Mike Ko Personal Portfolio

 

Home-School Education
2001-2012
Hong Kong

University of Durham
Bachelor of Science
2014-2017
United Kingdom

University of Sussex

Master of Arts
2017-2018
United Kingdom



Writing - Original

On the Matter of Stem Cells

 

                                       

 

                        In the distant past, people can easily die from flu and even simple injuries like a small cut can potentially be fatal. Those were the times when we were at the mercy of bacteria and viruses, and hampered by our ignorance. But all of that changed in the last century or so, as our knowledge of Biology, Medicine, and Physiology accumulated. We can now actively look for cures for specific diseases and heal serious injuries, all because of our knowledge on our body and medicine. It is quite different now than, say, our grandparents’ time.

                        Despite the progress that we have made, there are still certain ailments to which there is little that we can do about. One of them is spinal cord injuries. As the name suggests, it involves damaged cells in the spinal cord. To be specific, it is the nerve cells in the spine. Most nerve signals that goes from our brain to other parts of our bodies all pass through the spinal cord. When nerve cells in the cord are damaged, connections between the brain and certain parts of our body are either weakened or broken completely, which means that certain portions are cut off from brain signals and at the same time are unable to send feedback to the brain. That is why certain people who have spinal cord injuries have reduced mobility (the legs, for example). And we have no effective treatment for such injuries, mainly because spinal nerve cells, unlike most cells in the body, do not regenerate.

                        But that may soon change. In the last decade or so, science has found a possible solution, one that, if we can properly manipulate its capabilities, promises to be much more than a new and effective treatment for spinal cord injuries. And what exactly is this new solution that has excited so many scientists around the world? They are called Stem Cells. They are the subject of intense research and debate, have created excitement amongst scientists, and encountered opposition from various groups. In the following, we will look into what stem cells are, their functions, the benefits they can potentially yield, and why it has encountered major ethical problems.

What are Stem Cells?

                        Stem cells are not a new invention. In fact, all multi-cell organisms on earth have stem cells. But that does not mean they are unremarkable. If you take a look at the early embryonic development of humans, you can see an example of stem cells, with which we can answer the question: What exactly are stem cells?

                        Let’s start from the embryonic development that begins with the fusion of an egg and a sperm, which then becomes a zygote, a fertilized egg. In the next few days, it will start to divide, becoming a ball of multiple but identical cells. The zygote has now become an embryo. After about a week, the embryo will have divided into a lot of identical cells and arranged itself into a ball of cells with a liquid-filled interior cavity. Such a structure is called a blastocyst (for all animals it’s called a blastula), and it is in this stage in embryonic development that things start to become interesting.

                        Inside the blastocyst, between the cells and the liquid, there is a group of special cells called inner cell mass. These cells, which are different when compared to those that make up most of the blastocyst, play an important role in development. Until now, our blastocyst is composed of identical cells. But then we will begin to see many different cell types emerging, cells of our organs, brain, skin, etc. Where did all these cells come from? The inner cell mass.

                        What makes the inner cell mass so special is because unlike most cells, they are able to differentiate, the ability of a cell to give rise to other types of cell (normal cells only produces identical copies of themselves). In this case, the inner cell mass can turn into any type of cell present in our body as well as their own. This degree of differentiation ability is defined as pluripotency. Hence multi-cell organisms, including humans, have their organs, other complex structures, and everything else that make up their bodies today because they have inner cell mass. They are what allow organisms to grow from a blastula into a multi-cell type individual. Obviously, inner cell mass are quite important in multi-cell organisms' development.

                        But what does all of this have to do with stem cells? You might have heard of the term ‘embryonic stem cells’, probably from the news or from disgruntled religious groups. You might also have some vague ideas about their medical potential, but most of us have little or no idea as to what exactly embryonic stem cells are. The answer becomes clear when you consider our source of embryonic stem cells: embryos. The procedure for getting embryonic stem cells involves reaching into the embryo and retrieving a group of cells that we call inner cell mass. Yes, what we refer to as embryonic stem cells are just isolated inner cell mass.

                        There are two main reasons why we define inner cell mass as stem cells. One is because they can differentiate, and the other is their ability to reproduce by dividing while keeping their undifferentiated state at the same time.

                        As we understand the definitions of stem cells, their medical potential becomes apparent. Imagine if we can find a way to coax stem cells to differentiate into a particular kind of cell. We would then be able to grow a whole variety of human cells, which could be used for various purposes, ranging from replacing injured cells to giving us a better look at animal development. The potential of stem cells, medical or otherwise, can yield great benefits for society. Scientists, however, still have a long way to go before those benefits can be fully realized. Apart from the technical challenges, there are also major ethical implications that have caused public concern on the use of embryonic stem cells, which has prompted a change of focus from those cells to other stem cell varieties in research. We will get to know these varieties later, but now we shall return to embryonic stem cells, the type of stem cell that has been surrounded by controversy.

