The promise and pledge of adult stem cell research
It is almost an impossibility to live in the western world and not hear about how the Christian right groups have influenced President Bush and the Republican Party not to support stem cell research for the fear that it could promote abortion to meet up the demand for stem cells by medical researchers. Well, little these Christian right groups know of the innovativeness of scientists. The life scientists have figured out a way to get around to the problem the Republican lawmakers would create in connivance with the Christian right groups.
On December 7, 2004, I was able to attend a seminar at the center where I work on the use of adult stem cell to cure a variety of human maladies. Prof. Brian T. Butcher of 'Center for Gene Therapy' of Tulane University, New Orleans, was the seminar speaker. The professor gave a half-an hour technical talk on the promise and pledge of adult stem cell and its usage in repairing human tissue damage, which was followed by an intense half-an hour question-answer session. I learned a lot about a field that is growing by leaps and bounds in the last few years.
What is a stem cell? These are specialized and undifferentiated cells present in embryonic tissue (embryonic stem cells) and in bone marrow (adult stem cells). The reasons stem cells are getting attention from scientific communities allover the world are as follows: stem cells can help make a particular type of cells. In other words, they have the potential to make a specific cell such as lung cells, heart muscle cells, brain cells, spinal chord tissue cells, etc. After birth, in human body all we have is differentiated cells. Lungs have lung cells, brain has brain cells, and pancreas has pancreatic cells, so on, and so forth. The pancreatic cells have lost their power to make lungs cells or epithelial cells, and for that matter, no other cells. That is the reason when spinal cord injury happens due to accident, the spinal cord tissue being a differentiated cells do not have the power to regenerate spinal cord cells. That is precisely why a person with spinal cord injury never recovers fully from the injury. The plight of Hollywood actor Christopher Reeve, who brought a comic book hero to life in four “Superman” movies and who became a real-life crusader for medical research after a paralyzing, near-fatal horseback-riding accident, had to endure so much. His condition after the accident never did improve much and he died on October 10, 2004. Had there been a procedure to develop stem cell therapy, the doctors would have injected stem cells in his damaged tissue, spinal cord regeneration would have occurred, his condition would have gotten better. In principle, the stem cells when injected into the damage spinal cord would have started new cell growth in spinal cord and the damaged tissue could have been repaired by stem cells. That is the reason clinical physicians, scientists, etc., are all interested in stem cells because they can repair the damage of the injured tissues in a human body.
Technically, stem cells can be injected to a heart muscle right after a heart attack to repair the heart tissue damage. I learned from the seminar that this is now being done as an experimental therapeutics. As more knowledge is gained, who knows probably in the next 10-12 years from now stem cell mediated tissue repair will become available in the West as an experimental therapy. Eventually the art of repairing various damaged tissues through stem cells will become routine in years to come. Someday this new procedure will make its way to least developed nations on earth and many people round the world will be benefited by the marvels of stem cell research.
In a way of introduction Prof. Brian Butcher of Tulane University showed the picture of a young boy who suffered from a rare bone disease in which the patient’s bone are not dense enough; therefore, the patient’s bone is very brittle. Children who are afflicted with this rare disease cannot stand or walk because of the brittle nature of the bone. By injecting adult stem cells the Tulane Team and St. Jude Hospital in Memphis were able to induce bone growth in a patient by injecting adult stem cells. The results of this experimental therapy were simply amazing. The patient who has this bone disease usually dies early. Who knows, by this stem cell therapy, the patient may increase their bone density and live a little longer? Such is the promise of stem cell therapy.
Prof. Brian Butcher showed us a list of diseases where stem cell research may help find a cure. Spinal cord injury is one of the damage that could be cured by stem cells. The diabetic patient may get a shot of stem cells in the pancreas, which then may make millions of beta cells to produce insulin and thereby cure the disease for once and all. No more injection of insulin every day! In the same vein, a stroke victim may get a dose of stem cells in the brain so that the damaged tissue there could regenerate and repair itself. The possibilities of stem cell-mediated therapy are endless. No wonder that stem cells research had caught the fancy of medical and life scientists allover the globe.
From the seminar that I had attended on December 7, 2004, I also learned how to grow and purify adult stem cells. Medical scientists can extract stem cells from the bone morrow from a donor. From the two hips, doctors could extract bone marrow, usually a few cubic centimeters, after a localized anesthesia is given in the hips and drill a minute hole in it. It is a simple procedure. The bone marrow cells are then treated according to a protocol and then separated by a centrifuge to separate the stem cells from other contaminating cells. Finally, the purified stem cells are grown in the laboratory for few days to increase their mass. These stem cells are then harvested and concentrated, which will then be ready for injecting into the diseased tissue. The doctors will have to determine carefully the dose; after injecting the cells, the doctors would look for regeneration of the tissue. If the new tissue develops, then the disease will be cured. Of course, there is more to it then what I am describing here. However, the readers will get the idea what the therapy entails.
Dr. Brian Butcher told us at the seminar that by injecting adult stem cells in damaged spinal cord the patient may regenerate the tissue and then regain the ability to stand up, which otherwise is not possible. What I gathered is the following: the stem cell research is opening a new door of opportunity for the medical scientists to cure a myriad of diseases. Going into the future, there will be a hope for dismal accident victims, diabetic patients, heart attack victims, stroke victims, emphysema victims, people suffering from nervous disorders, and many more. Think about the stem cells as a new brand of medical arsenals.
