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  • 1
    Electronic Resource
    Electronic Resource
    Different measures of human hematopoietic cell culture performance are optimized under vastly different conditions (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 50 (1996), S. 505-513 
    Details
    ISSN: 0006-3592
    Keywords: bone marrow ; hematopoiesis ; perfusion ; culture optimization ; stroma ; stem cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Hematopoiesis, the formation of mature blood cells from stem (LTC-IC) and progenitor (CFU-GM) cells in the bone marrow, is a complex tissue-forming process that leads to many important physiological functionalities. Consequently, a functioning ex vivo hematopoietic system has a variety of basic scientific and clinical uses. The design and operation of such a system presents the tissue engineer with challenges and choices. In this study, three culture variables were used to control ex vivo human hematopoiesis. Systematic variation of inoculum density (ID), medium exchange interval (MEI), and the use of preformed stroma (PFS) showed that (1) all three variables significantly influenced culture performance, (2) the three variables interacted strongly, and (3) the variables could be manipulated to achieve the optimization of different performance criteria. Donor-to-donor variability in culture performance was great at low ID but was minimized at higher ID. PFS had a large positive effect on cell and CFU-GM output at low ID, but had minimal effect at higher ID. In fact, PFS caused a decrease in LTC-IC output at high ID. The effects of PFS indicated that stromal cell elements became more limiting than proliferative cell elements as ID was reduced.In cultures without PFS, maximum cell output was obtained with high ID using a short MEI, whereas the greatest cell expansion ratio was obtained at low ID with an intermediate MEI. Maximum CFU-GM output was obtained from cultures with high ID using a short to intermediate MEI, whereas the greatest CFU-GM expansion ratio was obtained at intermediate ID with an intermediate MEI. The addition of PFS altered the locations of these maxima. In general, PFS moved the maxima to lower ID, and culture output became more sensitive to MEI. Therefore, the optimization of one performance criterion always resulted in a decline of the others. This study demonstrates that ex vivo tissue function is sensitive to many culture variables in an interactive fashion and that systematic multivariable studies are required to characterize tissue function. Once the effects of individual variables and their interactions are known, this knowledge can be used to optimize tissue performance with respect to desired criteria. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 2
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    A common variant on chromosome 9p21 affects the risk of myocardial infarction (2007)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2007-05-05
    Description: The global endemic of cardiovascular diseases calls for improved risk assessment and treatment. Here, we describe an association between myocardial infarction (MI) and a common sequence variant on chromosome 9p21. This study included a total of 4587 cases and 12,767 controls. The identified variant, adjacent to the tumor suppressor genes CDKN2A and CDKN2B, was associated with the disease with high significance. Approximately 21% of individuals in the population are homozygous for this variant, and their estimated risk of suffering myocardial infarction is 1.64 times as great as that of noncarriers. The corresponding risk is 2.02 times as great for early-onset cases. The population attributable risk is 21% for MI in general and 31% for early-onset cases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Helgadottir, Anna -- Thorleifsson, Gudmar -- Manolescu, Andrei -- Gretarsdottir, Solveig -- Blondal, Thorarinn -- Jonasdottir, Aslaug -- Jonasdottir, Adalbjorg -- Sigurdsson, Asgeir -- Baker, Adam -- Palsson, Arnar -- Masson, Gisli -- Gudbjartsson, Daniel F -- Magnusson, Kristinn P -- Andersen, Karl -- Levey, Allan I -- Backman, Valgerdur M -- Matthiasdottir, Sigurborg -- Jonsdottir, Thorbjorg -- Palsson, Stefan -- Einarsdottir, Helga -- Gunnarsdottir, Steinunn -- Gylfason, Arnaldur -- Vaccarino, Viola -- Hooper, W Craig -- Reilly, Muredach P -- Granger, Christopher B -- Austin, Harland -- Rader, Daniel J -- Shah, Svati H -- Quyyumi, Arshed A -- Gulcher, Jeffrey R -- Thorgeirsson, Gudmundur -- Thorsteinsdottir, Unnur -- Kong, Augustine -- Stefansson, Kari -- New York, N.Y. -- Science. 2007 Jun 8;316(5830):1491-3. Epub 2007 May 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE genetics, Sturlugata 8, IS-101 Reykjavik, Iceland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17478679" target="_blank"〉PubMed〈/a〉
