Induction of angiogenic and inflammation-associated dermal biomarkers following acute UVB exposure on bio-engineered pigmented dermo-epidermal skin substitutes in vivo

Electrospun nanofibrous membrane for biomedical application

Electrospinning is a simple, cost-effective, flexible, and feasible continuous micro-nano polymer fiber preparation technology that has attracted extensive scientific and industrial interest over the past few decades, owing to its versatility and ability to manufacture highly tunable nanofiber networks. Nanofiber membrane materials prepared using electrospinning have excellent properties suitable for biomedical applications, such as a high specific surface area, strong plasticity, and the ability to manipulate their nanofiber components to obtain the desired properties and functions. With the increasing popularity of nanomaterials in this century, electrospun nanofiber membranes are gradually becoming widely used in various medical fields. Here, the research progress of electrospun nanofiber membrane materials is reviewed, including the basic electrospinning process and the development of the materials as well as their biomedical applications. The main purpose of this review is to discuss the latest research progress on electrospun nanofiber membrane materials and the various new electrospinning technologies that have emerged in recent years for various applications in the medical field. The application of electrospun nanofiber membrane materials in recent years in tissue engineering, wound dressing, cancer diagnosis and treatment, medical protective equipment, and other fields is the main topic of discussion in this review. Finally, the development of electrospun nanofiber membrane materials in the biomedical field is systematically summarized and prospects are discussed. In general, electrospinning has profound prospects in biomedical applications, as it is a practical and flexible technology used for the fabrication of microfibers and nanofibers.

This review summarizes recent research on the application of electrospun nanofiber membranes as tissue engineering materials for the cardiovascular system, motor system, nervous system, and other clinical aspects.

Research on the application of electrospun nanofiber membrane materials as protective products is discussed in the context of the current epidemic situation.

Examples and analyses of recent popular applications in tissue engineering, wound dressing, protective products, and cancer sensors are presented.

HSP27 Protects Skin From Ultraviolet B -Induced Photodamage by Regulating Autophagy and Reactive Oxygen Species Production

Ultraviolet (UV) irradiation has been well documented to be linked with almost all skin problems we know, and both dermis and epidermis may be affected to varying degrees by UV irradiation. Every time when exposed to sunlight without protection, our skin will step closer to photoaging, leading to irreversible consequences ultimately. Heat shock protein 27 (HSP27) is a vital protein involved in cell growth, autophagy, apoptosis, drug resistance, tumor genesis and metastasis. Evidence suggests that the organism is subjected to various internal and external environmental stresses (heat, oxidative stress, organic toxicants, etc.), and HSP27 with high expression has protective function. However, the expression of HSP27 in coping with UV irradiation have not been examined thoroughly. In this study, photodamage models were developed through different doses of UVB irradiation in human epidermal keratinocytes (HEKs) (30 mJ/cm²), human dermal fibroblasts (HDFs) (150 mJ/cm²) and mouse skin (2,700 mJ/cm²). HSP27 knockdown decreased cell viability and increased the incidence of UVB-induced reactive oxygen species (ROS) production. We got consistent results in vivo and vitro. Compared with that in the UVB group, the expression of LC3B was significantly lower, while the expression of p62 was significantly higher in the UVB + si-HSP27 group. It was also revealed that HSP27 knockdown reduced the expressions of some antioxidants, such as superoxide dismutase (SOD) and catalase (CAT), which accelerated UVB-induced ROS release. Moreover, histological results showed that epidermis was thickened and collagen fibers were disorganized in the UVB + si-HSP27 group. These findings have demonstrated that HSP27 might play a photoprotective role in the UVB-induced skin damage process by maintaining the normal autophagy and antioxidant level. It is implied that HSP27 could be a potential therapeutic target of photodamage. However, determination of the definitive mechanism requires further exploration.

Characterization of a melanocyte progenitor population in human interfollicular epidermis

It is still unknown whether the human interfollicular epidermis harbors a reservoir of melanocyte precursor cells. Here, we clearly distinguish between three distinct types of melanocytes in human interfollicular epidermis: (1) cKit⁺CD90^-, (2) cKit⁺CD90⁺, and (3) cKit^-CD90⁺. Importantly, we identify the Kit tyrosine kinase receptor (cKit) as a marker expressed specifically in mature, melanin-producing melanocytes. Thus, both cKit⁺CD90^- and cKit⁺CD90⁺ cells represent polydendritic, pigmented mature melanocytes, whereas cKit^-CD90⁺ cells display bipolar, non-dendritic morphology with reduced melanin content. Additionally, using tissue-engineered pigmented dermo-epidermal skin substitutes (melDESSs), we reveal that the cKit expression also plays an important role during melanogenesis in melDESS in vivo. Interestingly, cKit^-CD90⁺ cells lack the expression of markers such as HMB45, TYR, and TRP1 in vitro and in vivo. However, they co-express neural-crest progenitor markers and demonstrate multilineage differentiation potential in vitro. Hence, we propose that cKit^-CD90⁺ cells constitute the precursor melanocyte reservoir in human interfollicular epidermis.

