Adult Stem Cell Research Paper

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Abstract

This research paper focuses on some of the core ethical issues arising from human adult stem cell research. It begins with a brief exploration of the history and science behind adult stem cell research. It then addresses three main ethical concerns about adult stem cell use, namely, the question of whether research on human embryonic stem cells should be discontinued since an ethically less controversial alternative already exists in the form of adult stem cells, the possibility of creating gametes from adult stem cells which can be used for reproduction, and the issue of stem cell tourism, a situation where desperate patients travel abroad in search of unproven stem cell therapies. Regulatory and policy issues surrounding stem cell research are also discussed. The paper concludes by saying that whereas strict ethical regulation of stem cell research is required in order to protect the safety of research participants, this must be balanced against the need to advance stem cell biology and medicine.

Introduction

The derivation of human adult stem cells has been heralded as one of the major breakthroughs in the history of biomedicine. Adult stem cell research promises vast improvements in health care and for the ﬁrst time genuinely presents the possibility of ﬁnding treatments for some of mankind’s most debilitating ailments. Although adult stem cell research avoids some of the ethical issues raised by embryonic stem cell research, the proliferation in recent years of unregulated stem cell clinics around the world offering unproven stem cell interventions (both adult and embryonic) raise signiﬁcant ethical concerns.

History And Biology

The term “stem cell” (in German Stammzelle) was coined in 1868 by Ernst Haeckel, who used it to describe the ﬁrst single cells from which all multicellular organisms supposedly evolved. He also used the term to refer to the fertilized egg because it gives rise to all the cells that make up an organism (Ramalho-Santos and Willenbring 2007). However, today the term “stem cell” is used to refer to special types of cells that have the ability to divide indeﬁnitely and to give rise to specialized cells given the right conditions. These cells can be derived from mature adult tissues and preimplantation embryos. They can also be created by reprogramming somatic cells so that they behave like embryonic stem cells. Stem cells that are created in this manner are referred to as induced pluripotent stem cells (iPSCs).

The beginnings of adult stem cell research can be traced back to 1961 when Till and McCulloch discovered stem cells in the bone marrow of mice (Till and McCulloch 1961). Adult stem cells, also known as somatic stem cells, lie dormant in most adult tissues in a microenvironment known as the stem cell niche. Their primary function in the human body is to maintain the homeostasis of tissues and to repair them when damaged by replacing the cells that have either died or lost function. Adult stem cells can be derived from infants, children, and adults as well as from the placenta and the umbilical cord after the birth of a child. In humans, these cells are also found in the bone marrow, the skin, and the intestine, among other places.

Adult Stem Cells And Embryonic Stem Cells

Adult stem cells are often contrasted with embryonic stem cells. The latter are derived from the inner cell mass of a preimplantation embryo which has to be killed in the process. Embryonic stem cells were ﬁrst isolated in humans in 1998 (Thompson et al. 2008). Whereas embryonic stem cells are said to be pluripotent because they can differentiate into any type of tissue, adult stem cells are said to be multipotent, meaning that their potential to differentiate into different cell types is limited (they are lineage restricted). However, there is growing evidence that adult stem cells have greater plasticity than previously thought. For example, adult bone marrow stem cells have been found to differentiate into several tissue-forming cells including bone, muscle, tendon, liver, kidney, and heart cells (Groove et al. 2004).

Therapeutic Potential Of Adult Stem Cells

The proliferative and development potential of human adult stem cells means that they can be used to treat many degenerative diseases including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, diabetes, and Duchenne muscular dystrophy. These diseases result from the death or dysfunction of one or a few cell types. Replacing such cells by transplantation could therefore offer long-term treatment for these ailments and greatly help alleviate the suffering of patients and their families. Other potential beneﬁciaries of stem cell therapy include accident victims and war casualties.

Adult bone marrow-derived stem cells have been used routinely for over 50 years to treat leukemia and other blood disorders. They have also been used to replace the endogenous stem cells destroyed by high doses of chemotherapy and radiation used in cancer treatment (Saba et al. 2000). Because adult stem cells can be made to specialize into different kinds of cells, the generated cells could also be used to test the safety and efﬁcacy of new drugs for a variety of diseases, thus removing the need for using animal models and shortening the drug development process. Scientists also envision using adult stem cells to grow complete organs such as the kidney and liver for autologous transplantation.

