Magnetic microrobots in the body to regenerate knee cartilage

Microrobots that, once grafted into the body, can regenerate the cartilage of the knee, at least in rabbits: this is the result achieved by some researchers from various Chinese institutes and one Korean who published their study in Science Advances.

One of the most common disorders of older people is cartilage degeneration, especially in the hips and knees. The most common treatment to date is to replace the knee or hip joint with artificial devices. This is quite a serious problem considering also that the populations in the world are getting older and older and therefore problems like these, related to cartilage, are more and more widespread.

Previous research, however, had already shown that mesenchymal stem cells, those present in bone marrow and fat, can be transformed into cartilage cells in the laboratory and can also be used to repair damaged cartilage. However, the challenge has been to graft these special cells into the body and keep them in the right position to attach them to the surrounding tissue and trigger cartilage regrowth.

It seems that Chinese and Korean researchers have succeeded in just that: they created tiny hollow spheres with holes made from a polymer called PLGA or poly(lactic-co-glycolic acid). These small spheres were then sprinkled with a mixture of ferumoxytol (iron oxide) and chitosan (a sugar). The same balls were then filled with mesenchymal stem cells previously grown in the laboratory.

Finally, the same balls were inserted into the knees of various rabbits with damaged cartilage. Magnets from outside the body were used to hold them in place. After three weeks the researchers noticed that the cartilage of the rabbits’ knees showed signs of rejuvenation and at the same time the balls were emptying.

Now the researchers want to test animals with knees more similar to those of humans to see if such a technique can be used on people.

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