Biomedical subjects

Jung Bok Lee

Publications and source records attributed to Jung Bok Lee.

13 recordsLinked to original sources

PubMed2006

Differential expression profiling of genes in a complete hydatidiform mole using cDNA microarray analysis.

OBJECTIVES: To gain a better understanding of the genes involved in the pathogenesis of gestational trophoblastic diseases, we evaluated the genome-wide expression levels of genes in complete hydatidiform mole (H-mole) as compared to normal placenta using cDNA microarray technique. METHODS: The expression profiles of complete H-mole tissues were compared with those of normal placenta using cDNA microarray technique. The data obtained from 10,305 human genes were normalized by the print-tip-based LOWESS method. Significance analysis of microarray (SAM) was used to identify genes with statistically significant changes in expression. The expression levels of genes which showed significant differences between normal early placenta and complete H-mole tissues were further confirmed by RT-PCR. RESULTS: A cDNA microarray analysis consisting of 10,305 human genes revealed significant changes in the expression of 213 genes, with 91 genes being upregulated and 122 being downregulated. SAM revealed significant changes in gene expression, including those associated with signal transduction, cell structure, transcription, and apoptosis. Further RT-PCR analysis of altered gene expression in mole tissues supported the microarray analysis results. We confirmed the upregulation of TLE4, CAPZA1, PRSS25, RNF130, and USP1 in complete H-mole tissues. Moreover, our study provides the first evidence that ELK3, LAMA3, LNK, STAT2, and TNFRSF25 are downregulated in complete H-mole compared to normal early placenta tissues. CONCLUSIONS: These findings provide a large body of information regarding gene expression profiles associated with complete H-mole tumorigenesis and allow the identification of potential targets for tumor prevention or therapy.

DNA, Complementary↗

PubMed2005

Heat shock 70-kDa protein 8 isoform 1 is expressed on the surface of human embryonic stem cells and downregulated upon differentiation.

The cell-surface markers used routinely to define the undifferentiated state and pluripotency of human embryonic stem cells (hESCs) are those used in mouse embryonic stem cells (mESCs) because of a lack of markers directly originated from hESC itself. To identify more hESC-specific cell-surface markers, we generated a panel of monoclonal antibodies (MAbs) by immunizing the irradiated cell clumps of hESC line Miz-hES1, and selected 26 MAbs that were able to bind to Miz-hES1 cells but not to mESCs, mouse embryonic fibroblast cells, and STO cells. Most antibodies did not bind to human neural progenitor cells derived from the Miz-hES1 cells, either. Of these, MAb 20-202S (IgG1, kappa) immunoprecipitated a cell-surface protein of 72-kDa from the lysate of biotin-labeled Miz-hES1 cells, which was identified to be heat shock 70-kDa protein 8 isoform 1 (HSPA8) by quadrupole time-of-flight tandem mass spectrometry. Immunocytochemical analyses proved that the HSPA8 protein was also present on the surface of hESC lines Miz-hES4, Miz-hES6, and HSF6. Two-color flow cytometric analysis of Miz-hES1 and HSF6 showed the coexpression of the HSPA8 protein with other hESC markers such as stage-specific embryonic antigen 3 (SSEA3), SSEA4, TRA-1-60, and TRA-1-81. Flow cytometric and Western blot analyses using various cells showed that MAb 20-202S specifically bound to the HSPA8 protein on the surface of Miz-hES1, contrary to other anti-HSP70 antibodies examined. Furthermore, the surface expression of the HSPA8 protein on Miz-hES1 was markedly downregulated upon differentiation. These data indicate that a novel MAb 20-202S recognizes the HSPA8 protein on the surface of hESCs and suggest that the HSPA8 protein is a putative cell-surface marker for undifferentiated hESCs.

Antibodies, Monoclonal↗

PubMed2005

Patient-specific embryonic stem cells derived from human SCNT blastocysts.

Patient-specific, immune-matched human embryonic stem cells (hESCs) are anticipated to be of great biomedical importance for studies of disease and development and to advance clinical deliberations regarding stem cell transplantation. Eleven hESC lines were established by somatic cell nuclear transfer (SCNT) of skin cells from patients with disease or injury into donated oocytes. These lines, nuclear transfer (NT)-hESCs, grown on human feeders from the same NT donor or from genetically unrelated individuals, were established at high rates, regardless of NT donor sex or age. NT-hESCs were pluripotent, chromosomally normal, and matched the NT patient's DNA. The major histocompatibility complex identity of each NT-hESC when compared to the patient's own showed immunological compatibility, which is important for eventual transplantation. With the generation of these NT-hESCs, evaluations of genetic and epigenetic stability can be made. Additional work remains to be done regarding the development of reliable directed differentiation and the elimination of remaining animal components. Before clinical use of these cells can occur, preclinical evidence is required to prove that transplantation of differentiated NT-hESCs can be safe, effective, and tolerated.

