Sang-Myung Jung

In vitro evaluation of the effects of electrospun PCL nanofiber mats containing the microalgae Spirulina (Arthrospira) extract on primary astrocytes.

The blue-green microalgae, Spirulina, a harmless food and pharmaceutical additive, has several bioactive compounds that have therapeutic functions. Polycaprolactone (PCL) is a biocompatible and biodegradable polymer that has widely been used for tissue engineering. The electrospun PCL nanofiber containing Spirulina (PCL-Spirulina) was fabricated and tested as a potential extracellular matrix material for a culture of primary astrocytes, which play important roles in CNS injured systems. Spirulina extract was observed to increase growth and metabolic activity of rat primary astrocytes without any harm once added to the culture media. However, PCL-Spirulina nanofiber was proven to alleviate astrocyte activity. Through this research and to the best of our knowledge, we first suggest a novel composite nanomaterial, an electrospun PCL-Spirulina nanofiber that could be used to treat CNS injured systems.

Chitosan nanoparticle/PCL nanofiber composite for wound dressing and drug delivery

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.

Effect of topography of an electrospun nanofiber on modulation of activity of primary rat astrocytes.

Several biomaterials for neural tissue engineering have recently been proposed for regeneration of damaged tissue and promotion of axonal guidance following CNS injury. When implanted into damaged nerve tissue, biomaterials should favorably induce cell infiltration and axonal guiding while suppressing inflammation. Nanofiber scaffolds are regarded as adequate materials to meet the above requirements; however, most studies of these materials conducted to date have targeted neuronal cells, not glial cells, despite their important function in the injured CNS. In this study, an electrospun nanofibrous scaffold of polycaprolactone (PCL) was investigated with respect to its topographic effects on astrocyte behavior and expression of GFAP. The results revealed that the PCL nanofiber topograghy promoted adhesion, but GFAP expression was down-regulated, leading to reduced astrocytes activity. Taken together, these results indicate that the topographic structure of electrospun nanofibers provides a scaffold that is favorable to neural regeneration via alleviation of astrogliosis.

Assessment of Spirulina-PCL nanofiber for the regeneration of dermal fibroblast layers

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.

Thermodynamic Insights and Conceptual Design of Skin-Sensitive Chitosan Coated Ceramide/PLGA Nanodrug for Regeneration of Stratum Corneum on Atopic Dermatitis.

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.

Spirulina-PCL Nanofiber Wound Dressing to Improve Cutaneous Wound Healing by Enhancing Antioxidative Mechanism

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, Spirulina extract loaded PCL Spirulina-PCL nanofiber was evaluated as a cutaneous wound dressing in view of antioxidative mechanism. In addition to increasing fibroblast viability, the Spirulina extract and its dressing modulated intra- and extracellular ROS by enhancing antioxidant mechanism of fibroblast under oxidative stress. Finally, in vivo assays confirmed that Spirulina-PCL helps regenerate wounds and enhance regeneration. Taken together, the results of this study indicate that Spirulina and nanofiber have the potential for application to cutaneous wound to facilitate skin regeneration.

Development of a complex bone tissue culture system based on cellulose nanowhisker mechanical strain

In bone tissue engineering, scaffolds have been investigated for their ability to support osteoblast growth and differentiation for recovery of damaged bones. Tunicate cellulose nanowhisker (CNW) film and mechanical strain were assessed for their suitability for osteoblasts. In this study, sulfuric acid hydrolysis extraction of tunicates integuments was conducted to obtain CNWs, which were found to be acceptable for adhering, growing, and differentiating osteoblasts without cytotoxicity. Mechanical stress enhanced osteoblast differentiation, and cell survival rate was recovered at around day 3, although there was a slight increase in cell death at day 1 after stimulation. We also found that intracellular flux of calcium ion was related to increased differentiation of CNWs under mechanical stress. Overall, we demonstrated the suitability of tunicate CNWs as a scaffold for bone tissue engineering and developed a complex system based on CNW for osteoblast growth and differentiation that will be useful for bone substitute fabrication.

Implications of the oxygenated electrospun poly(ɛ‐caprolactone) nanofiber for the astrocytes activities

Astrocytes support structure of central nervous system (CNS) and provide nutrients to neurons. When CNS is injured, astrocytes are activated and produce glia scar. There are debates if the reactive astrocytes give beneficial or harmful effects on neuronal regeneration. In vitro tissue culture systems successfully have been used to investigate how the astrocytes activity is regulated in response to environmental conditions. Physicochemical characteristics of supporting materials for tissue culture are one of the most important environmental conditions. Electrospun nanofiber has physical uniqueness such as high surface area to volume ratio and high porosity, which is favorable to tissue culture. However, cellular activities can also be regulated in response to surface chemistry, which can be modified easily and diversely. Poly(ε-caprolactone) (PCL) is widely used for a scaffold for tissue culture. In this research, oxygen plasma-treated PCL nanofiber was assessed to ascertain whether it can have such potentials to regulate astrocytes activity. As a result, oxygen plasma treatment increased the hydrophilicity of the PCL nanofiber which made adhesion and viability of astrocytes enhanced without cytotoxicity Activation of astrocytes in the plasma treated scaffolds was confirmed by the fact of upregulation of glial fibrillary acidic protein. Above all, oxygenated nanofiber provides an initial culture environment which makes astrocytes activated.

Co-stimulation of HaCaT keratinization with mechanical stress and air-exposure using a novel 3D culture device.

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.

Evaluation of EPS-PCL nanofibers as a nanobiocomposite for artificial skin based on dermal fibroblast culture

Several natural bioactive molecules have been used in the development of scaffolds to enhance biocompatibility or biodegradability and macroalgae contain many bioactive compounds that regulate the physiological activities of cells. In this study, extrapolymeric substances (EPS) from brown algae, Undaria pinnatifida, were dispersed in poly-e-caprolactone (PCL) nanofiber, fabricated by electrospinning technique to mimic natural extracellular matrix (ECM), and tested as a scaffold for the production of artificial skin using rat primary fibroblasts. The level of adhesion, viability, and infiltration of cells on the EPS-PCL nanofibers were then assessed. The primary fibroblasts attached well, had good viability, and infiltrated through the nanofiber mat without cytotoxicity. Additionally, fibroblast on EPS-PCL nanofiber overcame the stress derived from high cell density at limited area. These results indicate that EPS-imbedded nanofiber has the potential to be used as scaffolds to develop artificial skin or as wound-healing nanomedicines to regenerate injured skin.