History of Organoid Research: From Sponge Cells to Functional Organs
- September 18, 2021
Let's begin with a simple definition of an organoid which refers to a three-dimensional assembly that contains multiple cell types that are arranged with realistic histology, at least at the micro-scale. Organoids may be formed from human or animal cells, which may be differentiated cells, stem cells, or a mixture of both.
The rising use of organoids is being fueled by rapid development in stem cell derivations and the desire to reduce the use of animal models. Organoids are already being used to understand disease development methods, neoplasia (cancer), they hold important medical and industrial applications (e.g., toxicology), and ultimately, for transplantation. Kerry Grens, an author at The Scientist Magazine, named organoids as one of the “advances of the year.”1 Organoids have already been developed to represent many different parts of the human body, with applications expected to grow over the next few years.
History of Organoid Research
3D organoids are undeniably at the center of disease modeling and drug discovery. Because these cell cultures self-organize into clusters and differentiate into cell types that make up a functional organ, they are much better at mimicking in vivo conditions.
Interestingly, the idea of organoids is not new. Today’s organoid technology is the product of decades of research. In fact, the foundations of the concept go back to the beginning of the 20th century.
Here is a brief rundown of the history of organoids and how Molecular Devices found itself a spot on the timeline with its extensive organoid research solutions.
- Before Stem Cell: Self-organization and Regeneration
- The Importance of Extracellular Matrix (ECM)
- Stem Cell Research
- Induced Pluripotent Stem Cells (iPSCs)
- After Stem Cell: Modern Organoid Research
- Organoid Image Gallery
- Organoid Research at Molecular Devices
Before Stem Cell: Self-organization and Re-aggregation
Self-organization of cells was observed for the first time by Henry Van Peters Wilson in 1907. While doing research for the US Bureau of Fisheries, he discovered that under certain conditions, siliceous sponge cells degenerate into undifferentiated masses of tissues which in turn could self-organize and differentiate into perfect sponges.2 This experiment demonstrated that cells contain the information to create a multicellular structure without external cues or the need for a specific anatomical arrangement.
Over the following decades, other research groups observed similar dissociation- reaggregation patterns with cost-effective and well-studied organisms, such as amphibian pronephros (primitive kidney) in 19443 and embryonic chick cells in 1960.4 These experiments showed the self-organization observed by Wilson also occurs in vertebrate models.
The first scientific theory for cell regeneration appeared in 1964 when Malcolm Steinberg hypothesized that cells were self-organizing according to “thermodynamics mediated by differential surface adhesion”.5 He proposed that cells that express the same ‘adhesive system’ will adhere more strongly to each other than cells that express different adhesive systems. Thus, cell mixtures would reaggregate based on their ‘adhesive’ type. Later evidence however showed that cellulate reaggregation requires more than simple thermodynamics and requires additional cellular mechanisms.
The Importance of Extracellular Matrix (ECM)
The 1980s saw significant milestones in organoid research, as the cell-matrix interactions were investigated in the context of organoid development.
To prevent the cell culture from getting contaminated by the plastic dish, researchers started to use scaffolds, hydrogels that mimic the natural ECM. More importantly, an ECM would provide the cell with proteins necessary to signal adhesion and differentiation.
In 1987, the importance of ECM was highlighted by Li et al., who used EHS (Engelbreth-Holm-Swarm) matrigel from mouse sarcoma cells, consisting of adhesive proteins commonly found in human ECM. Using the EHS medium, they could grow breast epithelia into fully-formed 3D ducts and ductules, which exhibited milk protein secretion.6
Shannon et. al. used the same ECM strategy to demonstrate functional differentiation of alveolar type II epithelial cells.7
Stem Cell Research
Prior to the development of stem cells, the formation of human organoids depended on the use of tissue fragments isolated from humans. Stem cell research was simultaneously thriving in the 80s. For instance, researchers could isolate pluripotent stem cells from mouse embryos for the first time in 1981.
