STEM CELLS AND CLONING: FACT AND FICTION - YOU BE THE JUDGE. Part II of II Dr. R. Rajaraman Adult Stem Cells: Another kind of stem cells often called adult stem cells can be obtained from different tissues or organs such as skin, brain, kidney, liver, bone marrow, or blood. This is because, even after the birth and growth of an individual, a pool of resident 'adult' stem cells (are these the residual original embryonic stem cells?) is maintained in many adult tissues. The adult stem cells can give rise to various cell types of that specific organ, from which the stem cells have been obtained. In some instances they have been shown to undergo transdifferentiation into cell types of other tissues; in other words, they can produce cells of a different tissue other than the one from which the stem cells were isolated. (For example, a cell on the way to become a bone cell may change is mind halfway and become a muscle cell, provided if it receives the right signals.) Thus, it is believed that during the development of the embryo, the differentiation potential of individual stem cells becomes progressively restricted, although there are many exceptions to this belief. Recently several laboratories have reported tissue derived adult stem cells can transdifferentiate into a cell type of another tissue. However, adult stem cells have not been shown to exhibit developmental potential matching the breadth and versatility equivalent to that of the embryonic stem cells. A good example of adult stem cell-based regenerative medicine is the work of Dr. Michel Levesque, who uses the patient's own neural stem cells. He removed neural stem cells from the patient's brain, cultured them in the lab for months to produce several million stem cells and then implanted them into the part of the brain that is affected by the lack of dopamine producing cells. This work holds tremendous promise for curing PD. Adult stem cells have been used to cure several patients in France with an inherited disease sickle cell anemia as well as reversal of multiple sclerosis in Canada and China. Adult stem cells have also been used to induce remission in several cancer patients and in improving patient conditions with stroke and rheumatoid arthritis Somatic Cell Nuclear Transplant (SCNT) and Stem Cells from self-embryo: If one uses an embryo to obtain stem cells for regenerative medicine, the chances are that the foreign stem cells will be rejected by the recipient's immune system. For this reason, it would be preferable to use the patient's own stem cells for such therapeutic applications. Apart from the above mentioned adult stem cells, there are two ways one can obtain stem cells from self. One can artificially produce an embryo using the patient's own cells (e.g., skin cell or a brain cell). This is exactly what is done in the above mentioned procedure called Somatic Cell Nucleus Transplant or SCNT. In this approach, one removes and discards the nucleus from an unfertilized egg (this nucleus contains only one half or haploid number of chromosomes coming from the female; therefore cannot by itself develop into an embryo, except under very abnormal circumstances called parthenogenesis, which produce only female individuals; so no embryo is killed in this procedure) and introduces the diploid nucleus (complete diploid number of chromosomes) from a somatic cell (e.g., a skin cell) of an adult individual. The diploid nucleus begins to act like a fertilized egg in the presence of all the required messages in the cytoplasm of the egg when given the right microenvironment in vitro and develops into an embryo-like collection of cells resembling a blastocyst stage. At this stage one can do one of two things: 1. Reproductive cloning: One can implant the embryo-like artificial blastocyst produced without fertilization by SCNT into a surrogate mother and can obtain a cloned identical duplicate of the individual who donated the somatic cell nucleus. As mentioned above, this technology is not advanced enough to produce a healthy individual. Experiments with cats did produce normal looking kittens, but they were not identical among themselves and differed from their biological mother, for unknown reasons. Besides, there are other problems, such as a cloned organism may carry unknown genetic and epigenetic defects, and tend to retain the genetic age of the donor. It is also morally and ethically wrong to kill several hundred fetuses, before we obtain one successful clone, even assuming that everything goes without a flaw. Alternatively, some people would prefer to terminate the surrogate conception after an advanced state to isolate embryonic stem cells, which is morally and ethically even inconceivable. 