    Keywords: Age of Onset ; Aged ; Case-Control Studies ; Chromosome Mapping ; Chromosomes, Human, Pair 9/*genetics ; Coronary Artery Disease/genetics ; Female ; Genes, p16 ; *Genetic Predisposition to Disease ; *Genetic Variation ; Genotype ; Haplotypes ; Heterozygote ; Homozygote ; Humans ; Linkage Disequilibrium ; Male ; Middle Aged ; Myocardial Infarction/*genetics ; *Polymorphism, Single Nucleotide ; Risk Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
    Electronic Resource
    Electronic Resource
    Frequent harvesting from perfused bone marrow cultures results in increased overall cell and progenitor expansion (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 609-616 
    Details
    ISSN: 0006-3592
    Keywords: stem cells ; bone marrow ; ex vivo expansion ; perfusion culture ; hematopoiesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The establishment of prolific long-term human bone marrow cultures has led to the development of hematopoietic bioreactor systems. A single batch expansion of bone marrow mononuclear cell populations leads to a 10- to 30-fold increase in total cell number and in the number of colony forming units-granulocyte/macrophage (CFU-GMs), and a four- to tenfold increase in the number of long-term culture initiating cells (LTC-ICs). In principle, unlimited expansion of cells should be attainable from a pool of stem cells if all the necessary requirements leading to stem cell maintenance and division are met. In this article, we take the first step toward the identification of factors that limit single batch expansion of ex vivo bone marrow cells in perfusion-based bioreactor systems. One possible constraint is the size of the growth surface area required. This constraint can be overcome by harvesting half the cell population periodically. We found that harvesting cells every 3 to 4 days, beginning on day 11 of culture, led to an extended growth period. Overall calculated cell expansion exceeded 100-fold and the CFU-GM expansion exceeded 30-fold over a 27-day period. These calculated values are based on growth that could be obtained from the harvested cell population. Growth of the adherent cell layer was stable, whereas the nonadherent cell population diminished with increasing number of passages. These results show that the bioreactor protocols published to date are suboptimal for long-term cultivation, and that further definition and refinement is likely to lead to even greater expansion of hematopoietic cell populations obtained from bone marrow. More importantly, these results show that the LTC-IC measured during the single pass expansion do have further expansion potential that can be realized by frequent harvesting. Finally, the present culture conditions provide a basis for an assay system for the identifications provide a basis for an assay system for the identification of the factors that determine the long-term maintenance and replication of human stem cells ex vivo. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440507
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  • 4
    Electronic Resource
    Electronic Resource
    Review: Tissue engineering: Reconstitution of human hematopoiesis ex vivo (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 909-930 
    Details
    ISSN: 0006-3592
    Keywords: tissue engineering ; hematopoiesis ; review ; bioreactors ; transplantation ; scaleup ; cell culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The reconstruction of functioning human tissues ex vivo is becoming an important part of biotechnology. There are compelling scientific, clinical, and biotechnological reasons for fully or partially reconstituting human tissues such as skin, bone marrow, and liver ex vivo. In particular, bone marrow is a tissue of much importance, and there are significant societal and health benefits derived from a successfully constructed ex vivo hematopoietic system. In this article, we review the current status of this effort. The topics covered include the current understanding of the biology of human hematopoiesis, the motivation for reconstructing it ex vivo, the current state of ex vivo human hematopoietic cultures, the development of important metrics to judge culture performance, and an approach based on in vivo mimetics to accomplish this goal. We discuss some applications of functional ex vivo hematopoietic cultures and the biological and engineering challenges that face research in this area. © 1993 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260420802
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  • 5
    Electronic Resource
    Electronic Resource
    Unilineage model of hematopoiesis predicts self-renewal of stem and progenitor cells based on ex vivo growth data (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 52 (1996), S. 24-33 
    Details
    ISSN: 0006-3592