During the question-answer session, I asked Fr. Butcher whether would it be possible to purify the growth factors or chemical signals that are there in the stem cells that would trigger new tissue-specific growth. My suggestion was that why inject the stem cells when we could inject the specific chemical (peptide, protein, hormone, growth factor, etc.) for each tissue. Jokingly, he asked me to undertake the research. However, he concurred with me that that should be the ultimate goal of medical research. We should understand that stem cells being undifferentiated cells have the ability to induce new tissue-specific cell growth because it contains specific growth factors.
Dr. Brian Butcher also said that embryonic stem cells are more potent in inducing the growth of cells but 25% of the stem cells may turn cancerous. He said he wouldn’t mind receiving adult stem cells but not the embryonic one because of the inherent danger. Medical scientists would like to do more research with embryonic stem cells but in the U.S. the devout Christians are dead against the research for the fear that the demand for embryonic stem cells may spur harvesting human embryo, which the fundamentalist Christians oppose because of morale ground. These Christians have influenced President George Bush and other Republican legislators in Washington DC banning embryonic stem cell research in America. These Christians will not object to adult stem cell research, which has the same ability as the embryonic ones to induce new tissue growth albeit with a weak potency.
For those of the readers who would like to know more about stem cells from technical perspective, I culled more information on both embryonic and adult stem cells by searching some scientific literature.
As I have mentioned in my article the future of stem cells (SC) lie in tissue repair, replacement, and regeneration. Stem cells are unspecialized precursor or primordial cells that have the unique ability to self-renew and generate additional stem cells as well as to differentiate into various progenitor cells in response to appropriate signals such tissue damage. These fantastic properties of SC have led researchers to explore new strategies for damaged tissue repair, replacement, and regeneration. Cell Biologists classify SC as either embryonic stem cells (ESCs) or adult stem cells (ASCs), which are tissue-specific.
ESCs are derived from the inner cell mass of preimplantation embryos and are considered the most pluripotent stem cell population. These cells (ESCs) can undergo both infinite and undifferentiated proliferation in vitro and can also differentiate into a wide variety of somatic and extra-embryonic tissues. Conversely, ASCs or adult stem cells are unspecialized cells found in differentiated tissues that can self-renew and differentiate into mature cell types of the specific tissue. While ESCs can proliferate forever, the ASCs can proliferate for a limited number of cycles and their healing power (response to differentiation signals) decline with each cell cycle.
For tissue regeneration (read therapy), a major emphasis is placed on “controlled differentiation” of stem cells into a desired cell or tissue type. Molecular cell biologists have recognized that several growth and differentiation factors are the key to shaping the destiny of stem cells. For example, TGF-β family members are shown to have a pronounced effect on the differentiation of ESCs and neural crest stem cells.
Despite the fact that the pluripotent ESCs have an added advantage over ASCs, ethical debates have restricted research on ESCs. Because of this, many researchers have gone into research with ASCs. Consequently, some advances have been made in the isolation and characterization of adult stem cells. In adult, hematopoietic (blood forming) stem cells (HSCs) are shown now to proliferate and differentiate throughout the life cycle to produce lymphoid and myeloid cell types. Researchers have shown in the laboratory that Interleukin-3 and 6, thrombopoietin, stem cell factor (SCF), and Flt-3 Ligand could induce blood formation. As I have mentioned earlier in my article, bone marrow-derived stem cells are shown to differentiate into various cell types, including adipocytes (fat cells), chondrocytes (cartilage cells), osteocytes (bone cells), hepatocytes (liver cells), and cardiomycetes (heart muscle cells). Similarly, in the nervous system, the plastic property of neural stem cells has been exploited to regenerate neural tissue damaged by either injury or neuro-degenerative diseases.
What lies ahead for stem cell research? The ultimate goal in present-day medical research dealing with tissue regeneration is to figure out the growth or chemical factors that can induce tissue-specific growth. Once that is elucidated, then, we do not have to harvest embryonic stem cells anymore. The tissue-specific growth factor will be farmed in a laboratory by recombinant DNA technology. Who knew 40-50 years ago that insulin, which used to be harvested from bovine (cow) or pig pancreas in a slaughterhouse, would be made inside bacteria by recombinant DNA methodology? Millions of diabetic patients around the world take insulin everyday but most people do not know that human insulin is made inside a bacteria. The same could happen to human growth factors, which is now only available in stem cells. It will be a mistake of giant proportion to block stem cell research. The Christians may block it in America but there will be many other nations where medical scientists will perform research to unlock the mystery of stem cells. One thing is for sure now. We will hear more medical reports in both respected journals and popular press the results of therapeutic studies involving adult stem cells. This new method of curing damaged tissue by stem cells will revolutionize the field of reconstructive surgery, cardiac, diabetic, and other discipline of medical field. All of this will be possible because a handful of rational minds have decided to perform research in the last decade on stem cell. Future belongs to stem cell and that is not an understatement either!
Dr. A.H. Jaffor Ullah is researcher in the field of genetics and protein chemistry in New Orleans, USA.