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        검색결과 289

        161.
        2017.05 서비스 종료(열람 제한)
        Background : Heat stress induced from high temperature are known to crucially affecting on physiological properties and yield in Cnidium officinale. Methods and Results : The effect of foliar application of mixture including a urea, ascorbic acid and calcium chloride on high temperature injury of Cnidium officinale. Photosynthesis and leaf temperature in Cnidium officinale were investigated after cultivating for 24 hours at 35℃. Net photosyntheis rate, transpiration was measured at 1,000 μmol m-2 s-1 of photon flux density and leaf temperature was analyzed by thermal image. Net photosyntheis rate, stomatal conductance and transpiration rate in mixture traetment were 2 times of higher than in control. Water use efficience was not different significantly. Leaf temperature was lower in mixture treatment (25.3℃) than in control (29.0℃). Conclusion : This result show that foliar application of urea, ascorbic acid and calcium chloride was reducing a high temperature injury through a improving photosynthetical capacity and decreasing leaf temperature of Cnidium officinale.
        162.
        2017.05 서비스 종료(열람 제한)
        Background : Management of air temperature are known to primarily affecting on physiological properties and yield in plant. Methods and Results : The effect of air temperature on characteristics of photosynthesis and chlorophyll fluorescence in Cnidium officinal were investigated using growth chamber after cultivating for 24 hours under controlled condition. Net photosyntheis rate, transpiration was measured at 1,000 μmol m-2 s-1 of photon flux density and chlorophyll fluorescence was analyzed by OJIP method. Net photosyntheis rate was highest in treatment of 25℃. Although transpiration rate was lowest, water use efficience was also in treatment of 25℃. Stomatal conductance was mainly influenced from ambient climatric factors such as vapor pressure deficit. As results of chlorophyll fluorescence by OJIP analysis, maximum quantum yield (Fv/Fm) of photosystem II (PSII), PIabs and the relative activities per reaction center such as ABS/RC, DIo/RC were not changed at air temperature. Therefore, elevated air temperatue during short term influence the dark reaction in photosystem through controlling a water use efficience and transpiration. Conclusion : This result show that 25℃ of air temperature may be a adequate temperature to improving the efficiency of photosynthesis in Cnidium officinale.
        163.
        2017.05 서비스 종료(열람 제한)
        Background : Methicillin-Resistant Staphylococcus aureus (MRSA) is a multidrug-resistant (MDR) strain. Especially, MRSA is developing resistance to available antibacterial agents and causing complications in the treatment of infections related to skin, soft tissue, respiratory, bone, joint, and endovascular disorders. Therefore, antibacterial agent combination therapy appears to be a useful option, particularly in developing countries where antibiotic availability is limited. (+)-Usnic acid (UA) is uniquely found in lichens, and is especially abundant in genera such as Usnea and Cladonia. UA has antimicrobial activity against human and plant pathogens. Therefore, UA may be a good antibacterial drug candidate for clinical development. Methods and Results : In search of a natural products capable of inhibiting this multidrug-resistant bacteria, we have investigated the antimicrobial activity of UA against MRSA. In this study, the effects of a combination of UA and permeable agents against MRSA were investigated. For the measurement of cell wall permeability, UA with concentration of Ethylenediaminetetraacetic acid (EDTA) was used. In the other hand, Sodium azide (NaN3) was used as inhibitors of ATPase. These results suggest that the antibacterial effect of UA was potentiated by membrane-binding agents and ABC transporter-inhibiting agents, implying that antibacterial activity is associated with damage of the cell wall and inhibition of ATPase function by UA. Conclusion : UA and in combination with EDTA and NaN3 could lead to the development of new combination antibiotics against MRSA infection. The results of this study appear to be promising, and they are expected to enhance the use of natural products as drugs.
        164.
