Harness the Power of Stem Cells

Stem cells are arguably one of the most heavily researched topics in the field of regenerative medicine. Their ability to divide and renew themselves for a long period of time and their potential to give rise to various specialized cells are what scientists all over the world are trying to harness for the advancement of global health. Through years of research and experiments, scientists have developed two methods of creating stem cells. These breakthroughs open up so much more opportunities for stem cell applications.

Method 1: Somatic Cell Nuclear Transfer (SCNT)

This method of creating stem cells requires the use of embryos, which generates moral issues that we will discuss later. To perform SCNT, a somatic cell is first isolated from the patient and the nucleus is removed through the process of enucleation. Simultaneously, a donor egg is also being enucleated. The next step is to transfer the nucleus of the somatic cell into the empty donor egg. When this happens, the egg cell "reprograms" the patient's DNA in the nucleus. When the egg cell is stimulated through electric pulses or other forms of stimulation, it will begin to divide and develop into the blastocyst stage. The inner mass of this blastocyst is the embryonic stem cells that will be extracted and conditioned to differentiate into a specific type of cells for the patient's health needs (Bartlett, 2014). A visual summary of the SCNT process can be seen below.

The benefit of this form of creating stem cells is that it eliminates the risk of immune rejection from the patient. Immune rejection is caused by the natural function of our immune system when it recognizes foreign organs or cells and attempts to eradicate it. However, in this case since the nucleus of the patient's somatic cell is transferred to the egg cell during the process of SCNT, the embryonic stem cells obtained at the end will be accepted by the patient's immune system. Despite the health benefits, SCNT has poor efficiency and thus its application is limited (Lee & Prather, 2014). Furthermore, one of the greatest issues with this process is the destruction of a healthy embryo. When the inner mass is removed from the embryo, the embryo can no longer become a fetus. This killing of a potential human being gives rise to debates regarding the moral status of an embryo. While the debates continue to take place, some legal frameworks are established in the United States regarding embryo research. It is currently illegal to create or destroy embryos in a laboratory for research purposes. In order to perform SCNT, the egg cell must be donated with the owner's complete consent (FDA, 2018).

Method 2: Induced Pluripotent Stem Cells (iPSCs)

This method of obtaining stem cells do not require the use of donor eggs or embryos, which avoids the ethical conflicts faced by SCNT discussed above. Another benefit with the use of iPSCs is that it also prevents immune rejection similar to SCNT. In order to conduct iPSCs, somatic cells such as skin or fibroblasts of the patient are isolated and grown in a petri dish. The cells are then treated with "reprogramming" factors carry out by virus vectors to allow the cells to revert back to their pluripotent state. By changing the culture conditions, we are able to stimulate these pluripotent stem cells to differentiate into various cell types for each patient's needs (Chang et al., 2019). A visual summary of the iPSCs process can be seen below.

So why haven't we used iPSCs more widely considering this method avoids many of the issues faced by SCNT? To answer this question, we must understand the risk of mutations. Mutations often occur during cell division when accidental mistakes were made during DNA replication. The nature of pluripotent stem cells have a high rate of turn over, in other words, they tend to proliferate rapidly, which increases the risk of mutations in the cell that can result in cancer (Doss & Sachinidis, 2019). Despite the barriers, with the speed at which modern science is advancing, it won't be long before we discover ways to create and apply stem cells safely. It's exciting to see the dreams we once had with stem cells slowly becoming a reality.

References

1. Bartlett, Zane, "Somatic Cell Nuclear Transfer in Mammals (1938-2013)". Embryo Project Encyclopedia (2014-11-04). ISSN: 1940-5030 http://embryo.asu.edu/handle/10776/8231.

2. Chang, Eun-Ah, et al. “Human Induced Pluripotent Stem Cells : Clinical Significance and Applications in Neurologic Diseases.” Journal of Korean Neurosurgical Society, Korean Neurosurgical Society, Sept. 2019, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6732359/.

3. Doss, Michael Xavier, and Sachinidis, Agapios. “Current Challenges of IPSC-Based Disease Modeling and Therapeutic Implications.” Cells, MDPI, 30 Apr. 2019, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6562607/.

4. FDA. “Therapeutic Cloning and Genome Modification.” U.S. Food and Drug Administration, FDA, http://www.fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/therapeutic-cloning-and-genome-modification#:~:text=In%20the%20United%20States%2C%20SCNT,been%20addressed%20by%20federal%20law.&text=Thus%2C%20though%20legal%2C%20SCNT%20cannot%20be%20federally%20funded.

5. Lee, Kiho, and Randall S. Prather. “Somatic Cell Nuclear Transfer.” Somatic Cell Nuclear Transfer - an Overview | ScienceDirect Topics, http://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/somatic-cell-nuclear-transfer.

Additional Articles

• Want to learn more about the history of SCNT and see how this process "gave birth" to Dolly the Sheep? Click here

• To learn more about iPSCs or if your are curious to see other kinds of stem cell research at the Broad Stem Cell Research Center at UCLA click here.