Researchers at Stanford have figured out a way to reprogram cells to build synthetic structures for various uses inside the body using synthetic materials.
The research is based on a new technique developed by the team, which they call genetically targeted chemical assembly, or GTCA. Through the use of GTCA, they were able to construct artificial structures in mammalian and C. elegans (a worm used as a model organism) neurons out of two biocompatible materials — an insulator and a conductor.
New build order
“We turned cells into chemical engineers of a sort, that use materials we provide to construct functional polymers that change their behaviors in specific ways,” said Karl Deisseroth, professor of bioengineering and of psychiatry and behavioral sciences, who co-led the work.
“We’ve developed a technology platform that can tap into the biochemical processes of cells throughout the body,” says study co-leader Zhenan Bao.
The team focused on brain cells or neurons, but they are confident that GTCA will work on other types of cells as well.
They began by genetically modifying the cells, using standard bioengineering techniques to insert the genes encoding the enzyme APEX2 into specific neurons. The next step involved submerging the worms and tissues in a solution of diluted hydrogen peroxide and particles of the two materials that the cells would employ.
The hydrogen peroxide was needed as it triggers a series of chemical reactions in cells with the APEX2 gene that polymerizes — ties together — the particles of raw material. The end products were mesh-like weaves wound around the cells that were either conductive or insulating. Depending on the electrical properties of this mesh, the neurons’ activity was amplified (they ‘fired’ signals more often) or dampened (making them fire more slowly). The team ran the experiment with slices of living mouse brain and on cultures of neurons (also harvested from rat brains) and, after testing the properties of the polymer meshes, they also tested to see if the solution was toxic to the cells upon being injected — it wasn’t.
The team doesn’t have medical applications in mind for their research so far, saying instead that it is a “tool for exploration”. However, the findings could have massive implications for the study of multiple sclerosis, a debilitating condition that stems from the breakdown of (myelin) insulation around neurons. Conductive polymer meshes may also help in the treatment of conditions such as epilepsy, but it’s still too early to tell.
In the future, the team plans to expand on the range of materials that can be used with their method and improve the “possibilities [of] this new interface of chemistry and biology,”
The paper “Genetically targeted chemical assembly of functional materials in living cells, tissues, and animals” has been published in the journal Science.