Meeju Kim

Dankook University, Eidō, North Chungcheong, South Korea

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Publications (9)29.22 Total impact

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    ABSTRACT: Graphical abstract Figure optionsDownload full-size imageDownload high-quality image (67 K)Download as PowerPoint slide
    Acta biomaterialia 01/2014; · 5.68 Impact Factor
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    ABSTRACT: Three-dimensional matrices that encapsulate and deliver stem cells with defect-tuned formulations are promising for bone tissue engineering. Here we designed a novel stem cell delivery system composed of collagen and alginate as the core and shell, respectively. Mesenchymal stem cells (MSCs) were loaded into the collagen solution and then deposited directly into a fibrous structure while simultaneously sheathing with alginate using a newly designed core-shell nozzle. Alginate encapsulation was achieved by the cross-linking within an adjusted calcium-containing solution that effectively preserved the continuous fibrous structure of the inner cell-collagen part. The constructed hydrogel carriers showed a continuous fiber with diameter of approximately 700-1000 µm for the core and 200-500 μm for the shell area, which was largely dependent on the alginate concentration (2-5%) as well as the injection rate (20-80 ml/h). Water uptake capacity of the core-shell carriers was as high as 98%, which could act as a pore channel to supply nutrients and oxygen to the cells. Degradation of the scaffolds showed weight loss of ~22% at 7 days and ~43% at 14 days, suggesting a possible role as a degradable tissue-engineered construct. The MSCs encapsulated within the collagen core showed excellent viability, exhibiting significant cellular proliferation up to 21 days with levels comparable to those observed in the pure collagen gel matrix used as a control. A live/dead cell assay also confirmed similar percentages of live cells within the core-shell carrier compared to those in the pure collagen gel, suggesting the carrier was cell compatible and was effective for maintaining a cell population. Cells allowed to differentiate under osteogenic conditions expressed high levels of bone-related genes, including osteocalcin, bone sialoprotein and osteopontin. Furthermore, when the core-shell fibrous carriers were implanted in a rat calvarium defect, the bone healing was significantly improved when the MSCs were encapsulated, and even more so after an osteogenic induction of MSCs prior to implantation. Based on these results, the newly-designed core-shell collagen-alginate fibrous carrier is considered promising to enable the encapsulation of tissue cells and their delivery into damaged target tissues including bone with defect-tunability.
    Tissue Engineering Part A 08/2013; · 4.64 Impact Factor
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    ABSTRACT: We report the ability of aminated mesoporous silica nanoparticles (MSN-NH(2) ) with large mesopore space and positive-charged surface to deliver genes within rat mesenchymal stem cells (MSCs). The amine functionalized inorganic nanoparticles were complexed with bone morphogenetic protein-2 (BMP2) plasmid DNA (pDNA) to study their transfection efficiency in MSCs. Intracellular uptake of the complex BMP2 pDNA/MSN-NH(2) occurred significantly, with a transfection efficiency of approximately 68%. Furthermore, over 66% of the transfected cells produced BMP2 protein. The osteogenic differentiation of the transfected MSCs was demonstrated by the expression of bone-related genes and proteins including bone sialoprotein, osteopontin, and osteocalcin. The MSN-NH(2) delivery vehicle for BMP2 pDNA developed in this study may be a potential gene delivery system for bone tissue regeneration. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
    Journal of Biomedical Materials Research Part A 11/2012; · 2.83 Impact Factor
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    ABSTRACT: Inorganic bioactive nanomaterials are attractive for hard tissue regeneration, including nanocomponents for bone replacement composites and nanovehicles for delivering therapeutics. Bioactive glass nanoparticles (BGn) have recently gained potential usefulness as bone and tooth regeneratives. Here we demonstrate the capacity of the BGn with mesopores to load and deliver therapeutic molecules (drugs and particularly genes). Spherical BGn with sizes of 80-90 nm were produced to obtain 3-5 nm sized mesopores through a sono-reacted sol-gel process. A simulated body fluid test of the mesoporous BGn confirmed their excellent apatite forming ability and the cellular toxicity study demonstrated their good cell viability up to 100 μg ml(-1). Small molecules like chemical drug (Na-ampicillin) and gene (small interfering RNA; siRNA) were introduced as model drugs considering the mesopore size of the nanoparticles. Moreover, amine-functionalization allowed switchable surface charge property of the BGn (from -20-30 mV to +20-30 mV). Loading of ampicillin or siRNA saturated within a few hours (∼2 h) and reflected the mesopore structure. While the ampicillin released relatively rapidly (∼12 h), the siRNA continued to release up to 3 days with almost zero-order kinetics. The siRNA-nanoparticles were easily taken up by the cells, with a transfection efficiency as high as ∼80%. The silencing effect of siRNA delivered from the BGn, as examined by using bcl-2 model gene, showed dramatic down-regulation (∼15% of control), suggesting the potential use of BGn as a new class of nanovehicles for genes. This, in conjunction with other attractive properties, including size- and mesopore-related high surface area and pore volume, tunable surface chemistry, apatite-forming ability, good cell viability and the possible ion-related stimulatory effects, will potentiate the usefulness of the BGn in hard tissue regeneration.
