Stem cell research is at the frontier of scientific discoveries in the modern age. Stem cells are created in early states of human development and retain the ability to specialize into a range of cell types. In theory, stem cells can differentiate into brain, muscle, and heart cells among other tissues. The types of stem cells used for medical purposes are hematopoietic cells. These cells are responsible for the formation of blood cells and are found in the bone marrow. (1) While stem cell research continues to be a controversial topic, calling into question the ethics of gene editing among other uses, it also has the potential to serve many purposes in developing cures or treatments for various viruses such as Human Immunodeficiency Virus (HIV).
HIV is an autoimmune virus that attacks one’s own cells and when left untreated can progress into Acquired Immunodeficiency Syndrome (AIDS). HIV patients are especially vulnerable if they have other health issues due to an already weakened immune system. Currently, there is no cure for HIV, but the common treatment is antiretroviral therapy which involves daily medications to reduce the amount of the virus in the blood as well as diminish the possibility of transmission (2).
In 2007, Timothy Ray Brown, also known as the “Berlin Patient,” became the first person to be cured of HIV. Diagnosed in 1995 with HIV and then with acute myeloid leukemia in 2006, Brown had been prescribed many different treatments (3). His doctors searched for a bone marrow donor with a genetic mutation causing resistance to HIV (4). The CCR5 receptor normally lies outside a white blood cell. Through interaction with this receptor, HIV works its way inside the cell. However, the CCR5 delta 32 mutation fails to have a functional receptor for HIV to communicate with rendering the white blood cell “resistant” (5) Subsequent tests revealed that the bone marrow transplant had significantly reduced the amount of HIV in Brown’s blood while simultaneously sending his cancer into remission (6).
More recently, Adam Castillejo, a man previously known as the “London Patient,” identified himself in 2020 as the second person to be cured of HIV. Castillejo had been diagnosed with HIV in 2003 and later discovered he had Stage IV Hodgkin’s lymphoma (7). Similar to Brown’s case, doctors gave Castillejo a bone marrow transplant in 2019, which effectively treated both the HIV and the cancer (8).
While a bone marrow transplant is a common treatment for many cancer types, in the case of both Brown and Castillejo, the transplant simultaneously cured their HIV. Stem cell transplants replace the cells of patients whose white blood cells are depleted through radiation and chemotherapy. Scientists and researchers note that these conditions will not necessarily allow for a common cure for all HIV positive patients, but these findings indicate the role that stem cells play in a potential treatment. The unusual circumstances under which both Brown and Castillejo were cured demonstrates the possibility of suppressing HIV through engineering resistant stem cells (8). Brown and Castillejo’s doctors chose donors with two copies of the CCR5 gene mutation to enable HIV resistance (9). The success of stem cell transplants in both Brown and Castillejo’s cases provides hope for a future cure for HIV positive patients also diagnosed with cancer. Yet, there remain ample research opportunities to edit the expression of the CCR5 gene in HIV positive patients who do not necessarily also have cancer.
The concept of bioethics surrounds stem cell research and therapies for many reasons. There are two types of stem cells: embryonic and adult. Use of embryonic cells from aborted fetuses continues to be a primary point of contention. However, broader concerns such as how the advancement of stem cell research could potentially lead to extreme outcomes like human cloning also exist. Apart from these issues, safety remains a priority when using stem cells in medical practice due to possible mutations from stem cell implantation, the human body’s rejection of foreign cells, and other complications (10). While continued debate over the ethics and uses of stem cells is expected, the future of medicine may involve stem cell generated treatments and cures for previously deadly diseases.
References:
- “What Are Stem Cells?” What Are Stem Cells? - Health Encyclopedia - University of Rochester Medical Center, www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=160&contentid=38.
- “HIV Treatment: The Basics Understanding HIV/AIDS.” National Institutes of Health, U.S. Department of Health and Human Services, 2 Mar. 2020, aidsinfo.nih.gov/understanding-hiv-aids/fact-sheets/21/51/hiv-treatment--the-basics#:~:text=treatment%20for%20HIV%3F-,The%20treatment%20for%20HIV%20is%20called%20antiretroviral%20therapy%20(ART).,HIV%20live%20longer%2C%20healthier%20lives.
- Cohen, Jon. “How Did the 'Berlin Patient' Rid Himself of HIV?” Science, 10 Dec. 2017, www.sciencemag.org/news/2014/09/how-did-berlin-patient-rid-himself-hiv.
- Cohut, Maria. “2nd Person Cured of HIV Thanks to Stem Cell Transplant.” Medical News Today, MediLexicon International, 11 Mar. 2020, www.medicalnewstoday.com/articles/2nd-person-cured-of-hiv-thanks-to-stem-cell-transplant.
- Kempner, Martha. “The Genetic Mutation Behind the Only Apparent Cure for HIV.” For the HIV/AIDS Workforce, TheBodyPro, 14 Mar. 2019, www.thebodypro.com/article/genetic-mutation-behind-hiv-cure.
- Salzman, Sony. “The Berlin Patient, the First Person Ever Cured of HIV, on Taking PrEP: ‘I Want a Full Sexual Life.’” For the HIV/AIDS Workforce, TheBodyPro, 12 Nov. 2019, www.thebodypro.com/article/timothy-ray-brown-prep.
- Haghighat, Leila, and Amrit Kamboj. “The 'London Patient' Goes into HIV Remission: Here's What That Means for HIV Treatment.” ABC News, ABC News Network, 8 Mar. 2019,abcnews.go.com/Health/london-patient-hiv-remission-means-hiv-treatment/story?id=61564150#:~:text=The%20so%2Dcalled%20%E2%80%9CLondon%20Patient,blood%20cancer%20called%20Hodgkin's%20lymphoma.
- Mandavilli, Apoorva. “The 'London Patient,' Cured of H.I.V., Reveals His Identity.” The New York Times, The New York Times, 9 Mar. 2020, www.nytimes.com/2020/03/09/health/hiv-aids-london-patient-castillejo.html.
- Warren, Matthew. “Second Patient Free of HIV after Stem-Cell Therapy.” Nature News, Nature Publishing Group, 5 Mar. 2019, www.nature.com/articles/d41586-019-00798-3#:~:text=A%20person%20with%20HIV%20seems,the%20virus%20using%20this%20method.
- Hyun, Insoo. “The Bioethics of Stem Cell Research and Therapy.” The Journal of Clinical Investigation, American Society for Clinical Investigation, Jan. 2010, www.ncbi.nlm.nih.gov/pmc/articles/PMC2798696/#:~:text=The%20main%20bioethical%20issues%20associated,derivation%20and%20use%20for%20research.&text=At%20present%2C%20new%20ethical%20issues,all%20types%20of%20human%20tissue.