The Effect of Hybridization of Hydrogels and Poly(L-lactide-co-ε-caprolactone) Scaffolds on Cartilage Tissue Engineering

Jung, Youngmee,Kim, Sang-Heon,Kim, Young Ha,Kim, Soo Hyun Informa UK (TaylorFrancis) 2010 Journal of Biomaterials Science. Polymer Edition Vol.21 No.5

<P>For repairing cartilage defects by cartilage tissue engineering, it is important that engineered cartilage that is fabricated with scaffolds and cells can maintain the biological and physiological functions of cartilage, and also can induce three-dimensional spatial organization of chondrocytes. In this sense, hydrogels such as fibrin gels (FG) and hyaluronan (HA) are widely used for application in cartilage treatment. However, the use of hydrogels alone as a scaffold has a physical weakness; the mechanical properties of hydrogels are too weak to endure complex loading in the body. In this study, for mimicking a native cartilage microenvironment, we made cell-hybrid scaffold constructs with poly(L-lactide-co-epsilon-caprolactone) (PLCL) scaffolds and hydrogels to guide three-dimensional spatial organization of cells and extracellular matrix. A highly elastic scaffold was fabricated from PLCL with 85% porosity and 300-500 microm pore size using a gel-pressing method. The mixture of rabbit chondrocytes and hydrogels was seeded on PLCL scaffolds, and was subcutaneously implanted into nude mice for up to eight weeks. The cell seeding efficiency of the hybrid scaffolds with FG or HA was higher than that of the PLCL scaffolds. From in vivo studies, the accumulation of cartilaginous extracellular matrices of constructs, which was increased by hybridization of hydrogels and PLCL scaffolds, showed that the cell-hybrid scaffold constructs formed mature and well-developed cartilaginous tissue. In conclusion, the hybridization of hydrogels and PLCL scaffold for three-dimensional spatial organization of cells would provide a biomimetic environment where cartilage tissue growth is enhanced and facilitated. It can enhance the production of cartilaginous extracellular matrices and, consequently, improve the quality of the cartilaginous tissue formed.</P>

Reconstruction of a Rabbit Ulna Bone Defect Using Bone Marrow Stromal Cells and a PLA/β-TCP Composite by a Novel Sintering Method

Jung, Youngmee,Park, Min Sung,Kim, Sang-Soo,Kim, Byung-Soo,Kim, Young Ha,Kim, Sang-Heon,Lee, Jin Woo,Kim, Soo Hyun WILEY-VCH Verlag 2009 Advanced Engineering Materials Vol.11 No.11

<B>Graphic Abstract</B> <P>We developed PLA/β-TCP composites with a novel sintering method in order to enhance cellular interaction with matrices for bone regeneration. Thereafter, we confirmed the superior bone-forming characteristics of PLA/β-TCP cell-composite constructs resulting from greater surface exposure of the β-TCP particles, which may yield higher osteogenic and osteoconductive properties. <img src='wiley_img/14381656-2009-11-11-ADEM200900013-content.gif' alt='wiley_img/14381656-2009-11-11-ADEM200900013-content'> </P>

The effects of dynamic and three-dimensional environments on chondrogenic differentiation of bone marrow stromal cells

Jung, Youngmee,Kim, Sang-Heon,Kim, Young Ha,Kim, Soo Hyun Institute of Physics Pub 2009 Biomedical materials Vol.4 No.5

<P>Articular cartilage is subjected to complex loading, which plays a major role in its growth, development and maintenance. Previously, we found that mechanical stimuli enhanced the development and function of engineered cartilage tissues in elastic mechano-active poly(lactide-co-caprolactone) (PLCL) scaffolds. In addition, it is well known that the three-dimensional spatial organization of cells and extracellular matrices in hydrogels is crucial to chondrogenesis. This study was conducted to enhance the chondrogenic differentiation of bone marrow stromal cells (BMSCs) in the hybrid scaffolds of fibrin gels and PLCL scaffolds in dynamic environments by compression. A highly elastic scaffold was fabricated from very elastic PLCL with 85% porosity and a 300–500 µm pore size using a gel-pressing method. A mixture of rabbit BMSCs and fibrin gels was then seeded onto the PLCL scaffolds and subjected to continuous compressive deformation of 5% strain at 0.1 Hz for 10 days in a chondrogenic medium containing 10 ng ml<SUP>−1</SUP> TGF-β<SUB>1</SUB>. The BMSCs-seeded scaffold constructs were then implanted subcutaneously into nude mice. As a control, the cell–PLCL scaffold constructs were cultured under dynamic conditions or the cell–PLCL/fibrin hybrid scaffold constructs and the cell–PLCL scaffold constructs were cultured under static conditions for 10 days <I>in vitro</I>. The results revealed that cells adhered onto the hybrid scaffolds of fibrin gels and PLCL scaffolds cultured under dynamic conditions. In addition, the accumulation of the extracellular matrix of cell–scaffold constructs, which was increased through mechanical stimulation, showed that chondrogenic differentiation was sustained and enhanced significantly in the stimulated hybrid scaffold constructs. Overall, the results of this study indicate that the proper periodic application of dynamic compression and the three-dimensional environments of the hybrid scaffolds composed of fibrin gels and elastic PLCL can encourage BMSCs to differentiate into chondrocytes, maintain their phenotypes and enhance GAGs production, thereby improving the quality of cartilaginous tissue formed <I>in vitro</I> and <I>in vivo.</I></P>

