• Reproductive and Developmental Biology
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• v.31 no.4
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• pp.267-272
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• 2007

Human embryonic stem (ES) cells are derived from the inner cell mass of the preimplantation embryo and have the capacity to differentiate into various types of cells in the body. Hence, these cells may potentially be an indefinite source of cells for cell therapy in various degenerative diseases including neuronal disorders. For clinical applications of human ES cells, directed differentiation of these cells would be necessary. The objective of this study is to develop the culture condition for the expansion of neural precursor cells derived from human ES cells. Human ES cells were able to differentiate into neural precursor cells upon a stepwise culture condition. Neural precursor cells were propagated up to 5000-fold in cell numbers over 12-week period of culture and evaluated for their characteristics. Expressions of sox1 and pax6 transcripts were dramatically up-regulated along the differentiation stages by RT-PCR analysis. In contrast, expressions of oct4 and nanog transcripts were completely disappeared in neural precursor cells. Expressions of nestin, pax6 and sox1 were also confirmed in neural precursor cells by immunocytochemical analysis. Upon differentiation, the expanded neural precursor cells differentiated into neurons, astrocytes, and oligodendrocytes. In immunocytochemical analysis, expressions of type III ${\beta}$-tubulin and MAP2ab were observed Presence of astrocytes and oligodendrocytes were also confirmed by expressions of GFAP and O4, respectively. Results of this study demonstrate the feasibility of long-term expansion of human ES cell-derived neural precursor cells in vitro, which can be a potential source of the cells for the treatment of neurodegenerative disorders.

• Reproductive and Developmental Biology
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• v.28 no.4
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• pp.247-252
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• 2004

Human embryonic stem (ES) cells are derived from the inner cell mass of the preimplantation embryo. Human ES cells have the capacity to differentiate into various types of cells in the body. Human ES cells are indefinite source of cells for cell therapy in various degenerative disorders including neuronal disorders. Directed differentiation of human ES cells is a prerequisite for their clinical application. The objective of this study is to develop the culture condition for the derivation of neural precursor cells from human ES cells. Neural precursor cells were derived from human ES cells in a stepwise culture condition. Neural precursor cells in the form of neural rosette structures developed into neurospheres when cultured in suspension. Suspension culture of neurospheres has been maintained over 4 months. Expressions of nestin, soxl, sox2, pax3 and pax6 transcripts were upregulated during differentiation into neural precursor cells by RT-PCR analysis. In contrast, expression of oct4 was dramatically downregulated in neural precursor cells. Immunocytochemical analyses of neural precursor cells demonstrated expression of nestin and SOX1. When induced to differentiate on an adhesive substrate, neuro-spheres were able to differentiate into three lineages of neural systems, including neurons, astrocytes and oligo-dendrocytes. Transcripts of sox1 and pax6 were downregulated during differentiation of neural precursor cells into neurons. In contrast, expression of map2ab was elevated in the differentiated cells, relative to those in neural precursor cells. Neurons derived from neural precursor cells expressed NCAM, Tuj1, MAP2ab, NeuN and NF200 in immunocytochemical analyses. Presence of astrocytes was confirmed by expression of GFAP immuno-cytochemically. Oligodendrocytes were also observed by positive immuno-reactivities against oligodendrocyte marker O1. Results of this study demonstrate that a stepwise culture condition is developed for the derivation of neural precursor cells from human ES cells.

• Korean Journal of Animal Reproduction
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• v.24 no.3
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• pp.289-297
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• 2000

