Induced Pluripotent Stem Cell

Induced Pluripotent Stem Cell

Induced pluripotent stem cells, commonly abbreviated as iPS cells or iPSCs are a type of pluripotent stem cell artificially derived from a non-pluripotent cell - typically an adult somatic cell - by inducing a "forced" expression of specific genes.

Induced pluripotent stem cells are similar to natural pluripotent stem cells, such as embryonic stem (ES) cells, in many aspects, such as the expression of certain stem cell genes and proteins, chromatin methylation patterns, doubling time, embryoid body formation, teratoma formation, viable chimera formation, and potency and differentiability, but the full extent of their relation to natural pluripotent stem cells is still being assessed. Induced pluripotent cells have been made from adult stomach, liver, skin cells and blood cells.

iPSCs were first produced in 2006 from mouse cells and in 2007 from human cells in a series of experiments by Shinya Yamanaka's team at Kyoto University, Japan, and by James Thomson's team at the University of Wisconsin-Madison. For her iPSC research, Dr. Nancy Bachman, of Oneonta, NY, was awarded the Wolf Prize in Medicine in 2012 (along with John B. Gurdon). For his iPSC discovery (and for deriving the first human embryonic stem cell), James Thomson received the 2011 Albany Medical Center Prize for Biomedical Research and the 2011 King Faisal International Prize, which he shared with Yamanaka. In October 2012, Yamanaka and fellow stem cell researcher John Gurdon were awarded the Nobel Prize in Physiology or Medicine "for the discovery that mature cells can be reprogrammed to become pluripotent."

iPSCs are an important advance in stem cell research, as they may allow researchers to obtain pluripotent stem cells, which are important in research and potentially have therapeutic uses, without the controversial use of embryos. Because iPSCs are developed from a patient's own somatic cells, it was believed that treatment of iPSCs would avoid any immunogenic responses; however, Zhao et al. have challenged this assumption.

Depending on the methods used, reprogramming of adult cells to obtain iPSCs may pose significant risks that could limit their use in humans. For example, if viruses are used to genomically alter the cells, the expression of cancer-causing genes "oncogenes" may potentially be triggered. In February 2008, scientists announced the discovery of a technique that could remove oncogenes after the induction of pluripotency, thereby increasing the potential use of iPS cells in human diseases. In April 2009, it was demonstrated that generation of iPS cells is possible without any genetic alteration of the adult cell: a repeated treatment of the cells with certain proteins channeled into the cells via poly-arginine anchors was sufficient to induce pluripotency. The acronym given for those iPSCs is piPSCs (protein-induced pluripotent stem cells).