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Throughout this presentation, I will give you an overview of stem cell science, as well as a primer on the structures and functions of human stem cells and tissues. I will provide you with the basic information required to know how and why stem cell researchers do what they do in the lab and break down the apparently unique properties of various stem cells and why they inspire so much hope for treating or curing so many devastating illnesses. Because the field of stem cell research has received so many headlines in recent years, it is easy to be fooled into thinking that stem cell research is a new concept. But this research is founded upon decades of investigation and discoveries regarding how and why living organisms work. It is my strong opinion ladies and gentlemen, that a great deal of research must go into the development and use of embryonic stem cells so as to alleviate and destroy the damaging and fatal effects of so many devastating illnesses.
HISTORY OF RESEARCH
Human stem cell research is a comparatively young scientific field, which can be argued as dating back to as recently as 1998. However, the term 'stem cell' has only been in general usage for the past 10 years or so and the concept of this research is still, for most people, a foreign and sometimes frightening endeavour. It was interesting to discover, that everything we know today about stem cells, was founded upon hundreds of years of observations, research and experimentation into the biology of a large array of organisms. Scientists knew, ladies and gentlemen, that blood contained several different types of cells, and they often discussed what properties stem cells would need to generate all of these cells. Concrete proof of the existence of stem cells was not discovered until the late 1960's. Two scientists by the name of James Till and Ernest McCulloch were the first to find and record the evidence that a solitary cell extracted from bone marrow had the ability to make copies of itself, furthermore, copies of multiple types of blood cells. These men defined the modern meaning of stem cells. Many scientists since then have managed to isolate human stem cells in skin, neurons and several other tissues.
ASPECTS OF BIOLOGY
It is difficult to believe ladies and gentlemen, that a minute scrap of matter, so tiny that it is impossible to observe with the naked eye, has the capability to change the entire world. Furthermore, the promise and potential of this piece of matter, the human stem cell, is greater than anything the scientific community has ever come across. Perhaps no other scientific field has such a dramatic potential to alleviate large amounts of human suffering. Many of our biggest killers could be stopped in their tracks by expanding on this research, kidney disease a thing of the past, heart disease conquered, and permanent brain damage healed entirely. Stem cells are seen to be as essential and unique as they are, due to two highly distinctive qualities. Firstly, they are able to give rise to more highly specialized cells in the human body, especially when it comes to embryonic stem cells. Secondly, they can renew themselves and this provides them with the ability to develop an a laboratory environment for extended periods without the possibility of their capacity to give rise to other cells depleting.
In human beings, after conception has occurred, the ensuing cells begin to lose their ability to regenerate and develop into brand new tissue as the foetus grows. Although the adult body continues to contain a little, but essential amount of stem cells, they have nowhere near the diversity or functionality as embryonic stem cells. Stem cells are often described as being the basis of human development. This is an accurate statement as they are essentially the metaphorical tree trunk of the body. This trunk can be seen as eventually developing into the branches and leaves of the tree, that in reality are the large variety of complex body cells and tissues. Embryonic stem cells donââ‚¬â„¢t technically exist in embryos. Normally, throughout the course of development, the blastocyst fuses with the uterine wall. It is at this vital stage that the inner cell mass amazingly begins to grow and develop to form all the cells that the mature body consists of. They are capable of doing this, not because they simply duplicate and make copies of themselves, but due to their production of daughter cells. These are cells that create cells comprised of structures and features that are required to perform highly specialised tasks. Cells that are derived from the stem cells include blood, brain, heart tissue, nerve cells, bones and the list goes on. Once the child is born, there are no body cells that scientists know of that have the capability to precisely mimic the original stem cells and their functions.