Bone Regeneration with PLA/β-TCP Composites by Novel Sintering and Bone Marrow Stromal Cells

Youngmee Jung,Ki Chul Chung,Min Sung Park,Yon Rak Choi,Jin Woo Lee,Sang-Heon Kim,Young Ha Kim,Byoung Goo Min,Soo Hyun Kim 한국고분자학회 2006 한국고분자학회 학술대회 연구논문 초록집 Vol.2006 No.10

In vitro Three-Dimensional Vascularized Beds Based on Decellularized Extracellular Matrix Hydrogels

Youngmee Jung,Tae Hee Kim,Jung Hwa Lee,Soo Hyun Kim 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

DMF as a Source of Oxygen and Aminomethine: Stereoselective 1,2-Insertion of Rhodium(II) Azavinyl Carbenes into the CO Bond of Formamides for the Synthesis of <i>cis</i>-Diamino Enones

Jung, Da Jung,Jeon, Hyun Ji,Kim, Ju Hyun,Kim, Youngmee,Lee, Sang-gi American Chemical Society 2014 ORGANIC LETTERS Vol.16 No.8

<P>A new catalytic reaction in which all the atoms of a formamide are incorporated into the product through a formal stereoselective 1,2-insertion of rhodium(II) azavinyl carbenes, generated in situ from readily available <I>N</I>-sulfonylated 1,2,3-triazoles, into the CO bond of DMF and other <I>N</I>,<I>N</I>-disubstituted formamides to afford <I>cis</I>-diamino enones is described.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/orlef7/2014/orlef7.2014.16.issue-8/ol500723s/production/images/medium/ol-2014-00723s_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ol500723s'>ACS Electronic Supporting Info</A></P>

Cartilaginous tissue formation using a mechano-active scaffold and dynamic compressive stimulation

Jung, Youngmee,Kim, Soo Hyun,Kim, Sang-Heon,Kim, Young Ha,Xie, Jun,Matsuda, Takehisa,Min, Byoung Goo Informa UK (TaylorFrancis) 2008 Journal of Biomaterials Science. Polymer Edition Vol.19 No.1

<P>It is known that complex loading is involved in the development and maintenance of articular cartilage in the body. It means the compressive mechanical stimulation is a very important factor for formation of articular cartilage using a tissue-engineering technique. The objective of this study is to engineer cartilaginous constructs with mechano-active scaffolds and to evaluate the effect of dynamic compression for regeneration of cartilage. The mechano-active scaffolds were prepared from a very elastic poly(L-lactide-co-epsilon-caprolactone) (PLCL) with 85% porosity and 300-500 mum pore size using a gel-pressing method. The scaffold was seeded with 2 x 10(6) chondrocytes and the continuous compressive deformation of 5% strain was applied with 0.1 Hz for 10 days and 24 days, respectively. Then, the chondrocytes-seeded constructs were implanted subcutaneously into nude mice. Mechano-active scaffolds with complete rubber-like elasticity showed almost complete (over 97%) recovery at an applied strain of up to 500%. The amount of chondral extracellular matrix was increased significantly by mechanical stimulation on the highly elastic mechano-active scaffolds. Histological analysis showed the mechanically stimulated implants formed mature and well-developed cartilaginous tissue, as evidenced by the chondrocytes within lacunae and the abundant accumulation of sulfated GAGs. However, unhealthy lacunae shapes and hypertrophy forms were observed in the implants stimulated mechanically for 24 days, compared with those stimulated for 10 days. In conclusion, the proper periodical application of dynamic compression can encourage chondrocytes to maintain their phenotypes and enhance the production of GAGs, which would improve the quality of cartilaginous tissue formed both in vitro and in vivo.</P>

