Researchers have created synthetic tissues containing hundreds of synthetic cells that can be controlled by light, allowing the cells to communicate with one another much like neurons do. These light-sensitive tissues could one day be developed into tunable biodevices that could be interfaced with living tissue and used for medical applications like controlled drug release. Synthetic biologists have previously created systems that can express proteins in a cell-like environment, but they haven't (until now) created systems where multiple, encapsulated cells can communicate with each other, nor have they achieved light-based control of protein expression inside such cells.
In 2013, researchers built tissue-like materials with the consistency of soft rubber using a three-dimensional printer that ejected individual water droplets containing chemicals and biochemicals. Here, a research team including some of the same scientists and led by Michael Booth improved on their previous 3D tissue-printing approach to create soft, synthetic tissues, containing hundreds of synthetic cells, each capable of synthesizing proteins. Critically, the researchers engineered each cell with light-activated DNA so that protein expression could be controlled (i.e. switched "on" or "off"). They demonstrated that light-activated expression of a membrane pore protein in a cell subsequently allowed for the diffusive transport of small molecules between adjacent cells. In their approach, after printing an array of droplets into 3D tissue, light can be applied to them, and protein expression will occur within a subset of the droplets as delineated by the controlled exposure to light. This new light-sensitive system not only provides a precise means to control protein expression, but could potentially be optimized to mimic neuronal transmission.
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