This comprehensive study underscores the remarkable potential of curcumin-loaded nanofibers to facilitate wound healing and lays a robust experimental foundation for developing innovative, natural product-based wound dressings.

Electrospun PVA Fibers for Drug Delivery: A Review

Innovation in biomedical science is always a field of interest for researchers. Drug delivery, being one of the key areas of biomedical science, has gained considerable significance. The utilization of simple yet effective techniques such as electrospinning has undergone significant development in the field of drug delivery. Various polymers such as PEG (polyethylene glycol), PLGA (Poly(lactic-co-glycolic acid)), PLA(Polylactic acid), and PCA (poly(methacrylate citric acid)) have been utilized to prepare electrospinning-based drug delivery systems (DDSs). Polyvinyl alcohol (PVA) has recently gained attention because of its biocompatibility, biodegradability, non-toxicity, and ideal mechanical properties as these are the key factors in developing DDSs. Moreover, it has shown promising results in developing DDSs individually and when combined with natural and synthetic polymers such as chitosan and polycaprolactone (PCL). Considering the outstanding properties of PVA, the aim of this review paper was therefore to summarize these recent advances by highlighting the potential of electrospun PVA for drug delivery systems.

The Effect of Fetal Bovine Acellular Dermal Matrix Seeded with Wharton's Jelly Mesenchymal Stem Cells for Healing Full-Thickness Skin Wounds

The treatment of full-thickness skin wounds is a problem in the clinical setting, as they do not heal spontaneously. Extensive pain at the donor site and a lack of skin grafts limit autogenic and allogeneic skin graft availability. We evaluated fetal bovine acellular dermal matrix (FADM) in combination with human Wharton's jelly mesenchymal stem cells (hWJ-MSCs) to heal full-thickness skin wounds. FADM was prepared from a 6-month-old trauma-aborted fetus. WJ-MSCs were derived from a human umbilical cord and seeded on the FADM. Rat models of full-thickness wounds were created and divided into three groups: control (no treatment), FADM, and FADM-WJMSCs groups. Wound treatment was evaluated microscopically and histologically on days 7, 14, and 21 post-surgery. The prepared FADM was porous and decellularized with a normal range of residual DNA. WJ-MSCs were seeded and proliferated on FADM effectively. The highest wound closure rate was observed in the FADM-WJMSC group on days 7 and 14 post-surgery. Furthermore, this group had fewer inflammatory cells than other groups. Finally, in this study, we observed that, without using the differential cell culture media of fibroblasts, the xenogeneic hWJSCs in combination with FADM could promote an increased rate of full-thickness skin wound closure with less inflammation.

Effective treatment of intractable diseases using nanoparticles to interfere with vascular supply and angiogenic process

Angiogenesis is a vital biological process involving blood vessels forming from pre-existing vascular systems. This process contributes to various physiological activities, including embryonic development, hair growth, ovulation, menstruation, and the repair and regeneration of damaged tissue. On the other hand, it is essential in treating a wide range of pathological diseases, such as cardiovascular and ischemic diseases, rheumatoid arthritis, malignancies, ophthalmic and retinal diseases, and other chronic conditions. These diseases and disorders are frequently treated by regulating angiogenesis by utilizing a variety of pro-angiogenic or anti-angiogenic agents or molecules by stimulating or suppressing this complicated process, respectively. Nevertheless, many traditional angiogenic therapy techniques suffer from a lack of ability to achieve the intended therapeutic impact because of various constraints. These disadvantages include limited bioavailability, drug resistance, fast elimination, increased price, nonspecificity, and adverse effects. As a result, it is an excellent time for developing various pro- and anti-angiogenic substances that might circumvent the abovementioned restrictions, followed by their efficient use in treating disorders associated with angiogenesis. In recent years, significant progress has been made in different fields of medicine and biology, including therapeutic angiogenesis. Around the world, a multitude of research groups investigated several inorganic or organic nanoparticles (NPs) that had the potential to effectively modify the angiogenesis processes by either enhancing or suppressing the process. Many studies into the processes behind NP-mediated angiogenesis are well described. In this article, we also cover the application of NPs to encourage tissue vascularization as well as their angiogenic and anti-angiogenic effects in the treatment of several disorders, including bone regeneration, peripheral vascular disease, diabetic retinopathy, ischemic stroke, rheumatoid arthritis, post-ischemic cardiovascular injury, age-related macular degeneration, diabetic retinopathy, gene delivery-based angiogenic therapy, protein delivery-based angiogenic therapy, stem cell angiogenic therapy, and diabetic retinopathy, cancer that may benefit from the behavior of the nanostructures in the vascular system throughout the body. In addition, the accompanying difficulties and potential future applications of NPs in treating angiogenesis-related diseases and antiangiogenic therapies are discussed.

