Just one dose of an innovative drug-carrying nanorobot therapy has managed to reduce the size of the most common bladder tumors by 90% in a trial with mice. The breakthrough, presented on Monday in the journal Nature Nanotechnology, opens the door to developing more efficient, economical and comfortable therapies to treat one of the most prevalent and costly cancers worldwide.
The nanorobots, developed by the Bioengineering Institute of Catalonia (IBEC) for more than seven years, are tiny spheres of silica, 100 times thinner than a hair. Each pellet is surrounded by enzymes called ureases, which react with urea, a chemical compound found in urine, and make the nanoparticle move. The ability to move is the distinguishing feature of the technology.
In the study, led by the IBEC and the Center for Cooperative Research in Biomaterials (CIC biomaGUNE) of Sant Sebastià, scientists have equipped these nanoscopic balls with radioactive iodine, an element that is commonly used to treat tumors. When injected directly into the bladder of mice, the nanorobots dramatically reduced tumor size with just one dose.
Currently, the usual treatment for the most prevalent bladder cancer involves administering drugs directly to the organ and involves between 6 and 14 hospital visits. The therapy is uncomfortable, because, since the therapeutic agents do not have the ability to move, it is the patient who has to change position every half hour so that the drug reaches all the corners of the organ. The effectiveness of the new therapy and the mobility of nanorobots open the door to shorter and more comfortable treatments for the patient.
The advance represents a milestone in the field. “Not only can we finally demonstrate the therapeutic application of nanorobots, now that it will be 20 years since the development of the first nanomotor in the world, but we achieve it with a mixture of multidisciplinary techniques and with a very beautiful image”, he emphasizes in statements to this means Samuel Sánchez, Icrea researcher at IBEC and leader of the study.
The publication, in which the Institut de Recerca Biomédica de Barcelona (IRB) and the UAB also participated, has extremely rich images, in which you can see at what exact point and at what depth each of the nanorobots inserted into the bladder of mice. To achieve this sharpness, the team had to develop new imaging techniques specifically for the project. This is a level of detail that “no one has published before”, says the IBEC researcher. In addition, it has served to see that the nanorobots are able to penetrate the tumor and destroy it from the inside, a surprising fact, because the outer layer of cancerous tissues is usually more rigid than healthy tissue.
We can find the explanation in the propulsion system of the tiny machines. When urea and urease react, they not only move the silica sphere, but if they are close to the tumor, they also change the outermost layer and make it more liquid and penetrable. “Each nanorobot is like a small drill” against cancerous tissue, explains Sánchez. Instead, the bladder wall is not affected, so the particles bounce off it. Because they are constantly moving, bouncing off healthy tissue and penetrating cancerous tissue, most nanorobots end up where the target was and therefore maximize the therapeutic effect and minimize side effects.
The immediate future of the research consortium involves seeing what happens after treatment. With current interventions, nearly half of bladder tumors recur after five years, because residual cancerous tissue is usually left behind and then grows back. The team wants to see if the treatment can prevent this recurrence. The project has received funding from the European Research Council and the La Caixa Foundation.
