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Research Containing: Cell Size

Enhanced cardiac differentiation of mouse embryonic stem cells by use of the slow-turning, lateral vessel (STLV) bioreactor

by on 9 June 2015in Biology & Biotechnology No comment

Embryoid body (EB) formation is a common intermediate during in vitro differentiation of pluripotent stem cells into specialized cell types. We have optimized the slow-turning, lateral vessel (STLV) for large scale and homogenous EB production from mouse embryonic stem cells. The effects of inoculating different cell numbers, time of EB adherence to gelatin-coated dishes, and rotation speed for optimal EB formation and cardiac differentiation were investigated. Using 3 x 10(5) cells/ml, 10 rpm rotary speed and plating of EBs onto gelatin-coated surfaces three days after culture, were the best parameters for optimal size and EB quality on consequent cardiac differentiation. These optimized parameters enrich cardiac differentiation in ES cells when using the STLV method.

Related URLs:
<Go to ISI>://WOS:000293752000009

Gravity and positional homeostasis of the cell

by on 9 June 2015in Biology & Biotechnology No comment

Normally bilateralization takes place in the presence of the Earth's gravity which produces torque, shear, tension and compression acting upon the naked aggregates of cytoplasm in the zygote which is only stabilized by a weak cytoskeleton. In an initial examination of the effects of these quantities on development, an expression is derived to describe the tendency of torque to rotate the egg and reorganize its constituents. This expression yields the net torque resulting from buoyancy and gravity acting upon a dumbbell shaped cell with heavy and light masses at either end and "floating" in a medium. Using crude values for the variables, torques of 2.5 x l0(-13) to 8.5 x 10(-1) dyne-cm are found to act upon cells ranging from 6.4 micrometers to 31 mm (chicken egg). By way of camparison six microtubules can exert a torque of 5 x 10(-9) dyne-cm. (1) Gravity imparts torque to cells; (2) torque is reduced to zero as gravity approaches zero; and (3) torque is sensitive to cell size and particulate distribution. Cells must expend energy to maintain positional homeostasis against gravity. Although not previously recognized, Skylab 3 results support this hypothesis: tissue cultures used 58% more glucose on Earth than in space. The implications for developmental biology, physiology, genetics, and evolution are considered. At the cellular and tissue level the concept of "gravity receptors" may be unnecessary.

Related URLs:
http://ovidsp.ovid.com/ovidweb.cgi?T=JS&CSC=Y&NEWS=N&PAGE=fulltext&D=med2&AN=11542443
http://sfxhosted.exlibrisgroup.com/mayo?sid=OVID:medline&id=pmid:11542443&id=doi:&issn=0273-1177&isbn=&volume=3&issue=9&spage=159&pages=159-68&date=1983&title=Advances+in+Space+Research&atitle=Gravity+and+positional+homeostasis+of+the+cell.&aulast=Nace&pid=%3Cauthor%3ENace+GW%3C%2Fauthor%3E&%3CAN%3E11542443%3C%2FAN%3E

Unique Differentiation Profile of Mouse Embryonic Stem Cells in Rotary and Stirred Tank Bioreactors

by on 9 June 2015in Biology & Biotechnology No comment

Embryonic stem (ES)-cell-derived lineage-specific stem cells, for example, hematopoietic stem cells, could provide a potentially unlimited source for transplantable cells, especially for cell-based therapies. However, reproducible methods must be developed to maximize and scale-up ES cell differentiation to produce clinically relevant numbers of therapeutic cells. Bioreactor-based dynamic culture conditions are amenable to large-scale cell production, but few studies have evaluated how various bioreactor types and culture parameters influence ES cell differentiation, especially hematopoiesis. Our results indicate that cell seeding density and bioreactor speed significantly affect embryoid body formation and subsequent generation of hematopoietic stem and progenitor cells in both stirred tank (spinner flask) and rotary microgravity (Synthecon (TM)) type bioreactors. In general, high percentages of hematopoietic stem and progenitor cells were generated in both bioreactors, especially at high cell densities. In addition, Synthecon bioreactors produced more sca-1(+) progenitors and spinner flasks generated more c-Kit(+) progenitors, demonstrating their unique differentiation profiles. cDNA microarray analysis of genes involved in pluripotency, germ layer formation, and hematopoietic differentiation showed that on day 7 of differentiation, embryoid bodies from both bioreactors consisted of all three germ layers of embryonic development. However, unique gene expression profiles were observed in the two bioreactors; for example, expression of specific hematopoietic genes were significantly more upregulated in the Synthecon cultures than in spinner flasks. We conclude that bioreactor type and culture parameters can be used to control ES cell differentiation, enhance unique progenitor cell populations, and provide means for large-scale production of transplantable therapeutic cells.

Related URLs:
<Go to ISI>://WOS:000283899600001

Microtubules as key cytoskeletal elements in cellular transport and shape changes: their expected responses to space environments

by on 9 June 2015in Biology & Biotechnology No comment

Application of reference standard reagents to alternatively depolymerize or stabilize microtubules in a cell that undergoes very regular cytoskeleton-dependent shape changes provides a model system in which some expected components of the environments of spacecraft and space can be tested on Earth for their effects on the cytoskeleton. The fertilized eggs of Ilyanassa obsoleta undergo polar lobe formation by repeated, dramatic, constriction and relaxation of a microfilamentous band localized in the cortical cytoplasm and activated by microtubules.

Related URLs:
http://ovidsp.ovid.com/ovidweb.cgi?T=JS&CSC=Y&NEWS=N&PAGE=fulltext&D=med3&AN=11537984
http://sfxhosted.exlibrisgroup.com/mayo?sid=OVID:medline&id=pmid:11537984&id=doi:&issn=0022-8443&isbn=&volume=95&issue=1&spage=45&pages=45-9&date=1992&title=Transactions+of+the+Kansas+Academy+of+Science&atitle=Microtubules+as+key+cytoskeletal+elements+in+cellular+transport+and+shape+changes%3A+their+expected+responses+to+space+environments.&aulast=Conrad&pid=%3Cauthor%3EConrad+GW%3C%2Fauthor%3E&%3CAN%3E11537984%3C%2FAN%3E

Gravity control of growth form in Brassica rapa and Arabidopsis thaliana (Brassicaceae): Consequences for secondary metabolism

by on 9 June 2015in Biology & Biotechnology No comment

How gravity influences the growth form and flavor components of plants is of interest to the space program because plants could be used for food and life support during prolonged missions away from the planet, where that constant feature of Earth's environment does not prevail. We used plant growth hardware from prior experiments on the space shuttle to grow Brassica rapa and Arabidopsis thaliana plants during 16-d or 11-d hypergravity treatments on large-diameter centrifuge rotors. Both species showed radical changes in growth form, becoming more prostrate with increasing g-loads (2-g and 4-g). In Brassica, height decreased and stems thickened in a linear relationship with increasing g-load. Glucosinolates, secondary compounds that contribute flavor to Brassica, decreased by 140% over the range of micro to 4-g, while the structural secondary compound, lignin, remained constant at approximately 15% (w/w) cell wall dry mass. Stem thickening at 4-g was associated with substantial increases in cell size (47%, 226%, and 33% for pith, cortex, and vascular tissue), rather than any change in cell number. The results, which demonstrate the profound effect of gravity on plant growth form and secondary metabolism, are discussed in the context of similar thigmostresses such as touch and wind.

Related URLs:
http://www.ncbi.nlm.nih.gov/pubmed/21628221