항공서비스전공 여대생의 진로장벽이 진로결정수준에 미치는 영향: 4년제 대학교와 전문대학 비교

정영미 ( Youngmee Jung ) 관광경영학회 2019 관광경영연구 Vol.88 No.-

This study aimed to examine effects of career barriers of female college students who major in airline service on their career decision level and differences in sub-factors of career barriers affecting career decision level between female college students in four-year and two-year colleges. The subjects included 400 female college students majoring in airline service, by selecting randomly selecting 4 four-year and 4 two-year colleges, in which the department of it is established, and SPSS WIN 21.0 was used for the statistical analysis. The results of the analysis show: first, sub-factors of the career barriers, such as lack of interest, interrelationship, anxiety for the future and collection of information have significantly negative effects on the career decision level; second, although there are no significant differences in the career barriers and career decision level, according to types of educational institutes for airline service major, sub-factors of the career barriers, which have significantly negative effects on the career decision level include lack of interest, interrelationship, problems related with age, physical inferiority, lack of definiteness, for four-year female college students and collection of information, anxiety for the future, interrelationship, lack of interest, for two-year female college students. The finding suggest that curriculum and career coaching, for changing college female students' recognition on the career barriers, who major in airline service and therefore, desirable career decision based on them are required.

Crystal structures and catalytic activities of Zn(II) compounds containing 1,3-bis(4-pyridyl)propane

Kim, Youngmee,Kim, Sung-Jin,Choi, Seung Hoon,Han, Jung Hee,Nam, Sang Ho,Lee, Jung Hwan,Kim, Hee Jin,Kim, Cheal,Kim, Dong Wook,Jang, Ho Gyeom Elsevier Sequoia [etc.] 2006 Inorganica chimica acta Vol.359 No.8

<P><B>Graphical abstract</B></P><P>The structures of new compounds containing Zn(II) ions and bpp ligands have been determined. The polymeric compounds <B>1</B> and <B>2</B> containing hydroxyl-bridged zinc cations [Zn<SUB>2</SUB>OH] were found to carry out the catalytic transesterification of a range of esters with methanol at room temperature under the mild conditions.</P><ce:figure></ce:figure> <P><B>Abstract</B></P><P>The structures of new compounds containing Zn(II) ions and bpp (1,3-bis(4-pyridyl)propane) ligands have been determined. The coordinating halides (Br<SUP>−</SUP> or Cl<SUP>−</SUP>) produce one-dimensional compounds <B>6</B> and <B>7</B>, and intra- and inter-chain CH⋯X (X=Br or I) interactions play roles for building crystal structures with the flexible bpp ligands. The non-coordinating PF6− anions do not produce hydroxyl bridged zinc cations or polymeric compounds, and produce only a monomeric complex <B>4</B> containing four bpp ligands and two water ligands. Previously reported polymeric compounds <B>1</B> and <B>2</B> containing hydroxyl-bridged zinc cations [Zn<SUB>2</SUB>OH] were found to carry out the catalytic transesterification of a range of esters with methanol at room temperature under the mild conditions, whereas the rest of compounds did not catalyze the transesterification reactions at all. In addition, the catalysts <B>1</B> and <B>2</B> have shown even better catalytic activity than zinc salts Zn(NO<SUB>3</SUB>)<SUB>2</SUB> and Zn(OTf)<SUB>2</SUB>.</P>

항공관광전공 선택 동기가 직업가치관과 전공만족도에 미치는 영향

정영미 ( Youngmee Jung ) 관광경영학회 2020 관광경영연구 Vol.98 No.-

University students' major selection is very important, in that it can develops their interest, aptitude and ability by fostering their scholarship and knowledge and has an effect on not only campus life but also their future job selection and whole life. This study therefore attempted to verify the effect of university students' major selection motivations, who major in the department of aviation tourism, on work values and major satisfaction. The subjects included 438 university students majoring in the department of aviation tourism and used SPSS WIN 21.0 for the statistical analysis. The findings are as follows: First, both individual motivations and social motivations, sub-factors of major selection motivations have significantly positive effects on intrinsic values and extrinsic values, those of work values. Second, both individual motivations and social motivations, sub-factors of major selection motivations also have significantly positive effects on academic satisfaction, perception satisfaction and relation satisfaction, those of major satisfaction factors. Third, intrinsic values has a significantly positive effect on academic satisfaction, perception satisfaction and relation satisfaction, while extrinsic values only has a significantly positive effect on perception satisfaction. The findings suggest that it is necessary to make effort to enhance the major capability of university students majoring in the department of aviation tourism, by establishing a system and developing curriculum, for changing their major satisfaction and work values.