Differential Compartmentalization of Enzymatic Reactions for Lactate Signaling Across Protocells

Protocells, by breaking down the intricate complexity of eukaryotic cells, are innovative tools for mimicking and understanding cellular phenomena. Protocells based on giant unilamellar vesicles (GUVs) supplemented with active species facilitate in situ biologically relevant enzymatic reactions. However, replicating intercellular communication in synthetic systems remains a major challenge for bottom-up approaches. Here, we take on this challenge by creating two different populations of protocells that communicate in a controlled and directional manner. By using double emulsion microfluidics, each protocell type consists of GUVs containing distinct biomolecules and artificial organelles (AOs) with unique structures and functions. A series of chemical reaction networks controlling the activity of the AOs provides the framework for the directional, lactate-mediated intercellular communication between protocells. The coordinated series of compartmentalized enzymatic reactions demonstrate that the intercellular communication is (i) selective for lactate, (ii) tunable according to its concentration; and (iii) sensitive to the sender/receiver protocell ratio and thus, the distance between them. These protocells capable of collective behavior by intercellular signaling have unique advantages for understanding complex biological processes and serve as basis for the development of advanced therapeutic strategies by interfacing synthetic protocells with native cells.