Research updates
Stem cells & therapeutic cloning   page 5
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4. The potential benefits of stem cell work    Link to the Medical Research Council web site
 
Professor Julia Polak (Figure 1) regularly gets interviewed by the media. Partly this is because of her research. She directs the Tissue Engineering Centre at The Hammersmith Hospital. Her work involves using stem cells in a search for medical breakthroughs that will help various categories of people including those who need transplants. But partly she gets interviewed because she herself is a remarkable survivor of a major transplant.
Figure 1 (from page 1). Julia Polak.
Remarkable coincidence
Back in 1995 Julia Polak was close to death. Thankfully, for her, in July of that year she was given a heart and lung transplant. The operation proved a complete success. She has made a full recovery and her life and work continue. The story is all the more remarkable because the condition from which she suffered, pulmonary hypertension, was one that she had spent years researching. Indeed, the surgeon who carried out the five and half hour transplant operation, Professor Sir Magdi Yacoub, was and still is a friend and colleague of hers.
Who works at the Tissue Engineering centre?
Julia Polak's Centre is a multi-disciplinary team with specialists in:
  • embryology
  • cell biology
  • molecular biology
  • transplant biology
  • gene expression
  • gene therapy
  • immunology
  • histochemistry
  • bioactive materials
  • extracellular matrices
  • orthopaedics
  • cardiovascular surgery
  • liver science
  • imaging
  • minimally invasive micro-surgery.
Using stem cells
One way in which stem cells may soon be used in this sort of work is shown in Figure 6. Pluripotent stem cells would be isolated from so-called 'spare' embryos produced during in vitro fertilisation. Most embryos produced by clinics that carry out in vitro fertilisation end up being put into women in the hope of enabling infertile couples to have children. However, the drugs used to get women to superovulate tend to mean that more eggs are produced than are needed. It is these eggs which, once fertilised, could be used to produce stem cells.
Figure 6. Possible way in which pluripotent stem cells obtained from the blastocysts of 'spare' in vitro fertilisation embryos could be used to treat a wide range of medical conditions.

Step 1: The 'spare' eggs are fertilised in vitro. In the laboratory, these embryos would be allowed to grow to form blastocysts. This takes about 5 days.

Step 2: Stem cells would be isolated from each embryo and the rest of the embryo destroyed.

Step 3: The stem cells would then be cultured and, it is hoped, develop into tissues that could be used for transplantation.

What are the problems?
One problem with this approach is that even if the scientists manage to get the stem cells to develop into the right sort of tissue, that tissue might end up getting rejected by the immune system of the person given the transplant.
Overcoming this problem
There are several ways in which it is hoped to get round this problem of transplant rejection.
  1. Tissue typing
  2. Drugs to prevent rejection
  3. Therapeutic cloning

You can find out more about these on the next page.

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    Question 4
    To which blood group(s) can blood from a person who is blood group A be safely given? Explain your answer.

    To find out more about blood groups and tranfusions, have a look at 'Engineering antibodies'. You can try the question on that page as well.