This study was conducted to investigate whether various protein sources and co-culture affect in vitro development of porcine zygotes derived from In vitro maturation/fertilization (IVM/IVF). These results obtained in these experiments are summarized as follows 1. When porcine oocytes matured and fertilized In vitro were cultured in NCSU 23 medium supplemented with various BSA concentrations (0.4, 0.8 and 3.2%), In vitro developmental rates of porcine zygotes to blastocyst stage were 22.9, 18.4 and 14.6%, respectively. High concentration of BSA (3.2%) showed a smaller nuclei number (36.1$\pm$11.8) of blastocysts than 0.4 and 0.8% BSA groups (53.2$\pm$27.4 and 61.2$\pm$22.5, respectively) (P<0.05). This result indicates that high concentration of BSA is detrimental on preimplantation development of IVF-derived porcine embryos. 2. No differences were detected in the developmental rate and mean nuclei number of porcine embryos between 10 and 20% FBS concentrations in culture medium. 3. IVF-derived porcine embryos co-cultured with mouse or porcine embryonic fibroblast cells showed a lower development to the blastocyst stage than those without co-culture system. Consequently, the present study suggests that high concentration of BSA as a protein source in culture medium suppresses development potential of porcine embryos produced In vitro. In addition, co-culture with somatic cells is not effective on in vitro development of IVF-derived porcine embryos to blastocyst stage.

• The Korean Journal of Zoology
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• v.38 no.4
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• pp.550-556
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• 1995

The c-myc proto-oncogene is Involved In the control of normal cell proliferation and differentiation of many cell lineages. Although it has heen suggested that c-myc may play an important role in the mammalian early development, it Is unclear whether the embryonic c-myc mRNA is originated from zygotic gene expression or stored maternal message. Thus, we have construded expression vectors, In which the 5, flanking sequences including c-myc promoter region and a large non-coding exon I are fused 'sith E. coli lacZ gene that encedes $\beta$-galactosldase as a reporter. As c-myc exon I contains a modulatory sequence, we designed t, vo types of vectors (pcmyc.Gall and pcmyc-Ga12) to examine the role of exon I in c-myc expression. The former contains the complete exon I and the later has a deletion in 40 bp of modulator sequence located In the exon I of c-myc These vectors were microInjected into fertilized one-cell embryos and $\beta$-galactosidase activity was examined by X-gal staining during early embryogenesis. $\beta$-galactosidase activity derived from c-myc promoter was decreased at two-cell stage. The expression level directed by pcmyc- Ga12 was similar to that of pcmyc-Gal1, indicating that the medulatory sequence in exon I may not be Involved at least In the regulation of embryonic c-myc expression. In summary, the present study indicates that the c-myc promoter is functional at the early stage embryo, and the regulation of c-myc expression is under the control of "zygotic" clock of preimplantation mouse embryos.e embryos.

• Korean Journal of Animal Reproduction
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• v.19 no.3
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• pp.227-234
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• 1995

This study was carried out to investigate the effects according to the time course of glucose exposure on the development of one-cell embryos beyond morula in CR$_laa$ medium. One-cell zygotes from B6CBA F$_1$ mice were recovered at 24 ~ 25h after hCG and cumulus cells were removed with 0.1% hyaluronidase. The embryos were pooled and subsequently divided into each groups and cultured in CR$_laa$ at 37$^{\circ}C$ in 5% CO$_2$ in aIr. The embryos were either, placed in CR$_laa$ containing various concentration (5.5, 16.5, 27.5 and 38.5 mM) of glucose for 1 min. and subsequently returned to the fresh culture medium (without glucose), or were transferred to the same media containing glucose at 72 h post hCG. The results obtained in these experiments were summarized as follows: 1. The development rates of zygotes, recovered from the oviducts in M2 and cultured in CR$_laa$ with 3mg/Im FAF-BSA, to expanded blastocysts (25.7%) and hatching bIastocysts (17.6%) were significantly higher than those of zygotes recovered in TL Hepes (0% and 0%, respectively). 2. The development rates of one-cell embryos exposed to 27.5 mM glucose at 72 h post hCG for 1 min, were 68.8% (CR$_1$+BSA) a and 77.1% (CR$_1$+FBS) of expanded blastocyst stage, but there were no significant differences between the embryos exposed for 1 min. or transferred at 72 h. 3. Regardless of glucose concentration (5.5, 16.5, 27.5 & 38.5mM), 45.7~61.5% of embryos developed to the blastocyst stage. There were no significant differences between any of the treatments on the devel-opment of one-cell embryos. Therefore, the detrimental effect of highly concentration was not appeared.