Technologies that enable the precise manufacturing of human tissues will have a transformative impact on human health. Engineered tissue constructs are already being used as benchtop models for systematically investigating human tissue development and disease, which can inform new therapies. Engineered tissue constructs are also used as testbeds for screening drugs or other therapies, which has the additional benefit of reducing the use of animals. In the future, engineered tissue constructs could be transplanted into patients to replace tissues damaged due to aging, disease, or injury. However, precisely reconstructing human tissues remains an outstanding technological challenge, in large part because human tissues consist of multiple specialized cell types organized in specific microscale architectures that are extraordinarily challenging to re-create in the lab.

Over the last decade, organoids have emerged as a promising technology for manufacturing human tissues. Organoids begin as a small cluster of stem cells that is treated with specific molecules at specific times to induce the stem cells to develop into a miniature tissue construct that comprises multiple cell types found in a specific organ. Because organoid protocols mirror human development more closely than other techniques, organoids generally generate multiple cell types with relatively high maturity that supersede those generated by other techniques. However, organoids have many caveats, including high variability, which is a major bottleneck that hinders the use of organoids for human disease modeling or drug screening.

In this project, our team collaboratively developed new technologies to address some of these challenges related to the low reproducibility of organoids. We focused on two parallel research efforts, described below.

First, we developed a new device for culturing human brain organoids. One PI on our team (Giorgia Quadrato) previously pioneered the generation of human cerebral organoids with advanced cellular diversity, maturity, and architecture. However, these organoids must be cultured in a bottle with a propeller (a spinner flask) to sufficiently exchange nutrients and waste. This is one major source of variability, as organoids collide and fuse randomly, and organoids may also be susceptible to mechanical trauma.

Another PI on our team (Megan McCain) is an expert in engineering “Organ on Chip” devices to control the physical environment of engineered tissues. The McCain lab designed and fabricated a small device that immobilizes brain organoids within a ring of pillars and enables the flow of culture media around the organoids such that organoids can be more controllably cultured and still provided proper nutrient and waste exchange. The Quadrato lab used this device to culture brain organoids for one to three months and compared the structure and function of these organoids to those cultured in spinner flasks or statically, without flow. The microfluidic device supported the survival and function of the organoids similar to the spinner flask. Most excitedly, the device also improved organoid-to-organoid reproducibility, in terms of the types and numbers of cell types, compared to both the spinner flask and static culture.

Our second research effort focused on leveraging synthetic biology to control the production and location of multiple specialized cell types within tissues. Our third PI (Leonardo Morsut) previously co-invented synthetic Notch receptors (synNotch) and engineered them into cells. synNotch receptors can be programmed to recognize specific molecules in the environment and respond by inducing the cell to turn into a specific cell type, such as a muscle cell. In this project, the Morsut lab engineered synNotch receptors that induce cells to turn into muscle cells or endothelial cells (the cells that line blood vessels) in response to user-defined molecules. In parallel, the McCain lab patterned materials with the user-defined molecules recognized by synNotch receptors. By combining these two technologies, we successfully engineered tissues with precise placement of developing muscle cells and endothelial cells. This approach has a similar benefit to organoids, in that multiple cell types co-develop into complex tissues. However, our technology enables more control over both the identity and location of different cell types, thus increasing the reproducibility of the resulting tissue compared to organoids. In the future, we envision that this technology can also be applied to organoids to improve where and how different cell types are generated.

This project had Intellectual Merit because we established new technologies to improve the reproducibility of brain organoids, which enables them to be used for more precise investigations into the development of the human brain and mechanisms of many neurological disorders. We also established new technologies to precisely engineer multi-lineage tissues that are complementary, and potentially synergistic to, organoids, which can lead to many new discoveries in tissue development and disease.

This project had Broader Impacts because our technologies help to advance the manufacturing of complex human tissues, which have many applications in regenerative medicine and drug screening. All three PIs were also active mentors and educators of many students in the topics investigated in this project.

Last Modified: 02/12/2025
Modified by: Megan L McCain