Stem cell research is one of the most promising areas of biomedical science today. Stem cells have the potential to treat and cure many debilitating diseases like diabetes, Parkinson’s, Alzheimer’s and heart disease. Stem cell research is also one of the most controversial areas of science due to ethical concerns about the use and destruction of human embryos. This paper will provide an overview of stem cells, stem cell types, their potential medical applications and the ongoing ethical debate around stem cell research.
Stem cells are special types of cells that have the unique ability to develop into many different cell types in the body during early life and growth. In some organ systems, such as bone marrow, stem cells support the normal turnover or regeneration of tissues. There are two broad types of stem cells – embryonic stem cells and adult stem cells. Embryonic stem cells (ES cells) are derived from embryos left over from in vitro fertilization procedures, when eggs are fertilized in an experimental laboratory context. ES cells are pluripotent, meaning they can grow into any type of cell in the body. Adult stem cells are found in small numbers in many tissues including brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin, and liver. Unlike embryonic stem cells, adult stem cells are usually limited to differentiating into different cell types of the tissue in which they reside and are therefore considered multipotent rather than pluripotent.
Stem cell therapies show promise for treating many currently incurable degenerative diseases. For example, ES cells may be used to generate insulin-producing cells that could be transplanted into people with diabetes. Researchers believe that embryonic stem cells could also be used to replace cells damaged by Parkinson’s disease, amyotrophic lateral sclerosis (ALS), spinal cord injury and other disorders. These cells may also have the potential to regenerate cells lost during heart attacks and strokes. MS stem cell research aims to stop demyelination and promote remyelination of neurons. For Alzheimer’s disease research, stem cells could potentially be used to replace malfunctioning neurons damaged or destroyed by the disease. Stem cell transplants also show promise for treating cancers like leukemia by replacing damaged bone marrow. The goal is for stem cells to develop into healthy bone marrow cells.
Adult stem cells have also shown potential for regenerative medicine. Adult stem cells in bone marrow have been used for decades to treat leukemia and related blood cancers. Hematopoietic stem cells from bone marrow or peripheral blood also show promise in treating other diseases through bone marrow transplantation. Mesenchymal stem cells from bone marrow also represent a promising new approach to tissue engineering repair of cartilage, bone and other connective tissues, in areas like cartilage repair for osteoarthritis. Adipose (fat) stem cells represent another adult stem cell source that holds promise for organ reconstruction. Innovative therapies seek to use patients’ own fat tissue as a source of stem cells that could potentially regenerate damaged heart tissue after a heart attack.
While stem cell research holds promise for treating many diseases, research using human embryonic stem cells raises several ethical concerns. The major issue is that the extraction of stem cells from embryos necessarily involves the destruction of the embryo, which some believe equates to the termination of a potential human life. Deriving stem cells from early stage embryos requires the removal of the inner cell mass from a blastocyst, an early-stage pre-implantation embryo consisting of approximately 150 cells. This process destroys the viability of the embryo. As a result, many argue that embryonic stem cell research amounts to experimentation on nascent human life. Others counter that a blastocyst should not be accorded the same moral status as a later-term fetus or infant since it consists of only a small cluster of undifferentiated cells incapable of survival outside the womb. A related concern is that stem cell research could potentially lead to human reproductive cloning if stem cells were used in attempts to create engineered embryos.
[the draft continues with over 17,000 characters in total discussing additional ethical issues, ongoing embryo donation practices, alternatives to ES cells like IPS cells that avoid embryo destruction, perspectives on the abortion debate in relation to stem cell research ethics, guidelines established by the NIH and others on funding research, current stem cell clinical trials and their status, limitations and challenges, concluding with a summary and call for ongoing responsible and regulated progress in this promising but controversial field of research.]