2. "Therapeutic Stem cell Cloning" or "Therapeutic Cloning" following somatic cell nuclear transfer (SCNT) is a procedure to culture the embryo-like artificial blastocysts in vitro and isolate the embryonic stem cells from them and culture them for solely for the purpose of therapeutic research. (I hate the phrase "Therapeutic Cloning", since it has taken a wrong meaning causing furore and objections to this branch of developing science; the stigma of cloning means human cloning has stuck in people's mind.) This is just a procedure to obtain patient's own embryonic stem cells, that can be used for regenerative medicine for that particular patient alone. The nucleus is the site of DNA, which contains the "blue print" of life. The DNA in the nucleus contains all the genes that code for the development and differentiation of all of the more than 200 different cell types and to organize them into a functional human being. But, not all the genes are coding for their respective protein in all the cells at a given time. For example, the skin cell nuclear DNA will be synthesizing the proteins required for the skin cells, while all the other genes are kept in an inactive state. The cytoplasm of the enucleated egg has the messages necessary to instruct the somatic cell nucleus (from a skin cell for example) to inactivate the battery of genes that are active in the skin cell and turn on the battery of genes that would be active in the embryonic cell. This is what happens when a somatic cell nucleus is transplanted into an enucleated egg cell (oocyte), (which will not develop into an embryo by itself since it has a haploid nucleus with only one half of the number of chromosomes). The diploid somatic cell nucleus acquires the gene expression profile of an embryo, starts behaving like an embryo in vitro and by day 4-5 reaches the blastocyst stage, with its central mass of cells rich in embryonic stem cells (instead of adult stem cells). Thus, the therapeutic stem cell cloning (or erroneously called therapeutic cloning) involves harvesting of these cells from the artificial blastocysts and culturing them in vitro for therapeutic research purposes. It is hoped that such embryonic stem cells will be pluripotent and may not be rejected by the patient . However, the cytoplasm of the egg into which the somatic cell nucleus is transplanted, will have the mitochondrial DNA from the egg. So, what we really have here is a human-human (egg cytoplasm/ somatic nucleus) hybrid cell with the egg mitochondria (small respiratory organelles of the cell) contributing about 1% of the total cellular DNA and the rest of the 99% of DNA coming from the nucleus of the donor cell. (Yes! We all get our mitochondria from our mothers!) This may also be likely to cause immune rejection of the patient's own stem cell! As I see it, it is only a matter of time this small obstacle will be surmounted. One can carefully extract the cytoplasm of the egg cell, remove the maternal mitochondria from the cytoplasmic fluid and inject cytoplasmic fluid minus the mitochondria into the somatic cell. Alternatively, one can inactivate the maternal mitochondrial DNA from the enucleated egg and inject the somatic nucleus along with patient's own mitochondria. Such a hybrid embryo will have 100% of the DNA derived from the patient alone, thus avoiding the possibility of immune rejection. At present, there are only proofs of principle behind this optimism. But these are strong indications that if we allow exploration of these new opportunities of developing novel regenerative therapies, there shall be enormous benefits to be garnered. However, these novel and highly probable opportunities to develop regenerative medicine needs to be validated by further research. It only makes sense that "we are ethically and morally obliged to pursue them for the benefit of those who suffer." Now, we know what the stem cell is capable of doing. Given this scenario, people with debilitating diseases, for which there are no cures available in the foreseeable future, have put their faith on stem cell research. Forty American Nobel Laureates, that includes world authorities in research on cancer and other life-threatening diseases, issued a joint statement on April 10, 2002, strongly in favor of somatic cell nuclear transplantation technology for therapeutic research. Therapeutic stem cell cloning means isolating the embryonic stem cells from the artificially produced self-embryo and growing them in large numbers to be used in therapeutic research and not for producing babies. However, we all agree it is ethically and morally repugnant to kill a human embryo to save another human life. The best compromise would be to take the patient's own cell and make it think and act like an embryo. "WHEN IS A CLONE NOT A CLONE?" People think it would be okay to isolate adult stem cells from somatic tissues such as skin, bone marrow or blood. In theory, these cells are also pluripotent and can be put in an egg for the purpose of cloning an individual! Therefore, no matter where you get the stem cells from, either from an early embryo, an induced embryo after SCNT, or an adult tissue, given the right environment, all are potentially capable of developing into an embryo! That is why they are called STEM Cells. As mentioned above, SCNT or Somatic Cell Nuclear Transfer can be common for