Development of the first human embryonic stem cell lines (Thomson et al 1998) and later human-induced pluripotent stem cell (hiPSC) lines were instrumental in driving interest in organoid research. More importantly, hiPSC can be differentiated into a variety of cell types in a medium conditioned with specific growth factors8 which, provides the starting materials for growing organoids at scale. The timing, temporal factor was also important in creating organoids. These observations were more than enough to carry stem cells to the front line of organoid research.
Induced Pluripotent Stem Cells (iPSCs)
An induced pluripotent stem cell, also referred to as iPS cell or iPSC, is a cell taken from adult tissue – usually derived from skin or blood cells – and genetically modified back into an embryonic-like, pluripotent state. First developed from mouse skins cells by Shinya Yamanaka's team at Kyoto University, Japan in 2006,9 iPS cells held promise in the field of regenerative medicine.
Pluripotent stem cells can propagate or self-renew indefinitely and can differentiate into any adult cell type in the body, such as neurons or heart, pancreatic, and liver cells. And, since iPSCs can be derived directly from adult tissues, they can be made in a patient-matched manner, which means that important disease-related cell models can be created carrying a mutated gene, which can screen drug efficacy or an individual patient's drug sensitivity can be tested in patient-derived cells. Potentially, each individual could have their own pluripotent stem cell line offering a single source of cells to replace damaged heart or liver tissue. Imagine iPSCs generated from blood cells that could create new blood free of cancer cells for a leukemia patient, or neurons to treat neurological disorders.
After Stem Cell: Modern Organoid Research
The isolation of stem cells accelerated organoid research and opened many doors. Stem cell-derived organoids were much more effective in monitoring immune response than patient biopsies, meaning they were much more insightful for disease modeling.
In 2008, Sasai et.al laid the foundations of brain organoids by demonstrating self-organization of human brain iPSCs into neural cells that formed polarized cortical tissues.10
2009 was another significant year for modern organoid research. Sato et al. demonstrated for the first time that intestinal adult stem cells (ASCs) could self-organize and differentiate to form intestinal crypt-villus structures that contained all the different intestinal cell types.11
Three years later, the same research lab also planted the seeds of stem cell therapy by demonstrating the transplantibility of intestinal organoids into a damaged mouse colon. The transplanted organoids could fully integrate into the mouse colon with sustained success even after six months.12
Modern organoid research quickly expanded over the previous decade to include various organs and disease models. Here are some highlights:
- 2010 – Renal organoids from murine fetus-derived kidney stem cells13
- 2012 – Formation of a self-organized optic cup structure from human ESCs in 3D culture
- 2013 – The first study to derive 3D cerebral organoids containing different brain tissues14
- 2014 – Lung organoids from the 3D co-culturing of endothelial cells and bronchioalveolar stem cells15
- 2013 – Lgr5+ liver stem cells were expanded as liver organoids and were differentiated into functional hepatocytes when transplanted into mice16
- 2013 – Formation of pancreatic organoids with the cancer disease model from adult pancreas tumors17
Organoid Image Gallery
View more images on our Organoids application page.
Organoid Research at Molecular Devices
Over the recent decade, the advances in organoid development have skyrocketed, generating more complex and life-like organoids than ever. Inevitably, imaging and analysis techniques need to keep up with the continuous developments. As sample types shift from 2D to 3D cell models, conventional methods will fall short of high-quality results and fast acquisition.
Molecular Devices strives to make organoid research much more feasible by bringing in automated characterization, high-content imaging, and advanced analysis techniques in a high-throughput platform. This platform has enabled us to automate workflows for a variety of operations, such as stem cell generation, organoid characterization, drug screening, and toxicity assessment, on various organoid types from lung to cerebral.
Visit our Organoids application page to access detailed organoid research notes, webinars, posters, and more.
The best part is, you don’t need to be experts in these solutions. Molecular Devices’ new Organoid Innovation Center is a collaborative hub where you can test automated workflows for organoid culturing and screening, with guidance from in-house scientists.
Visit the Organoid Innovation Center to read more about organoids insights, automated workflows, and groundbreaking collaborations.