Sunho Park

Melatonin attenuates doxorubicin-induced testicular toxicity in rats.

This study investigated the protective effects of melatonin (MLT) against doxorubicin (DXR)‐induced testicular toxicity and oxidative stress in rats. DXR was given as a single intraperitoneal dose of 10 mg kg−1 body weight to male rats at 1 h after MLT treatment on day 6 of the study. MLT at 15 mg kg−1 body weight was administered daily by gavage for 5 days before DXR treatment followed by an additional dose for 5 days. Sperm analysis, histopathological examination and biochemical methods were used for this investigation. DXR caused a decrease in the weight of seminal vesicles, epididymal sperm count and motility and an increase in the incidence of histopathological changes of the testis. In addition, an increased malondialdehyde (MDA) concentration and decreased glutathione content, glutathione reductase (GR), glutathione‐S‐transferase (GST), superoxide dismutase (SOD) and catalase activities were observed. On the contrary, MLT treatment significantly ameliorated DXR‐induced testicular toxicity in rats. Moreover, MDA concentration and GR, GST and SOD activities were not affected when MLT was administered in conjunction with DXR. These results indicate that MLT had a protective effect against DXR‐induced testicular toxicity and that the protective effects of MLT may be due to both the inhibition of lipid peroxidation and increased antioxidant activity.

Engineering structures and functions of mesenchymal stem cells by suspended large-area graphene nanopatterns

Inspired by the hierarchical nanofibrous and highly oriented structures of natural extracellular matrices, we report a rational design of chemical vapor deposition graphene-anchored scaffolds that provide both physical and chemical cues in a multilayered organization to control the adhesion and functions of cells for regenerative medicine. These hierarchical platforms are fabricated by transferring large graphene film onto nanogroove patterns. The top graphene layer exhibits planar morphology with slight roughness (~20 nm between peaks) due to the underlying topography, which results in a suspended structure between the nanoridges. We demonstrate that the adhesion and differentiation of human mesenchymal stem cells were sensitively controlled and enhanced by the both the nanotopography and graphene cues in our scaffolds. Our results indicate that the layered physical and chemical cues can affect the apparent cell behaviors, and can synergistically enhance cell functionality. Therefore, these suspended graphene platforms may be used to advance regenerative medicine.

Effect of diallyl disulfide on acute gastric mucosal damage induced by alcohol in rats

This study investigated the gastroprotective effects of diallyl disulfide (DADS), a secondary organosulfur compound derived from garlic (Allium sativum L.) on experimental model of ethanol (EtOH)-induced gastric ulcer in rats. The antiulcerogenic activity of DADS was evaluated by gross/histopathological inspection, pro-inflammatory cytokines, and lipid peroxidation with antioxidant enzyme activities in the stomach. DADS (100 mg/kg) was administered by oral gavage 2 h prior to EtOH treatment (5 ml/kg). The animals were killed 1 h after receiving EtOH treatment. Pretreatment with DADS attenuated EtOH-induced gastric mucosal injury, as evidenced by decreased severity of hemorrhagic lesions and gastric ulcer index upon visual inspection. DADS also prevented histopathological alterations and gastric apoptotic changes caused by EtOH. An increase in tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase was observed in the gastric tissues of EtOH-treated rats that coincided with increased serum TNF-α and interleukin 6 levels. In contrast, DADS effectively suppressed production of pro-inflammatory mediators induced by EtOH. Furthermore, DADS prevented the formation of gastric malondialdehyde and the depletion of reduced glutathione content and restored antioxidant enzyme activities, such as catalase, glutathione peroxidase, and glutathione reductase in the gastric tissues of EtOH-treated rats. These results indicate that DADS prevents gastric mucosal damage induced by acute EtOH administration in rats and that the protective effects of DADS may be due to its potent antioxidant and anti-inflammatory activities.

Hierarchically Micro- and Nanopatterned Topographical Cues for Modulation of Cellular Structure and Function

Living cells receive biochemical and physical information from the surrounding microenvironment and respond to this information. Multiscale hierarchical substrates with micro- and nanogrooves have been shown to mimic the native extracellular matrix (ECM) better than conventional nanopatterned substrates; therefore, substrates with hierarchical topographical cues are considered suitable for investigating the role of physical factors in tissue functions. In this study, precisely controllable, multiscale hierarchical substrates that could mimic the micro- and nanotopography of complex ECMs were fabricated and used to culture various cell types, including fibroblasts, endothelial cells, osteoblasts, and human mesenchymal stem cells. These substrates had both microscale wrinkles and nanoscale patterns and enhanced the alignment and elongation of all the cells tested. In particular, the nanotopography on the microscale wrinkles promoted not only the adhesion, but also the functions of the cells. These findings suggest that the hierarchical multiscale substrates effectively regulated cellular structure and functions and that they can be used as a platform for tissue engineering and regenerative medicine.Living cells receive biochemical and physical information from the surrounding microenvironment and respond to this information. Multiscale hierarchical substrates with micro- and nanogrooves have been shown to mimic the native extracellular matrix (ECM) better than conventional nanopatterned substrates; therefore, substrates with hierarchical topographical cues are considered suitable for investigating the role of physical factors in tissue functions. In this study, precisely controllable, multiscale hierarchical substrates that could mimic the micro- and nanotopography of complex ECMs were fabricated and used to culture various cell types, including fibroblasts, endothelial cells, osteoblasts, and human mesenchymal stem cells. These substrates had both microscale wrinkles and nanoscale patterns and enhanced the alignment and elongation of all the cells tested. In particular, the nanotopography on the microscale wrinkles promoted not only the adhesion, but also the functions of the cells. These findings suggest that the hierarchical multiscale substrates effectively regulated cellular structure and functions and that they can be used as a platform for tissue engineering and regenerative medicine.