        2017.05 서비스 종료(열람 제한)
        Background : Platycodon grandiflorum root (PGR) was one of the primary herbs used in a phlegm-relieving herb from the past. Platycoside compounds on PGR may exhibit neuroprotective, antimicrobial, anti-inflammatory, anti-cancer, anti-allergy, improved insulin resistance, and cholesterol-lowering properties. In order to developing a concentrate product that improved the functionality and preference of PGR, it was fermented using lactic acid bacteria (Lactobacillus plantarum N76-10 and 56-12). Methods and Results : The concentrate products were created by PGR-concentrate (PGRC, 60 ºBrix) mixed with fermented PGR-extract (FPGRE, 2 ºBrix) at the level of 0, 50, 100, 150 and 200%. Sweetness and preference were supplemented by other added materials including honey, oligosaccharide, concentrate of jujube (60 ºBrix) and pear (60 ºBrix), and cactus Chounnyouncho extract (2 ºBrix). The products were put into investigation for their preference of taste, antimicrobial activity in accordance with amount of FPGRE. When it comes to preference of taste, the most favor is adding 100% of FPGRE on PGRC. The product added 150% FPGRE exhibited a strong microbial anti-proliferation in all four kinds (Corynrbacterium diphtheriae, Klebsiella pnneumoniae, Staphylococcus aureus, and Streptococcus pyogenes) of bacteria inducing bronchus diseases and was higher antimicrobial activity than concentrate without FPGRE. In terms of the sensory evaluation (taste, texture and visco-elasticity), concentrate mixed with FPGRE (10), jujube concentrate (2), pear concentrate (10), cactus Chounnyouncho extract (10), oligosaccharide (2), honey (1) and xanthan gum (0.02) showed the highest scores. Conclusion : Thus, A PGR concentrate was made by adding FPGRE (100%) and it was increased organoleptic quality, antimicrobial activity. These studies may provide new product development for effective utilization on Platycodon grandiflorum root.
        165.
        2017.05 서비스 종료(열람 제한)
        Background : Black Non-Woven Fabric Mulch Culture was knowned increased crop Yield and saved weeding labor in Liriope Pilatyphylla Wang et Tang. But to the removal and planting labor is more needed, So some famers are avoidance that culting method. Methods and Results : So this study was experimented in order to selecting optimun removal time in Liriope Pilatyphylla Wang et Tang mulch culture. Removal time were conventional practices (in April next yesr), September, October and November. In early, Plant length, Root length, Leaf number and number of plants was the long and many by the sooner removal time and also, dry weight was heavier. Black non-woven fabric removal labor was saved by the sooner removal time. The main event of weeds were Cyperus serotinus Rottb and Portulaca oleracea L. In harvest time, Plant length and plants of numbers was the longest and heavier at conventional practice (in April next year) and November removed. Tuberous root number was the more in September removal, Because, the tuber was tall and long. Total1y consideration of the including weeds shooting, weeding labor and Growth and development situation, Black non-woven fabric removal optimum time was September or Conventional practices (in April next year). Conclusion : Black non-woven fabric optimum removal time was the september . In this experiment, increased yield 9, income 16 percent than conventional practices (in April next year).
        166.
        2017.05 서비스 종료(열람 제한)
        Background : Natural Mortality Vinyl much culture are increased crop yield and saved weeding workforce. But research is insufficient that of Liriope Pilatyphylla Wang et Tang. Black non-woven fabric mulch culture are increased crop yield and superior to occurrence of weeds, but to the removal and planting more labor needed, so, Farmers are avoidance using that. Methods and Results : So this study designed in order to selecting the best covering material. Using in this study, covering materials were Conventional practices (non covering), Natural mortality vinyl and black non-woven fabric. Soil temperature was continued highly after planting from in mid-may to in august a regular. among them natural mortality vinyl mulch was the highest. Natural mortality vinyl mulch was the fastest that humidity of soil change and Growth and development situation by maintaining proper temperature and humidity. Non mulching was little change in temperature and humidity and the slowest in the Growth and development situation. The main event of weeds were Cyperus serotinus Rottb and Portulaca oleracea L. Weeding labor was saved from 43 to 57 percent in the natural mortality vinyl and black non-woven fabric mulch. Plant length was the shortest in the conventional practices and Root length, Leaf number and number of plants were little changed. Yield was increased from 27 to 29 percent in the natural mortality vinyl and black non-woven fabric mulch than conventional practices. Result of comprehensive economic analysis including weeding labor and yield, the natural mortality vinyl mulch culture was income increased 92 percent than conventional practices. Conclusion : Natural mortality vinyl mulch culture were weeds shooting controled and increased yield 39, income 92 percent than conventional practices (non covering).
