A few months back, bioengineers created the world’s tiniest rendition of the Mona Lisa using DNA origami. Now, building off of prototypes , Chinese and American scientists are using the technology to snuff-out cancer with microscopic precision.
If cancer is a criminal, blood vessels are its accomplice. Not only do they feed and nurture cancer, promoting its survival, but they also help shuttle cancer cells to rest of the body, sowing the seeds of metastasis. Scientists can identify these accomplices through a protein structure called nucleolin ; it’s built right into the walls of blood vessels that feed cancer, and also attracts a specific DNA sequence, making it easy to target.
The DNA-origamists coded the cancer-targeting DNA into a DNA nanobot and armed it with a weapon familiar to anyone who’s ever scraped their knee—thrombin. Thrombin is a blood clotting catalyst which stops our wounds from bleeding. It does so by triggering the formation of blood-capturing nets, and for years, doctors have spritzed it onto surgical sites to limit blood-loss.
In theory, this reliable coagulant could cut-off cancer’s resources, but injecting thrombin itself into the circulatory system is deadly—too many blood clots can lead to strokes, pulmonary embolisms, and more. To make thrombin an effective cancer treatment, scientists must conceal it right up until it contacts the cancer.
So DNA-origamists folded a paper-like mesh of DNA into a neatly shaped tube that wraps around the thrombin like a taquito. The outer surface is coated with cancer-targeting DNA. Once DNA hits the cancer’s blood vessels, the origami quickly inverts itself, revealing the thrombin and sparking a cascade of events that isolates tumors.
Test runs of the treatment in tumor-laden mice have cut off a cancer’s blood supply, stifling tumor growth and effectively starving cancer to death. The nanobots small size makes them ideal for spotting cancer cells that would evade detection by surgeons. And, in theory, it is more specific to tumors than chemotherapy—allowing regenerating non-cancer cells (such as hair) to survive the treatment.
Currently, researchers are still evaluating the safety of this new technology. Considering that some cancers themselves are decorated with the telltale structure nucleolin, the DNA-origami approach seems promising – but nucleolin protein is also present inside non-cancer cells. When healthy cells break open and release their guts into the bloodstream, it’s possible origami nanobots could be triggered, releasing their thrombin and forming clots in otherwise healthy parts of the body. Another important obstacle is removing unwanted nanobots from a patient, if at all. Thus far, the DNA nanobots haven’t raised an immune response in pigs or mice—a potentially problematic outcome—although these experiments followed animal health for a brief five-day period. Surely, time will tell if this new technology is safe enough for human patients – and it may not be long before we see it enter clinical trials.
Image credit: Jason Drees, Arizona State University