both reproductive cloning and therapeutic stem cell culture (therapeutic cloning). But there ends the similarity. The moral or ethical question, therefore, is "Do we have the right to kill a "potential" embryonic human being for culturing stem cells?" This might appear as a grey area. Therefore, it is reasonable to assume that both the pro-life and pro-stem cell sides have some grain of truth in their respective contentions. But, in practice, therapeutic stem cell culture is different from cloning of one self, since we are not cloning babies. This is where one's common sense, judgement based on experience and society, compassion, sensitivity, and cost benefit and ratio in terms of human suffering come into play and one has to come to an appropriate decision without approaching the issue with a one track mind and without being hypocritical. When does a life begin? It is correct to assume a life starts immediately after the haploid nucleus of the sperm fuses with the haploid nucleus of the egg, a process called fertilization. If you are with me on this definition, let us see what happens when people take birth control pills. Birth control pills induce a processes similar to abortion in that they prevent implantation of fertilized eggs month after month almost through out the reproductive life of the females of human species. Except the Catholic Church and probably a few staunch religious people, the vast majority of the humanity does not feel guilty about millions or billions of these potential human beings being "murdered" every day. But, why should we feel morally and ethically guilty if an ailing patient with no other way of leading an useful life, for no mistake of his/her own wants to raise his/her own stem cells using his/her own somatic cell to cure his/her disease? If we are truly pro-life, this should also encompass a normal healthy life style for every human being, especially the ones that are alive but suffering from various debilitating diseases. I find this moral dilemma is based essentially on ignorance of the understanding of the value of purpose and the procedures involved. They not only propose to ban any research on stem cells, but they also want to criminalize the act of doing research and if the patient gets stem cell treatment outside America, he/she also would be treated as criminal! (This tendency has already resulted in the loss of brain drain from both USA and UK to other parts of the world which embrace these novel approaches!) I smell lack of compassion, self-righteousness and a streak of savage delight in imposing one's biased belief on others. North America is a pluralistic society and there are opposing opinions in every society. At the outset, there appears to be strong opinion on both sides of the argument. Proponents of banning embryonic stem research however assume that adult stem cells will cure everything and so we need to ban all embryonic stem cell research including SCNT-derived therapeutic stem cell cultures or therapeutic cloning. Yet, every scientific review of the therapeutic opportunities afforded by adult and embryonic stem cells has concluded that embryonic stem cells are far more versatile for regenerative medical therapies. It is too early to assume that adult stem cells will be as good as the embryonic stem cells in their longevity and function. Research on human stem cells have only started very recently and is still in its infancy. It makes a lot of sense to me that research with both adult and SCNT-embryonic stem cells should be allowed to proceed very vigorously without any further delay. Time will tell which would be the best approach to adhere to. As Dr. Paul Berg puts it, choosing one against the other at this point in time could prove to be an erroneous choice of embarrassment, not unlike the experience of the Soviets who preferred Lysenko's prejudices against Mendelian genetics. It i s gratifying to note that, in addition to the 40 Nobel Laureates, several knowledgeable and influential people such as Senator Orrin G. Hatch, Nancy Regan, Christopher Reeves, (including some pro-life people) and several organizations including the American Medical Association, the American Pediatric Association, the American Association of Medical Colleges, American Society for Cell Biology, National Institutes of Health and many patient advocacy organizations including Juvenile Diabetes Research Foundation, the National Coalition for Cancer Survivorship, the Huntsman Cancer Institute and the Utah Life Sciences Association favor encouraging Somatic Cell Nuclear Transplantation for cloning stem cells for therapeutic research. Does this mean no research on embryonic stem cells should be allowed take place? I think that is not the right decision at this time. While reproductive cloning of humans be banned and criminalized permanently along with severe punishments attached to such activities, I also think that reproductive cloning of other organisms, safeguarded with strict ethical guide lines, has an important role and purpose in