19. The Influence of Sputtered Bone Substitutes on Cell Growth and Phenotypic Expression

Abstract The commitment process of a human megakaryoblastic cell line (MEG-O1) induced with phorbol ester, TPA, was investigated with special reference to glycoprotein (GP) IIb/IIIa expression, multinuclear formation, and DNA replication. TPA (10(-7) mol/L) completely inhibited cellular division in MEG-O1, but did not suppress de novo DNA synthesis. Two days' culture with 10(-7) mol/L TPA was sufficient for MEG-O1 cells to initiate an irreversible commitment process. These cells could not resume cell growth and expressed GP IIb/IIIa antigen; some of them showed multinuclear form and DNA polyploidy even after removal of TPA from the culture medium. DNA histogram analysis showed that, upon treatment with TPA, the percentage of cells whose DNA ploidy was more than 8N was 5 to 10 times higher than that of control cells. Precise analysis using cell size fractionation by centrifugal elutriation method showed that there was strong correlation between the percentage of multinuclear cells and DNA polyploidy in TPA-treated cells. The percentage and staining intensity of GP IIb/IIIa and other megakaryocytic phenotypes such as von Willebrand factor and PAS staining were highest in large multinuclear cell populations, suggesting that these cells are the most differentiated population in this system. In TPA-treated cells, the activity of DNA polymerase alpha, a marker for cell growth, remained at the same level as in control cells. Aphidicolin, a specific inhibitor of DNA polymerase alpha, completely inhibited the differentiation induction of MEG-O1 cells with TPA measured by either GP IIb/IIIa expression or multinuclear cell formation. Therefore, DNA replication appears to be involved in the process of phenotypic expression as well as endomitosis in megakaryocyte differentiation of MEG-O1 cells. Aphidicolin was also effective in inhibiting megakaryocytic differentiation of other leukemia cell lines such as human erythroleukemia (HEL) and K562 cell lines induced with TPA, suggesting the close interplay of DNA replication and phenotypic expression in megakaryopoiesis.

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Human endothelial cell growth and phenotypic expression on three dimensional poly(lactide-co-glycolide) sintered microsphere scaffolds for bone tissue engineering

Biotechnology and Bioengineering ◽

10.1002/bit.21495 ◽

2007 ◽

Vol 98 (5) ◽

pp. 1094-1102 ◽

Cited By ~ 24

Author(s):

Ehsan Jabbarzadeh ◽

Tao Jiang ◽

Meng Deng ◽

Lakshmi S. Nair ◽

Yusuf M. Khan ◽

...

Keyword(s):

Tissue Engineering ◽

Endothelial Cell ◽

Cell Growth ◽

Bone Tissue Engineering ◽

Bone Tissue ◽

Phenotypic Expression ◽

Three Dimensional ◽

Human Endothelial Cell ◽

Endothelial Cell Growth

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Aphidicolin, an inhibitor of DNA replication, blocks the TPA-induced differentiation of a human megakaryoblastic cell line, MEG-O1

Blood ◽

10.1182/blood.v78.12.3168.bloodjournal78123168 ◽

1991 ◽

Vol 78 (12) ◽

pp. 3168-3177 ◽

Cited By ~ 1

Author(s):

T Murate ◽

T Hotta ◽

K Tsushita ◽

M Suzuki ◽

T Yoshida ◽

...

Keyword(s):

