The race is now on. California is funding a lot of human embryonic stem cell research and the first fruits are appearing on the vine. Using a new technique called high resolution genomics, they are able to examine the genes of an individual or a small number of cells. It turns out that two stem cell lines use different genes to produce neurons. So, there is not one but possibly multiple solutions to the differentiation problem. Worse, one possibility is that different lines have different solutions.

Wise.


http://www.cloningresources.com/rese...cell_lines.asp

High-res technology shows significant differences in stem cell lines (4/5/2008)

embryonic stem cells, stem cells

UCLA stem cell researchers using a high-resolution technique to examine the genome of a pair of human embryonic stem cell lines have found that while both lines could form neurons, they differed in the numbers of certain genes that could control such things as individual traits and disease susceptibility.

The study appears in the April issue of the peer-reviewed journal Stem Cells.

The researchers used a technique known as array CGH (comparative genomic hybridization) to study the total DNA content of the lines, all the genes on 46 chromosomes. The use of higher-resolution techniques like array CGH and, soon, whole-genome sequencing will enhance the ability of researchers to examine stem cell lines to determine which are best - or least likely to result in diseases and other problems - for creating therapies for use in humans.

Array CGH provided a much better look at the gene content on the chromosomes, with a resolution about 100 times better than standard clinical methods. Clinical specialists commonly generate a karyotype - a technique involving the staining and photographing of a cell sample - to examine the chromosomes of cancer cells or for amniocentesis in prenatal diagnosis; karyotyping has a much lower resolution than array CGH, said Michael Teitell, a researcher with the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA and the senior author of the study. Small defects that could result in big problems later on could be missed using karyotyping for stem cells.