Electrospun Polycaprolactone (PCL) Degradation: An In Vitro and In Vivo Study

Polycaprolactone (PCL) is widely used in tissue engineering due to its interesting properties, namely biocompatibility, biodegradability, elastic nature, availability, cost efficacy, and the approval of health authorities such as the American Food and Drug Administration (FDA). The PCL degradation rate is not the most adequate for specific applications such as skin regeneration due to the hydrophobic nature of bulk PCL. However, PCL electrospun fiber meshes, due to their low diameters resulting in high surface area, are expected to exhibit a fast degradation rate. In this work, in vitro and in vivo degradation studies were performed over 90 days to evaluate the potential of electrospun PCL as a wound dressing. Enzymatic and hydrolytic degradation studies in vitro, performed in a static medium, demonstrated the influence of lipase, which promoted a rate of degradation of 97% for PCL meshes. In an in vivo scenario, the degradation was slower, although the samples were not rejected, and were well-integrated in the surrounding tissues inside the subcutaneous pockets specifically created.

Single unit functionally graded bioresorbable electrospun scaffold for scar-free full-thickness skin wound healing

Full-thickness wounds are difficult to heal spontaneously. Scaffolds, meant for treating full-thickness wounds, should ensure proper tissue regeneration, both structurally and functionally. An ideal scaffold should mimic the physical, mechanical and biochemical properties of natural skin. However, available mono- or bi-layer skin scaffolds lack in the precise architecture and functionality, thus, failing to provide scar-free regeneration of full-thickness skin wounds. These unmet challenges of scar-free skin regeneration have been addressed in the present study for the first time. This research deals with the synthesis of a low-cost, structurally and functionally graded single unit biodegradable polymeric scaffold. The functional gradient in this scaffold was achieved by varying polymer concentration and electrospinning parameters. This gradient in the scaffold provided the required microenvironment for proper functional and structural reconstruction of all the layers of natural skin. The mechanical property of the scaffold matched that of the natural skin. Besides, the degradation kinetics of the scaffold was in coordination with the regeneration time for the full-thickness wound. The porosity and hydrophilicity gradients of the scaffold helped it mimic the in vivo hypodermal, dermal and epidermal microenvironments of the skin, simultaneously. Co-culturing PCS-201 (dermal fibroblasts) and HaCaT (keratinocytes) on the scaffold resulted in successful regeneration through cellular proliferation, differentiation and organization of the skin tissue. The scaffold also displayed better wound healing in vivo, in terms of speedy wound closure and proper tissue regeneration, in comparison to the standard treatment. Altogether, this study successfully established a simple, one-step synthesis process of a functionally graded, bioresorbable scaffold for scar-free, native-like, structural and functional regeneration of full-thickness skin wounds. Due to cost-effectiveness, easy synthesis process and microarchitectural features, the designed scaffold possesses a potential of translation to a good commercial wound healing product.

Self-propelled micro/nanobots: A new insight into precisely targeting cancerous cells through intelligent and deep cancer penetration

Cancer overlooks are globally one of the most dangerous and life-threatening tribulations. While significant advances have been made in the targeted delivery of anti-cancer medications over the last few years, several challenges, such as low efficacy and strong toxic effects, remain to be addressed. Micro/nanomotors have been thoroughly studied for both effective cancer detection and treatment, as demonstrated by significant advancements in the architecture of smart and functional micro/nanomotor biomedical systems. Able to self-propelled within fluid media, micro/nanomotors have attractive vehicles to maximize the efficacy of tumor delivery. Here, we present the current developments in the delivery, detection, and imaging-guided treatment of micro/nanomotors in the clinical field, including cancer-related specific targeted drug delivery, and then discuss the barriers and difficulties encountered by micro/nanomotors throughout the medical process. Furthermore, this paper addresses the potential growth of micro/nanomotors for medical applications, and sets out the current drawbacks and future research directions for more advancement.

Growth Factor Immobilization Strategies for Musculoskeletal Disorders

PURPOSE OF REVIEW

Tissue regenerative solutions for musculoskeletal disorders have become increasingly important with a growing aged population. Current growth factor treatments often require high dosages with the potential for off-target effects. Growth factor immobilization strategies offer approaches towards alleviating these concerns. This review summarizes current growth factor immobilization techniques (encapsulation, affinity interactions, and covalent binding) and the effects of immobilization on growth factor loading, release, and bioactivity.

RECENT FINDINGS

The breadth of immobilization techniques based on encapsulation, affinity, and covalent binding offer multiple methods to improve the therapeutic efficacy of growth factors by controlling bioactivity and release. Growth factor immobilization strategies have evolved to more complex systems with the capacity to load and release multiple growth factors with spatiotemporal control. The advancements in immobilization strategies allow for development of new, complex musculoskeletal tissue treatment strategies with improved spatiotemporal control of loading, release, and bioactivity.

Combination Therapy of Stem Cell-derived Exosomes and Biomaterials in the Wound Healing

Wound healing is a serious obstacle due to the complexity of evaluation and management. While novel approaches to promoting chronic wound healing are of critical interest at the moment, several studies have demonstrated that combination therapy is critical for the treatment of a variety of diseases, particularly chronic wounds. Among the various approaches that have been proposed for wound care, regenerative medicine-based methods have garnered the most attention. As is well known, regenerative medicine's three primary tools are gene/cell therapy, biomaterials, and tissue engineering. Multifunctional biomaterials composed of synthetic and natural components are highly advantageous for exosome carriers, which utilizing them is an exciting wound healing method. Recently, stem cell-secreted exosomes and certain biomaterials have been identified as critical components of the wound healing process, and their combination therapy appears to produce significant results. This paper presents a review of literature and perspectives on the use of stem cell-derived exosomes and biomaterials in wound healing, particularly chronic wounds, and discusses the possibility of future clinical applications.