Adult↗

PubMed2005

Comparative characteristics of three human embryonic stem cell lines.

Human embryonic stem (hES) cells have unique features including unlimited growth capacity, expression of specific markers, normal karyotypes and an ability to differentiate. Many investigators have tried to use hES cells for cell-based therapy, but there is little information about the properties of available hES cell lines. We compared the characteristics of three hES cell lines. The expression of SSEA-1, -3, -4, and APase, was examined by immunocytochemistry, and Oct-4 expression was analyzed by RT-PCR. Differentiation of the hES cells in vitro and in vivo led to the formation of embryoid bodies (EBs) or teratomas. We examined the expression of tissue-specific markers in the differentiated cells by semiquantitative RT-PCR, and the ability of each hES cell line to proliferate was measured by flow cytometry of DNA content and ELISA. The three hES cell lines were similar in morphology, marker expression, and teratoma formation. However there were significant differences (P < 0.05) between the differentiated cells formed by the different cell lines in levels of expression of tissue-specific markers such as renin, kallikrein, Glut-2, beta- and delta-globin, albumin, and alpha1-antitrypsin (alpha1-AT). The hES cell lines also differed in proliferative activity. Our observations should be useful in basic and clinical hES cell research.

Animals↗

PubMed2005

Efficient derivation of new human embryonic stem cell lines.

Human embryonic stem (hES) cells, unlike most cells derived from adult or fetal human tissues, represent a potentially unlimited source of various cell types for basic clinical research. To meet the increased demand for characterized hES cell lines, we established and characterized nine new lines obtained from frozen-thawed pronucleus-stage embryos. In addition, we improved the derivation efficiency from inner cell masses (to 47.4%) and optimized culture conditions for undifferentiated hES cells. After these cell lines had been maintained for over a year in vitro, they were characterized comprehensively for expression of markers of undifferentiated hES cells, karyotype, and in vitro/in vivo differentiation capacity. All of the cell lines were pluripotent, and one cell line was trisomic for chromosome 3. Improved culture techniques for hES cells should make them a good source for diverse applications in regenerative medicine, but further investigation is needed of their basic biology.

Animals↗

PubMed2005

Identification of developmental pluripotency associated 5 expression in human pluripotent stem cells.

Pluripotent embryonic germ cells (EGCs) can be derived from the culture of primordial germ cells (PGCs). However, there are no reports of gonocytes, following the stage of PGC development, becoming stem cell lines. To analyze the gene expression differences between PGCs and gonocytes, we performed cDNA subtractive hybridization with mouse gonads containing either of the two cell populations. We confirmed that developmental pluripotency associated 5 (Dppa5), originally found in mouse embryonic stem cells (ESCs) and mouse embryonic carcinoma cells (ECCs), was strongly expressed in mouse PGCs and the expression was rapidly downregulated during germ cell development. A human sequence homologous to Dppa5 was identified by bioinformatics approaches. Interestingly, human Dppa5 was expressed only in human PGCs, human EGCs, and human ESCs and was not detected in human ECCs. Its expression was downregulated during induced differentiation of human ESCs. These findings confirmed that Dppa5 is specifically and differentially expressed in human cells that have pluripotency. The results strongly suggest that Dppa5 may have an important role in stemness in human ESCs and EGCs and also can be used as a marker of pluripotent stem cells. Human pluripotent stem cells may have their own ways to be pluripotent, as opposed to the much uniform mouse stem cells.

Animals↗

PubMed2004

Expression of estrogen receptor-alpha and -beta, glucocorticoid receptor, and progesterone receptor genes in human embryonic stem cells and embryoid bodies.

Human embryonic stem cells (hESCs) have the potential to differentiate into various cell types, and the three germ layers in vivo and in vitro. They are therefore useful in transplantation and tissue engineering. Here, we describe the expression patterns of selected steroid receptor mRNAs - estrogen receptor-alpha (ER-alpha), ER-beta, glucocorticoid receptor (GR), and progesterone receptor (PR) - in undifferentiated hESCs and embryoid bodies (EBs) cultured for 2, 4, and 6 d, as assessed by real-time PCR, in order to define the possible influence of steroid hormones on the differentiation of hESCs. These receptor mRNAs were expressed in undifferentiated hESCs and EBs. The expression of PR mRNA only decreased during the differentiation of EBs but not of hESCs. Immunohistochemical analysis gave strong staining of ER-alpha, ER-beta, and GR proteins in the nuclei of hESCs and EBs, whereas PR was not detected. We also examined the potential of these steroid hormones to direct the differentiation of hESCs in vitro. The expression of 11 cell-specific markers representing 3 germ layers and 5 tissue types was used to assess the differentiation of hESCs. We found that certain endodermal marker genes were either only expressed in the estrogen-treated group or their expression was stimulated in that group, suggesting that steroid hormones can control the differentiation of hESCs into various cell types.