        167.
        2016.12 KCI 등재 서비스 종료(열람 제한)
        Lectins belong to the pattern-recognition receptors (PRRs) class and play important roles in the recognition and elimination of pathogens via the innate immune system. Recently, it was reported that lily-type lectin-1 is involved when a pathogen attacks in the early immune response of fish. However, this study is limited to information that the lectin is involved in the innate immune response against viral infection. In the present study, the lily-type lectin-2 and -3 of Oplegnathus fasciatus (OfLTL-2 and 3) have been presented to be included B-lectin domain and two D-mannose binding sites in the amino acid sequence that an important feature for the fundamental structure. To investigate the functional properties of OfLTLs, the tissue distribution in the healthy rock bream and temporal expression during early developmental stage analysis are performed using quantitative real-time PCR. OfLTL-2 and 3 are predominantly expressed in the liver and skin, but rarely expressed in other organ. Also, the transcripts of OfLTLs are not expressed during the early developmental stage but its transcripts are increased after immune-related organs which are fully formed. In the challenge experiment with RBIV (rock bream iridovirus), the expression of OfLTLs was increased much more strongly in the late response than the early, unlike previously known. These results suggest that OfLTLs are specifically expressed in the immune-related tissues when those organs are fully formed and it can be inferred that the more intensively involved in the second half to the virus infection.
        168.
        2016.12 KCI 등재 서비스 종료(열람 제한)
        The objective of this study was to find a rapid determination of the hot air stress in maize (Zea mays L.) leaves using a portable chlorophyll fluorescence imaging instrument. To assess the photosynthetic activity of maize leaves, an imaging analysis of the photochemical responses of maize was performed with chlorophyll fluorescence camera. The observed chlorophyll imaging photos were numerically transformed to the photochemical parameters on the basis of chlorophyll a fluorescence. Chlorophyll a fluorescence imaging (CFI) method showed that a rapid decrease in maximum fluorescence intensity (Fm) of leaf occurred under hot air stress. Although no change was observed in the maximum quantum yield (Fv/Fm) of the hot air stressed maize leaves, the other photochemical parameters such as maximum fluorescence intensity (Fm) and Maximum fluorescence value (Fp) were relatively lowered after hot air stress. In hot air stressed maize leaves, an increase was observed in the nonphotoquenching (NPQ) and decrease in the effective quantum yield of photochemical energy conversion in photosystem II (Φ PSII). Thus, NPQ and ΦPSII were available to be determined non-destructively in maize leaves under hot air stress. Our results clearly indicated that the hot air could be a source of stress in maize leaves. Thus, the CFI analysis along with its related parameters can be used as a rapid indicating technique for the determining hot air stress in plants.
        169.
        2016.12 서비스 종료(열람 제한)
        The study aimed to evaluate the usability of sterile bag collection (SBC) urinalysis and urine culture for diagnosing urinary tract infections (UTI). Urine culture is key for diagnosing UTI, and transurethral catheterization (TUC) or suprapubic aspiration is recommended for non-toilet-trained children. Although urine testing using SBC is non-invasive and easy, UTI can be diagnosed only if other criteria including clinical symptoms and positive urinalysis results are met. This study included 228 infants who were hospitalized for unexplained fever from October 2015 to June 2016. TUC culture, SBC urinalysis, and urine culture were performed for all patients. UTI was diagnosed when the TUC culture results met the criterion of ≥104 colony-forming units (CFU)/mL. When UTI diagnosis was made based on SBC urine colony counts ≥105 CFU/mL, the false-positive and false-negative rates were 6.3% and 70.0%, respectively. When the criterion was set as ≥104 CFU/mL, they were 23.7% and 30.0%, respectively. When both the criteria of ≥105 CFU/mL and positive urinalysis results were met, the false-positive rate was 2.4%, and the false-negative rate was 80%. Our results suggest that diagnosing UTI using SBC urinalysis and urine culture is not useful in infants with unexplained fever.
