Shinya Yamanaka MD, PhD

Here are answers to frequently asked questions about induced pluripotent stem cells, or iPS cells, the type of cell that has been reprogrammed from an adult cell, such as a skin or blood cell.

What are induced pluripotent stem cells?

Induced pluripotent stem cells, or iPS cells, are a type of cell that has been reprogrammed from an adult cell, such as a skin or blood cell. iPS cells are pluripotent cells because, like embryonic stem cells, they can develop into virtually any type of cell. iPS cells are distinct from embryonic stem cells, however, because they are derived from adult tissue, rather than from embryos. iPS cells are also distinct from adult stem cells, which naturally occur in small numbers in thehuman body.

In 2006, Shinya Yamanaka developed the method for inducing skin cells from mice into becoming like pluripotent stem cells and called them iPS cells. In 2007, Yamanaka did the same with adult human skin cells.

Yamanakas experiments revealed that adult skin cells, when treated with four pieces of DNA (now called the Yamanaka factors), can induce skin cells to revert back to their pluripotent state. His discovery has since led to a variety of methods for reprogramming adult cells into stem cells that can become virtually any cell type such as a beating heart cell or a neuron that can transmit chemical signals in the brain. This allows researchers to create patient-specific celllines that can be studied and used in everything from drug therapies to regenerative medicine.

How are iPS cells different from embryonic stem cells?

iPS cells are a promising alternative to embryonic stem cells. Embryonic stem cells hold tremendous potential for regenerative medicine, in which damaged organs and tissues could be replaced or repaired. But the use of embryonic stem cells has long been controversial. iPS cells hold the same sort of promise but avoid controversy because they do not require the destruction of human embryos. Nor do they require the harvesting of adult stem cells. Rather, they simply require a small tissue sample from a living human.

Why is iPS cell technology so important?

In addition to avoiding the controversial use of embryonic stem cells, iPS cell technology also represents an entirely new platform for fundamental studies of human disease. Rather than using models made in yeast, flies or mice for disease research, iPS cell technology allows human stem cells to be created from patients with a specific disease. As a result, the iPS cells contain a complete set of the genes that resulted in that disease and thus represent the potential of a farsuperior human model for studying disease and testing new drugs and treatments. In the future, iPS cells could be used in a Petri dish to test both drug safety andefficacy for an individual patient.

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Stem Cell Science Q & A