What Are Organoids? Exploring Their Role in Advancing Medical Research and Improving Human Health

What are organoids?

Organoids are tiny three-dimensional structures of cells that are derived from stem cells and prepared outside of the human body. They are structurally and functionally similar to the actual organs in the human body.

Intestinal Organoid. Credit: Meritxell Huch

How are they made?

Scientists grow organoids from stem cells. Typically, human pluripotent stem cells are taken from embryonic or adult tissues. These stem cells are grown in lab cultures with optimum conditions for differentiation and growth into the desired organoid. The stem cells obtain their nutrients and growth factors through the cultural environment and gradually develop into three-dimensional structures resembling the structure and function of the organ.

What are some of the types of organoids?

Stem cells are used to develop different tissues by providing the conditions for their development and utilizing various techniques. Some of the main types of organoids are:

Brain organoids

Due to their complex structure and unique functions in humans, studying brain development in animal models is highly ineffective. Brain organoids provide a unique opportunity to simulate the development of different brain regions and study their functions in a three-dimensional structure.

Brain organoids are stem-cell-derived three-dimensional structures mimicking the physiology and anatomy of the brain. Using human pluripotent stem cells or embryonic stem cells from mice, scientists create brain organoids by growing the stem cells in optimum conditions.

Brain organoids are used in many research areas like modeling diseases, studying brain development, understanding the progression of diseases, for example, neurodevelopmental, genetic, and other neurological conditions, and testing drugs for various brain-related conditions.

Lung organoids

Lungs are also complex to study due to the complex vasculature and enhanced functional variety of cells. Lung organoids can be grown using stem cells. These organoids differentiate into complex structures which resemble actual lung tissue.

Similarly to brain organoids, lung organoids are used to understand diseases, test drugs, and study lung development. The development of lung organoids has opened doors for studying and modeling diseases in new ways.

Cancer organoids

Scientists use patients’ tumor cells to develop a 3D organization of cells structure resembling actual cancer cells. Cancer organoids provide a significant improvement over studying cancer on previous types of cell cultures and animal models. They provide a more detailed structural and functional resemblance to the tumor cells that is beneficial in understanding the behavior of cancer cells accurately. Another advantage of cancer organoids is that they maintain the genetic and molecular signatures to provide an accurate picture to study cancer cells and their response to treatments. Cancer organoids are also useful in adjusting treatments depending on the patient’s cancer cells’ specificities and responses. It provides opportunities for patient-specific treatment strategies.

Intestinal organoids

Intestinal organoids are also called enteroids or colonoids. They are hard to develop due to the complex structure of the intestinal tissues. The intestinal tissues are placed closely to neural and immune tissues, and microbiomes in the intestines also influence many processes in the gastrointestinal system (GIT).

However, scientists have been able to develop intestinal organoids, including specific microbiome environments. Intestinal organoids are used to replicate different regions of the intestines, and they are used to study GIT diseases such as inflammatory bowel disease and colorectal cancer and test different types of treatments for these diseases.

Similarly, other types of organoids can be developed. Liver, pancreatic, and kidney organoids are some of the other types of organoids that scientists develop to model diseases, test drugs and study the progression of diseases.

What are the advantages of organoids?

In developmental biology, organoid development is an exciting area of research. Organoids offer many advantages over traditional cell cultures that can be beneficial in understanding disease mechanics, studying the effects of the drugs, and improving individualized treatments. Some of these advantages are:

Structural and functional similarity

As organoids develop out of stem cells, they develop through similar pathways as human organs that preserve the cellular structures of the tissues. Due to their three-dimensional structure, they provide better morphological complexity compared to traditional 2-D cell cultures.

Furthermore, their close anatomical and physiological resemblance to the organ under study makes them the most suitable models for studying different tissues and whole organs.

Extracellular interactions

Organoids also make studying cell-to-cell and cell-to-extracellular interactions feasible as they are grown in an extracellular matrix and develop into structures that resemble human organs.

Reducing the need for animal models

As organoids make it possible to study human organs in their complete structures, the need for using animal models for such studies significantly diminishes. Organoids are an effective substitute for animal models, and they improve on them by preserving the structural complexities of an organ, hence, providing a suitable model to study diseases.

Individualized disease modeling

Organoids are developed by taking cells from an individual which allows the development of an individualized study approach for studying various phenomena. It also helps to study disease specifics for a particular individual and develop experiments to test drugs specific to that individual.

What are some of the applications of organoids?

Organoids can be used for various purposes, including studying organ development and understanding disease pathogenesis, enhancing understanding of cancers, and developing drugs by testing them in a similar environment. Some of the common areas of application of organoid research are as follows:

Personalized medicine

Another area for organoid research is personalized medicine. Organoids are used to study the specific mechanism of diseases in individuals and to test drugs for those individuals. It provides an opportunity to develop treatments that can be specific to the needs of the individuals. Genetic similarity allows for studying individual variations in a disease mechanism and analyzing individual responses to various drugs.

Regenerative medicine

Regenerative medicine deals with engineering and replacing the tissues of the body that are damaged due to injury, disease, or inherited issues. Currently, this area is the focus of many organoid studies. Organoids can be developed to graft and transplant tissues in the human body and this will help restore the function of the tissues eliminating the need for current treatment strategies that focus on clinical improvement.

Cancer research

Organoids can also be used to study unhealthy tissues as well as replicate healthy organs of the body. One such fascinating application is studying tumor cells by developing tests to detect abnormalities and testing drug sensitivities of the cancer cells. It allows an understanding of the tumor behavior that helps predict the response of cancer cells to different drugs, and it also helps study the outcomes of the disease process.

Biomedical research

Due to their structural and functional similarity to human organs, organoids are widely used in biomedical research for various purposes. They are used to study organ development and disease pathogenesis. Scientists also use organoids to test the efficacy of drugs and study the toxic effects of drugs on the physiology of those organoids. Research is also ongoing in analyzing the potential of organoids in developing viable human organs for their use in organ transplantation.