Organoids: what are they and how are they made?

Organoids are a three dimensional miniaturised version of an organ or tissue that are derived from stem cells.

Heart organoids look like the the picture on the left, and act and function like a heart does.

These heart organoids that have been engineered from stem cells can be used for a variety of research as well as have medical applications.

Heart organoids can be used for disease modelling, especially coronary heart disease, and can be used to see scenarios which include ventricular septal defects that can happen during maternity. They may also be used for regenerative medicine and tissue engineering, as they can be engineered to produce specific cardiac tissues, that can be used to treat medical issues; such as myocardial infarction and heart failure. The risk of heart failure in the USA has increased to 24% in 2024. This is expected to carry on increasing. At the moment heart failure is treated with either a pacemaker, heart surgery or medication. These measures only help prevent heart failure from worsening. Cardiac organoids can be used to restore the damage on the cardiac tissue as well as restore the damaged blood vessels. This is still in the preclinical stages of testing, however is very promising, but leads to the question of how and where will we get these stem cells that are required to form the organoids?

Stem cells are able to regenerate/differentiate into specialised cell types. There are multiple different types of stem cells, Multipotent stem cells, Pluripotent stem cells, embryonic stem cells and induced pluripotent stem cells.

These all have different functions through the human life and are needed at different times throughout growth.

What is the difference between embryonal and induced pluripotent stem cells?

Embryonic stem cells are acquired from early stage embryos (blastocyst) and are able to differentiate in to any cell type within the body, they have no limitations. However, the use of embryonal stem cells leads to ethical concerns and debates. The testing and growing of embryos leads to multiple questions, when is an embryo considered alive? How long do can this embryo grow for before it becomes a cause for concern? What testing is allowed on the embryo?

I think these questions will always be open for debate, due to there being no definitive answer to any of these questions, so where do scientist draw the line? At the moment there is a 14 day rule, and after 14 days the embryos must be killed.

Should this be extended, reduced or kept the same?

The other type of stem cell that can be used to produce organoids are induced pluripotent stem cells. These are created by altering adult (somatic) stem cells by using genetic factors. The use of induced pluripotent stem cells eliminates the ethical debate that using embryonic stem cells creates.

This video explains how induced pluripotent stem cells are made using transcription factors.

Is stem cells the future of medicine? Will scientists eventually be able to grow organs and use them as transplants? Only time will tell.

References

Aleksandra Kostina, Volmert B, Aguirre A. Human heart organoids: current applications and future perspectives. European Heart Journal [Internet]. 2023 Dec 16;45(10). Available from: https://academic.oup.com/eurheartj/article/45/10/751/7476619?login=true

Delivering cardiac organoids to help the heart to recover after a heart attack [Internet]. Musc.edu. 2025 [cited 2025 Mar 11]. Available from: https://web.musc.edu/about/news-center/2023/06/05/cardiac-organoid-delivery

Bozkurt B, Ahmad T, Alexander K, Baker WL, Bosak K, Breathett K, et al. HF STATS 2024: Heart Failure Epidemiology and Outcomes Statistics An Updated 2024 Report from the Heart Failure Society of America. Journal of Cardiac Failure [Internet]. 2024 Sep 1;31(1). Available from: https://www.sciencedirect.com/science/article/pii/S107191642400232X?via%3Dihub