Induced Pluripotent Stem Cells (IPS)

IPS cells, which were created in 2007 by teams led by Professor Thomson and Professor Shinya Yamanaka, of Kyoto University in Japan, are made by manipulating adult skin tissue to give it versatile properties of embryonic stem (ES) cells.

These master cells can be grown into any type of tissue, offering a limitless source of specialised cells for use in research. There is hope that they may eventually be used to produce cell therapies for Parkinson’s disease, diabetes and paralysis. As IPS cells are made without destroying embryos, their use is ethically acceptable.

Powerful stem cells made by reprogramming adult tissue could reduce the need for animal testing of new drugs, according to a scientific pioneer of the technology.

Jamie Thomson, of the University of Wisconsin, told The Times that “in-vitro trials” based on so-called induced pluripotent stem (IPS) cells would refine pharmaceutical development so that fewer animal experiments would be required.

The cells were already being used as a source of human tissue for testing candidate drugs for safety and effectiveness, he said. As a result, fewer unworkable drugs would advance to animal studies, and some animal tests may become unnecessary.

“If what we are doing is successful it will dramatically reduce animal testing, and maybe towards the end of our lifespan actually eliminate it for some things,” Professor Thomson said. “I think we will have much better models for these things.”

IPS cells, which were created in 2007 by teams led by Professor Thomson and Professor Shinya Yamanaka, of Kyoto University in Japan, are made by manipulating adult skin tissue to give it versatile properties of embryonic stem (ES) cells.

These master cells can be grown into any type of tissue, offering a limitless source of specialised cells for use in research. There is hope that they may eventually be used to produce cell therapies for Parkinson’s disease, diabetes and paralysis. As IPS cells are made without destroying embryos, their use is ethically acceptable.

Cellular Dynamics, a company founded by Professor Thomson, is already using IPS cells to grow heart cells for pharmaceutical companies to use in the development of cardiac drugs.

Next year Cellular Dynamics will produce heart cells using IPS cells taken from people with particular ethnic backgrounds or genetic traits. Any candidate drugs that have damaging side-effects on cells with a particular genetic profile or on cells from people from certain ethnic groups could then be withdrawn, averting the failure of an expensive full-patient trial.

As much of this toxicity testing is currently performed in animals, there is great potential for reducing the number of animal experiments.

Human tissue grown from IPS cells may even provide a better laboratory model than animals, Professor Thomson said. “I trained as a veterinary pathologist, and the correlation [between results in animal and human trials] is not that great at the end of the day,” he said.

Professor Thomson said that the chief value of IPS cells would be as laboratory models for studying disease and testing drugs, rather than cell replacement. While it may prove possible to grow patient-specific spare-part tissue, which would not risk immune rejection, the costs are high.

“This gives us access to the basic building blocks of the human body,” he said. “We’ll learn a tremendous amount about the human body, and that will profoundly change human medicine.”

The master key

— Stem cells are master cells from which all types of human tissue are ultimately derived

— Induced pluripotent stem (IPS) cells, pictured, are made by genetically modifying skin cells. This turns them into an embryo-like state, allowing them to develop into any type of tissue.

— IPS cells are acceptable to some opponents of embryo research, and as they are grown from skin they can carry genetic characteristics.

— Adult stem cells are less powerful than IPS or embryonic stem cells, as they have already started to “specialise”. They can be used to make only a narrower range of tissue.

Source: Times Online Copyright 2010 Times Newspapers Ltd.(03/05/10)