        170.
        2016.10 KCI 등재 서비스 종료(열람 제한)
        MRI검사는 조직의 대조도가 우수하여 근골격계 진단에 유용한 검사방법이다. 근골격계 검사 시 환자상태에 따라 보조기구가 이용되는 보조기구의 종류가 다양하지 않을 뿐 아니라 비용도 비싸다. 이에 본 연구는 3D 프린팅 기술의 활용하여 MRI 검사 보조기구를 제작하였다. 보조기구 제작과정으로는 3D 모델링(3D MAX.2014, Fusion360)을 사용해 STL파일로 변환 후 슬라이싱 프로그램(Cubicreater 2.1ver., Cura 15.4ver)을 통해 G-code로 변환시킨 후 FDM방식의 프린트(Cubicon Style, MICRO MAKE)로 출력하였다. 출력물이 MRI영상에 미치는 SNR을 평가하기 위해 FDM에서 사용하되는 PLA, ABS, TPU를 두께 3mm로 된 Water Phant om 케이스를 제작하여 case 사용 전, 후를 시험을 실시하여 비교하였으며, 보조기구 사용 전, 후의 임상영상을 정성적으로 평가 하였다. 영상을 획득하여 나타난 Warter Phantom의 SNR은 T1 NON 123.778 ± 28.492, PLA 123.522 ± 28.373, ABS 124.461 ± 25.716, TPU 124.843 ± 27.272 로 평가되었다. T2 NON 127.421 ± 26.949, PLA 124.501 ±2 7.768, ABS 128.663 ± 26.549, TPU 130.171 ± 25.998 로 평가되었다. 그 결과 통계 적으로 유의미한 차이를 보이지 않았다. 보조기구의 사용 전, 후의 임상영상 평가 결과 고식적 방법 3.20 ± 0.88, 보조기구 사용 3.95 ± 0.76 으로 보조기구 사용 후 영상의 질이 향상되었다. 향후 3D프린팅을 이용한 보조기구의 제작은 임상적으로 사용이 가능할 것으로 생각되고, 환자들의 검사 시 보다 안전하고 편안한 보조기구제작을 할 수 있어 기존에 쓰이는 보조기구의 문제점들을 개선하는 대안이 될 것으로 전망된다.
        171.
        2016.10 서비스 종료(열람 제한)
        Background : Ginseng, one of most famous traditional oriental medicines, has been known for a number of pharmacological properties including anti-tumor, anti-diabetic, anti-fatigue, anti-stress, anti-oxidative, and anti-aging effects. 20(S)-Protopanaxadiol (PPD), a intestinal metabolite of ginsenosides, is one of the active ingredients in ginseng. In this study, we investigated the synergistic anticancer effect of 20(S)-PPD and temozolomide (TMZ) and the mechanism of 20(S)-PPD on glioblastoma cells. Methods and Results : We examined cell viability and the morphological changes of C6 cells after treatment of 20(S)-PPD and TMZ. 20(S)-PPD showed a potent antiproliferative activity against C6 cells by triggering apoptosis. 20(S)-PPD-induced apoptosis was characterized by a dose-dependent mitochondrial damage. 20(S)-PPD and TMZ had a synergistic effect in increasing mitochondrial damage via caspase 3 activation. Conclusion : These results revealed an unexpected mechanism of 20(S)-PPD and TMZ, triggering a mitochondrial-mediated apoptosis in C6 cells. Our findings encourage further studies of 20(S)-PPD as a promising chemopreventive agent against glioblastoma.
        172.
