Stem Cell Research The field

Stem Cell Research

The field of regenerative medicine has achieved great strides in the recent years. Particularly, the research on stem cells and the promising possibilities for several degenerative diseases, cardiovascular, and neurological conditions has created a paradigm shift in our medical perspective. Stem cells have the unique ability to differentiate into different types of cells based on the environment. This new field of research has however been marred by controversies pertaining to the ethics and the morality of doing research with human embryos. More recently though, medical focus has shifted towards another interesting and non-controversial possibility -- that of umbilical cord blood stem cell research. This holds great promise and offers a whole new approach to management of diseases. Diseases such as leukemia, spinal injuries, diabetes, immunological disorders, stroke related neurological damage could now be effectively treated offering a new ray of hope for millions of patients. We are yet a long way from perfecting the technology and there are a lot of ethical controversies surrounding stem cell research. A brief overview of the issues related to stem cell research will help us better understand this controversial yet promising development in medical science.

Stem Cells

Before discussing the controversies pertaining to stem cell research it is necessary to understand the specialty of stem cells. Stem cells are the basic cells of the body that have both differentiating as well as replicating properties. Researchers have categorized stem cells into four major types namely totipotent, pluripotent, multipotent and unipotent cells. Totipotent cells refer to those cells that are formed immediately after the fusion of the egg and the sperm. Totipotent cells have the capability to differentiate in to embryonic as well as other non-embryonic cell types of the human body. Pluripotent cells are the cells derived from totipotent cells and can differentiate and form into any tissue type of the human body. Multipotent cells on the other hand can typically differentiate into cells of closely related tissue types. One good example of multipotent cells would be hematopoietic stem cells. The hematopoietic cells differentiate into white blood cells, red blood cells, platelets, etc. Lastly, unipotent stem cells as the name suggests are stem cells that can develop into only one particular type of tissue. [Holland Suzanne, 2001]

Sources of Stem cells and Ethics

The controversy about stem cell research comes from its source. There are many different sources of stem cells namely embryonic stem cells, embryonic germ cells, adult stem cells and umbilical cord blood. Adult stem cell research has been around for a long time and the first bone marrow transplant took place in 1968. The main problem with adult stem cells is the difficulty of in vitro cultivation of the stem cells. Embryonic stem cells on the other hand are obtained from the human embryos and therefore stir ethical controversies. As the physician's Oath in the 1948 Declaration of Geneva, states: "I will maintain the utmost respect for human life from the time of conception.." [the White House] This implies that even embryos are not any different from human life and hence using them as a source for research is not permissible. Therefore the opinion against the destruction of embryos for experimental purposes is justified.

In 2001 a new policy on stem cell research was established by president Bush that encouraged research without compromising on the ethics. As per the policy decision, federal funding for stem cell research was allowed only for the embryonic stem cell lines that were already in existence as on Aug 9, 2001. (21 separate cell lines) the absence of funding for new embryonic cell lines was a measure to discourage the destruction of new embryos for research purposes. More than $130 million have been spent on embryonic research over the last six years and around 3 billion $ for all forms of stem cell research. [the White House] Embryonic germ cells on the other hand are obtained from aborted fetuses. In this case also the ethics of abortion come into play. Besides there is also a problem that abortion clinics around the country might do business by selling dead fetuses to stem cell research centers. There are other problems besides ethics that are also to be seriously considered. First comes the potential immunological rejection of embryonic stem cells by the host cells, which may even necessitate life long dependency on immune suppression drugs. Ways to circumvent this problem such as somatic cell nuclear transplant or genetic reengineering of the embryonic cells to make them immunologically acceptable are all steeped in ethical and moral controversies. Secondly, the high tumurogenic tendency of embryonic stem cells is well documented and this presents additional problems. [Maureen L. Condic] However, an encouraging result for scientists came in February 2008 with the publication of a study of the successful treatment with brain tissues developed from human embryonic stem cells in rats. In this research, the rats, which had significantly affected limb movements due to experimentally induced stroke in their right hemispheres, recovered considerably when transplanted with human neural stem cells. The highpoint of this study was that all the rats remained tumor free after successful treatment with embryonic stem cells. As Stanford University biologist and co-author of the research Mr. Marcel Daadi said, 'This is really exciting, just to overcome this obstacle of tumorigenicity' [JR Minkel]

Research is in full swing and over the last 5 years more than 900 research papers were published on embryonic stem cells. It is expected that the first human clinical trial to test the effectiveness of embryonic stem cells in the treatment of spinal injuries will commence very shortly. The California-based Biotech Company Geron Corporation is sponsoring this study, which is much awaited by the medical research community particularly in the wake of the reported success of a similar experiment on rats in a 2005 study. [Jordan Lite] in the said study, researchers found that rats with spinal cord injuries remylineated quickly and recovered motor skills when treated with Human embryonic stem cells derived oligodendrocyte progenitor cells seven days after the injury.

