21ENGBIO A Universal and Controllable Interface between Synthetic Cells and Living Cells

A growing area of research is the creation of 'synthetic cells' from discrete building blocks. Through this research we can gain an understanding of how life started and evolved. Additionally, as synthetic cells are completely modular and cannot self-replicate, they offer promise as novel drug delivery systems and as tools to interface living and non-living materials. These interfaces might be used to study or modify living tissue, without the need for genetic modification. Approaches to interface synthetic cells with living cells often arise from mimicking specific processes in living cells, without other competing processes. However, currently there are no universal methods to allow synthetic cells to communicate with living cells using a wide range of signal molecules. For instance, the two most common approaches rely on identifying signal molecules that will move across the synthetic cell membrane by themselves, or the use of proteins that form holes in the membranes. However, beyond not being universal, both approaches have significant downsides and limitations. We will generate a method that allows the release of any-sized signal molecule. This will be a step change in the use of synthetic cells as research tools and drug delivery devices.

Our approach will mimic the communication of neurons in the brain. Neurotransmitters are held within neurons in small compartments. Release of neurotransmitters at the synapse is achieved by the fusion of these small compartments to the cell membrane, by forcing them together. We will generate synthetic cells that contain small compartments. These small compartments will be able to be filled with any-sized signal molecule. Fusion of the small compartment to the synthetic cell membrane, like is seen in neurons, will be initiated by using a mix of DNA and RNA strands. DNA and RNA complementarity is ideal for this function as it is strong and programmable. By incorporating functional signal molecules within the small compartments, we will then interface these synthetic cells with neighbouring living cells to control their function.

For real world application, the function of synthetic cells needs to be triggered, ideally with a remote stimulus, to inhibit the synthetic cell activity where it is not wanted. Light is an ideal stimulus as it can be applied remotely at a precise point in space and time. To achieve this, we will incorporate a light-activated template that the synthetic cells with function from, which we have previously generated.

Our method to interface synthetic and living cells will be universal and remote controllable. By encapsulating neurotransmitters within the small compartments, this externally controlled release might be used as a computer-brain interface between synthetic cells and neurons. Additionally, as any molecule could be encapsuled in the synthetic organelles and released with light, there is the potential for precision drug targeting to any living cell. This basic research project to broaden the functionality of synthetic cells has the potential to revolutionise the research area and bring about the real-world potential of synthetic cells.

Synthetic cells, lipid membrane-bound compartments that mimic living cells, are a promising technology for study living systems and for drug delivery vehicles. However, real world application of synthetic cells requires the development of universal methods to interface them with living cells, in a controlled fashion. Here, we will create a method to release any sized molecule from synthetic cells by mimicking the way neurons communicate at a synapse. Synthetic organelles, containing any sized molecule, will be held within the synthetic cells. Fusion of the synthetic organelles to the cell surface, and hence release of its contents to neighbouring living cells, will be mediated by the hybridisation of nucleic acid strands embedded in their membranes. Hybridisation will be initiated by the in-vitro transcription of complementary RNA within the synthetic cell. External control of this process will be enabled by our previously generated light-activated DNA, which tightly regulates cell-free expression. Release of biologically functional molecules from these synthetic cells to neighbouring living cells will be carried out to demonstrate a universal and controllable synthetic to living cell interface. By encapsulating neurotransmitters within the synthetic organelles, this externally controlled release might be used as a computer-brain interface between synthetic cells and neurons. Additionally, as any molecule could be encapsulated in the synthetic organelles and released with light, there is the potential for precision drug targeting to any living cell.