        2016.10 서비스 종료(열람 제한)
        Background : Recently, ginseng (Panax ginseng C.A. Meyer.) berry has been used as a health-promoting supplements. Also, Mulberries (Morus alba L.) fruit have been used in traditional herbal medicine to treat and prevent diabetes. In this study, we measured the cytotoxicity after fermentation of the extracts in Panax Ginseng Berry and Mulberry Fruit. Methods and Results : The extracts were prepared by decoction for 3 hours in distilled water (100 g/L). The dried extract was then dissolved in phosphate-buffered saline (PBS) in preparation for use. Cell viability was examined by an MTT assay. RAW 264.7 cells were seeded at 1 × 104/mL densities in 96-well plates. Each grouping had a non-treated group as the control. The extracts were added to each well and incubated for 24 hours at 37°C and 5% CO2. The MTT solutions (5 mg/mL) were added to each well, and the cells were cultured for another 2 hours. The supernatant was then discarded, and 100 μL of dimethyl sulfoxide was added to each well. The optical density was read at 540 nm. Conclusion : Probiotics and prebiotics modulate the composition of human and domestic animal gut microbiota. The beneficial effects may result from suppression of harmful microorganisms or stimulation of organisms which contribute in a positive way to the nutrition and health of human and domestic animal. Recently, fermentation using microorganisms for the production of more effective compounds has been extensively studied. In particular, the novel pharmacological effects of a new compound generated by fermentation have been reported. Some previous studies have demonstrated that Fermented herbal medicine extract showed better bioactivity than normal herbal Plants extract when used at the same concentration.
        173.
        2016.09 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        We present proton-induced single event effects (SEEs) and γ-ray-induced total ionizing dose (TID) data for 1 Gbit lowpower double data rate synchronous dynamic random access memory (LPDDR SDRAM) fabricated on a 5 μm epitaxial layer (54 nm complementary metal-oxide-semiconductor (CMOS) technology). We compare our radiation tolerance data for LPDDR SDRAM with those of general DDR SDRAM. The data confirms that our devices under test (DUTs) are potential candidates for space flight applications.
        174.
        2016.05 서비스 종료(열람 제한)
        Background : Platycodon grandiflorum root(PGR) was one of the primary herbs used in a phlegm-relieving herb from the past. Purified platycoside compounds from the roots of PGR may exhibit neuroprotective, antimicrobial, anti-inflammatory, anti-cancer, anti-allergy, improved insulin resistance, and cholesterol-lowering properties. To evaluate preference and functionality of PGR extracts, PGR was fermented by several lactic acid bacteria. Lactic acid bacteria used were Leuc. mesenteroides N12-4 and N58-5, L. plantarum N76-10 and 56-12, L. brevis N70-9 and E3-8. Methods and Results : This study was performed in order to investigate the changes of platycosides, as well as the antimicrobial activities on bronchus diseases inducing bacteria(C. diphtheriae, K. pnneumoniae, S. aureus, S. pyogenes) of Platycodon grandiflorum root(PGR) fermented by using lactic acid bacteria(Leuc. mesenteroides N12-4, Leuc. mesenteroides N58-5, L. plantarum N76-10, L. plantarum N56-12, L. brevis N70-9, L. brevis E3-8). Growth of L. plantarum on PGR was the most active during lactic acid fermentation by some different strains. Total platycoside, platycoside E, platycodin A, polygalacin D2, polygalacin D and diapioplatycoside E contents of PGR fermented for 96 hours at 37℃ by Leuc. mesenteroides and L. plantarum were increased, while platycodin D and platycodin D3 were decreased. The antimicribial activity on PGR fermented by L. plantarum N56-12 exhibited a strong microbial proliferation in all four kinds of bronchus diseases inducing bacteria and was higher than non-fermented PGR extract. Conclusion : Thus, this results showed antimicrobial activities on bronchus diseases inducing bacteria and platycosides content of PGR by L. plantarum N56-12 were higher than non-fermented PGR extract.
        175.
