Coming from different backgrounds doesn’t make it impossible to find common ground. Just look at nuclear transfer-derived ES (ntES) and in vitro fertilized embryo-derived ES (IVFES) cells. Sure, they’re from different sides of the ES cell tracks, but as researchers from Michigan State University found out, once they’ve differentiated it hardly seems to matter.
NtES cells result from plopping a somatic cell nucleus into the cytoplasm of a denucleated egg, whereas IVFES cells are obtained from an in vitro-fertilized blastocyst.
Some researchers have wondered whether human ntES cells are completely “normal” ES cells, or whether their production creates Frankenstein-ESque cells with epigenetic changes affecting their differentiation. So, the authors compared DNA methylation and histone modifications in Oct4 and Nanog, two pluripotency-related genes, in rhesus monkey ntES and IVFES cells, before and after neuronal differentiation was induced.
Overall, epigenetic modifications of Oct4 and Nanog were pretty similar in both cell types. However, in IVFES cells both alleles of Oct4 were hypomethylated, whereas ntES cells were only mono-allelic and showed lower Oct4 mRNA levels (suggesting incomplete reprogramming of DNA methylation after somatic cell nuclear transfer). Interestingly, this epigenetic difference didn’t seem to affect neural differentiation potential: in both ES cell types, Oct4 and Nanog were silenced and neural-specific genes were activated when differentiation was induced.
Although much more work remains to be done, these results bolster the feasibility of using nuclear transfer to produce patient-specific human ES cells for therapeutic applications. Check out the interESting findings for yourself at Cloning and Stem Cells, December 2009.