It must be emphasized that with the exception of the treatment for leukemia and other blood disorders, all other adult stem cell therapies are experimental in nature and do not therefore ﬁt into the medical futility debate. It is not that adult stem cell interventions have a very low probability for success; rather, we simply do not have solid empirical evidence to support the medical use of adult stem cells at this point in time.

Ethical Issues

Adult Stem Cells And The Principle Of Subsidiarity

Because the isolation of adult stem cells does not involve the destruction of embryos, some authors have invoked the principle of subsidiarity and called for a moratorium on human embryonic stem cell research in favor of adult stem cell research. According to this principle, the instrumental use of embryos can be justiﬁed only if no suitable alternatives exist for achieving the same goals (see Pennings and Steirteghem 2004; Town and Jones 2004). Indeed, opponents of embryonic stem cell research contend that such an alternative exists in the form of adult stem cells, which already have a track record of success in treating diseases. These cells have recently been found to be more versatile than previously thought, and because they can be taken from the patient whom they will treat, the problem of immune rejection can be circumvented. In the case of embryonic stem cells, this problem can only be avoided by using expensive immunosuppressive drugs or by cloning, which raises its own unique ethical problems.

A major problem with this line of reasoning, however, is that it assumes that the two research programs are alternatives. At the moment, scientists are unable to tell which of the two types of cells offers more potential for developing new therapies. Indeed, the general consensus within the scientiﬁc community seems to be that all stem cell research programs, including induced pluripotent stem cell (iPSC) research, should be pursued simultaneously in order to maximize the chances of discovering new therapies. Furthermore, the versatility of adult stem cells is still under debate, and compared to embryonic stem cells, they are less restricted in potency. This may limit how they can be used to treat diseases. Another point of concern is that adult stem cells are found in very small quantities and are difﬁcult to access and culture.

Adult Stem Cell-Generated Gametes

Another signiﬁcant ethical issue concerning adult stem cells is the possibility of creating human gametes – spermatozoa and ova from adult stem cells for reproductive purposes. A team of scientists has already been able to turn human bone marrow stem cells into spermatogonia, the precursor of sperm which can be grown into mature sperm (Drusenheimer et al. 2007). This technology could help gametically infertile couples and gay people (both male and female) to have their own genetically related children. This however raises a gamut of religious and moral quandaries which are unaddressed neither by the polemics of beneﬁts nor the notion that both the donor and end user of adult stem cell-derived gametes are one and the same person. Besides, in order to test the functionality of gametes derived from stem cells, scientists will have to speciﬁcally create embryos for research purposes.

To be sure, those who believe that human embryos have the same moral status as adult humans might argue that this is tantamount to using another human being merely as a means to an end, which is morally objectionable. Moreover, gametes that are created in this manner have a high risk of being damaged or may have undetectable genetic abnormalities that could cause disease in offspring.

Stem Cell Tourism

But the main ethical issue concerning adult stem cells is the rise of stem cell tourism, a phenomenon where desperate patients from around the world travel abroad in search of unproven stem cell interventions not available in their home countries. Hundreds of stem cell clinics have sprouted throughout the world claiming to offer a cure for a host of neurodegenerative diseases ranging from muscular dystrophy, Stach’s disease, and Alzheimer’s disease. However, with the exception of stem cell transplants for certain types of cancers and blood disorders, there is no evidence to suggest that stem cell transplants are therapeutically efﬁcacious. These clinics mainly operate in developing countries such as China, India, Thailand, Mexico, South Africa, the Dominican Republic, and Costa Rica. A few of these clinics are also to be found in America and Germany and in some eastern European countries such as Russia and Ukraine. The demand for stem cell interventions has been fuelled by a rapidly aging population and the concomitant increase in neurodegenerative disorders. The uncritical portrayal of stem cell therapies by the media has also contributed to the growth of this industry.

