Cellular 'backpacks' could treat disease while minimizing side effects

March 16, 2016
Monocytes -- a kind of white blood cell -- carry drug-loaded backpacks (red). (The scale bar is 5 micrometers.) Credit: Roberta Polak & Rosanna Lim

Drug therapies for many conditions end up treating the whole body even when only one part—a joint, the brain, a wound—needs it. But this generalized approach can hurt healthy cells, causing nasty side effects. To send drugs to specific disease locations and avoid unwanted symptoms, researchers developed cellular "backpacks" that are designed to carry a therapeutic cargo only to inflamed disease sites.

The researchers present their work today at the 251st National Meeting & Exposition of the American Chemical Society (ACS).

"What we want to do is take advantage of whose job it is to seek out disease in the body, and use them to deliver cargo for us," says Roberta Polak, a postdoctoral research associate. "How do we do that? Our lab developed cellular backpacks that can be loaded with therapeutic compounds and unloaded."

Polak and fellow in the Massachusetts Institute of Technology (MIT) labs of Michael Rubner, Ph.D., and Robert Cohen, Ph.D., make the backpacks by stacking ultra-thin layers of polymer materials on top of each other. According to Rubner, they could be used to treat a wide range of diseases from cancer to Parkinson's.

The resulting pack has different functional regions. One is Velcro-like, attaching via antibody-antigen binding to immune cells, such as monocytes and macrophages. These are the body's defense cells that travel to sites of inflammation—a natural reaction to infection and disease—and gobble up foreign invaders or attack cancer cells. In vitro testing has shown that the backpacks can stick to the surfaces of the immune cells without getting engulfed. In collaboration with the group of Samir Mitragotri at the University of California at Santa Barbara, the MIT team has also demonstrated in mice that these backpack-functionalized immune cells accumulate in locations where inflammation—a sign of disease—occurs.

But there was a problem. The medicine they were using to test the backpacks, a cancer called doxorubicin, was leaking out—even during the initial fabrication process. So Polak worked on this part of the backpack, its payload region. To stop the premature release of the drug, she trapped it in liposomes, tiny bubbles that have already been used to carry therapeutic compounds for other delivery systems, and then incorporated them into the backpacks. She found that she could fit nine times the amount of doxorubicin in the liposomes than in the backpacks alone, potentially transforming them into an even more potent weapon.

To control the release of the drug payload, Polak used liposomes that are echogenic, or sensitive to ultrasound. So in principle, when backpacks infused with these bubbles reach their destination, they can be burst open with ultrasound waves.

Now, to see how well they work to treat a specific disease, Polak is collaborating with Elena Batrakova, Ph.D., at the University of North Carolina at Chapel Hill. Batrakova has been working with mice to develop new treatments for brain inflammation, a characteristic of diseases such as Parkinson's and Alzheimer's. They want to see if they can use the backpacks to carry an inflammation-fighting enzyme across the blood-brain barrier.

Explore further: 'Cellular backpacks' attached to white blood cells that target inflammation can provide therapy

More information: Design and Production of Functional Thin-Film Backpacks for Cell-Based Therapies, the 251st National Meeting & Exposition of the American Chemical Society (ACS), 2016.

Related Stories

Heat-activated 'grenade' to target cancer

October 31, 2015

Researchers have developed cancer drug-packed 'grenades' armed with heat sensitive triggers, allowing for treatment to be targeted directly at tumours, according to two studies due to be presented at the National Cancer Research ...

Recommended for you

Scientific advances can make it easier to recycle plastics

November 17, 2017

Most of the 150 million tons of plastics produced around the world every year end up in landfills, the oceans and elsewhere. Less than 9 percent of plastics are recycled in the United States, rising to about 30 percent in ...

The spliceosome—now available in high definition

November 17, 2017

UCLA researchers have solved the high-resolution structure of a massive cellular machine, the spliceosome, filling the last major gap in our understanding of the RNA splicing process that was previously unclear.

Ionic 'solar cell' could provide on-demand water desalination

November 15, 2017

Modern solar cells, which use energy from light to generate electrons and holes that are then transported out of semiconducting materials and into external circuits for human use, have existed in one form or another for over ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.