Bio-engineering a prevascularized human tri-layered skin substitute containing a hypodermis

Severe injuries to skin including hypodermis require full-thickness skin replacement. Here, we bioengineered a tri-layered human skin substitute (TLSS) containing the epidermis, dermis, and hypodermis. The hypodermal layer was generated by differentiation of human adipose stem cells (ASC) in a collagen type I hydrogel and combined with a prevascularized dermis consisting of human dermal microvascular endothelial cells and fibroblasts, which arranged into a dense vascular network. Subsequently, keratinocytes were seeded on top to generate the epidermal layer of the TLSS. The differentiation of ASC into adipocytes was confirmed in vitro on the mRNA level by the presence of adiponectin, as well as by the expression of perilipin and FABP-4 proteins. Moreover, functional characteristics of the hypodermis in vitro and in vivo were evaluated by Oil Red O, BODIPY, and AdipoRed stainings visualizing intracellular lipid droplets. Further, we demonstrated that both undifferentiated ASC and mature adipocytes present in the hypodermis influenced the keratinocyte maturation and homeostasis in the skin substitutes after transplantation. In particular, an enhanced secretion of TGF-β1 by these cells affected the epidermal morphogenesis as assessed by the expression of key proteins involved in the epidermal differentiation including cytokeratin 1, 10, 19 and cornified envelope formation such as involucrin. Here, we propose a novel functional hypodermal-dermo-epidermal tri-layered skin substitute containing blood capillaries that efficiently promote regeneration of skin defects. STATEMENT OF SIGNIFICANCE: The main objective of this study was to develop and assess the usefulness of a tri-layered human prevascularized skin substitute (TLSS) containing an epidermis, dermis, and hypodermis. The bioengineered hypodermis was generated from human adipose mesenchymal stem cells (ASC) and combined with a prevascularized dermis and epidermis. The TLSS represents an exceptional model for studying the role of cell-cell and cell-matrix interactions in vitro and in vivo. In particular, we observed that enhanced secretion of TGF-β1 in the hypodermis exerted a profound impact on fibroblast and keratinocyte differentiation, as well as epidermal barrier formation and homeostasis. Therefore, improved understanding of the cell-cell interactions in such a physiological skin model is essential to gain insights into different aspects of wound healing.

Oleogel Formulations for the Topical Delivery of Betulin and Lupeol in Skin Injuries-Preparation, Physicochemical Characterization, and Pharmaco-Toxicological Evaluation

The skin integrity is essential due to its pivotal role as a biological barrier against external noxious factors. Pentacyclic triterpenes stand as valuable plant-derived natural compounds in the treatment of skin injuries due to their anti-inflammatory, antioxidant, antimicrobial, and healing properties. Consequently, the primary aim of the current investigation was the development as well as the physicochemical and pharmaco-toxicological characterization of betulin- and lupeol-based oleogels (Bet OG and Lup OG) for topical application in skin injuries. The results revealed suitable pH as well as organoleptic, rheological, and textural properties. The penetration and permeation of Bet and Lup oleogels through porcine ear skin as well as the retention of both oleogels in the skin were demonstrated through ex vivo studies. In vitro, Bet OG and Lup OG showed good biocompatibility on HaCaT human immortalized cells. Moreover, Bet OG exerted a potent wound-healing property by stimulating the migration of the HaCaT cells. The in ovo results demonstrated the non-irritative potential of the developed formulations. Additionally, the undertaken in vivo investigation indicated a positive effect of oleogels treatment on skin parameters by increasing skin hydration and decreasing erythema. In conclusion, oleogel formulations are ideal for the local delivery of betulin and lupeol in skin disorders.