Animals↗

PubMed2004

Establishment and maintenance of human embryonic stem cell lines on human feeder cells derived from uterine endometrium under serum-free condition.

Human embryonic stem (hES) cells are usually established and maintained on mouse embryonic fibroblast (MEFs) feeder layers. However, it is desirable to develop human feeder cells because animal feeder cells are associated with risks such as viral infection and/or pathogen transmission. In this study, we attempted to establish new hES cell lines using human uterine endometrial cells (hUECs) to prevent the risks associated with animal feeder cells and for their eventual application in cell-replacement therapy. Inner cell masses (ICMs) of cultured blastocysts were isolated by immunosurgery and then cultured on mitotically inactivated hUEC feeder layers. Cultured ICMs formed colonies by continuous proliferation and were allowed to proliferate continuously for 40, 50, and 55 passages. The established hES cell lines (Miz-hES-14, -15, and -9, respectively) exhibited typical hES cells characteristics, including continuous growth, expression of specific markers, normal karyotypes, and differentiation capacity. The hUEC feeders have the advantage that they can be used for many passages, whereas MEF feeder cells can only be used as feeder cells for a limited number of passages. The hUECs are available to establish and maintain hES cells, and the high expression of embryotrophic factors and extracellular matrices by hUECs may be important to the efficient growth of hES cells. Clinical applications require the establishment and expansion of hES cells under stable xeno-free culture systems.

Animals↗

PubMed2004

Establishment of a human embryonic germ cell line and comparison with mouse and human embryonic stem cells.

Human embryonic stem (ES) cells and embryonic germ (EG) cells are pluripotent and are invaluable material for in vitro studies of human embryogenesis and cell therapy. So far, only two groups have reported the establishment of human EG cell lines, whereas at least five human ES cell lines have been established. To see if human EG cell lines can be reproducibly established, we isolated primordial germ cells (PGCs) from gonadal ridges and mesenteries (9 weeks post-fertilization) and cultured them on mouse STO cells. As with mouse ES colonies, the PGC-derived cells have given rise to multilayered colonies without any differentiation over a year of continuous culture. They are karyotypically normal and express high levels of alkaline phosphatase, Oct-4, and several cell-surface markers. Histological and immunocytochemical analysis of embryoid bodies (EBs) formed from floating cultures of the PGC-derived cell colonies revealed ectodermal, endodermal, and mesodermal tissues. When the EBs were cultured in the presence of insulin, transferrin, sodium selenite, and fibronectin for 1 week, markers of primitive neuroectoderm were expressed in cells within the EBs as well as in cells growing out from the EBs. These observations indicate that our PGC-derived cells satisfy the criteria for pluripotent stem cells and hence may be EG cells.

Animals↗

PubMed2004

Clinical significance of variceal hemorrhage in recent years in patients with liver cirrhosis and esophageal varices.

BACKGROUND AND AIMS: Recent progress in the treatment of variceal bleeding might have reduced the impact of variceal bleeding on survival in patients with esophageal varices. We conducted a retrospective cohort study in an attempt to re-evaluate the clinical significance of variceal bleeding. METHODS: A cohort of 304 patients with liver cirrhosis and esophageal varices, who had no previous history of variceal bleeding and no prophylactic therapy, was studied. RESULTS: During a median follow-up period of 32 months, 55 patients (18%) bled from varices and 111 (37%) died. Variceal hemorrhages accounted for 15% of total deaths. The mortality of first variceal bleeding was 25% in the whole group, but was remarkably different depending on liver function at the time of bleeding (0% in grade Child A vs 55% in grade C; P < 0.05). Among the survivors of first bleeding, 30% experienced rebleeding. Form of varix, red color sign and heavy drinking were the independent risk factors for first variceal bleeding. Multivariate analysis revealed that variceal bleeding still had a significant (P < 0.001) impact on death in the whole cohort, when other independent prognostic factors such as age, ascites, encephalopathy, platelet count, serum albumin level and hepatocellular carcinoma were adjusted. Furthermore, in subgroup analyses, variceal bleeding was more strongly (P < 0.001) linked to death in patients with alcoholic cirrhosis than in those with non-alcoholic cirrhosis, and showed a significant association with survival only for the patients in Child grade B. CONCLUSIONS: Variceal bleeding has various prognostic impacts depending on the etiology of cirrhosis or on the degree of liver dysfunction, and this needs to be taken into account in the prophylaxis against first variceal bleeding.

