What are ‘induced pluripotent cells’ or iPS cells?

The generation of mouse iPS cells was reported in 2006 and the generation of human iPS cells at the end of 2007.

Typically, iPS cells are produced by inserting copies of three or four genes known to be important in embryonic stem cells using viruses into fully mature cells such as skin cells or immune cells. Different research groups have used slightly different combinations of genes and different methods to get them into the cell. It is not completely understood how each of these genes functions to confer Pluripotency and ongoing research is addressing this question.

iPS cells hold great promise for creating patient – and disease-specific cell lines - for research purposes. A great deal of work remains before these methods can be used to generate stem cells suitable for safe and effective therapies.

Can induced pluripotent cells replace research on embryonic stem cells?

At this stage, iPS cells cannot replace embryonic stem cells. Although the derivation of human iPS cells opens up exciting new areas of stem cell research, this technology is at a very early stage and many fundamental questions remain unanswered. While iPS cells and embryonic stem cells share many characteristics, they are not identical. The similarities and differences are still being explored. Furthermore, genetic manipulation of cells is required to generate iPS cells. The long-term consequences of this manipulation, in particular when transplanted into a patient, are unknown. For these reasons, it is essential that both embryonic stem cells and iPS cells are studied.

How are the induced pluripotent stem (iPS) cells produced?

Currently, iPS cells are produced by inserting copies of four stem cell-associated genes; Oct 3/4, Sox 2, Klf4, and c-Myc (or Oct 3/4, Sox 2, Nanog, and LIN28) into specialized cells using viral vectors. Shinya Yamanaka produced the first iPS cells from mouse cells in 2006. This was followed in 2007 by the generation of iPS cells from human somatic cells by both the Yamanaka lab and the lab of James Thomson.

What are the advantages of iPS cells over embryonic stem cells?

The advantage of iPS cells is that they are not derived from human embryos, which is the ethical concern in this field. By removing the bioethical issues, the scientists are more likely to obtain more federal funding and support. Another significant benefit of iPS cell technology would permit for creation of cell lines that are genetically tailored to a patient. This could eliminate the concern of immune rejection, where the body’s immune system identifies implanted cells or tissues as unknown and attacks them.

What are the risks associated with iPS cell use in humans?

The retroviruses used in the generation of iPSc are associated with cancer because they insert DNA anywhere in a cell's genome, which could potentially trigger the expression of cancer-causing genes. Another risk associated with iPS cell technology applied to humans is the fact that c-Myc, which is one of the genes used in reprogramming, is a known oncogene whose overexpression could also cause cancer.

How are iPS cells similar to ES cells?

iPS cells are similar to ES cells in morphology, teratoma formation, proliferation, as well as their ability to differentiate along a given lineage. They also express cell surface markers and genes that characterize ES cells.

Does iPS cell technology eliminate the need for embryonic stem cell research?

Recent advances do not eliminate the need for ES cell research since it is not yet quite clear whether iPS cells differ extensively from the embryonic stem cells. To bring stem cell research to clinical realization, it is necessary to investigate all the aspects in this field.

What are disease specific iPS cells?

Disease specific iPS cells are iPS cells generated from subjects with a genetic disease.

Which media should be used for culturing iPS cells?

The recipe for media for culturing iPS cells was acquired from WiCell MEF-based iPS Cell Culture Protocols. (Sigma Aldrich)

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