Stem cell memory

Published on October 1, 2007 Updated on December 31, 2017   64 min

A selection of talks on Reproduction & Development

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Hello. My name is James L. Sherley. I am the Director of Asymmetrex.LLC located in Boston, Massachusetts in the United States. The topic of my presentation is Stem Cell Memory.
Part one of the presentation is: Defining stem cell memory.
I would like to begin with a brief discussion of the two main types of stem cells that are of interest for biomedicine and biotechnology. The first of these embryonic stem cells are derived from an early stage in development called the blastocyst. Within the blastocyst, there's an inner cell mass composed of cells called epiblast. When epiblast are placed in culture on appropriate conditions, they give rise to embryonic stem cells. There is much excitement over embryonic stem cells because each of these cells has the potential to give rise to all of the diverse cell types found in the mature body. The second type of stem cells, adult stem cells, occur late in fetal development at about the time that organs begin to form. As we will see, adult stem cells are found in most adult tissues.
These two main types of stem cells, embryonic and adult, differ in several important respects. Embryonic stem cells are derived from embryos, whereas adult stem cells are found in adult tissues. Embryonic stem cells are easily identified as the epiblast and blastocysts. In contrast, adult stem cells are difficult to identify in tissues. And in fact, there are no known unique identifiers of adult stem cells, making it difficult to effect their isolation study. Embryonic stem cells are pluripotent, meaning that each cell has the potential to give rise to all of the different types of cells in the adult body. In contrast, adult stem cells are limited in this potential. In general, they have evolved to be multipotent or unipotent, being able to produce only the several different cell types or a single different cell type in their tissue of residence. In respect to this talk, embryonic stem cells have no cellular memory. Stem cell memory is a feature of adult stem cells. As noted before, both embryonic stem cells and adult stem cells are of interest for potential applications in biomedicine, in particular, self-replacement therapies. However, embryonic stem cell research faces two major problems. Production of human embryonic stem cells requires the death of human embryos which raises difficult moral questions and objections to this research. The embryonic stem cells form tumors when transplanted into adult tissues, further complicating their application for human cell therapy. Adult stem cells offer solutions for both of these problems. Informed consent is possible for donors of adult stem cells avoiding ethical and moral issues, and these cells do not form tumors in adult tissues.