        2016.05 서비스 종료(열람 제한)
        Background : Water uptake and flow across cellular membranes is a fundamental requirement for plant growth and development, and plant water status is important not only for plant growth under favorable conditions but also for ability of a plant to tolerate adverse environmental conditions. Thus identification of plasma membrane water channel genes (aquaporins) in ginseng provides extensive information for functional studies and the development of markers for salinity stress tolerance. Methods and Results : For salinity treatment, the plants were grown for 4 weeks in culture medium gelled with 0.8% Phytoagar, and the old media were replaced with the fresh medium containing NaCl at 0, 50, 100, 200 and 400 mM, respectively. The samples for stress treated and non-stressed plants were collected from 6h to 72h, and frozen immediately into liquid nitrogen. According to the sequence information from the assembled transcripts, four primer pairs were designed from the aquaporin gene regions. In order to determine the pattern of aquaporins expression in ginseng seedlings to salinity stress, we conducted semi-quantitative RT-PCR. Conclusion : A tonoplast intrinsic protein 1 (TIP1)-type aquaporin is not only believed to be essential for plant life, but also to be beneficial for growth under salinity stress. Therefore, a deeper understanding of aquaporin genes in ginseng will be essential for crop improvement, which could help us to understand the molecular genetic basis for the ginseng genetic improvement and also provide the functional genetic resources for selective breeding and transgenic research.
        176.
        2016.05 서비스 종료(열람 제한)
        Background : This study was carried out to understand the effect of seedling weight (SW) on growth and flowering in Panax ginseng. Methods and Results : The testing materials were Chunpoong (CP), Yunpoong (YP) and Jakyeongjong (JK). The increase of seedling (1yr) weight led to an increase in ratio of flowering plant and in number of flower per plant. The seed setting rate of two year-old plant (CP, YP, JK) increased with increase of SW at the planting time (PT) and number of flower per plant of three year-old plant (CP, YP) increased also. In the two year-old plant (JK), the ratio of three leaves per plant was 8.8, 19.6, 31.0, 42.0, 44.7 and 58.2%, respectively, in the SW of >0.6, 0.6~0.8, 0.8~1.0, 1.02~1.2, 1.2~1.4 and 1.4g<. The growth of ginseng plant was good with increase of SW at the PT. Conclusion : There was a highly positive correlation between seedling weight and flowering characteristics.
        177.
        2016.05 서비스 종료(열람 제한)
        Background : Due to immature development of embryo in ripened berries, dehiscence process is required for the proper germination of ginseng seeds. Such process involves the preparation of the container with alternating layers of seed and moist sand. In order to make sand fully moist, water sprayer has been usually used by farmers, which is labor intensive, time consuming and causing uneven sand moisture. Methods and Results : In this study, we investigated the effects of different stratification methods on dehiscence ratio of ginseng seeds. Ginseng seeds were stratified for 90 days in a total of 12 different treatments and the dehiscence ratios were compared; drainage methods, drainage time, the ratio between ginseng seeds and sand, and etc. Seed stratification process was performed according to the guideline of ginseng GAP. One thousand ginseng seeds were used for each treatment. It was found that the average of dehiscence of the 12 treatments was 84.6 %. The highest dehiscence ratio (90.3 %) was observed in the seeds that were treated with water soaking, immediately followed by drainage. Higher ratio was also observed in the seeds that were soaked for 60 min, followed by drainage. Therefore, our findings indicate that ginseng seeds soaked in water less than 60 min could dehisce more efficiently than traditional method. Conclusion : Our study demonstrated that ginseng seeds that are subjected to water soaking and then drainage showed better ration of dehiscence. This method will eventually decrease the time and labor used for seed stratification.
        178.