Effect of Different Wavelengths of Laser Irradiation on the Skin Cells

The invention of systems enabling the emission of waves of a certain length and intensity has revolutionized many areas of life, including medicine. Currently, the use of devices emitting laser light is not only an indispensable but also a necessary element of many diagnostic procedures. It also contributed to the development of new techniques for the treatment of diseases that are difficult to heal. The use of lasers in industry and medicine may be associated with a higher incidence of excessive radiation exposure, which can lead to injury to the body. The most exposed to laser irradiation is the skin tissue. The low dose laser irradiation is currently used for the treatment of various skin diseases. Therefore appropriate knowledge of the effects of lasers irradiation on the dermal cells’ metabolism is necessary. Here we present current knowledge on the clinical and molecular effects of irradiation of different wavelengths of light (ultraviolet (UV), blue, green, red, and infrared (IR) on the dermal cells.

Bioengineered Skin Substitutes: Advances and Future Trends

As the largest organ in the human body, the skin has the function of maintaining balance and protecting from external factors such as bacteria, chemicals, and temperature. If the wound does not heal in time after skin damage, it may cause infection or life-threatening complications. In particular, medical treatment of large skin defects caused by burns or trauma remains challenging. Therefore, human bioengineered skin substitutes represent an alternative approach to treat such injuries. Based on the chemical composition and scaffold material, skin substitutes can be classified into acellular or cellular grafts, as well as natural-based or synthetic skin substitutes. Further, they can be categorized as epidermal, dermal, and composite grafts, based on the skin component they contain. This review presents the common commercially available skin substitutes and their clinical use. Moreover, the choice of an appropriate hydrogel type to prepare cell-laden skin substitutes is discussed. Additionally, we present recent advances in the field of bioengineered human skin substitutes using three-dimensional (3D) bioprinting techniques. Finally, we discuss different skin substitute developments to meet different criteria for optimal wound healing.

Hair(y) Matters in Melanoma Biology

Melanocyte stem cells (MeSCs), one candidate for the cellular origin of melanoma, reside in the bulge region of the hair follicle (HF), an immune-privileged tissue niche with impaired tumor immunosurveillance. Surprisingly, however, primary melanoma is only very rarely associated with HFs. Here, we explore the hypothesis that this profoundly immunoinhibitory signaling environment deprives both MeSCs and melanocytes of the anagen hair matrix of proinflammatory signals required for full oncogenic transformation. Understanding the cellular and molecular mechanisms for generating a putative antimelanoma tissue habitat, namely in the bulge, could help to recreate a similar melanoma-suppressive signaling environment in melanoma high-risk individuals. We further discuss how mimicking the bulge immune privilege may be an effective melanoma prevention strategy.

Light or Dark Pigmentation of Engineered Skin Substitutes Containing Melanocytes Protects Against Ultraviolet Light-Induced DNA Damage In Vivo

Engineered skin substitutes (ESS) containing autologous fibroblasts and keratinocytes provide stable wound closure in patients with large, full-thickness burns, but are limited by hypopigmentation due to absence of added melanocytes. DNA damage caused by ultraviolet radiation (UV) increases risk for skin cancer development. In human skin, melanocytes provide pigmentation that protects skin from UV-induced DNA damage. This study investigated whether inclusion of human melanocytes (hM) affects the response of ESS to UV in vivo. Specifically, pigmentation and formation of cyclobutane pyrimidine dimers (CPDs), the most prevalent UV-induced DNA photoproduct, were analyzed. Three groups of ESS were prepared with fibroblasts and keratinocytes, ± melanocytes, and grafted orthotopically to immunodeficient mice: ESS without melanocytes (ESS-hM), ESS with light skin-derived (Caucasian) melanocytes (ESS+hM-L), and ESS with dark skin-derived (African-American) melanocytes (ESS+hM-D). Pigmentation of ESS+hM-L and ESS+hM-D increased significantly after grafting; pigmentation levels were significantly different among groups. Mean melanocyte densities in ESS+hM-L and ESS+hM-D were similar to each other and to densities in normal human skin. After 8 weeks in vivo, grafts were irradiated with 135 mJ/cm2 UV; non-UV-treated mice served as controls. UV modestly increased pigmentation in the ESS+hM groups. UV significantly increased CPD levels in ESS-hM, and levels in ESS-hM were significantly greater than in ESS+hM-L or ESS+hM-D. The results demonstrate that light or dark melanocytes in ESS decreased UV-induced DNA damage. Therefore, melanocytes in ESS play a photoprotective role. Protection against UV-induced DNA damage is expected to reduce skin cancer risk in patients grafted with ESS containing autologous melanocytes.