Organoids in Disease Modeling

Organoids represent the cutting edge of 3D cell culture, in part because their stronger resemblance to tissues and organs (compared to 2D cultures) endows them with a greater capacity to model disease states. But technical challenges mean that this application is only just getting off the ground. Here are some expert perspectives on using organoids in disease modeling, now and in the future.

Organoids and personalized medicine

An over-arching goal in using organoids for disease modeling is personalized medicine, using patient-derived organoids to screen drug therapies to find the most effective one for each patient. “Some of the most recent advances involve protocols for culturing patient-derived organoids for personalized medicine, as well as for generating libraries of data for associating drug response with gene expression,” says Hilary Sherman, Senior Applications Scientist at Corning Life Sciences.

Researchers are using “organoids derived from patients with rare forms of cystic fibrosis to identify their optimal course of treatment,” says Alexander Schlacht, Product Manager in Epithelial Cell Biology at STEMCELL Technologies. “The use of patient-derived organoids to model disease has resulted in significantly improved patient outcomes and quality of life.”

Using patient-derived tumor tissue to create organoids— or “tumoroids”— is a promising new avenue of personalized medicine. “Recent proof-of-concept [work] indicates that patient-derived tumoroids could be used to identify personalized cancer therapies,” says Matt Dallas, Senior Manager for R&D in Cell Biology at Thermo Fisher Scientific. “If this can be confirmed, it would be transformational for personalized medicine, which has almost entirely relied on genetic testing for the presence of a relatively small number of druggable mutations.”

Tumoroid advances have significant pharmaceutical and therapeutic potential. “In contrast with cell lines, one of the signatures of primary tumors is their cellular heterogeneity, which can be better replicated in organoids,” says Oksana Sirenko, Research Scientist at Molecular Devices. “Cancer drugs can kill some types of tumor cells but not others, leading to escape from therapy and subsequent drug resistance.”

It is hoped that patient-derived tumoroids can provide better models for effective drug screening with the more recalcitrant diseases. “One example is triple-negative breast cancer, which is notorious for being insensitive to traditional chemotherapy,” says Sirenko. “These studies are still preclinical, but this is an actively developing area.”

Overcoming limitations using technology

Organoids are more difficult to work with technically— researchers find organoid reproducibility, consistency, accuracy, and scalability more challenging than working with their 2D cell culture counterparts. Organoids also take longer to establish in culture (growing brain organoids can take several months).

Companies are developing media, instrumentation, and protocols to facilitate organoid research, and Sirenko believes that new methods must be developed that are robust and reproducible. “Our company and others are introducing new imaging instruments with more powerful optics, confocality, water immersion, powerful lasers, and other technologies to allow imaging through 3D organoids and microtissues, which is more challenging than imaging cells in 2D culture,” she says.

The 3-dimensional nature of organoids incurs its own unique culture challenges. “The lack of vascularization could lead to necrotic cores in organoids,” says Elizabeth Abraham, Global Business Manager in Advanced Cell Culture/Drug Discovery at Corning Life Sciences, who notes two approaches for vascularization of organoids: in vivo vascularization involves transplanting organoids into animal models, while in vitro vascularization uses a combination of gene editing, mixed cell culture, and microfluidics. “When microfluidic platforms are combined with artificial intelligence and sensor technology, perhaps maturation of organoids can be achieved more successfully by adjusting temperature, oxygen, and carbon dioxide, as well as regulated changes of media to replenish cultures with nutrients,” she explains.

High-throughput screening

Future advances will likely involve the development of high-throughput drug screening methods using organoids. Though organoid drug screening is occurring now, “the throughput, robustness, and reproducibility need to be increased tremendously,” says Sirenko. “This is an achievable goal and a lot of scientists are working in this direction.”

Adapting automation for organoid culture will assist in this goal. “Liquid handling and automation is an up-and-coming area in organoid culture, and it hopefully will ease some of the manual burden of keeping these models in culture and using them in higher throughput applications,” says Dallas. High-throughput and high-content organoid assays will also require software that is up to the acquisition and analysis tasks. “Assessment of organoids through high-content imaging and the use of AI and deep learning software helps with feature extraction and pattern recognition, all important elements that can be used to develop functional organoid assays,” adds Abraham.

Increasing complexity

Another evolving trend is increasing the complexity of organoid disease models. “Organoid cultures generally model only one tissue type, and lack supporting factors such as the surrounding mesenchyme, vascularization, and an immune component—all of which are important for the basic function and maintenance of a given organ,” says Schlacht.

Yet multiple tissue types play important roles in many diseases, so incorporating multiple tissue types may build better disease models. “For example, researchers are building better immuno-oncology models by adding immune cells to their intestinal organoid cultures, which is enabling a better understanding of disease progression and the overall response to therapeutic compounds,” says Schlacht.

Looking forward

Faced with months to grow organoids, researchers would greatly benefit from the ability to purchase standardized tumoroid models. Bioprinting may facilitate the production of more complicated organoids. “Bioprinting can be used to build more complex structures, such as precise printing of organoids resulting in organoid fusion to build artificial organs,” says Abraham.

Schlacht believes that improving scaffolding and bioprinting can lead to significant advances in using organoids as regenerative medicine. “Expanding intestinal organoids and transplanting them into a patient with a resected bowel would change the way we think about organ transplantation,” he says. Dallas suggests that using organoids to study host-pathogen interactions and immune responses may be another emerging application.

But all will require ongoing technological advances. “Organoids are complex biological systems that are essentially a transition between cells and organs,” says Sirenko. “For scientists to derive more knowledge from organoid studies, a concomitant increase in the sophistication of technology and methods is required.”