    Nanoscale 10/2012; · 6.73 Impact Factor
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    ABSTRACT: Combining calcium phosphate cements (CPCs) with bioactive molecules improves their bone regeneration potential. Although CPCs are highly osteoconductive, sometimes they have limited biological responses, especially in terms of cell proliferation. Here, we used basic fibroblast growth factor (bFGF) in an α-tricalcium phosphate cement with different initial powder sizes (coarse vs. fine; designated as CPC-C and CPC-F, respectively) and investigated the behavior of bFGF loading and release, as well as the effects on osteoblast responses. bFGF was loaded at 10 μg/ml or 25 μg/ml onto the set form of two types of CPCs, aiming to allow penetration into the pore structure and adsorption onto the cement crystallites. The CPC formulated with fine powder (CPC-F) had higher specific surface area and smaller-sized pores and retained slightly higher amounts of bFGF within the structure. The bFGF release study performed for 3 weeks showed a sustained-release profile; after an initial rapid release over approximately 3 days, further release pattern was almost linear. Compared to CPC-F, CPC-C showed a much faster release pattern. The effects of the bFGF incorporation within CPCs on cellular responses were assessed in terms of cell proliferation using MC3T3-E1 pre-osteoblastic cells. Compared with bFGF-free CPCs (both CPC-C and CPC-F), those containing bFGF stimulated cell proliferation for up to 7 days. An inhibition study of bFGF receptor demonstrated that the improvement of cell proliferation resulted from the role of bFGF released from the CPCs. This study provides beneficial information on improving the biological properties of CPCs by combining them with specific therapeutic molecules, and particularly with bFGF, showing that the cell proliferative ability was significantly stimulated, which may have potential applications for further use in stem cell-based bone tissue engineering. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
    Journal of Biomedical Materials Research Part A 09/2012; · 2.83 Impact Factor
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    ABSTRACT: Silver nanoparticles (AgNPs) have found a variety of uses including biomedical materials; however, studies of the cytotoxicity of AgNPs by size effects are only in the beginning stage. In this study, we examined the size-dependent cellular toxicity of AgNPs using three different characteristic sizes (∼ 10, 50, and 100 nm) against several cell lines including MC3T3-E1 and PC12. The cytotoxic effect determined based on the cell viability, intracellular reactive oxygen species generation, lactate dehydrogenase release, ultrastructural changes in cell morphology, and upregulation of stress-related genes (ho-1 and MMP-3) was fairly size- and dose-dependent. In particular, AgNPs stimulated apoptosis in the MC3T3-E1 cells, but induced necrotic cell death in the PC12 cells. Furthermore, the smallest sized AgNPs (10 nm size) had a greater ability to induce apoptosis in the MC3T3-E1 cells than the other sized AgNPs (50 and 100 nm). These data suggest that the AgNPs-induced cytotoxic effects against tissue cells are particle size-dependent, and thus, the particle size needs careful consideration in the design of the nanoparticles for biomedical uses.
    Journal of Biomedical Materials Research Part A 03/2012; 100(4):1033-43. · 2.83 Impact Factor
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    ABSTRACT: Nerve regeneration and functional recovery have been a major issue following injury of nerve tissues. Electrospun nanofibers are known to be suitable scaffolds for neural tissue engineering applications. In addition, modified substrates often provide better environments for neurite outgrowth. This study was conducted to determine if multi-walled carbon nanotubes (MWCNTs)-coated electrospun poly (l-lactic acid-co-caprolactone) (PLCL) nanofibers improved the neurite outgrowth of rat dorsal root ganglia (DRG) neurons and focal adhesion kinase (FAK) expression of PC-12 cells. To accomplish this, the DRG neurons in either uncoated PLCL scaffolds (PLCL group) or MWCNTs-coated PLCL scaffolds (PLCL/CNT group) were cultured for nine days. MWCNTs-coated PLCL scaffolds showed improved neurite outgrowth of DRG neurons. Moreover, FAK expression was up-regulated in the PLCL/CNT group when compared to the PLCL group in a non-time-dependent manner. These findings suggest that MWCNTs-coated nanofibrous scaffolds may be alternative materials for nerve regeneration and functional recovery in neural tissue engineering.
    Neuroscience Letters 06/2011; 501(1):10-4. · 2.03 Impact Factor
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    ABSTRACT: Neurite outgrowth from endogenous or transplanted cells is important for neural regeneration following nerve tissue injury. Modified substrates often provide better environments for cell adhesion and neurite outgrowth. This study was conducted to determine if MWCNT (multiwalled carbon nanotube)-coated electrospun PLCL [poly (l-lactic acid-co-3-caprolactone)] nanofibres improved the neurite outgrowth of PC-12 cells. To accomplish this, two groups, PC-12 cells in either uncoated PLCL scaffolds or MWCNT-coated PLCL scaffolds were cultured for 9 days. MWCNT-coated PLCL scaffolds showed improved adhesion, proliferation and neurite outgrowth of PC-12 cells. These findings suggest that MWCNT-coated nanofibrous scaffolds may be an attractive platform for cell transplantation application in neural tissue engineering.
    Cell Biology International 02/2011; 35(7):741-5. · 1.64 Impact Factor

Publication Stats

72 Citations
29.22 Total Impact Points

Institutions

  • 2011–2014
    • Dankook University
      • Institute of Tissue Regeneration Engineering (ITREN)
      Eidō, North Chungcheong, South Korea
  • 2013
    • Institute of Tissue Regeneration and Engineering(ITREN)
      Sŏul, Seoul, South Korea