Hans S. Keirstead et.al, (May 2005)]

Umbilical Cord Stem cells (New Developments)

All the furor in the scientific community lies with cord blood stem cell research as it offers greater possibilities unlike adult stem cells as well as being without any ethical or moral concerns (as is embryonic stem cells research) as the umbilical cord is usually considered a biological waste. Unlike adult stem cells, umbilical cord cells have high replication rate and can be easily cultivated in vitro. Also, cord stem cells are less susceptible to adverse immunological reactions when compared with adult bone marrow transplantation procedures. Currently more than 70 disorders are treated with umbilical cord blood as scientists have shown that cord blood derived stem cells could be used not only in the treatment of blood related and immunological problems but also for genetic disorders and in regenerative medicine. Recent research has also proved that embryonic-like stem cells (CBE) could be isolated from UCB (Umbilical cord blood). Their similarity with embryonic stem cells was attested from the positive results of immunoreactivity tests with embryonic stem cell markers. [Colin McGuckin et.al, 2006]

Also the new revelation of IPSC (Induced Pluripotent Stem Cells) whereby it is possible to convert normal adult somatic cells into pluriportent stem cells is very encouraging. However, presently IPSC are riddled with viruses that could cause mutations requiring more time and research for the perfection of technology. As George Daley, of Harvard Medical School in Boston, Massachusetts, who was part of the team that successfully reported the possibility of converting adult somatic cells into pluripotent stem cells said, "One of the next big milestones will be making these cells without the use of viruses -- leaving the cells in a genetically pristine state," [Nature]

Conclusions

Stem cell research offers a new ray of hope for millions of people affected by degenerative, genetic and other disorders. More research has to be undertaken for increasing our understanding of the tissue growth factors, translation protocols and control parameters to harness the full potential that stem cells therapy has to offer. This, it is hoped, would be realized in the near future with the rapid strides in the biotech field. While embryonic stem cells, considered to be the potential panacea for many deadly diseases is steeped in ethical controversies and awaits further research for its safety, the successful therapy with umbilical cord stem cells is already considered a huge victory. Further, the promising possibility of a new and novel method of stem cell generation such as Induced pluripotent Stem cells (IPSC) opens an entirely new dimension for stem cell research offering researchers a source of stem cells which does not have any ethical or moral stigma attached to it. Stem cell therapy could very well change the face of disease management and it would not be long before we can actualize IPSC technology which would put to rest any remaining controversies.

Bibliography

The White House, 'Advancing Stem cell Science Without Destroying Human Life', Jan 9, 2007, Available online at, http://www.whitehouse.gov/dpc/stemcell/2007/stemcell_010907.pdf

Maureen L. Condic, 'What we Know About Embryonic Stem Cells', January 2007, First Things, Available Online at, http://www.firstthings.com/article.php3?id_article=5420

Jordan Lite, 'Spinal cord stem-cell trial could start soon, report says', Scientific American, Oct 20, 2008, Available Online at, http://www.sciam.com/blog/60-second-science/post.cfm?id=spinal-cord-stem-cell-trial-could-s-2008-10-20

JR Minkel, 'Human Embryonic Stem Cells Fix Stroke-Afflicted Rats', Scientific American, Feb 20, 2008, Available online at, http://www.sciam.com/article.cfm?id=stem-cells-fix-stroke-afflicted-rats

Hans S. Keirstead,1 Gabriel Nistor,1 et.al, 'Human Embryonic Stem Cell-Derived Oligodendrocyte Progenitor Cell Transplants Remyelinate and Restore Locomotion after Spinal Cord Injury', the Journal of Neuroscience, May 11, 2005, 25(19):4694-4705

Colin McGuckin, Nicolas Forazz et.al, ' Embryonic-like Stem cells from Umbilical Cord Blood and Potential for Neural Modeling', Acta Neurobiol Exp 2006, 66: 321 -329, Available online at, http://www.nencki.gov.pl/pdf/an/vol66/mcguckin.pdf

Nature, 'Stem Cells: A new path to pluripotency', Accessed Nov 6th 2008, Nature 451, 858 (14 February 2008), Available online at, http://www.nature.com/nature/journal/v451/n7180/full/451858a.html

Holland, Suzanne (2001), the Human Embryonic Stem Cell Debate: Cambridge MIT Press