Ladies and gentlemen, I would like to introduce you to the idea that not all stem cells are created equal. The factor that separates the slightly useful stem cells from ones that are able to produce fantastic results is the degree of 'developmental plasticity'. The amount of plasticity that a cell is able to maintain is categorised by a number of different names, the most common of those being pluripotency. Just as with molten glass fresh out of the furnace, the level of plasticity decreases quickly as it ages. Glassblowers can shape and blow an object to create the final form, but there is a definite point when the basic structure is irrevocably fixed. The same principle is in place when it comes to human stem cells, as time rapidly reduces their flexibility. The different stages of cellular plasticity have different categorizations. Stem cells are specialised and have no structure, due These categories assist scientists and researchers in defining exactly what they are looking for and the extent of application that they intend on wringing out of the cells they are working with. The first type are totipotent stem cells. These are formed when an egg and sperm become a zygote and these eventually differentiate to become all cells in an animal or human body. Secondly, pluripotent stem cells can become any cell, but cannot give rise to an entire organism. Thirdly, multipotent stem cells can become several types of cells within an organ or tissue, for example, blood or skin cells. This type of stem cell can be found in both adults and embryos. They can be further specialised in olgiopotent, these cells can only differentiate to form a few types of body cells. Quadripotent stem cells can only specialise into, as suggested by the name, four cell types. Just like unipotent can only become one cell type. Nullipotent is a totally specialised cell, for example, a white blood cell.
Doctors have been utilising the amazing and unique properties of stem cells for years to treat things such as leukaemia and burns. Researchers are currently testing potential therapies for many other diseases such as, spinal cord injury, heart disease and diabetes. However, the biggest challenge they are yet to overcome, is producing the treatments they aspire to, while ensuring that they are both safe and effective.
I am sure you have seen ladies and gentlemen, newspapers and magazine articles containing headings such as;
"Placenta-Derived Stem Cells Show Promise in Treating Lung Disease."
"Stem Cell Hope for Cerebral Palsy Patients."
"Stem Cells Could Boost Dementia Hopes."
These types of headlines can be both confusing and encouraging. The media is reporting exciting news of fundamental breakthroughs in stem cell therapies on a daily basis, sky rocketing the hopes for patients with diseases that have showed no sign of improvement after all avenues of treatment and effort have been exhausted. This is not the case however. Ladies and gentlemen, may I ask you to imagine, as hard as it may be, that your son, your daughter, your husband, or your wife, was involved in a tragic accident and now has a spinal cord injury. Their only hope is a form of one of these supposed breakthroughs in stem cell treatments. Just try obtaining access to one of these treatments, a last hope perhaps, and it suddenly seems as though no such treatment is available.
The only real stem cell treatments that work well and in saying that, by 'work well' I mean treatments with any degree of certainty and amount of evidence to conclude that the likely benefit to the patient outweighs the risk, are mostly limited to diseases involving blood disorders.
One such disease that a vast majority of you would have heard of ladies and gentlemen, is leukaemia. Leukaemia is a disease that causes the patient's body to produce more white blood cells than are needed at a much higher that that is normal. As the disease progresses, these out of control cells begin invading and disrupting the functions of other tissues, inclusive of the production of other blood cells. Bone marrow transplants are quite effective when it comes to treating this disease but the procedure as a whole is a tough experience for the patient. Doctors initially make use of chemotherapy or radiation therapy to eliminate as many of the leukaemia cells as possible. They then perform a bone marrow transplant to access and inject blood that is enriched with blood forming stem cells. When a good donor match is found, this treatment is almost always curative. Some researchers
NO. OF DAYS
Under 3 Days
3 ââ‚¬" 14 Days
Over 14 Days
NO. OF CELLS
1 - 16
Up to several 100
Are made from cells that exist only in embryos that are in the early stages of development.
Are found in, or near tissue.
Can give rise to all cells in the body, inclusive of all non-regenerative types.
Can give rise to any functional cells in their tissue.
Can be divided numerous, (possibly infinite) times in culture.
Usually only found in tissues that regularly turnover.
As they mature, their capability to multiply and function decreases.