Growth factors, as biological macromolecules in bioactivity enhancing of electrospun wound dressings for diabetic wound healing: A review

Impaired wound healing is of the most conspicuous characteristics of diabetic mellitus. Reduced blood flow, chronic inflammatory reactions, infection, endothelial dysfunction, elevated levels of reactive oxygen species, and metabolic disorders cause wounds to heal more slowly in these patients. Previous studies have reported useful impacts of growth factors in management of such wounds. However, due to their short half-life and low stability, a suitable delivery platform with sustained release profile may boost their healing potential. Controlled and localized delivery of growth factors via electrospun fibers have been extensively explored in previous studies. The electrospinning method; although not new, has turned out to be extremely effective for the preparation of delivery carriers for growth factors. Due to their structural resemblance to native tissues' extracellular matrix, high encapsulation efficacy, tunability, and high surface to volume ratio, electrospun scaffolds have gained significant attention in drug delivery and tissue engineering. In the current review, careful integration of current research regarding the applications of growth factors' delivery through electrospun fibers in diabetic wounds healing has been done. This review will not only give an insight into the current updates, but will also highlights the future perspectives and challenges.

Biomimetic nanoengineered scaffold for enhanced full-thickness cutaneous wound healing

Wound healing is a complex process based on the coordinated signaling molecules and dynamic interactions between the engineered scaffold and newly formed tissue. So far, most of the engineered scaffolds used for the healing of full-thickness skin wounds do not mimic the natural extracellular matrix (ECM) complexity and therefore are not able to provide an appropriate niche for endogenous tissue regeneration [1]. To address this gap and to accelerate the wound healing process, we present biomimetic bilayer scaffolds compositing of gelatin nanofibers (GFS) and photocrosslinkable composite hydrogels loaded with epidermal growth factors (EGF). The nanofibers operate as the dermis layer, and EGF-loaded composite hydrogels acted as the epidermis matrix for the full-thickness wound healing application. The hydrogels are composed of gelatin metacryloyl (GelMA) modified with silicate nanoplatelets (Laponite). To overcome the challenges of transdermal delivery of EGF, including short half-life and lack of efficient formulation precise, controlled delivery was attained by immobilization of EGF on Laponite. It is shown that the addition of 1wt% silicate nanoplatelet increases the compressive modulus of the hydrogels by 170%. In vitro wound closure analysis also demonstrated improved adhesion of the scaffolds to the native tissue by 3.5 folds. Moreover, the tunable hemostatic ability of the scaffolds due to the negatively charged nanoplatelets is shown. In an established excisional full-thickness wound model, an enhanced wound closure (up to 93.1 ± 1.5%) after 14 days relative to controls (GFS and saline-treated groups) is demonstrated. The engineered adhesive and hemostatic scaffolds with sustained release of the growth factors have the potential to stimulate complete skin regeneration for full-thickness wound healing.

Bilayer Scaffolds for Interface Tissue Engineering and Regenerative Medicine: A Systematic Reviews

PURPOSE

This systematic review focus on the application of bilayer scaffolds as an engaging structure for the engineering of multilayered tissues, including vascular and osteochondral tissues, skin, nerve, and urinary bladder. This article provides a concise literature review of different types of bilayer scaffolds to understand their efficacy in targeted tissue engineering.

METHODS

To this aim, electronic search in the English language was performed in PMC, NBCI, and PubMed from April 2008 to December 2019 based on the PRISMA guidelines. Animal studies, including the "bilayer scaffold" and at least one of the following items were examined: osteochondral tissue, bone, skin, neural tissue, urinary bladder, vascular system. The articles which didn't include "tissue engineering" and just in vitro studies were excluded.

RESULTS

Totally, 600 articles were evaluated; related articles were 145, and 35 full-text English articles met all the criteria. Fifteen articles in soft tissue engineering and twenty items in hard tissue engineering were the results of this exploration. Based on selected papers, it was revealed that the bilayer scaffolds were used in the regeneration of the multilayered tissues. The highest multilayered tissue regeneration has been achieved when bilayer scaffolds were used with mesenchymal stem cells and differentiation medium before implanting. Among the studies being reported in this review, bone marrow mesenchymal stem cells are the most studied mesenchymal stem cells. Among different kinds of multilayer tissue, the bilayer scaffold has been most used in osteochondral tissue engineering in which collagen and PLGA have been the most frequently used biomaterials. After osteochondral tissue engineering, bilayer scaffolds were widely used in skin tissue engineering.

CONCLUSION

The current review aimed to manifest the researcher and surgeons to use a more sophisticated bilayer scaffold in combinations of appropriate stem cells, and different can improve multilayer tissue regeneration. This systematic review can pave a way to design a suitable bilayer scaffold for a specific target tissue and conjunction with proper stem cells.