Periodic Reporting for period 4 - ARTIST (Artificial cell-cell interactions for light switchable cell organization and signaling)
Reporting period: 2022-11-01 to 2024-06-30
The concept of using cells to build tissues from the bottom-up is a highly promising yet challenging approach to tissue engineering. Similar to how Lego allows for the construction of complex structures, the bottom-up approach in tissue engineering aims to create tissues with any desired structure and function by assembling different cell types, one cell at a time. The main challenge is controlling the interactions between the cells, which determine how they organize, cooperate, and whether the resulting multicellular architecture will function properly. In this project, we regulate cell-cell interactions—both within the same cell type and between different cell types—using visible light and optogenetics. These photoswitchable interactions offer sustainable, non-invasive, dynamic, and reversible control over cell behavior. Crucially, light allows us to control when and where cells interact, as we can precisely direct the illumination. Furthermore, by combining different photoswitchable interactions, we can build tissue-like structures with varied substructures from multiple cell types. Ultimately, this approach will enable the bottom-up assembly of multicellular architectures with predictable and programmable organization, while also controlling how cells collaborate within a tissue. In combination with traditional material based approaches the preformed multicellular architectures can be used for the formation of cell rich tissues such as liver and kidney that are still difficult to engineer with existing approaches in tissue engineering.
For the first time, we are able to control the interaction between two different cell types using visible light. These photoswitchable cell-cell interactions provide unprecedented spatiotemporal control, allowing us to build tissue structures layer by layer. Different photoswitchable interactions offer varying dynamics in cell interactions, which determines whether compact, ball-like assemblies form under thermodynamic control, or loose, snowflake-like assemblies emerge under kinetic control. By utilizing these photoswitchable interactions, we can control how cells self-assemble and self-sort into multicellular structures, mirroring the principles of self-assembly seen in non-living colloids. In doing so, we have established key rules for the bottom-up assembly of tissues from single cells.
The photoregulation of native cell-cell adhesions directly impacts intracellular signaling and cell behavior. In this project, we developed a photoswitchable version of the native cell-cell adhesion molecule E-cadherin, called opto-Ecad, enabling us to study cellular processes during the epithelial-mesenchymal transition, where intercellular adhesions are spatiotemporally controlled. For example, we demonstrated that 3D spheroids composed of cells with initially strong cell-cell adhesions can invade a collagen gel once the adhesions are turned off with light. On the other hand, we found that artificial photoswitchable cell-cell adhesions, which do not directly link to intracellular signaling, are a valuable tool for studying membrane-generated signals. We showed that these artificial adhesions lead to coordinated collective cell migration and even increase the speed of individual cells by enhancing membrane tension. Through this work, we have highlighted the previously overlooked role of membrane signaling and tension in collective cell migration.
The photoregulation of native cell-cell adhesions directly impacts intracellular signaling and cell behavior. In this project, we developed a photoswitchable version of the native cell-cell adhesion molecule E-cadherin, called opto-Ecad, enabling us to study cellular processes during the epithelial-mesenchymal transition, where intercellular adhesions are spatiotemporally controlled. For example, we demonstrated that 3D spheroids composed of cells with initially strong cell-cell adhesions can invade a collagen gel once the adhesions are turned off with light. On the other hand, we found that artificial photoswitchable cell-cell adhesions, which do not directly link to intracellular signaling, are a valuable tool for studying membrane-generated signals. We showed that these artificial adhesions lead to coordinated collective cell migration and even increase the speed of individual cells by enhancing membrane tension. Through this work, we have highlighted the previously overlooked role of membrane signaling and tension in collective cell migration.
In this project, we have built tissue-like multicellular architectures with various micro-scale structures, starting from single cells. The photoswitchable cell-cell adhesions provided us with unmatched spatiotemporal control over the organization and function of cells within these microtissues. The photoswitchable cell-cell interactions developed here also offer a powerful tool to address key questions in biological processes where cell-cell interactions play a pivotal role, such as embryogenesis, cancer progression, and tissue development.