Tissue engineering using human embryonic stem cells.
ABSTRACT The possibility of using stem cells for tissue engineering has greatly encouraged scientists to design new platforms in the field of regenerative and reconstructive medicine. Stem cells have the ability to rejuvenate and repair damaged tissues and can be derived from both embryonic and adult sources. Among cell types suggested as a cell source for tissue engineering (TE), human embryonic stem cells (hESCs) are one of the most promising candidates. Isolated from the inner cell mass of preimplantation stage blastocysts, they possess the ability to differentiate into practically all adult cell types. In addition, their unlimited self-renewal capacity enables the generation of sufficient amount of cells for cell-based TE applications. Yet, several important challenges are to be addressed, such as the isolation of the desired cell type and gaining control over its differentiation and proliferation. Ultimately, combing scaffolding and bioactive stimuli, newly designed bioengineered constructs, could be assembled and applied to various clinical applications. Here we define the culture conditions for the derivation of connective tissue lineage progenitors, design strategies, and highlight the special considerations when using hESCs for TE applications.
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ABSTRACT: Asymmetric stem cell division is a fundamental process used to generate cellular diversity and to provide a source of new cells in developing and adult organisms. Asymmetric stem cell division leads to another stem cell via self-renewal, and a second cell type which can be either a differentiating progenitor or a postmitotic cell. Experimental studies in model organisms including the nematode Caenorhabditis elegans, the fruitfly Drosophila melanogaster and the laboratory mouse, Mus musculus, have identified interrelated mechanisms that regulate asymmetric stem cell division from polarity formation and mitotic spindle orientation to asymmetric segregation of cell fate determinants and growth control. These mechanisms are mediated by evolutionary conserved molecules including Aurora-A, aPKC, Mud/NuMa, Lgl, Numb and Brat/TRIM-NHL, which in turn regulate a binary switch between stem cell self-renewal and differentiation. The mechanistic insights into asymmetric cell division have enhanced our understanding of stem cell biology and are of major therapeutic interest for regenerative medicine as asymmetrically dividing stem cells provide a powerful source for targeted cell replacement and tissue regeneration.12/2010: pages 103-123;
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ABSTRACT: Human embryonic stem cells are pluripotent cells derived from the inner cell mass of the blastocyst. Once isolated in culture, they can produce stable cell lines with the capacity to provide differentiated cells from all three germ layers. This ability is the centre of an emerging field of research into applications ranging from tissue engineering and drug discovery to developmental biology and treatments for serious conditions such as Parkinson’s, diabetes and heart disease. An essential prerequisite for these developments is the production of banks of well-characterised and safety-tested cells for research and as seed stocks for therapeutic applications. This requires the cryopreservation of stem cells for long-term storage. Currently, conventional freezing and vitrification when applied to these cells has met with varying degrees of success. This has led to an emerging debate on the suitability of either method for cryopreservation of these cells. Such studies as have been undertaken have been empirical in nature, and to date, no methodological studies, such as those carried out on haematopoietic stem cells, have been published. This paper reviews the current debate on cryopreservation and places it in the context of stem cell banking for both research and therapy.Transfusion Medicine and Hemotherapy 01/2007; 34(4):293-304. · 1.59 Impact Factor