Recently, I have had an article published in the annual magazine of Dhaka Medical College, “the Barshiki 2006” (ISBN # 984-300-000539-9; page 102-103). Here it is…
STEM CELL RESEARCH: YES / NO?
Sanjoy Kumar Chowdhury
Batch K61, Dhaka Medical College.
Remember Prometheus, who created man ‘in godlike image’ from clay, and gifted them ‘fire’? Legends say, Zeus had him carried to a Mountain where Ethon, the eagle would pick at his liver during the day, and it would grow back during the night – only to be picked at again the next day. Now, if you ask Prometheus, surely he would attribute regeneration as the cause of one of his “torments”- for which he desired ‘death rather than life’.
I wonder what our answers might be. We have heard about ‘super’-heroes in comic books and movies, whose injuries are ‘healed’ within seconds. We envy animals like salamanders as they can regenerate parts of their body. We can easily plan for partial hepatectomy knowing that it would grow back. Under this modern context, if you come to know that the new era in medical science is going to be “regenerative medicine”, what might your answer be?
The source of all hope is what we call Stem cells. The unique characteristics of stem cells include its self-renewal capacity and asymmetrical (and symmetrical – wherever applicable) replication technique, along with the most coveted feature – unlimited potency. Stem cells can be totipotent, pluripotent or multipotent cells; and sometimes even unipotent progenitor cells can be stem cells.
That is why we have the two basic types of stem cells (based upon their potency / source):
1. Unlimited / Embryonic Stem Cells (ESC)
2. Limited / Adult / Somatic Stem Cells (ASC)
Human Embryonic Stem Cells are currently obtained (for research purpose) from the ‘excess’ blastocysts of the In-vitro fertilization (IVF) clinics. In case of animals, Nuclear transfer (NT) or Altered Nuclear Transfer (ANT) techniques are also followed, popularly known as research / therapeutic cloning.
The advantages of ESC include truly unlimited potency and more importantly, their ability to grow outside the body in a laboratory. Also, they are relatively easier to find, isolate and maintain. ESCs formed by NT technique are genetically identical to the host they are obtained from – providing room for autografts.
But implanting undifferentiated ESC in living tissues can lead to teratomas. More important limitations include controversies regarding their source. Since human ESCs have only been obtained from the inner cell mass of blastocysts – which in fact ‘kills’ the blastocyst; ethical issues remain unsettled.
Obtaining Adult Stem Cells are easier and involve less controversial processes, and they are always genetically matched with the host. But they are only multi/uni-potent and difficult to identify, isolate and maintain. The advantage with ASC is their use in research and therapy is not as controversial as the ESCs.
Currently alternatives of ESC are being searched for due to the controversies they give rise to. Some of the prospective researches include:
• the use of umbilical cord stem cells,
• collecting cells from morula instead of blastocyst (since morula can sustain the loss of a few cells),
• ‘Reprogramming’ adult cells to turn on genes that allow versatility.
Progress in research regarding stem cells was rapid. Although it technically started with the first successful Bone marrow transplant in 1956, the first human ESC was isolated in 1998 by James Thomson and co-workers at the University of Wisconsin-Madison. In 2002, pancreatic cells derived from mouse ESC was used to cure Diabetes in mice.
Earlier this year (07 January, 2007), scientists at Wake Forest University and Harvard University report discovery of a new type of stem cell in amniotic fluid. This may potentially provide an alternative to embryonic stem cells for use in research and therapy.
Among the Diseases & Injuries Stem Cell Research has the potential to impact are Neurological (Parkinson’s disease, Multiple sclerosis, Neuroblastoma); Hematological (Leukemia, Sickle-cell anemia, Immunodeficiency, Lymphomas, Hodgkin’s disease, Bone marrow failure); Endocrine (Type 1 Diabetes); and Other diseases (Burns, Ovarian cancer, Breast cancer, Liver disease including hepatitis, Injuries)
Culturing stem cells and establishing stable stem cell line is one the most important aspects of stem cell research. Debates have risen regarding the ethical as well as the medical aspects of such research.
Firstly; acceptable, available and applicable sources of ESC still remain undiscovered. Using techniques like ANT to design blastocysts only for culturing (as they are rendered incapable of implantation into the uterus) can never be ethical for use in humans.
There is doubt regarding whether stable stem cell lines will actually be ‘stable’. Eventually all cell lines typically accumulate genetic mutations and stem cell lines will have to be monitored for such developments.
Moreover, actual use of such cells in therapeutic purpose has numerous questions to be answered. Chances of teratoma or oncogenic development remain. It was only in 2006 that the first mouse ESC was grown without animal products in the culture – which means we have a long way to go to exclude the probability of ‘chimeras’ human formation or unknowingly transmitting diseases by using such cells.
These are perspectives which we, the medical students of todays will have to consider. The decision will surely and soon be upon us to make – whether we will fear the wrath of Zeus and say ‘no’, or go ahead with the research and say ‘yes’ to a new mode of life…
I sincerely wish that it won’t take us 30,000 years… and I just hope that we have ‘the Hercules’ (who set Prometheus free), while we move along – to ensure ‘what promises to be the ultimate cure’ does not end up being a Frankenstein…
Pictures:
1. Microscopic 20x view of a colony of undifferentiated human embryonic stems cells. (University of Wisconsin Board of Regents, http://www.news.wisc.edu)
2. Mouse embryonic stem cells visible using fluorescent marker. (From http://en.wikipedia.org/wiki/Stem_cell)
Sources:
1. http://www.stemcellresearchfoundation.org/
2. http://stemcells.alphamedpress.org/
3. http://en.wikipedia.org/wiki/Stem_cell
4. http://stemcells.nih.gov/info/basics/
Posted by sanjoy 
Posted by sanjoy 