    Keywords: unilineage model ; tissue function ex vivo ; hematopoiesis ; stem cell expansion ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Stem cell models are used to describe the function of several tissues. We present unilineage kinetic description of stem cell models and their application to the analysis of ex vivo hematopoietic cell expansion data. This model has the capability to simulate the total cell number and the number of cells at each stage of differentiation over time as a function of the stem cell self-renewal probability, the growth rate of each subpopulation, and the mature cell death rate. The model predicts experimental observations in perfusion-based hematopoietic bioreactor systems. To obtain net cell expansion ex vivo, the model simulations show that the stem cell self-renewal probability must exceed one-half, thus resulting in net expansion of the stem cell population. Experimental data on long-term culture-initiating cells (LTC-IC) confirm this prediction and the probability of self-renewal is estimated to be 0.62 to 0.73. This self-renewal probability, along with the death rate, define a relationship in which the apparent overall growth rate is less than the compartmental growth rate. Finally, the model predicts that cells beyond the stem cell stage of differentiation must self-renew to achieve the level of expansion within the time frame observed in experimental systems. © 1996 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    The influence of extra-cellular matrix and stroma remodeling on the productivity of long-term human bone marrow cultures (1992)
    Springer
    Cytotechnology 10 (1992), S. 217-224 
    Details
    ISSN: 1573-0778
    Keywords: hematopoiesis ; extra-cellular matrix ; stromal cells ; conditioned medium ; rapid perfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The stromal cell layer is believed to play an important role in long-term human bone marrow cultures (LTHBMCs). At present, neither the role that the stromal cell extra-cellular matrix (ECM) plays in influencing stroma behavior is well understood nor are the effects of stroma aging. Rapid medium exchanged LTHBMCs were established on surfaces precoated with human natural fibronectin and type 1 rat tail collagen. Although initial adhesion of hematopoietic cells was improved by the presence of both ECMs, the overall progenitor and nonadherent cell productivity was not improved nor did the stroma grow to confluency faster. Thus, the ECMs used did not significantly influence the cell productivity of LTHBMCs. To examine the influence of stromal cell layer aging, conditioned medium was obtained from the first two weeks of LTHBMCs that was subsequently concentrated and used as a medium supplement in a second set of slowly exchanged LTHBMCs. The presence of the concentrated conditioned medium (conCM) enhanced the production of nonadherent cells three-fold compared with control over an eight week culture period. Control cultures that were exposed to conCM after 4 weeks in culture significantly improved their cell productivity during the latter 4 weeks of culture compared with control. The productivity of cultures exposed to conCM for 4 weeks dropped significantly when unsupplemented medium was used for the latter 4 weeks of culture. Interestingly, phytohemagglutin-stimulated leukocyte-conditioned medium stimulated LTHMBCs in a similar fashion, as did conditioned medium from early LTHBMCs. Taken together, these results strongly suggest that the stromal cell layer does produce important factors for active hematopoiesis during its growth to confluence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146672
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  • 7
    Electronic Resource
    Electronic Resource
    The construction of high efficiency human bone marrow tissue ex vivo (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 45 (1991), S. 268-272 
    Details
    ISSN: 0730-2312
    Keywords: hematopoiesis ; stem cell ; perfusion ; hematopoietic growth factor ; genetic engineering ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The successful ex vivo reconstruction of human bone marrow is an extraordinarily important basic scientific and clinical goal. Fundamentally, the system is the paradigm of a complex interactive tissue, in which the proliferation and regulated differentiation of one parenchymal cell type (the hematopoietic stem cell) is governed by the surrounding stromal cells. Understanding and reproducing the molecular interactions between bone marrow stromal cells and stem cells in tissue culture models is therefore the critical step in successful bone marrow tissue culture. Clinically, successful reconstruction of human bone marrow would permit the controlled production of mature blood cells for transfusion therapy, and immature bone marrow