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Many investigations of wound dressings equipped with drug delivery systems have recently been conducted. Chitosan is widely used not only as a material for wound dressing by the efficacy of its own, but also as a nanoparticle for drug delivery. In this study, an electrospun polycaprolactone nanofiber composite with chitosan nanoparticles (ChiNP-PCLNF) was fabricated and then evaluated for its drug release and biocompatibility to skin fibroblasts. ChiNP-PCLNF complexes showed no cytotoxicity and nanoparticles adsorbed by van der Waals force were released into aquatic environments and then penetrated into rat primary fibroblasts. Our studies demonstrate the potential for application of ChiNP-PCLNF as a wound dressing system with drug delivery for skin wound healing without side effects.

Atopic dermatitis (AD) is a complex skin disease primarily characterized by psoriasis of the stratum corneum. AD drugs have usually been used in acidic and hydrophilic solvents to supply moisture and prevent lipid defects. Ceramide is a typical treatment agent to regenerate the stratum corneum and relieve symptoms of AD. However, ceramide has limitation on direct use for skin because of its low dispersion properties in hydrophilic phase and side effects at excessive treatment. In this study, ceramide imbedded PLGA nanoparticles were developed with chitosan coating (Chi-PLGA/Cer) to overcome this problem. The chitosan coating enhanced initial adherence to the skin and prevented the initial burst of ceramide, but was degraded by the weakly acidic nature of skin, resulting in controlled release of ceramide with additional driving force of the squeezed PLGA nanoparticles. Additionally, the coating kinetics of chitosan were controlled by manipulating the reaction conditions and then mathematically modeled. The Chi-PLGA/Cer was not found to be cytotoxic and ceramide release was controlled by pH, temperature, and chitosan coating. Finally, Chi-PLGA/Cer was demonstrated to be effective at stratum corneum regeneration in a rat AD model. Overall, the results presented herein indicated that Chi-PLGA/Cer is a novel nanodrug for treatment of AD.

Skin regeneration is a complex process involving massive proliferation and alignment of cells, where there are obstacles to completion of regeneration, the main one being excessive generation of reactive oxygen species (ROS) from inflammation or infection.Spirulina, blue-green algae that has antioxidant and anti-inflammatory activities, has been used to relieve such ROS stress. In this study,Spirulinaextract loaded PCL (Spirulina-PCL) nanofiber was evaluated as a cutaneous wound dressing in view of antioxidative mechanism. In addition to increasing fibroblast viability, theSpirulinaextract and its dressing modulated intra- and extracellular ROS by enhancing antioxidant mechanism of fibroblast under oxidative stress. Finally,in vivoassays confirmed thatSpirulina-PCL helps regenerate wounds and enhance regeneration. Taken together, the results of this study indicate thatSpirulinaand nanofiber have the potential for application to cutaneous wound to facilitate skin regeneration.

Skin is a barrier which protects injured tissues, and thus, skin regeneration is one of many important medical issues. Tissue engineering is an attractive approach to make artificial tissue or regenerate lost tissues. While constituting artificial tissues, cells must infiltrate through scaffolds, maintaining viability and proliferation. However, a three-dimensional tissue culture involves stressful environments due to several reasons such as mass or gas transport and high cell density. Once stressed, cells produce reactive oxygen species, resulting in alleviating cellular viability and activity. Spirulina is well known to have antioxidant molecules, which have been known to modulate oxidative stress to cells. Electrospun nanofiber has widely been used as a scaffold to mimic natural extracellular matrix. In this research, we assessed Spirulina extract-imbedded nanofiber as a scaffold for an artificial skin tissue. Spirulina extract was proven to positively affect viability and proliferation of mouse fibroblasts. In addition, fibroblasts infiltrated through Spirulina extract-imbedded electrospun nanofiber without cytotoxicity.

Artificial skin or skin equivalents have been used for clinical purpose to skin graft and as substitutes for animal experiments. The culture of cell lines such as HaCaT has the potential to produce large amounts of artificial skin at a low cost. However, there is a limit to keratinization due to the restriction of differentiation in HaCaT. In this study, a culture device that mimics the in vivo keratinization mechanism, co-stimulated by air-exposure and mechanical stimulation, was developed to construct skin equivalents. The device can reconstruct the epidermal morphology, including the cornified layer, similar to its formation in vivo. Under the condition, epidermis was differentiated in the spinous and granular layers. Formation of the stratum corneum is consistent with the mRNA and protein expressions of differentiation markers. The device is the first of its kind to combine air-exposure with mechanical stress to co-stimulate keratinization, which can facilitate the economically viable production of HaCaT-based artificial skin substitutes.

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