Wow, some science!
Wow, some science!
At long last, something besides political issues on stem cells has crossed my path. Actually, there are a couple stories. First, a press release from the journal Genome Research reports that scientists from the Burnham Institute for Medical Research (BIMR) and Illumina Inc. have found that the DNA of embryonic stem cells is chemically modified in a recognizable pattern. It does appear to be a set back to therapeutic cloning, as the research suggests that any DNA inserted into an egg would need to be modified itself. The researchers say that more basic biology of the stem cell needs to be studied.
Essentially, the embryonic stem cell DNA differs from the DNA of adult stem cells, cancer cells, or differentiated stem cells. Embryonic stem cells are extracted from the embryo at a time when it is undergoing rapid division, an activity which is accompanied by the chemical addition of methyl groups to specific DNA sequences. It has already been established that when the methyl groups bond in something other than the normal pattern a number of birth defects can arise, including mental retardation and immunological deficiencies. (Methylation affects what genes are suppressed and what are expressed.)
The researchers have now identified the pattern of the methyl groups in the embryonic stem cell DNA. They analyzed stem cells from 14 different lines and tested over 1500 places in the DNA. The pattern they found is notably different from the pattern of other cells. Since the pattern is different from that of adult stem cell DNA, that DNA would have to have its methylation altered to match normal embryonic DNA for subsequent normal cell development.
The second story, also a press release, reports that researchers at UCLA found that when they compared neural cells derived from embryonic stem cells to neural cells derived from fetal tissue, the embryonic stem cells were deficient in the expression of one gene, CPT1A (they expressed it, but at lower levels than normal). The embryonic stem cells did not, however, share any of the mutations that are found in cancer cells.
The research was conducted on one of the federally funded stem cell lines, and the researchers want to perform the same study on other lines to see if this was an aberration. They also want to try to identify what component(s) of the laboratory differentiation techniques caused the difference from normally differentiated cells.