Microbots are able to deliver stem cells throughout the body

A team of scientists from the City University of Hong Kong announced the invention of a new stem cell (SC) delivery tool using tiny magnetically controlled robots. The new technology, described on June 27, 2018 in the journal Science Robotics, will help non-invasively deliver SCs to hard-to-reach tissues and organs.

The amazing property of stem cells to turn into any type of body cells for many years excites the minds of scientists. With the help of stem cells and animal models, many methods of restoring and replacing damaged tissues are created. Such studies are widely covered in the scientific literature.

One of the less common areas in the study of stem cells is addressing the problem of delivering stem cells to hard-to-reach places of the body. Usually, scientists use injections. However, the needle can damage healthy tissue, especially if the SC needs to be delivered when the target is a deep brain structure, or delicate vasculature, or the inner ear.

A group of researchers from Hong Kong, led by Professor Dong Sun, invented a new non-invasive method for delivering stem cells using tiny, magnetically controlled microbots. The invention is remarkable in that scientists were able to successfully demonstrate it on living models – mice and zebrafish.

“It’s really uncertain how to make these tiny machines move in living organisms”, – says Bradley Nelson, a microroboticist at ETH Zürich, who was not involved in the project.
Several other groups, including the Nelson team, have developed microbots that carry stem cells in computer simulations or in test tubes. “However, in vivo it harder”, – says Nelson.

Sun have developed robots that look like a burr (the prickly spherical seed pods that cling to clothing).

Together with colleagues, he designed them using 3D laser lithography, coated with nickel to create magnetic properties and titanium for biocompatibility.

The porous, burr-shaped bots hold the cells between their spikes. Using magnetic fields, researchers can guide the bots to any desired part of the body. There, they release the stem cells, which, then proliferate and do their job in regenerating damaged tissue.

The Sun team tested mobility of robots by injecting them into the yolks of zebrafish embryos. Scientists controlled the movement of bots between pre-established points in the yolk, while watching how the heart of the embryo continues to beat.

In the next stage of the experiment, the researchers tested the ability of robots to transfer and release cells. They equipped the bots with HeLa cancer cells labeled with a fluorescent label so that they could be identified later and injected they into the mice. A month later the target site in the body of the mice glowed, which meant that the microbots had successfully completed their work on the delivery of cells.

Ultimately, the technique should help in developing new ways of treating cancer, and not in spreading cancer in animals. In this experiment, cancer cells were used because they proliferate rapidly, and they are easy to detect after a few weeks.

A next step of the scientists would be to test the therapeutic capabilities of the microbots that carry stem cells. However, so far one of the significant limitations of the structure of bots is the design features that release cells uncontrollably and spontaneously.

Nelson emphasizes that Sun’s robots are just the first step on the path to developing therapy for the treatment of organs and diseases using stem cells. Still need to do a lot of work.

Dong Sun says: “With these findings, we are doing a pre-clinical study of delivering stem cells into animals for precise treatment of diseases such as cancers.”