Adult↗

PubMed2004

Available human feeder cells for the maintenance of human embryonic stem cells.

Mouse embryonic fibroblasts (MEFs) have been previously used as feeder cells to support the growth of human embryonic stem cells (hESCs). In this study, human adult uterine endometrial cells (hUECs), human adult breast parenchymal cells (hBPCs) and embryonic fibroblasts (hEFs) were tested as feeder cells for supporting the growth of hESCs to prevent the possibility of contamination from animal feeder cells. Cultured hUECs, hBPCs and hEFs were mitotically inactivated and then plated. hESCs (Miz-hES1, NIH registered) initially established on mouse feeder layers were transferred onto each human feeder layer and split every 5 days. The morphology, expression of specific markers and differentiation capacity of hESCs adapted on each human feeder layer were examined. On hUEC, hBPC and hEF feeder layers, hESCs proliferated for more than 90, 50 and 80 passages respectively. Human feeder-based hESCs were positive for stage-specific embryonic antigen (SSEA)-3 and -4, and Apase; they also showed similar differentiation capacity to MEF-based hESCs, as assessed by the formation of teratomas and expression of tissue-specific markers. However, hESCs cultured on hUEC and hEF feeders were slightly thinner and flatter than MEF- or hBPC-based hESCs. Our results suggest that, like MEF feeder layers, human feeder layers can support the proliferation of hESCs without differentiation. Human feeder cells have the advantage of supporting more passages than when MEFs are used as feeder cells, because hESCs can be uniformly maintained in the undifferentiated stage until they pass through senescence. hESCs established and/or maintained under stable xeno-free culture conditions will be helpful to cell-based therapy.

Adult↗

PubMed2004

Effects of type IV collagen and laminin on the cryopreservation of human embryonic stem cells.

Previous reports have indicated that extracellular matrices (ECMs) affect the developmental fate of human embryonic stem cells (hESCs). Specially, type IV collagen and laminin, which belong to a group of macromolecular proteins with a substantial proportion of ECMs, are known to influence the proliferation and differentiation of hES cells. In this study, we evaluated the effects of type IV collagen and laminin in freezing medium on the survival and differentiation rates of hES cells after slow freezing and rapid thawing. The addition of type IV collagen (1 microg/ml) to the freezing medium significantly increased the survival rate of hES cells after thawing compared with that of a control group. The spontaneous differentiation rates of groups treated with type IV collagen (1 microg/ml) or laminin (1 microg/ml) were significantly lower than those of the control group. Frozen-thawed hES cells have currently been cultured for more than 70 passages and retain key properties of hES cells such as morphological characteristics, normal karyotype, marker expression (alkaline phosphatase, SSEA-1, SSEA-3, SSEA-4, TRA-1-60, TRA-1-81, Rex-1, and Oct-4), basement membrane-related gene expression, and the potential to differentiate into derivatives of all three germ layers. This new slow freezing method by ECM treatment is a reliable and effective cryopreservation method for pluripotent hES cells.

Alkaline Phosphatase↗

PubMed2003

The prognosis of liver cirrhosis in recent years in Korea.

The survival of a recent series of 823 cirrhosis patients who were followed up for a mean of 48 months was analyzed. Cirrhosis was ascribed to alcohol (26%), hepatitis virus B (58%), hepatitis virus C (11%) or both (2%), or was cryptogenic (3%). Features of decompensation were observed in 51% of the patients at entry, and newly developed in 44% of compensated patients within 5 yr. The 5-yr survival after decompensation was 25%. The leading causes of death were liver failure (53%), hepatocellular carcinoma (HCC, 23%), and variceal bleeding (10%). Early detection of HCC significantly improved the survival of cirrhosis patients. Biannual ultrasonography increased the detection rate of small HCC. Mortality of variceal hemorrhage was much lower in patients with Child-Pugh scores from 5 to 8 than in those with scores above 8 (5% vs. 52%). Endoscopic prophylaxis significantly decreased the incidence of first variceal hemorrhage, but the effect was insufficient to improve the rate of survival. Mortality of first spontaneous bacterial peritonitis was 18%. These data suggest that the mortality of major complications of liver cirrhosis has considerably decreased during the last two decades, while there was no remarkable improvement in long-term survival. More efficient management of etiologic factors would be required.

Adult↗