Scientists Create Nanorobots that Destroy Tumors





Scientists from the Arizona State University and the National Center for Nanoscience and Technology (NCNST) of the Chinese Academy of Sciences have programmed nanorobots which are able to seek and destroy tumours.

"We have developed the first fully autonomous, DNA robotic system for a very precise drug design and targeted cancer therapy," said Hao Yan, an expert in the field of DNA origami and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics.

"Moreover, this technology is a strategy that can be used for many types of cancer, since all solid tumour feeding blood vessels are essentially the same," said Yan.

The technology was successfully demonstrated in mice for breast cancer, melanoma, ovarian and lung cancer.


How the nanorobots work

Nanomedicine aims to use nanotechnology to develop new and innovative treatments, such as using nanoparticles to diagnose and treat diseases such as cancer.

The technology behind the nanorobots are essentially programmed sheets of DNA, which are a thousand times smaller than the width of a human hair. The scientists hope this technology will one day revolutionize computing, electronics and medicine.

The advancement of nanomedicine has been challenging until now because scientists wanted to ensure nanorobots are able to destroy cancerous tumours without harming healthy cells. A problem which was overcome by a using a simple strategy to very precisely seek and destroy a tumor: by starving it out.

The strategy was to cut-off blood supply to the tumour by inducing blood coagulation using nanocarriers. Yan’s fully programmable nanorobots were able to perform the mission entirely on their own.  

"These nanorobots can be programmed to transport molecular payloads and cause on-site tumour blood supply blockages, which can lead to tissue death and shrink the tumour," said Baoquan Ding, a professor at the NCNST, located in Beijing, China.


The experiment

The study was performed by deploying nanorobots to intervene a tumour in a mouse. The nanorobots, made from a flat, rectangular DNA origami sheet, 90 nanometers by 60 nanometers in size. Thrombin, a key blood-clotting enzyme was attached to the surface of the bot.

Thrombin is able to block blood flow to a tumor by clotting the blood within the vessels that feed tumour growth, leading it to its death.

Four thrombin molecules were attached to a flat DNA sheet, which was then folded on itself to make a cylinder. These were then injected using an IV. The robots traveled through the bloodstream, accurately moving towards their target, the tumour.  


How were they able to only target cancerous cells?

The key was to include a special payload on the surface of the nanorobot called a DNA aptameter. This is able to target a specific protein called a nucleolin, which is found in large quantities on the surface of tumour endothelial cells, and is not found on the surface of healthy cells.

Once the nanorobot was bound to the blood vessel surface of the tumour, it was able to deliver its payload at its core. This technique resulted in the nanorobots working with great speed and effectivity, surrounding the tumour within just hours of injection.



The nanorobots proved to be safe and effective. "The nanorobot proved to be safe and immunologically inert for use in normal mice and, also in Bama miniature pigs, showing no detectable changes in normal blood coagulation or cell morphology," said Yuliang Zhao, also a professor at NCNST and lead scientist of the international collaborative team.

There was no indication of the nanorobots reaching the brain, where they could potentially cause serious side effects such as a stroke.

"The nanorobots are decidedly safe in the normal tissues of mice and large animals," said Guangjun Nie, another professor at the NCNST and a key member of the collaborative team.

The treatment was able to block blood supply to the tumor and damage the tumor tissue within 24 hours whilst having no effect on healthy tissues. The majority of nanorobots were also evacuated from the body after 24 hours.



Yan believes this represents the end of the beginning for nanomedicine.

"The thrombin delivery DNA nanorobot constitutes a major advance in the application of DNA nanotechnology for cancer therapy," said Yan. "In a melanoma mouse model, the nanorobot not only affected the primary tumour but also prevented the formation of metastasis, showing promising therapeutic potential."

The Scientists are now actively pursuing clinical partners to progress the technology further.

"I think we are much closer to real, practical medical applications of the technology," said Yan. "Combinations of different rationally designed nanorobots carrying various agents may help to accomplish the ultimate goal of cancer research: the eradication of solid tumours and vascularised metastases. Furthermore, the current strategy may be developed as a drug delivery platform for the treatment of other diseases by modification of the geometry of the nanostructures, the targeting groups and the loaded cargoes."


Story Source:  Materials provided by Arizona State University. Original written by Joe Caspermeyer (Content may be edited for style) Photo Credit: Wikimedia Commons CC BY-SA 4.0  (The photograph provided bears no relation to the study.)