stem cells for bone marrow transplantation. In approaching the bone marrow culture system, we recognize the critical role that hematopoietic growth factors (HGFs) play in hematopoiesis. Since stromal cells in traditional human bone marrow cultures produce little HGFs, we have begun by asking whether local supplementation of hematopoietic growth factors via genetically engineered stromal cells might augment hematopoiesis in liquid cultures. The results indicate that locally produced GM-CSF and IL-3 do augment hematopoiesis for several weeks in culture. In combination with geometric and dynamic approaches to reconstructing physiological bone marrow microenvironments, we believe that this approach has promise for reconstructing human bone marrow ex vivo, thereby permitting its application to a variety of basic and clinical problems.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jcb.240450308
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  • 8
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    An association between the kinship and fertility of human couples (2008)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2008-02-09
    Description: Previous studies have reported that related human couples tend to produce more children than unrelated couples but have been unable to determine whether this difference is biological or stems from socioeconomic variables. Our results, drawn from all known couples of the Icelandic population born between 1800 and 1965, show a significant positive association between kinship and fertility, with the greatest reproductive success observed for couples related at the level of third and fourth cousins. Owing to the relative socioeconomic homogeneity of Icelanders, and the observation of highly significant differences in the fertility of couples separated by very fine intervals of kinship, we conclude that this association is likely to have a biological basis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Helgason, Agnar -- Palsson, Saebjorn -- Gudbjartsson, Daniel F -- Kristjansson, Thornordur -- Stefansson, Kari -- New York, N.Y. -- Science. 2008 Feb 8;319(5864):813-6. doi: 10.1126/science.1150232.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE Genetics, Sturlugata 8, 101 Reykjavik, Iceland. agnar@decode.is〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18258915" target="_blank"〉PubMed〈/a〉
    Keywords: Consanguinity ; *Family ; *Family Characteristics ; Female ; *Fertility ; Humans ; Iceland ; Male ; Socioeconomic Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 9
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    Sequence variants in the RNF212 gene associate with genome-wide recombination rate (2008)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2008-02-02
    Description: The genome-wide recombination rate varies between individuals, but the mechanism controlling this variation in humans has remained elusive. A genome-wide search identified sequence variants in the 4p16.3 region correlated with recombination rate in both males and females. These variants are located in the RNF212 gene, a putative ortholog of the ZHP-3 gene that is essential for recombinations and chiasma formation in Caenorhabditis elegans. It is noteworthy that the haplotype formed by two single-nucleotide polymorphisms (SNPs) associated with the highest recombination rate in males is associated with a low recombination rate in females. Consequently, if the frequency of the haplotype changes, the average recombination rate will increase for one sex and decrease for the other, but the sex-averaged recombination rate of the population can stay relatively constant.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kong, Augustine -- Thorleifsson, Gudmar -- Stefansson, Hreinn -- Masson, Gisli -- Helgason, Agnar -- Gudbjartsson, Daniel F -- Jonsdottir, Gudrun M -- Gudjonsson, Sigurjon A -- Sverrisson, Sverrir -- Thorlacius, Theodora -- Jonasdottir, Aslaug -- Hardarson, Gudmundur A -- Palsson, Stefan T -- Frigge, Michael L -- Gulcher, Jeffrey R -- Thorsteinsdottir, Unnur -- Stefansson, Kari -- New York, N.Y. -- Science. 2008 Mar 7;319(5868):1398-401. doi: 10.1126/science.1152422. Epub 2008 Jan 31.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE Genetics Inc, 101 Reykjavik, Iceland. kong@decode.is〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18239089" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Chromosomes, Human, Pair 4/*genetics ; Fathers ; Female ; *Genome, Human ; Haplotypes ; Humans ; Linkage Disequilibrium ; Male ; Meiosis ; Molecular Sequence Data ; Mothers ; Polymorphism, Single Nucleotide ; *Recombination, Genetic ; Sex Characteristics ; Synaptonemal Complex/metabolism ; Ubiquitin-Protein Ligases/*genetics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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