The Causes of Controversy

                        Embryonic stem cells (which from now I will abbreviate to ES cells), being the first type of stem cells discovered, has provided us most of our knowledge on stem cells. The more we knew about its nature, the more it seemed to be a vital key to solving a range of mankind’s medical woes. However, a glaring problem arose before scientists could initiate large-scale research on ES cells. And it was a problem that scientists could not solve alone. In the following we shall take a look at that problem, one that has stalled or at least discouraged most ES cell research around the world, and shall affect the value that society places on a human individual.

                        To obtain animal ES cells, we need to isolate the inner cell mass of an embryo. However, when the embryo is deprived of its inner cell mass, it loses its ability to generate the different cell types that it needs to build a body, and as a result the embryo dies. What is implied here is that if we destroy a mouse embryo, we would have prevented a baby mouse from coming into being, which is what the embryo would develop into had it been implanted into a female mouse's uterus. That seems to be fine for a mouse or, for that matter, any other animal. But when it comes to human embryos, it becomes an entirely different matter. When we destroy a human embryo, we prevent a human from coming into being. This would immediately become a problem, for it would seem that in order to obtain ES cells we will have to kill a human individual; scientists’ pursuit of knowledge and possible cures will have to come by at the expense of future individuals' lives.

                        This is only what the situation seems to be, however, because embryos are not individuals or persons. They are just a ball of cells, although one with the potential to develop into a person. So, should society consider the termination of an embryo to be equivalent to human murder? Or should we just take it as just another type of human cell that scientists would like to study and experiment with? How much value should we give to the embryo's potential to transform into individuals? And what should we expect to get from a better understanding of the mechanisms of ES cells? These are some of the questions that underlie the problems that ES cells poses to society, one that we have no solutions to today. It is a situation that, as we shall see now, is very likely to persist for years to come.

                        I do not have any particularly feasible solutions to propose, and I suspect that no one yet on the planet does. ES cells has over time become a major source of frustration to many people – including scientists, people with religious beliefs, and perhaps even government officials (at least for those tasked with attending the hearings on the matter), and even after years worth of debate and hearings no one seems to have any satisfactory solutions. Our apparent inability to find a solution on the issue, in my opinion, can be attributed to the following factors.

                        The first factor is due to the dual-identity of the embryo. By dual-identity I am referring to the fact that embryos can develop in about ten months from a ball of cells to a fully grown baby individual, and so has the identity of cells at one time and that of an individual at another. This is the main reason why we have problems with using embryos as a source of ES cells: we seem to have two definitions for the embryo. And this causes problems when we try to determine whether it is ethical to destroy embryos. Are we killing a ball of cells (as scientists might do with other cell types) or are we murdering an individual? What identity of the embryo should we consider when we ask such questions about the ethics of ES cell usage? In short, we do not even have a stable footing on our definition of the embryo against which we could judge whether killing embryos poses ethical problems. And without a clear definition, we can’t even start to consider whether it is wrong to destroy embryos. As such, it will be very difficult for society to adopt any particular stance on the matter. That is one of our main problems with ES cells.

                        In contrast, there are no such ethical uncertainties when we consider cells or individuals. Suppose that scientists would want to experiment with (or kill), say, a ball of liver cells (not embryonic cells, but human liver cells). Would they encounter problems? Probably not, at least not from an ethical standpoint. Human cells, ultimately, are not defined as individuals; rather, they are part of an individual. So scientists working on human cells do not encounter any ethical problems. Experiments on individuals or persons, however, would be an entirely different matter. Most of such experiments have a very high chance of violating the subject’s human rights or our ethical values, and as such are highly limited by either the scientists’ own moral values or the laws of their country. Our ethical standpoints for these two cases of experiments are clear-cut, unlike the case of ES cells.

                        The second factor is our apparent bond to embryos. All of us have been embryos for a short time. Every human individual first started out as a zygote and then a developing embryo. Without embryos, we wouldn’t exist. This can sometimes reinforce the impression that an embryo can be taken as individuals, perhaps similar to how hopeful parents may look upon their embryos as babies. Furthermore, the outcome of the whole issue has the potential to alter how society values an ‘individual’, to alter our ‘human identity”. Inevitably, these social aspects are going to play a large part in the debates to come.

                        The third and final reason that I’ll give here is religion. Religion has been an integral part of human culture, from simple, tribal god-worshipping rituals to well-developed ones like Christianity and Islam. Most of them are opposed to ES cell research, stating that embryos should be taken as individuals and as such should not be denied a life. And if that’s the view of most religions (or the view of their leaders, at least), then it shall be the view of most of their followers; a sizable portion of our population.

