More MS news articles for Jan 2002

Determining Embryonic Stem Cell Potential

http://www.the-scientist.com/yr2002/jan/defrancesco_p28_020107.html

Jan. 7, 2002
The Scientist 16[1]:28
By Laura DeFrancesco

Two reports in the December issue of Nature Biotechnology show that the potential of human embryonic stem cells is being realized.1,2 One group led by S.C. Zheung at the University of Wisconsin, Madison, and another led by B.E. Reubinoff from Hadassah University, Jerusalem, have isolated highly purified populations of neuronal progenitor cells from human embryonic stem cell (ESC) cultures.

These papers demonstrate that human ESC cultures can be enriched for a single and specific progenitor cell type. Furthermore, the cells, which by all measures appear to be neuronal progenitor cells, behave this way in vitro and in vivo, and give rise to the major cell types of the central nervous system (CNS).

The two groups used different schemes, but their outcomes were remarkably similar. They first induced ESCs to become neuronal progenitor cells and identified them by certain morphological features. In the Zheung paper, neural, tube-like structures formed after the cultures were grown for a few weeks in FGF-2-containing media. Reubinoff simply starved the cultures, which caused ESCs to clump into little islands of differentiating cells. Each group isolated the neuronal progenitor cells away from the non-neuronal cells and treated them with various factors to send them down the neuronal cell pathway. In culture, the cells turned into the three major CNS cell types, some even showing signs of neurotransmitter synthesis. After transplanting the neuronal precursor cells into mouse brains, both groups found human cells in numerous brain regions, where they appeared to have responded to host cues, as they differentiated into neuronal cells and migrated along established pathways.

In addition to pure cultures of nerve cells having obvious therapeutic uses, these cultures will provide a platform for studying brain development. Zheung says, "When you compare what we know about human brain development, in terms of time and landmarks, everything is there in the dish. Critical structures in neuroendothelial cells are almost identical to what we see in embryos."

Zheung and Reubinoff are certain that the non-neuronal cells, which represent only a few percent of the total, are differentiated ESCs, because they don't react with an ESC-specific marker. This would pose the greatest threat, but neither can say for sure what they are. Undifferentiated cells produce teratomas, so had they reacted with the ESC marker, it would be problematic.

Laura DeFrancesco is a freelance writer in Pasadena, Calif.

References

1. S.C. Zhang et al., "In vitro differentiation of transplantable neural precursors from human embryonic stem cells," Nature Biotechnology, 19:1129-33, December 2001.

2. B.E. Reubinoff et al., "Neural progenitors from human embryonic stem cells," Nature Biotechnology, 19:1134-40, December 2001.

The Scientist 16[1]:28, Jan. 7, 2002

 
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