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Human embryonic stem cells used to restore sight in two patients — our expert gives his view on the breakthrough

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In response to the use of embryonic stem cells to restore vision in two patients with macular degeneration, WideCells Group CSO Professor Peter Hollands provides insight into the history - and his personal experience of — this controversial branch of regenerative medicine:

Human embryonic stem cells

A recent report on the use of human embryonic stem cells to treat a damaged retina and restore vision is very encouraging.

Two patients, a man in his 80s and a woman in her 60s, received embryonic stem cell grafts to their eyes to treat age-related macular degeneration. The result has been the restoration of normal vision in these patients with no side effects. They can now see well enough to read. Further clinical trials are needed but the benefits to these two patients are clear.

Ethical concerns

In the early 1980s I was a Clinical Embryologist at Bourn Hall Clinic which was the first in vitro fertilisation clinic in the world. I was working under the supervision of Prof R.G. Edwards and Mr P.C. Steptoe who had created the first ‘test-tube’ baby in 1978. These were pioneering days and it was an honour to be part of the team bringing this new technology to the world.

Each day I would look down the microscope in the dimly lit laboratory and see human embryos growing and thriving. It was interesting to think that, at that time, I was one of the very few people in the world who had seen a living human embryo. When the team discussed our work we all agreed that within the embryos we were seeing there would be stem cells which would eventually develop into the fetus, the placenta and the membranes of pregnancy.

What we did not know at that stage was whether or not it would be possible to extract and manipulate these human embryonic stem cells. My PhD at Cambridge University had investigated the possibility of finding stem cells in early implantation mouse embryos. This work not only showed that stem cells were present but that they could be used to repair the bone marrow of other mice and even cure a genetic anaemia in a particular strain of mice.

The stage was set for the discovery and manipulation of embryonic stem cells but we also knew that such technology would bring much opposition. We had already faced severe opposition for the development of IVF from religious, ethical, legal and moral groups so taking this to the next step for embryonic stem cells would be a great challenge for those involved. My own interests moved away from embryonic stem cells to adult stem cells, such as bone marrow, cord blood, cord tissue, teeth and so on — and this has been my focus of attention ever since.

The ultimate stem cell

The crucial next step was the discovery of embryonic stem cells in mouse embryos by Martin Evans in 1981 and the subsequent discovery of human embryonic stem cells by James Thomson in 1998.

Human embryonic stem cells were then hailed as the ultimate stem cell which could in theory treat any disease. There was much media hype at this time which sometimes resulted in other stem cell types being ignored.

It soon became clear, however, that there was much opposition to the creation and use of embryonic stem cells because to create human embryonic stem cells it is necessary to take a group of cells called the inner cell mass from a developing embryo and grow these cells on in the laboratory. This process of extracting the inner cell mass results in the destruction of the embryo and this destruction of a human embryo to obtain stem cells was deemed unacceptable by many people.

The source of the human embryos to develop human embryonic stem cells has also been a subject of great debate. At present ‘unwanted’ frozen embryos at IVF clinics are donated by the parents so that they can be used to extract human embryonic stem cells. This is clearly a limited source compared to adult stem cell technology such as umbilical cord blood which can be collected at every birth with no side effects or ethical objections.

New technology

Despite these problems scientists continued to develop embryonic stem cell technology and slowly began to understand the properties of human embryonic stem cells. One of the concerns was that human embryonic stem cell may form tumours when grafted into recipient patients and these concerns have not yet been fully resolved.

Fast forward to today and human embryonic stem cells have now been developed to the point where they can be frozen and used as and when required. The nature of human embryonic stem cells is that they can, in theory, produce any tissue type in the body which gives them great theoretical potential in regenerative medicine technology.

It is essential that we all keep an open mind about stem cell technology and the potential it has to drive regenerative medicine procedures in the future.

My opinion is that we will find that certain stem cells are good at treating certain diseases in a similar way that we have found that certain medication is good for certain diseases. I have no doubt that embryonic stem cells will play an important role in these technologies but only alongside the many other stem cell types which are being discovered.

Stem cell-based regenerative medicine could become routine in the future and even replace standard pharmaceutical medication for many diseases and types of trauma.

By Professor Peter Hollands, Group Chief Scientific Officer at WideCells

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