Farouq Manji examines the controversial potential of stem cells.
The complex nature of stem cells is analogous to a community of workers. Each person has a role in the community; there are lawyers, landscapers and desperate housewives, all doing their jobs correctly. But when something goes wrong, for instance your dentist is hit by a bus, what do you do? You can’t replace her with the engineer. They are far too different. The only plausible scenario is to grab a youngster, and sternly tell them “Young lady, you’re going to be a dentist when you grow up.”
Now consider your own body. There are many different ‘professionals’: the nerve cells in your brain, blood cells in your bones, skin cells, and of course mad X-Box cells. Each one might need to be replaced at some point, at which time a stem cell – would ‘train’ to take over.
The only problem is, sometimes there are no stem cells available to replace the dying professional ones. For example, nerves have no stem cells, and neither does heart tissue. So how do you replace the lost stem cells?
A number of scenarios could play out. Stems cells could be taken from another region and attempts could be made to integrate these cells with the part of the body that needs them. This is akin to what occurs in a heart transplant.
This might work, but chances are the cells wont integrate with the other established cells in that area, clashing with the body’s immune system. This is exactly what happens when organ transplants are rejected.
Sometimes certain tissues lack stem cells, and therefore cannot be repaired once damaged. It is difficult in general to find organs for transplant, especially ones that won’t be rejected. A natural problem presents itself when an injury occurs after a heart attack when there are no appropriate stem cells to amend the injury.
From what it appears, science has not yet found ways to change established adult stem cells into different tissues. Normally, once stem cells have chosen a tissue type, they are exceedingly stubborn and will not be malleable.
However, a recently discovered method involving the removal of abundant stem cells from blood, and transforming them into nerve cells has highlighted new departure for this science. This is especially useful in neurodegenerative diseases such as multiple sclerosis, which destroys brain tissue and debilitates patients.
Currently this procedure uses autologous transplants – that is – stem cells from an individual are used in their own body. Using this method avoids the host body rejecting the new stem cells – since they are simply returning to their source. These procedures are still experimental, yet they show enormous promise.
Another option could involve implanting stem cells. Under these circumstances, the new cells could potentially become anything you wanted. As they are young and, as yet, undefined cells, they would not trigger an immune reaction – and therefore there would be no rejection.
These undefined cells need to be obtained from somewhere. Where these cells can be derived from is a matter of much controversy and debate. The most commonly propounded option is to obtain the cells from unused human embryos.
When a sperm and ovum combine, they create a single cell which then divides. The daughter cells divide again, and so on, until the entire human body is formed. As these cells split, they slowly become the different types of tissue that compose our body. After the first few divisions however, each cell still has the potential to become anything.
During the process of in -vitro fertilisation, numerous unions of male and female cells are created and grown so that there are several embryos to choose from, and then the most viable ones are inserted into the mother’s uterus.
And the unviable, unused ones? In countries that have permissive legislature, it is these embryos that are utilised as a source for stem cells.
The use of embryonic stem cells in this way is currently embroiled in controversy. Opponents argue that all embryos, even those destined to be discarded, should not be used for such experiments. Supporters argue that these stem cells carry incredible scientific potential and should be used – especially in light of their disuse.
As a result of this disagreement various countries maintain different policies – Canada permits embryonic research, whereas the United States does not. In the EU, only three member states allow the use of embryonic stem cells – and Ireland is not one of them.
Other countries have even gone so far as to allow scientists to clone their own embryos solely for the use of research. Australia, the UK and Belgium are a few nations which have permissive laws that give scientists such leeway. The result is that research in these countries has far surpassed that which other countries have produced.
Still, it has been put forward that countries that do not permit the use of stem cells have also been able to make promising contributions to science.
Scientists in Harvard University have developed ways of cloning and developing new stem cell lines without using embryos, instead using skin cells.
They warn that the technology may take up to ten years to perfect, however instead of being limited by US legislature, their creative breakthrough circumvents the problem completely.
Stem cells have been implicated in other areas of medicine as well. It is now a common belief that fast-growing cancers are stem cells gone bad.
This postulation would explain why many cancers so readily regenerate after anti-cancer therapy – and researchers are now using this knowledge to develop novel treatments. A more thorough understanding of stem cells may lead to better ways of stopping tumours.
Like many pre-pubescent prodigies, embryonic stem cells have proven difficult to deal with. Theoretically they carry enormous promise, however they are complicated and still barely understood.
Beleaguered by differing international laws, development in the stem cell field has been sporadic and limited by the lack of international co-operation. Their medical uses are just being unlocked, but they are youngsters with boundless potential, and it will take time and resources to coax them into successful, effective members of your working community.