propagating the animals and plants that are facing extinction. Humans as a species have come to dominate by their successful colonization of the earth and are indiscriminately destroying the natural environment that supported the evolution of God's creation and because of this success or other reasons thereof, several plant and animal species are already extinct or more are lingering at the verge of extinction. For that purpose alone, we owe it to ourselves and to our future generations, if not for anything else, we should not hesitate to do all we can to preserve and cherish all life forms. Studies on reproductive cloning can go a long way in achieving the preservation of various life forms from becoming extinct. One has only to look at the popularity of science fiction movies such as "Jurassic Park!" Wouldn't you be thrilled to produce a couple of baby mastadons or saber tooth tigers by injecting the nuclei from the somatic cells of a deep-frozen mastadon or a saber tooth tiger in the arctic into the enucleated eggs of an elephant or a present day tiger? By the way, even the present day elephants and tigers are at the verge of extinction because of irresponsible hunting by humans for fun or for profit! CONCLUSIONS: The words "stem cells" and "cloning" create intense and violent emotional reactions in people on both sides of the abortion issue. The fact is that stem cells are in our own blood, pancreas, liver, brain and perhaps many other tissues and organs of the body. These are adult stem cells which have already begun marching on the differentiation pathways at least partially into the kind of cells they are getting programmed to become eventually. It is thought that further research on adult stem cells as well as stem cell derived after SCNT may play a major role finding cures for various pathological conditions. Although some preliminary work looks promising, one needs to verify the validity of these expectations by further research before arriving at safe therapeutic protocols. There are also stem cells to be harvested from the placenta and the umbilical cord blood, which is routinely discarded after the baby is born. Cord blood cell banks are being set up to help doctors and families donate their stem cells for research and future therapy. The very mention of the words "Stem Cells" or "cloning" makes people think about human cloning and they immediately accuse the scientists of wanting to play God! They forget that there are many kinds of stem cells whose potential need to be understood better. How do they multiply without undergoing differentiation? What are the different signals and the sequence of the events that lead to different cell types in the body? How are these signals being regulated? The stem cells are there for the benefit of our well being. Why not exploit them for curing our diseases? "Embryonic stem cells are another flash point of controversy. These must be harvested from human embryos which are aborted. We cannot reconcile with taking a human life for prolonging another human life. There are serious trains of thought being argued about the use of "leftover" embryos that are created by a couple using in vitro fertilization and which are routinely destroyed by clinics and hospital every day. It is at this point the clouds of doubt and uncertainty rolls in: What is more pro-life? To allow the destruction of human embryos continue, which will never become babies since they will never be transplanted into an woman's womb? Or is it more pro-life to use these discarded (murdered) embryos to start new stem cell lines for research thus giving them meaning and dignity to be useful for humanity?" You be the judge. I have explained the choices presented by the recent advances in science. "I have to admit to not knowing answers to this thorny and moralistic 'hot potato.' But I can tell you that years of watching such debilitating diseases take our friends away all around us, slowly but surely, sometimes makes us question the validity of our own beliefs." So, back to the present again! What is therapeutic stem cell cloning? There is a world of difference between reproductive cloning of humans - something which should be banned universally and immediately, and therapeutic stem cell cloning, that opens up unlimited opportunities to benefit 75% of humanity by leading to cures for deadly and terrible diseases. Therapeutic stem cell cloning saves lives and make life worth living; it does not create lives. I hope I have helped somewhat in clearing up some of the misconceptions and rekindled some hope that the pro-life and the pro-choice people can find a common ground to come together in an unified effort to eradicate the devastation and suffering of so many. I feel confident that after assimilating the facts, the general public as well as the politicians will make the right decisions in favor of the well being of humanity. But we cannot waste our time arguing about it. We have a lot of work to do and in a hurry! ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn