Scientists have successfully guided a microbot through the nasal pathways to the brain of a mouse. If the same approach can be replicated in humans, it could be a game-changer against neurodegenerative disease, enabling doctors to deliver therapies directly to the brain.
A research team led by DGIST (the Daegu Gyeongbuk Institute of Science and Technology in South Korea) has created a microrobot propelled by magnets that can navigate the human body. The trial, published in the journal Advanced Materials, describes how they manufactured the microrobot, dubbed a Cellbot, by magnetizing stem cells extracted from the human nasal cavity. The scientists then tested the ability of the Cellbot to move through the body's confined vessels and passages to reach its target, which it completed with ease.
DGIST said in a statement that "This approach has the potential to effectively treat central nervous system disorders in a minimally invasive manner."
Building an intranasal microrobot
Brain conditions affect tens of millions of people worldwide, with experts estimating that the number of Americans with Alzheimer's alone could stand at 6.2 million people. Unfortunately, there's no available cure for many of them. However, much of the research in this field focuses on stem cell therapies.
These therapies comprise special cells that can develop into many different tissue types, making them ideal for regenerative medicine as they can replace structures within the body damaged by disease or harsh therapeutics such as chemotherapy. However, problems may arise when using this type of therapy as the blood-brain barrier (the vascular system that supplies blood to the central nervous system) tightly regulates molecules that go in and out of the brain. This neural boundary prevents most therapeutics from entering without the use of high-risk surgery.
The current study may have finally found a solution for this problem.
The Institute explains their Cellbot consists of human stem cells scraped from structures known as turbinates in the nasal cavity – which they then soaked in a solution containing iron nanoparticles. The metallic particles, invisible to the naked human eye, are amalgamated with the stem cells to magnetize them, which then enables the propulsion of the Cellbots using an external magnetic field. After measuring the magnetization of the microbots, the team put the Cellbots through a rigorous set of trials to test their mobility and regenerative properties.
A microbot obstacle course
In the first test involving microfluid channels, the scientists mapped a tortuous route for the biobots around tiny pillars measuring no more than the width of a human hair placed in microscopic canals full of viscous liquid. In this way, they demonstrated that the Cellbots could traverse obstacles in confined spaces, as would be the case if they were injected into your nose.
They then tested whether the Cellbots were still safe to use as a therapy due to the presence of iron. Micro-brain organoids were grown in the lab, and the Cellbots successfully grafted onto them in the same fashion as stem cells. These results suggested that the Cellbots could differentiate into neuronal cells and help to regenerate damaged brain tissues just like their native counterparts.
Finally, a swarm of Cellbots was propelled by an external magnetic field to a target region in the mouse brain via the nasal pathway. The biobots were tagged using a fluorescent marker and guided by the scientists to traverse the blood-brain barrier and target the cortex of the frontal region of the animal's brain – where the nervous system accepted and integrated them.
New hope for untreatable brain disease
In their whitepaper, the researchers conclude that the collective results of their experiments demonstrate that the Cellbots can be successfully administered nasally and guided manually to the target brain region. The study represents a promising approach for untreatable central nervous system diseases. Professor Choi, DGIST head researcher, concluded:
"This research overcomes the limitations in the delivery of a therapeutic agent into brain tissues owing to the blood-brain barrier." He added, "It opens new possibilities for the treatment of various intractable neurological diseases, such as Alzheimer's disease, Parkinson's disease, and brain tumors, by enabling accurate and safe targeted delivery of stem cells through the movement of a magnetically powered microrobot via the intranasal pathway."