In the age of incredible medical advancements, stem cell research has become one of the most controversial yet potentially beneficial fields in medicine. From the promise of repairing nerve damage to the potential to cure currently incurable diseases like Parkinson’s, stem cells have inspired a strong sense of hope for the future of healthcare and medicine. However, that same hope has been met with hesitation and controversy, particularly around how stem cells are sourced. Back in 2001, President George W. Bush restricted federal funding for stem cell research, only allowing cell lines that already existed and had been created prior to his policy [1]. Later, in 2009, President Barack Obama established an executive order that revoked Bush’s policy and allowed federal funding for stem cell research[2].
At the center of the debate is the question of whether embryos, which are used in some types of stem cell research, are human life and whether they deserve the same moral status as a developed person. Some believe that they are, and some believe that they aren’t for many different reasons. With the development of alternatives, such as induced pluripotent stem cells (iPSCs), which come from adult stem cells, this debate has become even more complex–blending science, ethics, and innovation in ways that demand thoughtful conversations.
This blog explores the science and medical potential of stem cells, the ethical dilemmas surrounding their use, and ultimately argues that stem cell research benefits society despite the controversies.
What are stem cells?
Unlike most cells in the body, stem cells can self-renew themselves. Muscle cells, blood cells, and nerve cells, for example, typically cannot replicate [3]. This is one reason why paralysis is often permanent: once nerve cells are damaged, they generally cannot regenerate. Another remarkable trait of stem cells is their ability to develop into many different cell types. There are two main categories of stem cells: “pluripotent” stem cells and somatic stem cells (commonly referred to as “adult” stem cells) [3].
Pluripotent stem cells have the ability to differentiate into all cells of the adult body, including brain, nerve, skin, hair, and muscle cells–highlighting their vast potential for medical treatments. There are two main types of pluripotent stem cells: induced pluripotent stem cells (iPS cells), which are made from skin or blood cells, and embryonic stem cells (ES cells), which are derived from early-stage human embryos.
Figure 1 from [3]: a diagram displaying the generation of embryonic stem cells
Somatic or “adult” stem cells are found in specific adult tissues or organs and can only differentiate into a specialized cell type of that tissue or organ. These cells serve to replace cells that have either been damaged or lost in the tissue. [4] Adult stem cells, specifically ones found in bone marrow, can be used to treat leukemia and other diseases as well as potential treatment for conditions like type 1 diabetes [4]. Unlike embryonic stem cells, adult stem cells do not result in the destruction of embryos, becoming a major focus as a potential replacement of ES cells for the future.
Figure 2 from [15]: a diagram displaying where somatic (“adult”) stem cells are found in the human body
Benefits of stem cell research and therapy
There are many ways stem cell research applies to treating patients such as stem cell therapy, and there are various forms of that therapy and other techniques. One specific field is oncology. Cancers that affect blood cells, such as leukemia and lymphoma, result in a large number of an individual's blood stem cells being destroyed due to chemotherapy and radiation therapy. Stem cell transplants help restore blood-forming stem cells for an individual. These blood stem cells can be white blood cells, which are a part of your immune system; red blood cells, which help carry oxygen; and platelets, which help prevent blood clots–all of which are very crucial for an individual's health [6].
Another field where stem cells show great potential is peripheral nerve regeneration. The peripheral nervous system is the part of one’s nervous system that lies outside the brain and spinal cord, which controls things like senses, movement, and unconscious processes [7]. As mentioned before, pluripotent stem cells can differentiate nearly into any cell type, including Schwann cells, which are crucial for peripheral nerve repair. Various stem cell sources–such as bone marrow mesenchymal stem cells (BMSCs), ES cells, adipose-derived stem cells (ADSCs), neural stem cells, and iPSCs--all have demonstrated efficiency in improving function recovery, reducing muscle atrophy, and encouraging axonal regrowth in animals with nerve injuries [8].
Stem cells can also be applied to treating people with Parkinson’s disease. Parkinson’s disease is a neurodegenerative disorder that affects the dopamine-producing neurons within the brain [9]. Recent clinical trials tested the safety and feasibility of transplanting human embryonic stem cells to replace dopamine cells in the brain that have been damaged by Parkinson’s. The trials found that there were no safety issues with the transplanted cells, no tumors or graft-induced dyskinesias (GID) were observed up to 18 months, and most treatment-emergent adverse events were mild or moderate. Furthermore, patients were showing meaningful improvements in motor functions, increased dopamine activity in the brain, and no long term immunosuppression [10].
The controversy
Though there are many potential benefits stem cells can have in medicine and improve people’s lives that were thought to not be recoverable, stem cells have remained one of the most controversial discussions within medicine over the past 20 years. As mentioned earlier, pluripotent stem cells often come from embryos, though not always, which leads to the debate over the ethics of destroying human embryos, and whether embryos are considered human life. And if it is considered human life, is that equivalent to killing a human child? Michael Sandel, an American political philosopher and professor at Harvard University, in an interview stated that the embryos are not implanted and growing in a uterus, nor is it a fetus and doesn't have any human features or form. It is rather a cluster of cells in a petri dish [11]. In this regard, an embryo is not a fetus, which therefore is not a human life and destroying it would not deem it killing a child. However, others, such as Robert P. George and Christopher Tollefsen, are full human from the moment they are fertilized and how each and every one of us were once embryos. Further, they also emphasize that embryos deserve full moral respect [12].