        2015.09 서비스 종료(열람 제한)
        Hepatocytes and hepatic progenitors derived from human ES cells may be a useful source for clinical application. Therefore, identification and purification of these cell types would be following important issues. There are very few candidate surface markers that can be used to identify and purify hepatic progenitor cells. In addition, indocyanine-green can be uptaken by mature hepatocytes, but cannot be applied for fluorescence activated cell sorting (FACS) due to its long emission wavelength. In the present study, we tested EpCAM as a potential marker for magnetic-activated cell sorting (MACS) of hepatic progenitors and also modified indocyanine-green into fluorescent indomonocarbocyanine for FACS-mediated sorting of mature hepatocytes after differentiation of human ES cells. Hepatic progenitor cells were sorted by MACS after incubation with anti-human EpCAM antibodies. After the final differentiation, the differentiated cells and mouse primary hepatocytes (control group) were incubated with indomonocarbocyanine and were sorted by FACS. MACS and immunocytochemistry data showed that approximately 45% of differentiated cells were EpCAM-positive cells. EpCAM-positive cells expressed α-fetoprotein, FOXa2, HnF4a, and CK18. Differentiation efficiency into albumin-positive cells was significantly higher in EpCAM-positive cells, compared to EpCAM-negative cells. Importantly, indomonocarbocyanine successfully stained cells that expressed ALB. Furthermore, FACS analysis data showed that the purity of hepatocytes that expressed albumin was significantly increased after purification of indomonocarbocyanine-positive cells. Our data demonstrated that human ES cell-derived hepatic progenitors can be efficiently isolated by MACS using EpCAM antibody. In addition, we also showed that indomonocarbocyanine can be successfully used to identify and purify mature hepatocytes using FACS.
        179.
        2015.09 서비스 종료(열람 제한)
        Highly homogeneous and functional stem cell-derived hepatocyte-like cells (HLCs) are considered a promising option in the treatment of liver disease and the development of effective in vitro toxicity screening tool. However, the purity of cells and expression and/or activity of drug metabolizing enzymes in stem cell-derived HLCs are usually too low to be useful for clinical or in vitro applications. Here, we describe a highly optimized differentiation protocol, which produces more than 90% albumin-positive HLCs with no purification process. In addition, we show that hepatic enzyme gene expressions and activities were significantly improved by generating three-dimensional (3D) spheroidal aggregate of HLCs. The 3D differentiation method increased expressions of nuclear receptors that regulate the proper expression of key hepatic enzymes. Furthermore, a significantly increased hepatic functions such as albumin and urea secretion were observed in 3D hepatic spheroids and HLCs in the spheroid exhibited morphological and ultrastructural features of normal hepatocytes. Importantly, we show that repeated exposures to xenobiotics facilitated the functional maturation of HLC, as confirmed by increased expression of genes for drug metabolizing enzymes and transcription factors. In conclusion, the 3D culture system with repeated exposures to xenobiotics may be a new strategy for enhancing hepatic maturation of stem cell-derived HLCs as a cell source for in vitro high-throughput hepatotoxicity models.
        180.
        2015.09 서비스 종료(열람 제한)
        Hepatocyte-like cells (HLCs) derived from human pluripotent stem cells have received extensive attention in the development of drug screening and toxicity testing. However, it has been reported that stem cell-derived HLCs showed hepatic functions that were too limited to be of use in drug screening and toxicity testing, possibly due to the lack of sufficient intercellular communication under conventional two-dimensional (2D) culture conditions. Therefore, a 3D differentiation system may overcome the in vitro limitation of 2D culture to produce stem cell-derived hepatocytes with mature metabolic functions. In this study, the feasibility of using a silicone-based spherofilm, specifically designed to produce spherical cell clusters, to generate uniformly sized 3D hepatic spheroids from hESCs was investigated. Hepatic spheroids generated on the spherofilm showed more homogenous size and shape than those generated in conventional low-attachment suspension culture dishes. Results of immunohistochemical analysis showed that expression of the mature hepatic marker albumin (ALB) increased over time during the hepatic maturation process. Furthermore, the 3D culture system mimicked the in vivo 3D microenvironment. Laminin, which is an important component of hepatic ECM, was expressed in hepatic spheroids. The results of immunohistochemical analysis indicated that the 3D culture environment is capable of generating an in vivo-like microenvironment. In addition, quantitative PCR analysis showed that the mature hepatic marker ALB and cytochrome P450 (CYP) enzymes CYP3A4 and CYP3A7 were expressed at higher levels in 3D culture than in 2D culture. This indicates that the 3D culture system is suitable for hepatic maturation and that our size-controlled 3D culture conditions might accelerate hepatic function. These results suggest that 3D hepatic spheroids significantly enhance metabolic maturation of hepatocytes derived from hESCs