When a spinal cord injury occurs, sometimes it's the body's own immune system that causes the subsequent paralysis. In the not-too-distant future, however, it's possible that an injection of nanoparticles at the injury site may be able to rein in the well-meaning but destructive immune cells.
Ordinarily, when they travel to the location of an injury, immune cells help with the healing by clearing up debris and beginning the regenerative process.
The delicate neural tissues of the central nervous system, however, can be damaged by the robust activity of these cells. Normally, those tissues are protected from the cells by a membrane known as the blood-brain barrier. In the event of a spinal cord injury, though, the barrier is breached and the immune cells get in.
When this happens, the resulting inflammation kills neurons, it destroys nerve cells' insulating myeline sheath that allows them to communicate effectively, and it produces scars that keep nerve cells from regenerating. In some cases, one or more of these factors produce paralysis below the injury site.
That's where the new nanoparticles come in.
Being developed at the University of Michigan, they're made from a biodegradable polymer known as poly(lactide-coglycolide), and they contain no actual medication that could potentially cause side effects. Instead, they bind with immune cells that are on their way to the injury, reprogramming them. This causes most of the cells to travel away from the injury, while those that continue on to it produce less inflammation than they would otherwise, plus their regenerative qualities are boosted.
The nanoparticles have already been successfully tested on mice. It is hoped that once developed further, the technology could be incorporated into an EpiPen-like device that would be used to rapidly inject the particles as soon as possible after an injury occurs.
"The immune system underlies autoimmune disease, cancer, trauma, regeneration – nearly every major disease," says lead scientist Prof. Lonnie Shea. "Tools that can target immune cells and reprogram them to a desired response have numerous opportunities for treating or managing disease."
A paper on the research was recently published in the journal Proceedings of the National Academy of Sciences.
And this isn't the first time we've heard about poly(lactide-coglycolide) nanoparticles being used to keep the immune system from causing damage. An international team of scientists has previously utilized them to preserve the myelin sheaths of mice suffering from multiple sclerosis.
Source: University of Michigan
