With the creation of genetic transistors, a team of Stanford bioengineers has produced the final component needed for the construction of a “biological computer” that could be inserted into living cells.
According to researchers at the Endy Lab, led by Assistant Professor of Bioengineering Andrew Endy, such biological computers could collect information about cells, such as the rate of cellular reproduction, and detect the presence of toxins. They could even command actions like the destruction of cancerous cells.
“We were looking for hard things to work on,” Endy said. “[We] set out to do very fundamental things—[to] get better at putting biomolecules together to engineer systems, and program cells to work like we want.”
While standard computers use electrical transistors as on-off switches for programs, Endy’s computer utilizes biological “transcriptors.” These transcriptors control whether or not RNA polymerase can travel through logic gates by the transmission of true or false answers based on information from within the cell.
The development of the transistors builds upon previous work in the Endy Lab, which previously developed other necessary components of a biological computer—a memory system for storing data and a mechanism that can transfer genetic information between cells.
According to Pakpoom Subsoontorn M.S. ’10 Ph.D. ’14, a researcher in the Endy Lab, Endy’s new model of programming biological cells is much simpler to implement than previous methods.
Monica Ortiz M.S. ’09 Ph.D. ’13, who is also a researcher in the Endy Lab, noted that that simplicity offers greater potential for application on a broad range of projects. To that end, Endy’s team has made the logic gates accessible to scientists around the world for their own research.
“Our hope is that [other researchers] will take these logic gates as a nice starting point to do increasingly complex tasks within biological cells,” Ortiz said. “It is going to be exciting to see what other people do in building upon this work. The applications can be really broad.”
Outside researchers have already employed the lab’s logic gates in controlling the metabolism of cells, measuring levels of proliferation of therapeutic T-cells and regulating biosynthesis, the process by which a living organism creates a chemical.
While initial research seems promising, lab researchers emphasized the work yet to be done, such as expanding the logic gates’ usage from E. Coli cells to other organisms or accelerating and extending the capabilities of biological computers to approach those of conventional electronics.
“We have four enzymes. Every time we build a transcriptor we have to use one,” Endy said. “We can only build computers that are four switches big, so these are some of the world’s weakest computers.”
Subsoontorn agreed that, although the team’s results are encouraging, the project needs further development before biological computers can be widely implemented.
“This project is exciting but it is important to keep in mind that we have a long way to go,” Subsoontorn said. “Any scientific engineering enterprise is incremental, and someone will build upon our work long before this gets out to application or to make a huge impact.”