Most, if not all, cell types in the body can be reprogrammed to become stem-cell-like, suggests a review of the so-called 'induced pluripotent stem (iPS) cells' in Nature. But complete and uniform reprogramming needs to be achieved if the resulting iPS cells are ever to be used in the clinic.
Shinya Yamanaka was the first to reprogram mature, differentiated cells into iPS cells, by using a retrovirus to add in a handful of genes. The cells, which can differentiate into many other cell types, were hailed as an ethical alternative to mainstream stem cell production methods that involve destroying embryos and require hard-to-come-by human eggs. However, the process of reprogramming is inefficient and often incomplete.
In this review, Yamanaka considers the reasons for bottlenecks in iPS cell production and proposes a model in which most or all cells have the potential to become stem-cell-like, given the right conditions - the reprogramming genes must be expressed in a particular pattern, and some other non-genetic events, such as methylation levels, are probably crucial. It's only when these factors can be reliably controlled that iPS cells are likely to achieve their full potential as key players in disease research, drug screening, toxicology and regenerative medicine.
Shinya Yamanaka (Kyoto University, Japan)
(C) Nature press release.
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