by Dr. Y.L.M
I have been hearing so much about stem cells from billboards, newspaper reports and talk shows discussing about the ethics of it all. I am not quite sure I understand the concept of stem cells.
Stem cells are cells from humans and animals (and yes, all of us have them) that are unspecialised. This means they have not yet been differentiated within the body to perform a specific function. For example, our red blood cells are specialised to carry oxygen, our brain cells are specialised to govern our body's workings and our reproductive cells are specialised to reproduce.
But a stem cell has not been differentiated yet to become a specific cell that performs any of these highly specialised functions, which makes their capacity tremendous. Only recently have scientists understood their potential in the treatment of disease and healing.
You see, stem cells have three very important properties :
* They can divide and replicate many times. They are capable of long-term cell renewal.
* They are yet unspecialised, as mentioned before.
* They can develop into any type of cell that you need in your body, and can be induced to develop into what is needed. Stem cells are often described as a 'blank microchip' in which you can programme what you need.
In 1998, scientists discovered a method to harvest human stem cells from test tube human embryos.
Is it true that only babies have stem cells?
There are two types of stem cells. Embryonic stem cells (from a 3- to 5-day old embryo) basically consist of stem cells which will divide and later differentiate into functional cells that will form the organs and system of the body.
Adult stem cells still exist in adults even though most of your body's cells are already specialised, especially in areas where high growth and regeneration is needed, such as your bone marrow, skin, gut or your reproductive cells (eggs, sperm). And stem cells from one type of tissue, for example your bone marrow, can give rise to cells of a totally different tissue, for example your nerves. This is a phenomenon known as plasticity.
For harvesting purposes, adult stem cells are usually harvested from your bone marrow or your blood stream.
So the furore over the use of stem cells is mainly due to the fact embryonic stem cells have been harvested and used?
Yes. The process involved is as follows :
The embryos are cultivated in a test tube by in-vitro fertilisation. The donors of the sperm and the egg have completely given their consent. Then the embryo is grown on a culture dish.
It is the inner cell mass of the embryo that is desired, so these are allowed to divide, multiply and when they crowd out a dish, they are transferred to another dish. After 6 months or so, an original cell mass of 30 cells may have proliferated to millions of embryonic stem cells. This is called an embryonic stem cell line.
Batches of embryonic cells can be frozen and shipped to other labs.
The ethical furore of course is over whether or not embryos should be used for these purposes, because some people deem a 5 day embryo to have a life of its own.
Moreover, an embryo is meant to differentiate into a human being – and by stopping and cultivating its differentiation, test tube or not, you are deemed to be stopping a human life from developing on its own and channelling it to develop into something grotesque, without mass or form.
It is, in part, like the ethical issue over abortion.
What can stem cells be used for?
There is much scientists do not know yet. However, stem cells can theoretically offer a renewable source of replacement cells to treat diseases such as Parkinson's (a renewable source of dopamine producing cells), Alzheimer's, spinal cord injuries (where nerve cells can be regenerated), burns (where skin grafts can be regenerated), strokes (brain cells), heart diseases (cardiac muscle and lining cells), diabetes (insulin producing cells in a person's pancreas that has been partially destroyed by antibodies, which give rise to type 1 diabetes mellitus), osteoarthritis and rheumatoid arthritis (bone cartilage cells and even bone cells which have been destroyed) and blindness (where retinal cells can be grown to repopulate a destroyed retina).
In the future, perhaps research will enable us to treat cancer, grow new limbs and grow new organs to replace the ones that have been destroyed.
Already, the stem cells of the bone marrow can be used to seed an 'empty' bone marrow which has been destroyed by cancer (leukemia) or chemotherapy. This is the basis of bone marrow transplant.
In Malaysia, there is a stem cell laboratory where you can harvest your cells and use them to treat diseases like diabetic ulcers and thalassemia.
Of course, bone marrow transplant has been going on in many centres already for many years. You can also bank in your baby's cord blood (which contains stem cells) so it can be used in the future.
More info on STEM CELLS here.
by Dr. Y.L.M