Embryonic stem cells (ESCs), derived from the inner cell mass of a blastocyst, are pluripotent stems cells which give rise to all somatic cell types in an embryo. Therefore, making them an invaluable tool in the understanding of complex processes involved in the production of specialised cells and the building of organ structures. The First ESCs were derived in 1981 by two scientists, M. J. Evans and M. H. Kaufman, in which they took 3.5 day old blastocysts from mice and grew them in a cell culture containing mouse embryonic fibroblasts. It was only 8 years later for the first human ESCs to be isolated!

Although, ESCs have high scientific potential, the method of isolating them raises many ethical concerns as they are typically harvested from surplus embryos from vitro fertilisation procedures (IVF)

Applications of Embryonic Stem Cells

The pluripotency and the indefinite self-renewal ability of ESCs has allowed for the in-vitro generation of a limitless number of distinct cell types. This has proved extremely useful in studies relating to early human development and regenerative medicine for degenerative diseases.

Applications of ESCs include but are not limited to the following:

• Germline Modification – Correct potential genetic disorders by making genetic alterations on the ESCs but this raises many ethical issues.
• Knockout Mice – Genetically modified mice, in which a specific gene or genes are selectively switched off. This enables studies of gene function and the modelling of human diseases and thus substantial advancements have been made in both genetic research and therapeutic development.
• Treatment of Degenerative Diseases – ESCs have the capability to treat diseases such as Parkinson’s disease, Alzheimer’s disease and heart disease. This is due to ESCs being able to replace damaged tissues, for example, ESCs being directed to differentiate into dopamine-producing neurons to treat Parkinson’s disease. The added bonus of using ESCs is that there is a reduced risk of immune rejection due to their immature state.
• Future Prospects of Organ Transplantation – As ESCs have furthered our understanding of how cells differentiate into specialised cells it provides hope for the potential of growing whole organs for transplantation.

The Ethical Debate and the 14-Day rule

Although there are many benefits to the pluripotency of human ESCs, there are also numerous ethical issues around how ESCs originate. This is because ESCs are extracted from human embryos therefore research on human ESCs correlates to human testing. Additionally, areas of research like Germline Gene editing on human embryos has many ethical implications around the breaching of human rights and the unknown consequences of gene editing in people.

To balance scientific progress and ethical considerations, the 14 day rule was established in 1990 under the Human Fertilisation and Embryology Act. This international guideline and key governing bodies like the Human Fertilisation and Embryology Authority (HFEA), restricts researchers from growing in-vitro human embryos for longer than 14 days. However, in recent years many scientists have called for an extension in the limit to enable further studies into early human development, provoking ongoing ethical debates.

Human Embryonic Stem Cells have the capability to transform medicine, whether it’s deepening our understanding of genetic disease and early human development or regenerating damaged tissues. However, the shroud of ethical debates regarding embryo destruction and the 14-day rule restricts their use as a potential source of regenerative medicine. Ultimately, finding and establishing a consensus that allows for both further scientific research and strong ethical standards is key to unlocking the full potential of human Embryonic Stem Cells.

Sources:

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Hyun, I., Wilkerson, A. and Johnston, J. (2016). Embryology policy: Revisit the 14-day rule. Nature, [online] 533(7602), pp.169–171. doi:https://doi.org/10.1038/533169a.

Lancs.ac.uk. (2023). Is it time to revisit the 14-day rule? [online] Available at: https://wp.lancs.ac.uk/futureofhumanreproduction/14-day-rule/.

McConnell, S.C. and Blasimme, A. (2019). Ethics, Values, and Responsibility in Human Genome Editing. AMA Journal of Ethics, [online] 21(12), pp.1017–1020. doi:https://doi.org/10.1001/amajethics.2019.1017..

National Research Council (US) and Institute of Medicine (US) Committee on the Biological and Biomedical Applications of Stem Cell Research (2002). Embryonic Stem Cells. [online] Nih.gov. Available at: https://www.ncbi.nlm.nih.gov/books/NBK223690/.

Vazin, T. and Freed, W.J. (2010). Human embryonic stem cells: Derivation, culture, and differentiation: A review. Restorative Neurology and Neuroscience, 28(4), pp.589–603. doi:https://doi.org/10.3233/rnn-2010-0543.