Editors' ChoiceRegenerative Medicine

Grow Your Own Stem Cells

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Science Translational Medicine  09 Dec 2009:
Vol. 1, Issue 10, pp. 10ec36
DOI: 10.1126/scitranslmed.3000681

Often cited as one of the most important discoveries in stem cell research, induced pluripotent stem (iPS) cells are made from adult somatic cells by the forced expression of genes that encode four transcriptional regulatory proteins that are highly expressed in embryonic stem (ES) cells. iPS cells share key characteristics with ES cells, such as pluripotency, gene expression and chromatin methylation patterns, and the ability to form teratomas (germ cell tumors containing tissue from each of the three germ layers, ectoderm, mesoderm, and endoderm). Use of iPS cells for research and regenerative medicine circumvents the controversy that arises when human embryos are used to isolate ES cells. However, certain technological walls still stand in the way of application of these multipotent cells for therapeutic use. Now, Takahashi et al. bring iPS cells a crucial step closer to the clinic.

Most researchers maintain their iPS and ES cells in culture on a feeder layer of mouse embryonic fibroblasts (MEFs), but this system is far from ideal. MEF cells are not human and might pass immunogenic mouse antigens or uncharacterized pathogens to the iPS cells. Growing iPS cells in culture without a feeder cell layer can cause chromosomal aberrations. Finally, some scientists have used human cells and tissues as feeders, but the passing of pathogens such as viruses or prions from the feeder cells to the iPS cells remains a problem. The authors cleverly sidestep these issues by using as a feeder the same human fibroblasts used to make the iPS cells. Through 19 passages in culture, iPS cells fed by their parental fibroblasts remained undifferentiated, displayed no changes in their chromosomal structures, and proliferated normally. Most important, these cells could differentiate into all three germ layers and form teratomas. Taken together, these findings pave the way for the production of clinical-grade iPS cells.

K. Takahashi et al., Human induced pluripotent stem cells on autologous feeders. PLoS ONE 4, e8067 (2009). [Full Text]

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