Publications by authors named "Chan-Hum Park"

The interactions between various cellular populations in the oral cavity, including gingival keratinocytes, tonsil-resident stem cells, periodontal ligament fibroblasts, and vascular endothelial cells, are crucial for maintaining oral health. These interactions regulate essential functions like tooth support and pathogen defense. However, conventional 2D and 3D models often fail to capture the complexity of these interactions and the multicellular architecture of the oral environment.

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In this present study, we introduce an innovative hybrid 3D bioprinting methodology that integrates fused deposition modeling (FDM) with top-down digital light processing (DLP) for the fabrication of an artificial trachea. Initially, polycaprolactone (PCL) was incorporated using an FDM 3D printer to provide essential mechanical support, replicating the structure of tracheal cartilage. Subsequently, a chondrocyte-laden glycidyl methacrylated silk fibroin hydrogel was introduced via top-down DLP into the PCL scaffold (PCL-Sil scaffold).

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The importance of hydrogels in tissue engineering cannot be overemphasized due to their resemblance to the native extracellular matrix. However, natural hydrogels with satisfactory biocompatibility exhibit poor mechanical behavior, which hampers their application in stress-bearing soft tissue engineering. Here, we describe the fabrication of a double methacrylated gelatin bioink covalently linked to graphene oxide (GO) via a zero-length crosslinker, digitally light-processed (DLP) printable into 3D complex structures with high fidelity.

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The reciprocal crosstalk between testicular Sertoli and Leydig cells plays a vital role in supporting germ cell development and maintaining testicular characteristics and spermatogenesis. Conventional 2D and the recent 3D assay systems fail to accurately replicate the dynamic interactions between these essential endocrine cells. Furthermore, most in vitro testicular tissue models lack the ability to capture the complex multicellular nature of the testis.

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Adapted immune cells are known to develop memory functions that increase resistance to subsequent infections after initial pathogen exposure, however, it is unclear whether non-immune cells, like tissue-resident stem cells, have similar memory functions. Here, it is found that tissue-resident stem cells crucial for tissue regeneration show diminished adverse effects on diverse stem cell functions against successive exposure to foreign antigen (β-glucan) to maintain tissue homeostasis and stability both in vitro and in vivo. These data suggest that endometrial stem cells may possess a robust memory function, in contrast, fully differentiated cells like fibroblasts and vesicular cells do not show these memory mechanisms upon consecutive antigen exposure.

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Although memory functions of immune cells characterized by increased resistance to subsequent infections after initial pathogen exposure are well-established, it remains unclear whether non-immune cells, especially tissue-resident stem cells, exhibit similar memory mechanisms. The present study revealed that detrimental effects of initial viral antigen exposure (human papillomavirus [HPV]) on diverse stem cell functions were significantly exacerbated upon subsequent secondary exposure both in vitro and in vivo. Importantly, endometrial stem cells exhibited robust memory functions following consecutive HPV antigen exposures, whereas fully differentiated cells such as fibroblasts and vesicular cells did not show corresponding changes in response to the same antigen exposures.

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Conventional 2D or even recently developed 3Dculture models for hypothalamus and pituitary gland cannot successfully recapitulate reciprocal neuroendocrine communications between these two pivotal neuroendocrine tissues known to play an essential role in controlling the body's endocrine system, survival, and reproduction. In addition, most currentculture models for neuroendocrine tissues fail to properly reflect their complex multicellular structure. In this context, we developed a novel microscale chip platform, termed the 'hypothalamic-pituitary (HP) axis-on-a-chip,' which integrates various cellular components of the hypothalamus and pituitary gland with biomaterials such as collagen and hyaluronic acid.

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Macrophages become activated by a variety of stimuli such as lipopolysaccharide (LPS) and participate in the process of immune responses. Activated macrophages produce various inflammatory mediators. In the present study, we investigated the anti-inflammatory mechanism of a serotonin derivative, N-feruloylserotonin, isolated from safflower seeds in RAW 264.

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Oxidative stress is closely associated with the pathology of neurodegenerative diseases. The seeds of L. (CTS) and (TC) are reported as herbal medicines for neuroprotection.

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Background: We aimed to investigate the effects of oxiracetam on cognitive impairment in the early phase of traumatic brain injury (TBI), for which no specific treatment is currently available.

Methods: The in vitro study used a cell injury controller to damage SH-SY5Y cells and evaluate the effect of oxiracetam at a dosage of 100 nM. The in vivo study used a stereotaxic impactor to induce a TBI model in C57BL/6 J mice and analyzed immunohistochemical changes and cognitive function after an intraperitoneal injection of oxiracetam (30 mg/kg/day) for 5 days.

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Objective: There are no effective clinically applicable treatments for neuronal dysfunction after mild traumatic brain injury (TBI). Here, we evaluated the therapeutic effect of a new delivery method of mouse neural stem cell (mNSC) spheroids using a hydrogel, in terms of improvement in damaged cortical lesions and cognitive impairment after mild TBI.

Methods: mNSCs were isolated from the subventricular zone and subgranular zone by a hydrogel-based culture system.

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Traditional medicines are recently being focused on to treat diabetes and its complications because of their lack of toxic and/or side effects. This report describes the effects of 7-O-galloyl-D-sedoheptulose (GS), a polyphenolic compound isolated from Corni Fructus, on type 2 diabetic db/db mice with hepatic and pancreatic damage. We examined several biochemical factors and oxidative stress- and inflammation-related markers.

