Fibroblasts - a common cell type found in connective tissue - can be coaxed back into an embryonic stem-cell-like state with a little genetic trickery, two Nature papers suggest. The improved method, which sees a handful of genes added back to the cells before selection for a stem cell marker, means that no embryos are harmed in the creation of these embryonic stem-cell-like cells.
Teams led by Shinya Yamanaka and Rudolf Jaenisch added four genes (Oct4, Sox2, c-Myc and Klf4) into adult and embryonic mouse fibroblast cells. They then selected cells that expressed either Nanog or Oct4 - both genetic markers of pluripotency, the stem-cell-like ability to self-renew and turn into many different cell types - and created clonal cell lines.
The cells share similar patterns of gene expression and DNA methylation with embryonic stem cells, more so than similar lines reported last year by Yamanaka which were selected for on the basis of a different gene. In culture, the new cells look and grow like embryonic stem cells. And both teams were also able to generate viable chimaeras from the cells, which also passed through the germ line to the next generation.
Although the revised method still needs some tweaking, it offers the prospect of making customized embryonic stem cells for patient-specific cell treatment from a simple skin biopsy. The method is less controversial than current alternatives which involve destroying early embryos, thus side-stepping many of the ethical objections that surround stem cell research.
Shinya Yamanaka (Kyoto University, Japan)
Rudolf Jaenisch (Whitehead Institute for Biomedical Research & MIT, Cambridge, MA, USA)
Abstracts of articles available online:
Abstract of Article 1
Abstract of Article 2
(C) Nature press release.
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