Stem Cells: Weighing Scientific Potential and Ethics

Introduction

A picture of stem cells

Human embryonic stem cell (hES cell) research is extremely important in the field of medicine. Scientists have used these cells to regenerate portions of an injured spinal cord and have created pancreatic beta cells to cure diabetes. In addition, scientists can test drugs on hES cells rather than on live animals or humans. hES cell research has also led to the discovery of induced pluripotent stem cells (iPS cells), which are similar to hES cells and can be created from adult tissue.

However, the ethical dilemmas surrounding the use of embryonic stem cells must be resolved before this research can proceed. According to pro-research advocates, the use of hES cells in research is moral because these cells do not have the moral status of a human, as evinced by the phenomenon of twinning, the potential of the embryos in consideration, and the massive spontaneous abortion of embryos that occurs in the womb. However, pro-life advocates believe that embryos do have the moral statusof a human being because of their ability to develop and that hES cell research is immoral and unnecessary due to the development of iPS cells.

 

Background

hES cells are human embryonic cells that have not yet differentiated, or determined what type of cell to become. When extracted from the embryos, these cells can be forced to differentiate in vitro into one of the approximately 210 cell types in the human body [1]. In 1998, the first hES cells were isolated from embryos by James A. Thomson at the University of Wisconsin in Madison. These cells were extracted from the inner cell mass of blastocysts, or five- to seven-day-old embryos, which were created at a fertility clinic through in vitro fertilization (IVF) but were not transferred into a woman [1].

Since 1998, hES cells have been artificially differentiated into most of the cell types found in the body. In addition, research using hES cells has yielded valuable information regarding tissue creation and development [2].

hES cell research has also produced a surprising result: that it is possible to convert certain adult cells into partial undifferentiation, turning them into induced pluripotent stem cells (iPS cells). These iPS cells are not as powerful as hES cells in that they cannot differentiate into all cell types, but they are still useful in treating certain diseases, such as diabetes and spinal cord injury [2].

Finally, the most important advantage of hES cell research involves aiding the treatment of diseases. One possible use of hES cells is drug testing to determine toxicity and possible side effects before performing animal and clinical trials. Most importantly, hES cells can be used as cures for particular diseases, as outlined below [2].

 

The Potential of hES Cells

One example of medicine based on the use of hES and iPS cells is regenerative medicine. Currently, doctors can cultivate iPS cells from a patient, force these iPS cells to differentiate into another cell type, and then inject the differentiated cells into the patient. This therapy is useful when combating diabetes and spinal cord injury, since iPS cells can differentiate into the pancreatic beta cells that diabetes patients need and neurons to reconnect broken portions of the spinal cord [3]. However, hES cells can provide even more powerful cures for such diseases. It may be possible to force a hES cell, not necessarily cultivated from a particular person, to differentiate into a pancreatic beta cell. If done successfully, this could be used as a universal treatment for diabetes and would be less expensive than an iPS cell-based treatment [3,4]. Regenerative medicine has been somewhat successful on either animals or humans for the following diseases: Parkinson’s disease, age-related macular degeneration, amyotrophic lateral sclerosis (ALS), and heart disease [4].

Another important application of hES cells in medicine involves drug screening. An example of this is motor neuron disease (MND), a genetic disease. Experimentation can be performed on hES cells that would determine whether certain mutations in the genome cause MND. Cells susceptible to MND can then be differentiated into neurons, which can be observed to determine the causes of the disease. In addition, a list of possible treatments can be created by testing the effects of various chemicals on the differentiated MND-susceptible neurons [5]. This form of testing is applicable not only to MND but also to other genetic diseases, such as cardiomyopathy and cancer [5].

Also, this system of testing can help scientists understand the causes of, symptoms of, and potential treatments for a particular disease. A variation of drug screening involves using iPS cells to identify potential side effects of chemotherapeutic drugs [4]. Scientists can cultivate cancerous and non-cancerous cells from a patient and force them to become iPS cells. They can then treat the iPS cells with a particular drug and determine whether the drug is effective in preventing cancer as well as possible side effects on the non-cancerous cells. This method is valuable, because it enables doctors to determine whether or not a drug harms a patient without actually injecting the drug.

 

Ethical Considerations

hES cell research should be subject to ethical guidelines; however, differing views exist regarding exactly what guidelines the government should enforce. It is clearly immoral to force parents to sacrifice their embryos for research. Pro-research advocates believe that ethical guidelines should ensure that embryos are produced through in vitro fertilization (IVF) and are no longer needed by the patient. In addition, embryos should be under fourteen days old and still in blastocyst form. Finally, consent should be obtained from the donors and no financial benefits should be offered [3].

Pro-research advocates claim that these criteria adequately address ethical arguments that claim hES research is immoral because an embryo, due to its potential, is a human being. According to them, the embryos being used in this form of research cannot be considered as human beings. First, they do not have the potential to become human beings. The guidelines outlined above ensure that embryos will never otherwise realize their potential: they have no access to a womb or the nutrients required to become a baby [2]. In addition, while in the blastocyst form, an embryo can twin, or divide in two to form two perfectly identical embryos. If embryos are recognized as human beings and moral agents, then one moral agent divides into two when it twins [2, 6].

