Studies reveal iPS cells stay true to their roots

Two research groups connected with the Harvard Stem Cell Institute this week published the results of studies which highlight crucial differences between embryonic and induced pluripotent stem (iPS) cells.

A team at the Children’s Hospital Boston compared embryonic stem cells from SCNT (somatic cell nuclear transfer) and iPS cells derived from different starting cells in mice. What they found was that iPS cells leaned towards making their tissue of origin as opposed to SCNT-derived cells which showed behaviour more like embryonic stem cells.

Over at Harvard University, researchers, also working with mice, reached a similar conclusion after comparing iPS cells from different starting tissues including muscle, skin and blood. They found that the behaviour of the iPS cells corresponded to the tissue from where the original cells were derived from. The upshot of the two studies is that the process of reprogramming to make iPS cells appears not to completely erase the markers that indicate which genes are used by a given cell.

This means that scientists will be forced to undertake more detailed analysis of the various types of stem cells including from iPS as well as embryonic stem cells derived from both IVF embryos and SCNT. The studies are also expected to pave the way for important improvements to cell reprogramming techniques.

The results of the Children’s hospital and Harvard University studies were published this week in the journals Nature Biotechnology and Nature respectively.

First appearing in 2006, iPS cells are the result of mature cell being genetically reengineered back to a pluripotent stem cell similar to an embryonic stem cell. Prior to this the main technique for accessing reprogrammed cells was SCNT, which sees an egg reprogram an adult cell with the resulting embryo providing the source of stem cells. To date, scientists have been able to make embryonic stem cells from SCNT embryos from many different types of animals but never humans.