September Issue 2014
A New Lease of Life?
Stem cells are unique, remarkable in their ability to replicate indefinitely, adept at adopting the cellular characteristics of the body’s various organs, be it the brain, liver, kidneys, etc., as and when needed. It was only a matter of time before scientists and researchers discovered the secrets of stem cells and their infinite potential. Since then, they’ve been using the knowledge to cure people of numerous diseases, including assorted cancers. And this is not just happening in the ‘civilised’ First World. Karachi’s Aga Khan University (AKU) Hospital now has a dedicated transplant unit, where international standards are maintained round the clock, and where stem cell research and therapy is underway.
Like other mammals, we ‘multicellular organisms’ are complex, with different types of cells for each of our organs. Stem cells are marshalled into action by the body’s own defense mechanism. They’re needed to replenish the human body when life’s normal wear and tear takes its toll, or in the case of injury or disease.
In addition to proving efficacious for the treatment of cancers, therapy with these cells is also effective for treating hereditary disorders that cause damage and death of nerve cells in the arms, legs and eyes. Historically, a bone marrow transplant, BMT for short, has been the procedure of choice for replacing a diseased patient’s bone marrow with a healthy donor’s marrow. The process involves high-dose chemotherapy, sometimes total body irradiation and prolonged use of immuno-suppressant drugs (drugs that suppress the body’s natural defense mechanism), to avoid graft failure (of the donated bone marrow). Now, after more than 50 years, this methodology is an integral part of cancer centre facilities (including the one at the AKU Karachi), offering treatment for patients with haematological disorders and cancers. In view of the anticipated increasing use of stem cell therapy, there are plans to expand the unit at the AKU, with a simultaneous refinement and improvement of the transplant technique. This appears essential, as there is now a greater prevalence and higher incidence of malignant and non-malignant diseases. The ultimate benefit will be improvement in the overall survival rate of patients, and the reduction of complications.
Currently, most BMT centres utilise peripheral blood stem cells (PBSC) for the source of stem cells; a far simpler process than the uncomfortable one of bone marrow harvest, with its associated risks of surgical and general anaesthesia complications.
This entire process is termed Stem Cell Therapy or Transplant, where the source of stem cells is usually PBSC. This is extremely effective in many diseases, including non-Hodgkin’s lymphoma, Hodgkin’s disease, multiple myeloma, Ewing sarcoma, paediatric blastoma, testicular cancers and sometimes in acute myelogenous leukemia.
That is not all — as mentioned earlier, stem cell therapy has proved effective for the treatment of hereditary disorders that cause damage and death of nerve cells, and treatment outcomes have been pronounced amazing for diseases earlier considered untreatable. A case in point: retinopathy, which causes progressive damage to the retina, leading to blindness, is also treatable through stem cell therapy. Patients who have regained their eyesight pronounce the operation nothing short of miraculous.
These versatile cells grow and reproduce throughout one’s life span, during fetal and embryonic growth, in infancy and early childhood. They develop into multiple cell types in the body, and serve as a sort of internal repair system (the body’s toolbox), dividing without limit to replenish other cells throughout life. Every time a stem cell reproduces, it again has the potential to either remain a stem cell or to become, and reproduce, into something more specialised, depending on the organ for which they’re needed.
Researchers believe that the potential of adult stem cells is as yet untapped — and they are working towards the stage when people can be treated by their own stem cells, or with banked donor stem cells once genetically matched to the patients, much like blood from blood banks.
Although adult stem cells are generally less flexible and versatile than embryonic ones, they’re less controversial and more readily available. However, embryonic stem cells do have a far greater differentiation potential than the adult variety, because they can develop into almost any cell in the body. Conversely, adult stem cells may only develop into a limited number of cell types, which limits their potential.
So, when stem cells are needed by the doctor to counter an injury or disease process, where do they come from? Because now we’re talking about additional stem cells, collected from a human source and grown outside the body, being replicated in the lab, ‘in vitro.’
One important source of obtaining, or ‘harvesting’ stem cells is from the embryo, where the best option is to obtain an ‘embryonic harvest’ four to five days after fertilisation. Embryonic stem cells are located inside the embryo, but they’re also found in umbilical cord blood. Adult stem cells are present in organs, and tissues in babies, children and adults.
The process of harvesting embryonic stem cells, and the associated research, has, however, become extremely controversial: it has landed smack in the middle of the abortion debate, because in the process of harvesting the stem cells, the embryo is destroyed. This, according to anti-abortionists, is destruction of human life. In case of the abortion argument, the belief is that an embryo, no matter how old, is considered a human being and should be given all due respect as well as the right to life.
The controversy revolves around ethical issues: the creation, usage and destruction of human embryos — most commonly, embryonic stem cells.
Use of, and research on, adult stem cells, amniotic stem cells, and induced pluripotent stem cells do not involve creating, using or destroying human embryos, and are thus minimally, if at all, controversial. (Induced pluripotent stem cells are adult stem cells that have been genetically reprogrammed to an embryonic stem cell-like state, by being forced to express genes).
Embryos aren’t quite the same thing as human life — they’re still incapable of surviving on their own, outside the body; in fact, they soon self-destruct. More than one third of zygotes (fertilised ova) are destroyed naturally in the body’s metabolic process, after conception. More embryos are lost due to chance than are proposed to be used for embryonic stem cell research or treatment.
Nonetheless, beliefs persist. On the other end of the anti-abortion spectrum are those that believe that embryos are not human, that life begins only when the heartbeat develops, during the fifth week of pregnancy, or when the brain begins developing activity, which has been detected 54 days after conception.
According to Islamic law, the embryo is not considered human till ‘ensoulment’ has occurred. This step is believed to take place 12 weeks after conception. Therefore, abortion is permissible within the first 12 weeks of pregnancy.
People are also concerned that some scientists may be illegally tempted to attempt reproduction via cloning (remember Dolly the cloned sheep?), and may actually clone a human being. Such an attempt at playing God would undoubtedly be deeply frowned upon and, in religiously conservative societies, lead to a huge furore.
The supply of women’s eggs, or ova, for research also perturbs many. Research using therapeutic cloning requires a large number of human eggs/ova, and many are concerned that women, especially those from poorer countries, may be pressured or bribed into donating their eggs for research. Then again, many women may choose to donate their ova, fertilised or unfertilised, for research, as women’s ova are in any case, regularly destroyed as part of the body’s metabolic activity. There is enough substance here for endless debate!
Stem cell research typically utilises fetal cells. In this case, the fetus must die, as in the case of abortion, where stem cells are obtained from the aborted fetus. This makes the best possible use of someone’s completely separate choice and decision. Of course, stem cell research can be conducted on other non-embryonic cells (for instance, on an umbilical cord blood after birth), but this has so far proved impractical and expensive.
We live in a different world today, as compared to even just 100 years past. Globalisation brings everything, including research and its benefits, virtually to one’s doorstep. Viewpoints among humans are, and will remain, endlessly varied.
In view of the unarguably huge need for further research and therapy, this work remains essential, but equally so, it remains contentious for many. Anti-abortionists believe that embryonic stem cell research and therapy kills babies. In fact, the opposite is true — stem cell research takes the opportunity to turn the death of one embryo into life for many. We need that promise. It is imperative for human progress.
This article was originally published in Newsline’s September 2014 issue