• Biomaterials and Biomechanics in Bioengineering
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• v.3 no.3
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• pp.141-155
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• 2016

Two-dimensional (2D) cell culture and in vivo cancer model systems have been used to understand cancer biology and develop drug delivery systems for cancer therapy. Although cell culture and in vivo model studies have provided critical contribution about disease mechanism, these models present important problems. 2D tissue culture models lack of three dimensional (3D) structure, while animal models are expensive, time consuming, and inadequate to reflect human tumor biology. Up to the present, scaffolds and 3D matrices have been used for many different clinical applications in regenerative medicine such as heart valves, corneal implants and artificial cartilage. While tissue engineering has focused on clinical applications in regenerative medicine, scaffolds can be used in in vitro tumor models to better understand tumor relapse and metastasis. Because 3D in vitro models can partially mimic the tumor microenvironment as follows. This review focuses on different scaffold production techniques and polymer types for tumor model applications in cancer tissue engineering and reports recent studies about in vitro 3D polymeric tumor models including breast, ewing sarcoma, pancreas, oral, prostate and brain cancers.

• Journal of Embryo Transfer
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• v.32 no.4
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• pp.267-274
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• 2017

Alpha lipoic acid (ALA) is a biological membranes compound. As the antioxidant, it decreases the oxidized forms of other antioxidant substances such as vitamin C, vitamin E, and glutathione (GSH). To examine the effect of ALA on the in vitro maturation (IVM) of porcine oocytes, we investigated intracellular GSH and reactive oxygen species (ROS) levels, and subsequent embryonic development after parthenogenetic activation (PA). Intracellular GSH levels in oocytes treated with 50uM ALA increased significantly (P < 0.05) and exhibited a significant (P < 0.05) decrease in intracellular ROS levels compared with the control group. Oocytes matured with 50 uM of ALA during IVM displayed significantly higher cleavage rates (67.8% vs. 83.4%, respectively), and higher blastocyst formation rates and total cell number of blastocysts after PA (31.6%, 58.49 vs. 46.8%, 68.58, respectively) than the control group. In conclusion, these results suggest that treatment with ALA during IVM improves the cytoplasmic maturation of porcine oocytes by increasing the intracellular GSH levels, thereby decreasing the intracellular ROS levels and subsequent embryonic developmental potential of PA.

• International Journal of Oral Biology
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• v.42 no.2
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• pp.71-78
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• 2017

BMP-2 is a well-known TGF-beta related growth factor, having a significant role in bone and cartilage formation. It has been employed to promote bone formation in some clinical trials, and to differentiate mesenchymal stem cells into osteoblasts. However, it is difficult to obtain this protein in its soluble and active form. hBMP-2 is expressed as an inclusion body in the bacterial system. To continuously supply hBMP-2 for research, we optimized the refolding of recombinant hBMP-2 expressed in E. coli, and established an efficient method by using detergent and alkali. Using a heparin column, the recombinant hBMP-2 was purified with the correct refolding. Although combinatorial refolding remarkably enhanced the solubility of the inclusion body, a higher yield of active dimer form of hBMP-2 was obtained from one-step refolding with detergent. The refolded recombinant hBMP-2 induced alkaline phosphatase activity in mouse myoblasts, at $ED_{50}$ of 300-480ng/ml. Furthermore, the expressions of osteogenic markers were upregulated in hPDLSCs and hDPSCs. Therefore, using the process described in this study, the refolded hBMP-2 might be cost-effectively useful for various differentiation experiments in a laboratory.

• Korean Journal of Materials Research
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• v.31 no.5
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• pp.278-285
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• 2021

This study produces electroconductive polycaprolactone (PCL)-based film with different amounts of graphene (G) through electrospinning, and the characteristics of the produced G/PCL composites are investigated. The G/PCL results are analyzed by comparing them with those obtained using pure PCL electrospun film as a control. The morphology of electrospun material is analyzed through scanning electron microscopy and transmission electron microscopy. Mechanical and electrical properties are also evaluated. Composites containing 1 % graphene have the highest elongation rate, and 5 % samples have the highest strength and elasticity. Graphene contents > 25 % show electro-conductivity, which level improves with increase of graphene content. Biological characteristics of G/PCL composites are assessed through behavioral analysis of neural cell attachment and proliferation. Cell experiments reveal that compositions < 50 % show slightly reduced cell viability. Moreover, graphene combinations facilitated cell proliferation compared to pure PCL. These results confirm that a 25 % G/PCL composition is best for application to systems that introduce external stimuli such as electric fields and electrodes to lead to synergistic efficiency of tissue regeneration.

• BMB Reports
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• v.57 no.5
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• pp.250-255
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• 2024

Due to their stem-like characteristics and immunosuppressive properties, Mesenchymal stem cells (MSCs) offer remarkable potential in regenerative medicine. Much effort has been devoted to enhancing the efficacy of MSC therapy by enhancing MSC migration. In this study, we identified deubiquitinase BRCA1-associated protein 1 (BAP1) as an inhibitor of MSC migration. Using deubiquitinase siRNA library screening based on an in vitro wound healing assay, we found that silencing BAP1 significantly augmented MSC migration. Conversely, BAP1 overexpression reduced the migration and invasion capabilities of MSCs. BAP1 depletion in MSCs upregulates ERK phosphorylation, thereby increasing the expression of the migration factor, osteopontin. Further examination revealed that BAP1 interacts with phosphorylated ERK1/2, deubiquitinating their ubiquitins, and thus attenuating the ERK signaling pathway. Overall, our study highlights the critical role of BAP1 in regulating MSC migration through its deubiquitinase activity, and suggests a novel approach to improve the therapeutic potential of MSCs in regenerative medicine.

• Journal of Ginseng Research
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• v.48 no.4
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• pp.435-436
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• 2024

• BMB Reports
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• v.52 no.6
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• pp.409-414
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• 2019

Natural compounds isolated from medicinal herbs and plants have immense significance in maintaining bone health. Hydrolysable tannins have been shown to possess a variety of medicinal properties including antiviral, anticancer, and anti-osteoclastogenic activities. As a part of a study on the discovery of alternative agent against skeletal diseases, we isolated a hydrolysable tannin, 2-O-digalloyl-1,3,4,6-tetra-O-galloyl-${\beta}$-D-glucose (DTOGG), from Galla Rhois and examined the effect on osteoclast formation and function. We found that DTOGG significantly inhibited receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL)-induced osteoclast differentiation by downregulating the expression of the key regulator in osteoclastogenesis as well as osteoclast-related genes. Analysis of RANKL/RANK signaling revealed that DTOGG impaired activation of $I{\kappa}B{\alpha}$ and p65 in the nuclear factor kappa-lightchain-enhancer of activated B cells (NF-${\kappa}B$) signaling pathway. Furthermore, DTOGG reduced bone resorbing activity of osteoclasts, compared to the vehicle-treated control. These results suggest that DTOGG could be a useful natural compound to manage osteoclast-mediated skeletal diseases.

• Development and Reproduction
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• v.12 no.1
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• pp.87-95
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• 2008

Neural stem/precursor derived from pluripotent human embryonic stem cells (hESCs) has considerable therapeutic potential due to their ability to generate various neural cells which can be used in cell-replacement therapies for neurodegenerative diseases. However, production of neural cells from hESCs remains technically very difficult. Understanding neural-tube like rosette characteristic neural precursor cells from hESCs may provide useful information to increase the efficiency of hESC neural differentiation. Generally, neural rosettes were derived from differentiating hEBs in attached culture system, however this is time-consuming and complicated. Here, we examined if neural rosettes could be formed in suspension culture system by bypassing attachment requirement. First, we tested whether the size of hESC clumps affected the formation of human embryonic bodies (hEBs) and neural differentiation. We confirmed that hEBs derived from $500{\times}500\;{\mu}m$ square sized hESC clumps were effectively differentiated into neural lineage than those of the other sizes. To induce the rosette formation, regular size hEBs were derived by incubation of hESC clumps($500{\times}500\;{\mu}m$) in EB medium for 1 wk in a suspended condition on low attachment culture dish and further incubated for additional $1{\sim}2$ wks in neuroectodermal sphere(NES)-culture medium. We observed the neural tube-like rosette structure from hEBs after $7{\sim}10$ days of differentiation. Their identity as a neural precursor cells was assessed by measuring their expressions of neural precursor markers(Vimentin, Nestin, MSI1, MSI2, Prominin-1, Pax6, Sox1, N-cadherin, Otx2, and Tuj1) by RT-PCR and immunofluorescence staining. We also confirmed that neural rosettes could be terminally differentiated into mature neural cell types by additional incubation for $2{\sim}6$ wks with NES medium without growth factors. Neuronal(Tuj1, MAP2, GABA) and glial($S100{\beta}$ and GFAP) markers were highly expressed after $2{\sim}3$ and 4 wks of incubation, respectively. Expression of oligodendrocyte markers O1 and CNPase was significantly increased after $5{\sim}6$ wks of incubation. Our results demonstrate that rosette forming neural precursor cells could be successfully derived from suspension culture system and that will not only help us understand the neural differentiation process of hESCs but also simplify the derivation process of neural precursors from hESCs.

• International Journal of Oral Biology
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• v.37 no.2
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• pp.43-50
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• 2012

The use of high throughput screening (HTS) in drug development is principally for the selection new drug candidates or screening of chemical toxicants. This system minimizes the experimental environment and allows for the screening of candidates at the same time. Umbilical cord-derived stem cells have some of the characteristics of fetal stem cell and have several advantages such as the ease with which they can be obtained and lack of ethical issues. To establish a HTS system, optimized conditions that mimic typical cell culture conditions in a minimal space such as 96 well plates are needed for stem cell growth. We have thus established a novel HTS system using human umbilical cord derived-mesenchymal stem cells (hUC-MSCs). To determine the optimal cell number, hUC-MSCs were serially diluted and seeded at 750, 500, 200 and 100 cells per well on 96 well plates. The maintenance efficiencies of these dilutions were compared for 3, 7, 9, and 14 days. The fetal bovine serum (FBS) concentration (20, 10, 5 and 1%) and the cell numbers (750, 500 and 200 cells/well) were compared for 3, 5 and 7 days. In addition, we evaluated the optimal conditions for cell cycle block. These four independent optimization experiments were conducted using an MTT assay. In the results, the optimal conditions for a HTS system using hUC-MSCs were determined to be 300 cell/well cultured for 8 days with 1 or 5% FBS. In addition, we demonstrated that the optimal conditions for a cell cycle block in this culture system are 48 hours in the absence of FBS. In addition, we selected four types of novel small molecule candidates using our HTS system which demonstrates the feasibility if using hUC-MSCs for this type of screen. Moreover, the four candidate compounds can be tested for stem cell research application.

• Medical Lasers
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• v.9 no.1
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• pp.6-11
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• 2020

Hydrogels have been developed and used in tissue engineering and regenerative medicine to deliver therapeutics to injured or diseased tissue because of their versatility and properties that can be tailored to match the natural extracellular matrix. Hydrogels can be made with a variety of physical and chemical properties combined with light responsiveness ideal for applications in different fields of medicine that require the spatiotemporal control of therapeutics. Light, as a stimulus, is relatively inexpensive, contact-free, noninvasive with high spatial resolution and temporal control, convenient and easy to use, and allows deep tissue penetration that is relatively harmless. Photoresponsive hydrogels are ideal candidates for on-demand drug delivery systems that are capable of sustained and controlled drug release, minimizing the side effects, and ensuring the activity and efficient delivery of drugs to the target tissue.