According to pro-research advocates, this process is simply impossible; moral agents cannot spontaneously divide. In addition, if adult humans are considered identical to their embryos, then twins are also identical to the original undivided embryo. However, two different moral agents cannot be identical to a third [6]. Here, considering embryos as having the potential to become human beings leads to an illogical conclusion.

In addition, pro-research advocates note that humans inherently reject the idea that embryos are moral agents. The majority of fertilized eggs produced through sexual reproduction never actually become embryos. Anywhere from two-thirds to four-fifths of all embryos are spontaneously destroyed by the body [2]. If embryos were given the moral status of human beings, then this natural abortion process would have to be stopped. However, humans do not call for research into preventing spontaneous abortion and thus accept that embryos are not human beings. Pro-research advocates use these arguments to support the use of hES cells in research.

However, pro-life advocates do not support the use of hES cells in research. They point to the advances made in using iPS cells and propose alternative solutions using adult cells [2]. In addition, pro-life advocates believe that embryos can be considered a moral agent. The logical fallacy associated with the situation of twinning is irrelevant because, regardless of whether or not an embryo can divide, it is still considered a moral agent [7]. They believe that the embryo is considered a moral agent just as the baby is considered a moral agent: both can develop into adulthood. Despite the irrationality of both, since they have the potential to develop into a full-fledged human, they are considered moral agents [7]. Thus, pro-life advocates believe that regardless of the source of the embryo it should not be sacrificed in order to produce hES cells for research.

Conclusion

hES research has great potential in the field of medicine; examples of this include regenerative medicine and drug screening. The ethical considerations regarding hES cell research must be resolved. If exploited to its full potential, hES cell research can provide valuable tools for doctors to analyze genetic diseases such as cancer and predict the effects of drugs on patients. In addition, the problems associated with regeneration of neurons can be circumvented by the use of hES cells. The potential social benefits lying in hES cell research are huge due to the wide variety of diseases that can be treated as a result.

Article References

  1. Knowles L, Parens E. Encyclopaedia Britannica [Internet]. [place unknown]: Encyclopaedia Britannica 1999 [cited 2011 Oct 12]. Available from: http://puffin.harker.org:2053/all/eb/article-9342369?query=embryonic%20stem%20cell%20research&ct=null
  2. Lindsay R. Gale Opposing Viewpoints In Context [Internet]. [place unknown]: Gale. 2011 [cited 2011 Oct 12]. Available from: http://puffin.harker.org:2302/‌ic/‌ovic/‌ViewpointsDetailsPage/‌ViewpointsDetailsWindow?displayGroupName=Viewpoints&disableHighlighting=false&prodId=OVIC&action=e&windowstate=normal&catId=&documentId=GALE|EJ3010155230&mode=view
  3. Rugnetta M, Peroski M. Gale Opposing Viewpoints In Context [Internet]. [place unknown]: Gale. 2008 [cited 2011 Oct 12]. Available from: http://puffin.harker.org:2302/‌ic/‌ovic/‌ViewpointsDetailsPage/‌ViewpointsDetailsWindow?displayGroupName=Viewpoints&disableHighlighting=false&prodId=OVIC&action=e&windowstate=normal&catId=&documentId=GALE|EJ3010155231&mode=view
  4. Coalition for the Advancement of Medical Research. Gale Opposing Viewpoints In Context [Internet]. [place unknown]: Gale. 2011 [cited 2011 Oct 12]. Available from: http://puffin.harker.org:2302/ic/ovic/ViewpointsDetailsPage/ViewpointsDetailsWindow?displayGroupName=Viewpoints&disableHighlighting=false&prodId=OVIC&action=e&windowstate=normal&catId=&documentId=GALE|EJ3010155227&mode=view&
  5. Wilmut I. Gale Opposing Viewpoints In Context [Internet]. [place unknown]: Gale. 2006 [cited 2011 Oct 12]. Available from: http://puffin.harker.org:2302/‌ic/‌ovic/‌ViewpointsDetailsPage/‌ViewpointsDetailsWindow?displayGroupName=Viewpoints&disableHighlighting=false&prodId=OVIC&action=e&windowstate=normal&catId=&documentId=GALE|EJ3010212254&mode=view
  6. Lindsay R A. Gale Opposing Viewpoints In Context [Internet]. [place unknown]: Gale. 2008 [cited 2011 Oct 12]. Available from: http://puffin.harker.org:2302/‌ic/‌ovic/‌ViewpointsDetailsPage/‌ViewpointsDetailsWindow?displayGroupName=Viewpoints&disableHighlighting=false&prodId=OVIC&action=e&windowstate=normal&catId=&documentId=GALE|EJ3010112276&mode=view
  7. George R P, Lee P. Gale Opposing Viewpoints In Context [Internet]. [place unknown]: Gale. 2009 [cited 2011 Dec 15]. Available from: http://puffin.harker.org:2302/ic/ovic/ViewpointsDetailsPage/ViewpointsDetailsWindow?displayGroupName=Viewpoints&disableHighlighting=false&prodId=OVIC&action=e&windowstate=normal&catId=&documentId=GALE|EJ3010453243&mode=view

Vikram Sundar is a student at The Harker School in California, a part of The Triple Helix High School Chapter Program. Follow The Triple Helix Online on Twitter and join us on Facebook.