Most of these clinics are driven by commercial interests and have been accused of exploiting desperate patients (mainly from developed nations) by raising false hope and quick ﬁxes. These clinics use only adult stem cells, which are marketed as a viable alternative to the ethically controversial embryonic stem cells. Adult stem cell therapies are also promoted as being natural and safe because they come from the patient’s own body.

Unfortunately, the treatments being advertised by these clinics are mainly experimental in nature and lack clinical evidence of safety and efﬁcacy. This puts patients at the risk of infection on the transplantation site, aberrant stem cell migration, tumor formation, neurological complications, and autoimmune rejection in case of allogenic transplantation. In addition, the targeted disease may still be present in case of autologous use. These unregulated treatments may also render the patients ineligible for genuine experimental treatments (Gunter et al. 2010). Additional medical risks to patients include inadequate postoperative care and monitoring as patients have to go back to their home countries after treatment. There is also concern that some of these clinics may not even be offering any stem cell interventions. Patients and their families are also at risk of experiencing ﬁnancial harm. They have to raise funds to meet the high cost of treatment, travel, and accommodation, and some of these costs may not be covered by health insurance. The growth of these clinics also poses a threat to the ﬁeld of stem cell medicine itself. Public conﬁdence in cell-based therapies could be eroded, and scientists participating in legitimate clinical trials may be lumped together with the unscrupulous ones and denied research funds.

Access To Stem Cell Therapies And Global Justice

Another issue that needs to be addressed at this juncture is the positive and negative effects of stem cell tourism on the health-care systems of the destination countries. Stem cell tourism is a lucrative source of revenue, which can be used to improve the public health infrastructure of the destination country. Indeed, stem cell tourism has been a huge source of foreign exchange for Asian economies.

But stem cell tourism (like all other forms of medical tourism) also raises questions of global justice. Although most stem cell clinics in developing countries such as India and China are run by locals, the majority of patients attending these clinics come from highly developed countries such as the USA and the UK. This creates internal brain drain in that although the local health-care workers do not physically leave their home countries, they attend to foreign patients. The local people are often too poor to afford the high fees charged by these clinics. It has also been argued that medical tourism (and this includes stem cell tourism) makes destination countries redirect resources away from basic health-care services, thus depriving and disadvantaging local citizens and distorting local health-care priorities.

Unless stem cell tourism is properly regulated, it has the potential of undermining efforts to address structural inequity in health-care provision in the destination countries. This can ultimately contribute to the perpetuation of global health inequalities.

Ethical Guidelines And Regulation

There have been attempts at both international and national levels to address the problem of unregulated stem cell therapies. Some of the measures that have already been taken include the drafting of international research guidelines for stem cell scientists, patient education, tightening of national regulation, and reinforcing the already existing ethical guidelines (Zarzeczny et al. 2014). The International Society for Stem Cell Research (ISSCR) has already developed and published Guidelines for the Clinical Transplantation of Stem Cells (2008a) and a Patient Handbook for Stem Cell Therapies (2008b) for those seeking stem cell-based interventions. In May 2011, the largest stem cell clinic in Europe called the Xcell-

Center was closed down by the German authorities following the death of a baby undergoing autologous adult stem cell transplantation. The clinic had been operating through a loophole in the country’s regulations concerning experimental treatments which has since been sealed. In the Netherlands, private stem cell clinics are prohibited (Sheldon 2007). Whereas some countries such as Turkey have no regulations for stem cell practices, a number of countries such as China, India, and Malaysia have developed their own stem cell guidelines and policies. In the USA, the Food and Drug Administration (FDA) has the authority to regulate adult stem cell therapies.

Of course regulatory guidelines are effective only to the extent they are recognized and obeyed. In some jurisdictions, stem cell research guidelines have proved difﬁcult to enforce. This has largely been blamed on laxity and complicity on the part of the regulatory authorities especially government and medical establishments (Kiatpongsan and Sipp 2009).

Conclusion

Although adult stem cell research is not as controversial as embryonic stem cell research, it does raise ethical and policy challenges that are common to all types of stem cell research. The best way to address these challenges is to develop and implement a robust ethical and regulatory regime that will guarantee the safety and well-being of research participants. However, such regulation must be balanced against the need to promote scientiﬁc progress.

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