There is also a religious aspect to this ethical debate for many people. For instance, the United States Conference of Catholic Bishops stated that they opposed the National Institutes of Health guidelines for embryonic stem cell research, stating that embryos are human beings and the destruction of embryos is condemned as a moral offense and many more reasons [13]. However, Judaism has shown strong support for embryonic stem cell research, seeing stem cell research as a mitzvah (sacred obligation) and failing to heal when possible is akin to shedding blood [14].
Conclusion
Stem cell research remains to this day as an incredible scientific and medical field, but also a thought provoking ethical debate. As explored in this blog, stem cells have shown great benefits within various fields of medicine–from generating damaged nerves to helping patients with Parkinson’s disease and leukemia. These advancements highlight how impactful and diverse stem cells are in medicine, and how they can improve the quality of life for many people. Further, adult stem cells and iPSCs could possibly become a “replacement” or at least a different path in stem cell research that would remove the ethical dilemma of ES cells.
Ultimately, this deliberation shows that the promise of healing offered by stem cell research outweighs the controversy. While the debate over ES cells is a very important conversation to have and the reasons why one might be against the use of ES cells are valid, acknowledging and understanding the science behind the research and its benefits helps ensure the ethical concerns do not overshadow life-saving potential. By continuing to keep the public well informed as well as respect one’s beliefs and religion, stem cell research could offer many medical breakthroughs that could save or improve many people’s lives.
References
[1] Bush GW. 2006 Jul 19. President discusses stem cell research policy. The White House, President George W. Bush Archive. [accessed 2025 Jul 2]. https://georgewbush-whitehouse.archives.gov/news/releases/2006/07/20060719-6.html
[2] Obama BH. 2009 Mar 9. Removing barriers to responsible scientific research involving human stem cells. The White House, President Barack Obama Archive. [accessed 2025 Jul 2]. https://obamawhitehouse.archives.gov/the-press-office/removing-barriers-responsible-scientific-research-involving-human-stem-cells
[3] National Institutes of Health. STEM cell basics. Stem Cell Information [Internet]. Bethesda (MD): NIH; [updated unknown; cited 2025 Jul 3]. Available from: https://stemcells.nih.gov/info/basics/stc-basics
[4] Children’s Hospital Boston. Pluripotent stem cell research. Stem Cell Program Research [Internet]. Boston (MA): Children’s Hospital; [cited 2025 Jul 3]. Available from: https://research.childrenshospital.org/research-units/stem-cell-program-research/stem-cell-research/pluripotent-stem-cell-research
[5] Center for Stem Cells and Regenerative Medicine, University of Notre Dame. Adult stem cells. Alternative Stem Cell Sources. [accessed 2025 Jul 5]. https://stemcell.nd.edu/research/alternative-stem-cell-sources/adult-stem-cells/
[6] National Cancer Institute. Stem cell transplant [Internet]. Bethesda (MD): National Cancer Institute; [cited 2025 Jul 3]. Available from: https://www.cancer.gov/about-cancer/treatment/types/stem-cell-transplant
[7] Cleveland Clinic. Peripheral nervous system (PNS) [Internet]. Cleveland (OH): Cleveland Clinic; [cited 2025 Jul 3]. Available from: https://my.clevelandclinic.org/health/body/23123-peripheral-nervous-system-pns
[8] Yi S, Zhang Y, Gu X, Huang L, Zhang K, Qian T, Gu X. Application of stem cells in peripheral nerve regeneration. Burns Trauma. 2020;8:tkaa002.
[9] Parkinson’s Foundation. What is Parkinson’s? [Internet]. Miami (FL): Parkinson’s Foundation; [cited 2025 Jul 3]. Available from: https://www.parkinson.org/understanding-parkinsons/what-is-parkinsons
[10] Tabar V, Sarva H, Lozano AM, Fasano A, Kalia SK, Yu KKH, et al. Phase I trial of hES cell‑derived dopaminergic neurons for Parkinson’s disease [Internet]. Nature; 2025 [cited 2025 Jul 3]. Available from: https://doi.org/10.1038/s41586-025-08845-y
[11] Harvard Stem Cell Institute. Examining the ethics of embryonic stem cell research [Internet]. Cambridge (MA): Harvard Stem Cell Institute; Spring 2007 [cited 2025 Jul 3]. Available from: https://www.hsci.harvard.edu/examining-ethics-embryonic-stem-cell-research
[12] Condic SB, Condic ML. 2008. Embryonic human beings: scientific and philosophical perspectives on personhood and moral status. J Christ Bioeth [Internet]. [cited 2025 Jul 3];14(2):119–45.
[13] United States Conference of Catholic Bishops. President Bush’s stem cell decision. USCCB: Human Life & Dignity—Stem Cell Research. [accessed 2025 Jul 5]. https://www.usccb.org/issues-and-action/human-life-and-dignity/stem-cell-research/president-bushs-stem-cell-decision
[14] Union for Reform Judaism. Stem cell research. ReformJudaism.org. [accessed 2025 Jul 5]. https://reformjudaism.org/stem-cell-research
[15] MedChemExpress. Stem cell classification and its application. MedChemExpress Literature. [accessed 2025 Jul 5]. https://www.medchemexpress.com/literature/stem-cell-classification-and-its-application.html
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