                        These factors, as well as many others, are the reasons why society has failed to find any solutions so far, with difficulties in determining whether it is ethical to kill embryos and indeed the definition of the embryo itself, along with the social and cultural aspects that have to be considered. As debate on the issue continues, scientists, whatever their underlying reason, would be either unwilling or unable to work on ES cells. As such they have begun to look for alternatives.

Adult Stem Cells

                        One such alternative came in the form of adult stem cells. Adult stem cells are cells in our bodies which are undifferentiated, and can then give rise to certain types of cells. They are what allow our bodies to grow and maintain themselves. Each kind of adult stem cells can give rise to a number of different cells; skin adult stem cells can differentiate into the cells that exist in our skin structure, just as adult stem cells in the heart can maintain the valves or the muscles in the organ. And adult stem cells do so over our entire lives.

                        Unlike ES cells however, adult stem cells do not raise any ethical issues because it comes directly from adults. To get adult stem cells, all we have to do is to isolate a few from a person as we would with other cells, with no particular harmful effects. Work is being done now so that we can understand more of its properties, so we can properly manipulate them. However, because adult stem cells can only differentiate into a limited number of cells, it also makes it less useful when compared with ES cells, which can differentiate into all the cell types of the human body. Also, adult stem cells do not multiply much when isolated, so scientists have to find better ways to grow them outside of their natural environment. Although we have adult stem cells as a possible alternative to ES cells, scientists have also found another one in recent years, one that is pluripotent.

Induced Pluripotent Stem Cells (iPSCs)

                        That alternative is called Induced Pluripotent Stem Cells (iPSCs), and it is currently another subject of research by scientists. IPSCs do not involve embryos; rather, scientists induce a normal cell to revert back to an undifferentiated, pluripotent state, hence its name. So how exactly do we induce a normal cell to revert back to a more or less embryonic state? Scientists discovered that it was possible to do so simply by inserting several specific genes (stretches of DNA) into the cell’s genome (its complete collection of DNA). Doing so seems to reprogram the cell, which then exhibits ES cell-like properties.

                        iPSCs are a relatively new innovation; the first successful cases of the creation of human iPSCs were in 2007, by scientists in the US and Japan simultaneously. Researchers, however, are already paying significant interest to these cells. This is understandable; iPSCs are almost perfect candidates for their work when compared to other stem cells, as it does not involve destroying embryos and are pluripotent.

                        There is a great deal of excitement surrounding the notion that cell therapy and newly grown organs are going to be feasible in the near future. But there are also some concerns on iPSCs that we’re going to have to resolve before such potentials can be realized. For example, scientists must ensure that they can properly and reliably manipulate iPSCs to develop into particular cell types, otherwise certain reverted cells might become stuck in its undifferentiated state and so will continuously divide. Such indefinite divisions can create a teratoma, a benign tumor of human stem cells, which in effect makes them cancer cells. Scientists must also test for any differences between the pluripotency of ES cells and iPSCs.

                        Still, even though they might not be ready as cures yet, iPSCs are already used by scientists for various purposes. Apart from being the subject of research, iPSCs are utilized to create diseased tissues in vitro, like those found in patients with Parkinson’s disease or Alzheimer’s disease, just to name a few. By creating samples of these diseased tissues, researchers can readily observe the behavior of these cells, and hence devise effective treatments to combat the disease. From all of this, you can see that iPSCs has been a great breakthrough in science, and it is going to be the center of attention in stem cell research for years to come.

Potential Uses

                        In this last section I’m going to briefly describe the problems that stem cells have the potential of solving. What are scientists hoping to achieve from their work? I have, at the beginning, mentioned about injured spinal cords. Yet with stem cells, you can literally grow every part of your body, be it an organ, a patch of skin, or new spinal nerve cells. As such, patients who need new organs would simply have new ones grown for them, instead of requiring a transplant from somebody else. If such organs are grown from iPSCs, then they would not have any incompatibilities with the patient’s immune system, since the organs' cells were originally the patient’s own cells. They would be genetically identical to the patient’s DNA. Certain conditions or injuries where irreplaceable cells like brain cells or spinal nerve cells are damaged might also be cured by growing new ones, which can cure genetic neurological disorders like Parkinson’s disease.

                        We can also use stem cells to grow reserves of red blood cells of all types, thus solving our current shortage of them. These are just some examples of the possibilities that stem cells can offer us, and their potential does not stop there. As such, I think we should all be thankful to the discoverers of embryonic stem cells and iPSCs respectively, the former for introducing stem cells to humanity, the latter for allowing us to get around the ethical problems of ES cells – which I don’t think is going to be solved any time soon – by introducing iPSCs to us.


                                                                                                                                                                  Mike Ko
                                                                                                                                                                  ( 3,140 words )

 

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