Case studies Chemical Engineering and Chemistry 2015-2021

4 In recent years, we have developed an artificial cell platform with a number of features that are reminiscent of living cells (Figure 1). The internal phase is composed of a coacervate which has a crowdedness similar to the cytosolic environment. The membrane is semipermeable, which allows for the exchange of molecules with the external milieu, and multiple compartments (artificial organelles) can be included in the coacervate core for the performance of cascade reactions with control over positional assembly. 1,2 Figure 1: The process of forming a multicompartment artificial cell. The right picture shows a confocal image of an artificial cell loaded with three different polymersome nanoreactors, labeled with green, red and blue dyes. 2 Furthermore, we have developed methods that allow them to take up and release proteins in a highly controlled manner. 3,4 This is of great interest as proteins are key biomolecules for intercellular communication between living cells.Within the framework of the Spinoza premium, we are exploring this artificial cell platform to achieve a higher level of sophistication in life-like behavior and create hybrid cell communities and tissues composed of artificial and living cells. Artificial cells with life-like features First of all, a highly characteristic feature of cellular behavior is intracellular communication and process control. This is achieved through the signal-induced positional assembly of different proteins which, when brought together, can activate down-stream cascade processes. To incorporate this feature into artificial cells, we have introduced the crucial scaffold protein 14- 3-3 to our coacervates. This scaffold protein interacts with protein-binding partners when they are phosphorylated. These interactions can therefore be placed under the control of kinases and phosphatases, enzymes that regulate signaling cascades via (de)phosphorylation. Via this method, we can not only control the organization of protein networks within an artificial cell but also the direct uptake and release of proteins, thereby facilitating intercellular communication. Biological processes are, in many cases, governed by stochasticity. As artificial cells are composed of a limited set of building blocks, local fluctuations could also be steered into emergent behavior. We have demonstrated that stochasticity can be employed to induce motility in artificial cells. 5 However, stochasticity, dynamics and protein release capacity can be further explored for use in artificial antigen-presenting cells for the activation of T cells in immunotherapy. The dynamic nature of the membrane allows the formation of protein micro- clusters that form the immunological synapse. Cytokine release from the artificial cells can be used to achieve a specific T cell response.