Dna Replication ◽

Cell Growth ◽

Cell Line ◽

Cell Lines ◽

Dna Polymerase ◽

Phenotypic Expression ◽

Leukemia Cell ◽

Specific Inhibitor ◽

Dna Polymerase Alpha ◽

Multinuclear Cell

The commitment process of a human megakaryoblastic cell line (MEG-O1) induced with phorbol ester, TPA, was investigated with special reference to glycoprotein (GP) IIb/IIIa expression, multinuclear formation, and DNA replication. TPA (10(-7) mol/L) completely inhibited cellular division in MEG-O1, but did not suppress de novo DNA synthesis. Two days' culture with 10(-7) mol/L TPA was sufficient for MEG-O1 cells to initiate an irreversible commitment process. These cells could not resume cell growth and expressed GP IIb/IIIa antigen; some of them showed multinuclear form and DNA polyploidy even after removal of TPA from the culture medium. DNA histogram analysis showed that, upon treatment with TPA, the percentage of cells whose DNA ploidy was more than 8N was 5 to 10 times higher than that of control cells. Precise analysis using cell size fractionation by centrifugal elutriation method showed that there was strong correlation between the percentage of multinuclear cells and DNA polyploidy in TPA-treated cells. The percentage and staining intensity of GP IIb/IIIa and other megakaryocytic phenotypes such as von Willebrand factor and PAS staining were highest in large multinuclear cell populations, suggesting that these cells are the most differentiated population in this system. In TPA-treated cells, the activity of DNA polymerase alpha, a marker for cell growth, remained at the same level as in control cells. Aphidicolin, a specific inhibitor of DNA polymerase alpha, completely inhibited the differentiation induction of MEG-O1 cells with TPA measured by either GP IIb/IIIa expression or multinuclear cell formation. Therefore, DNA replication appears to be involved in the process of phenotypic expression as well as endomitosis in megakaryocyte differentiation of MEG-O1 cells. Aphidicolin was also effective in inhibiting megakaryocytic differentiation of other leukemia cell lines such as human erythroleukemia (HEL) and K562 cell lines induced with TPA, suggesting the close interplay of DNA replication and phenotypic expression in megakaryopoiesis.

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Electron Microscopic Study of the Epithelium of the Seminal Vesicle of Aging Rats

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100050706 ◽

1974 ◽

Vol 32 ◽

pp. 138-139

Author(s):

V. F. Allison ◽

G. C. Fink ◽

G. W. Cearley

Keyword(s):

Cell Growth ◽

Epithelial Cell ◽

Epithelial Cells ◽

Seminal Vesicle ◽

Seminal Vesicles ◽

Epithelial Layer ◽

Epithelial Hyperplasia ◽

Electron Microscopic ◽

Aging Rats ◽

Pseudostratified Epithelium

It is well known that epithelial hyperplasia (benign hypertrophy) is common in the aging prostate of dogs and man. In contrast, little evidence is available for abnormal epithelial cell growth in seminal vesicles of aging animals. Recently, enlarged seminal vesicles were reported in senescent mice, however, that enlargement resulted from increased storage of secretion in the lumen and occurred concomitant to epithelial hypoplasia in that species.The present study is concerned with electron microscopic observations of changes occurring in the pseudostratified epithelium of the seminal vescles of aging rats. Special attention is given to certain non-epithelial cells which have entered the epithelial layer.

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Rotary Beveling for In Situ Thin-Section Microscopy of Cell Cultures

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100099192 ◽

1981 ◽

Vol 39 ◽

pp. 550-551

Author(s):

Dean A. Handley ◽

Jack T. Alexander ◽

Shu Chien

Keyword(s):

Cell Growth ◽

Cell Cultures ◽

Molecular Interactions ◽

Convenient Method ◽

Petri Dish ◽

Simple Method ◽

Thin Section Microscopy ◽

Thin Sectioning ◽

Organic Fluids

In situ preparation of cell cultures for ultrastructural investigations is a convenient method by which fixation, dehydration and embedment are carried out in the culture petri dish. The in situ method offers the advantage of preserving the native orientation of cell-cell interactions, junctional regions and overlapping configurations. In order to section after embedment, the petri dish is usually separated from the polymerized resin by either differential cryo-contraction or solvation in organic fluids. The remaining resin block must be re-embedded before sectioning. Although removal of the petri dish may not disrupt the native cellular geometry, it does sacrifice what is now recognized as an important characteristic of cell growth: cell-substratum molecular interactions. To preserve the topographic cell-substratum relationship, we developed a simple method of tapered rotary beveling to reduce the petri dish thickness to a dimension suitable for direct thin sectioning.

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