Much like humans use the Internet to communicate, cells have mechanisms to pass on data to each other. It’s a system that is being hacked by scientists who realize the value of being able to send custom genetic data from cell to cell. Because when large groups of cells can be commanded by humans to work on complex tasks, the possibilities are endless.
Typically, scientists have spurred on communication by sending sugar molecules from cell to cell--the concentration of sugar either activates something in a receiver cell or doesn’t, depending on the command. But this is limiting, says Monica Ortiz, a doctoral candidate in bioengineering at Stanford. "You can’t send very much information with these sugar molecules." So Ortiz and Drew Endy, an assistant professor of bioengineering, set out to create a more complex system.
Their solution, published in a recent issue of the Journal of Biological Engineering: a bacteriophage, or virus that infect bacteria. "We recognized that phage are essentially nucleic acids packaged by protein, and we know that genes and other elements in the genome are always encoded into DNA. So we know that we can encode anything we want to in DNA," explains Ortiz. "We can encode genes, activation of transcription in various ways and we don’t need to rely on this middleman sugar molecule."
Ortiz and Endy selected M13 as their cell-communicating virus. It’s the ideal specimen: It doesn’t kill the host cell, scientists can vary the length of DNA that they’re packaging (M13 packages genetic messages), and it has been engineered to get its DNA into mammalian cells.
The M13 communication system is, as Stanford Engineering explains, like a wireless information network for cells to send and receive messages. M13 wraps up strands of DNA (programmed by scientists) and sends them out in proteins that infect cells and release the DNA messages once they have gained entry. Scientists can send whatever they want in the DNA--everything from a sentence in a book to a sequence that encodes fluorescent protein.
The M13 system dramatically increases the amount of data that can be transmitted at one time compared to previous cell-to-cell communication systems--roughly 80,000 bits compared to one bit with the sugar molecule system. M13 can also transmit data over long ranges.
"Practically I think sending DNA between cells has a lot of applications," says Ortiz. "What we’ve shown is that we can send and receive a message and do something in the receiver cell with that message." In the future--we’re talking decades down the line--the technology could be used in tissue engineering as well as in creating artificial organs and biomaterials that have no direct analog in nature.
Ortiz emphasizes that the research is just beginning. "People are calling it the biological Internet, and that’s a fairly good analogy. I want to make the point that this is a very early stage proof-of-principle paper."