In many cases, the precise delivery of drugs into diseased tissue remains a challenge. For example, drug delivery to pancreatic tumors is especially difficult due to its hypovascular and poorly perfused nature. Now, researchers at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany have developed microscopic drug delivery devices that can travel against the flow of blood.
To reach different tissues and organs in the human body, there is no better access route than the circulatory system. Cells or synthetic drug transporters can most reliably target diseased tissue such as tumors if they can move not only with the bloodstream but also against it. When building their latest microrobot, the researchers took inspiration from white blood cells. They developed a microrobot that resembles a white blood cell in size, shape, and mobility. A microroller was loaded with therapeutic drugs and adhered to diseased tissue cells with the help of antibodies on it, and additionally, it was rolled and steered through an artificial blood vessel using external magnetic fields. In further tests, a microtransporter targeted cancer cells and discharged an active substance at the spot, reports Max Planck Institute.
Metin Sitti, Director of the Physical Intelligence Department at the Max Planck Institute for Intelligent Systems, together with researchers in his department, developed a magnetic microtransporter, which they loaded with a tumor treatment and then steered through an artificial blood vessel using a small magnetic coil. “Our vision is to create the next generation of the vehicle for minimally invasive, targeted drug delivery that can travel even further into the body and reach even more inaccessible areas,” says Metin Sitti.
Each microroller has a diameter of fewer than eight micrometers and has a glass core. The researchers coated one side of the tiny sphere with a thin nickel and gold layer, making the tiny ball magnetic. They coated the other hemisphere with an anti-cancer drug, together with antibodies to steer the microroller towards tumor cells.
In a test in an artificial blood vessel, the spherical drug vehicle actively moved along the vessel wall against the flow of fluids such as mouse blood. “No microrobot has so far been able to withstand flows like this,” says Yunus Alapan, a postdoctoral researcher at the Intelligent Systems Department and co-author of the publication. “But we’ve managed it! And not only that, our robots can independently recognize the cells of interest, for example, cancer cells.”
However, there are further challenges to overcome before transporters like these can be launched under real-life conditions. In fact, they are still far from ready to be tested in the human body. Although the researchers have succeeded in observing the robots under a microscope, “In clinics, however, the resolution of current imaging techniques is not high enough for imaging individual microrobots in the human body,” says Ugur Bozuyuk, a Ph.D. student at the Max Planck Institute for Intelligent Systems and co-author of the study.
The researchers hope to create a new approach to controlled navigation through the circulatory system. This could one day pave the way for targeted drug delivery to diseased tissue using microrobots.