Graphene as an Enabling Strategy for Dental Implant and Tissue Regeneration

Graphene-based approaches have been influential in the design and manipulation of dental implants and tissue regeneration to overcome the problems associated with traditional titanium-based dental implants, such as their low biological affinity. Here, we describe the current progress of graphene-based platforms, which have contributed to major advances for improving cellular functions in in vitro and in vivo applications of dental implants. We also present opinions on the principal challenges and future prospects for new graphene-based platforms for the development of advanced graphene dental implants and tissue regeneration.

Nanopatterned Scaffolds for Neural Tissue Engineering and Regenerative Medicine

Biologically inspired approaches employing nanoengineering techniques have been influential in the progress of neural tissue repair and regeneration. Neural tissues are exposed to complex nanoscale environments such as nanofibrils. In this chapter, we summarize representative nanotechniques, such as electrospinning, lithography, and 3D bioprinting, and their use in the design and fabrication of nanopatterned scaffolds for neural tissue engineering and regenerative medicine. Nanotopographical cues in combination with other cues (e.g., chemical cues) are crucial to neural tissue repair and regeneration using cells, including various types of stem cells. Production of biologically inspired nanopatterned scaffolds may encourage the next revolution for studies aiming to advance neural tissue engineering and regenerative medicine.

Neurogenic Differentiation of Human Dental Pulp Stem Cells on Graphene-Polycaprolactone Hybrid Nanofibers

Stem cells derived from dental tissues—dental stem cells—are favored due to their easy acquisition. Among them, dental pulp stem cells (DPSCs) extracted from the dental pulp have many advantages, such as high proliferation and a highly purified population. Although their ability for neurogenic differentiation has been highlighted and neurogenic differentiation using electrospun nanofibers (NFs) has been performed, graphene-incorporated NFs have never been applied for DPSC neurogenic differentiation. Here, reduced graphene oxide (RGO)-polycaprolactone (PCL) hybrid electrospun NFs were developed and applied for enhanced neurogenesis of DPSCs. First, RGO-PCL NFs were fabricated by electrospinning with incorporation of RGO and alignments, and their chemical and morphological characteristics were evaluated. Furthermore, in vitro NF properties, such as influence on the cellular alignments and cell viability of DPSCs, were also analyzed. The influences of NFs on DPSCs neurogenesis were also analyzed. The results confirmed that an appropriate concentration of RGO promoted better DPSC neurogenesis. Furthermore, the use of random NFs facilitated contiguous junctions of differentiated cells, whereas the use of aligned NFs facilitated an aligned junction of differentiated cells along the direction of NF alignments. Our findings showed that RGO-PCL NFs can be a useful tool for DPSC neurogenesis, which will help regeneration in neurodegenerative and neurodefective diseases.

Directional Matrix Nanotopography with Varied Sizes for Engineering Wound Healing

Topographic features play a crucial role in the regulation of physiologically relevant cell and tissue functions. Here, an analysis of feature-size-dependent cell-nanoarchitecture interactions is reported using an array of scaffolds in the form of uniformly spaced ridge/groove structures for engineering wound healing. The ridge and groove widths of nanopatterns are varied from 300 to 800 nm and the nanotopography features are classified into three size ranges: dense (300-400 nm), intermediate (500-600 nm), and sparse (700-800 nm). On these matrices, fibroblasts demonstrate a biphasic trend of cell body and nucleus elongation showing the maximum at intermediate feature density, whereas maximum migration speed is observed at the dense case with monotonic decrease upon increasing feature size. The directional organization of cell-synthesized fibronectin fibers can be regulated differently via the nanotopographical features. In an in vitro wound healing model, the covering rate of cell-free regions is maximized on the dense nanotopography and decreased with increasing feature size, showing direct correlation with the trend of migration speed. It is demonstrated that the properties of repaired tissue matrices in the process of wound healing may be controlled via the feature-size-dependent cell-nanoarchitecture interactions, which can be an important consideration for designing tissue engineering scaffolds.

Eggshell membrane: review and impact on engineering

Abstract. Agricultural bioresources are being recognised as emerging functional platforms that can find application in biological, environmental, and agricultural engineering. Eggshell membrane (ESM), the protein-rich membrane between the eggshell and egg white, has usually been regarded as waste and overlooked. However, its potential is now being highlighted in many engineering fields. This review provides basic information about ESM starting with its structural, chemical, and physical properties, and expands on its role in engineering fields. It touches upon various fabrication methods for constructing compatible ESM-based functional platforms. The review focuses on the role and performance of ESM in engineering applications: electric devices, sensors, environmental engineering, biomedical engineering, and commercialization. Finally, new perspectives about the potential of ESM as a highly valuable bioresource in various engineering fields are discussed.

Synergistic effects of hyperosmotic polymannitol based non-viral vectors and nanotopographical cues for enhanced gene delivery

Here, we report the synergistic effects of hyperosmotic and nanotopographical cues designed using non-viral vectors and nanopatterned matrices for gene delivery. We show that efficiency of gene delivery can be further enhanced by two factors in combination, indicating the importance of synergistic cues in designing non-viral gene delivery platforms and strategies for gene therapy.