A research team in Switzerland has created the closest thing to a spaceship used to move inside blood vessels We were created like thisfamous cartoon from the late 1980s that tells how our bodies work. These tiny transport systems have proven promising in delivering drugs directly to the cells to be treated, reducing undesirable effects and the spread of active ingredients throughout the body’s tissues. The trials so far have involved pigs, sheep and human blood vessel models, but the research group believes the first clinical trials could be conducted within a few years.
The possibility of using small robots to inject into the body for highly targeted treatments has been explored for some time, as this would allow drugs to be administered more precisely and effectively. Some substances may more easily reach cancer cells in hard-to-reach areas of the body, or they may make it easier to dissolve blood clots (thrombus) that can cause strokes and other serious health problems. However, controlling and moving something within blood vessels, perhaps against the current, is not simple and has long been a major obstacle in the development of such new technologies.
A research group from the Federal Institute of Technology in Zurich (ETH) reported in a study published in a scientific journal Science that he has made important progress, designing a targeted drug delivery system based on tiny capsules that he calls “microrobots.” Each capsule is about the size of a peppercorn and is made of gelatin, which unites several iron oxide nanoparticles doped with zinc, the active ingredient that will be delivered into the body, and a small amount of tantalum, a metal that makes it possible to observe the capsule under X-rays as it moves in the blood vessels.
The capsule is inserted through a catheter, a similar type of tube that has been used for a variety of treatments that require access to a blood vessel. The catheter is inserted into a large blood vessel (such as the femoral artery in the groin) depending on the area of the body that needs to be treated and then guided to get as close to the affected area as possible. Only at that point is the capsule pushed out of the catheter, allowing it to move freely until it reaches the drug release point.
The movement of these iron-containing capsules is controlled thanks to a magnetic field generated by several pairs of coils placed around the patient. An operator uses a knob similar to those used for playing video games and, depending on the direction he chooses, the magnetic field changes to guide the capsule on its path inside the body. Tantalum makes it possible to observe the position of the capsule on X-rays or with systems used for vascular interventions (such as angiography), to ensure it reaches the desired point.
The research team explained that the hardest part was fine-tuning the navigation system, with a lot of calibration activity to achieve precision of less than one millimeter in 95 percent of applications. In large vessels, capsules can be transported through the bloodstream, with operator intervention only to adjust their trajectory, at speeds that can exceed 60 centimeters per second. In several simulations of the “Y” blood vessel branching model, the system proved effective in choosing the right direction even with flows up to 84 centimeters per second.
Possible movement of the capsule within the blood vessels (ETH Zurich)
Once the release point is reached, the capsule is “parked” and a magnetic field is generated that rotates continuously and very quickly, making the capsule itself vibrate and heating it within a few seconds. The heat melts the gelatin shell containing the drug, which then directly reaches the cells to be treated. Residual gelatin and iron are excreted normally by the body, whereas tantalum takes longer and is not excreted completely (but this is a minimal dose and is still inert).
Catheter model for capsule insertion (ETH Zurich)
This system has so far been successfully tested on pigs and sheep, but also on models that mimic the structure of blood vessels in various areas of the human body, and is commonly used by doctors for their training. Therefore, a start date for human clinical trials has not been determined, but it may be several years before trials begin. To obtain approval from regulatory agencies, the safety and tolerability of the treatment must be proven based on preclinical trials.
This research was received with great interest not only because of the results, but also because of the technology being tested and because the idea was considered increasingly practical for controlling the movement of external drug transport systems, thereby increasing the effectiveness of treatment. These systems require little intervention, but at the same time are largely based on systems already available in hospitals, with the exception of navigation systems, and this can result in lower costs for healthcare facilities.