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A three-dimensional (3D) artificial skin model offers diverse platforms for skin transplantation, disease mechanisms, and biomaterial testing for skin tissue. However, implementing physiological complexes such as the neurovascular system with living cells in this stratified structure is extremely difficult. In this study, full-thickness skin models were fabricated from methacrylated silk fibroin (Silk-GMA) and gelatin (Gel-GMA) seeded with keratinocytes, fibroblasts, and vascular endothelial cells representing the epidermis and dermis layers through a digital light processing (DLP) 3D printer.

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Background: The endometrium, the inner lining of the uterine cavity, plays essential roles in embryo implantation and its subsequent development. Although some positive results were preliminarily archived, the regeneration of damaged endometrial tissues by administrating stem cells only is very challenging due to the lack of specific microenvironments and their low attachment rates at the sites of injury. In this context, various biomaterial-based scaffolds have been used to overcome these limitations by providing simple structural support for cell attachment.

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Objective: We performed an expanded multi-ethnic meta-analysis to identify associations between inflammation-related loci with intracranial aneurysm (IA) susceptibility. This meta-analysis possesses increased statistical power as it is based on the most data ever evaluated.

Methods: We searched and reviewed relevant literature through electronic search engines up to August 2022.

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Hachimijiogan (HJG) and Bakumijiogan (BJG), two derivative prescriptions of Rokumijiogan (RJG), were selected to investigate their renoprotective potential in the 5/6 nephrectomized (5/6Nx) rat model. Rats were treated with HJG and BJG orally at 150 mg/kg body weight/day once daily for 10 weeks after resection of 5/6 of the renal volume, and their renoprotective effects were compared with 5/6Nx vehicle-treated and sham-operated control rats. Improvements in renal lesions, glomerulosclerosis, tubulointerstitial injury, and arteriosclerotic lesions estimated by histologic scoring indices in the HJG-treated group were compared with those in the BJG-treated group.

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Herein, we report the first study to create a three-dimensional (3D) bioprinted artificial larynx for whole-laryngeal replacement. Our 3D bio-printed larynx was generated using extrusion-based 3D bioprinter with rabbit's chondrocyte-laden gelatin methacryloyl (GelMA)/glycidyl-methacrylated hyaluronic acid (GMHA) hybrid bioink. We used a polycaprolactone (PCL) outer framework incorporated with pores to achieve the structural strength of printed constructs, as well as to provide a suitable microenvironment to support printed cells.

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Three-dimensional (3D) bioprinting has been developed as a viable method for fabricating functional tissues and organs by precisely spatially arranging biomaterials, cells, and biochemical components in a layer-by-layer fashion. Among the various bioprinting strategies, digital light-processing (DLP) printing has gained enormous attention due to its applications in tissue engineering and biomedical fields. It allows for high spatial resolution and the rapid printing of complex structures.

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3D-printed artificial skeletal muscle, which mimics the structural and functional characteristics of native skeletal muscle, is a promising treatment method for muscle reconstruction. Although various fabrication techniques for skeletal muscle using 3D bio-printers are studied, it is still challenging to build a functional muscle structure. A strategy using microvalve-assisted coaxial 3D bioprinting in consideration of functional skeletal muscle fabrication is reported.

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Objective: There are no effective treatments for relieving neuronal dysfunction after mild traumatic brain injury (TBI). Here, we evaluated therapeutic efficacy of human embryonic stem cell-derived cerebral organoids (hCOs) in a mild TBI model, in terms of repair of damaged cortical regions, neurogenesis, and improved cognitive function.

Methods: Male C57BL/6 J mice were randomly divided into sham-operated, mild TBI, and mild TBI with hCO groups.

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The pharmacological effectiveness of loquat leaf extract (LE) and its important component, ursolic acid (UA), in the treatment of diabetes mellitus, has been well established in traditional medicine; however, the mechanism underlying their action is still unclear. We evaluated the protective effects of LE and UA against hyperglycemia-induced advanced glycation end product (AGE) formations and hepatic pro-inflammation. Oral administration of UA and LE at a dose of 50 mg/kg/day for 15 days yielded no significant hypoglycemic effect in diabetic db/db mice.

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Hemostasis plays an essential role in all surgical procedures. Uncontrolled hemorrhage is the primary cause of death during surgeries, and effective blood loss control can significantly reduce mortality. For modern surgeons to select the right agent at the right time, they must understand the mechanisms of action, the effectiveness, and the possible adverse effects of each agent.

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Chemically modified silk fibroin (SF) bioink has been used for three-dimensional (3D) bioprinting in tissue engineering because of its biocompatibility and printability. Also, fluorescent silk fibroin (FSF) from transgenic silkworms has been recently applied in biomedicine because of its fluorescence property. However, the fabrication of fluorescent hydrogel from FSF has not been elucidated.

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Background: Copeptin has been reported as a predictive biomarker for the prognosis after traumatic brain injury (TBI). However, most of them were in patients with severe TBI and limited value in predicting outcomes in patients with moderate TBI defined as Glasgow Coma Scale (GCS) score from 9 to 12. We aimed to investigate the predictive value of copeptin in assessing the neurologic outcome following moderate TBI.

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Diabetes mellitus renders patients susceptible to chronic wounds and various infections. Regarding the latter, fungal infections are of particular concern since, although they are the source of significant morbidity and mortality in immunocompromised patients, they are generally resistant to conventional treatment and a definite treatment strategy has not yet been established. Herein, we report the treatment of skin wounds in a diabetic rat model, infected by , with low temperature helium plasma generated in a hand-held atmospheric jet device.

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