New arthritis treatment uses nanoparticles to take drugs directly into cartilage

The particles are able to travel deep into tissue in ways that other treatments simply can't.

  • Osteoarthritis is a debilitating condition that affects millions of people worldwide, and the only treatments available merely reduce the pain.
  • The new treatment delivers a growth factor into cartilage rather than into the surface of a joint, where it'd be less effective.
  • The treatment represents a "significant step for nanomedicines," one professor said, and it could someday be used to slow age-related osteoarthritis, a leading cause of chronic pain and lost productivity at work.

MIT engineers have successfully used nanoparticles to deliver arthritis-treating drugs directly into the cartilage of mice, a development that could greatly improve treatments for the debilitating condition.

The method is outlined in new paper published November 28 in Science Translational Medicine.

Osteoarthritis, a disease in which cartilage in joints gradually degenerates, currently affects more than 20 million people in the U.S. at an annual cost of about $60 billion. Worse are the costs of arthritis-attributable medical care, which have exceeded $300 billion in recent years. The condition can cause severe pain and impaired ability, and it often leaves people unable to work. But despite its far-reaching impacts, the only treatments currently available for osteoarthritis simply manage pain and symptoms.

The new treatment seeks to change that by delivering an experimental drug directly to the source of the degeneration. The goal was to deliver an experimental drug called insulin-like growth factor 1 (IGF-1) to cells within joints called chondrocytes, which are responsible for producing the cartilage that protects joints.

To do that, MIT engineers devised tiny sphere-shaped nanoparticles with branched structures, called dendrimers, whose tips maintain a positive charge that lets them bind to negatively charged cartilage. They then attached IGF-1 to these nanoparticles and injected them into the injured joints. From there, the nanoparticle-drug combination used its unique charge to travel deep into the joints, where it was able to bind to the chondrocyte receptors and stimulate cartilage growth.

Gieger et al.

After a couple of months, the researchers noticed not only reductions in joint inflammation and bone spur formation in the mice, but also that IGF-1's therapeutic effects lasted significantly longer than current, experimental methods of delivery.

"Delivery of growth factors using nanoparticles in a manner that sustains and improves treatments for osteoarthritis is a significant step for nanomedicines," Kannan Rangaramanujam, a professor of ophthalmology and co-director of the Center for Nanomedicine at Johns Hopkins School of Medicine, who wasn't involved in the research, told MIT News.

Still, using this same technique on human joints will require further research and passing clinical trials.

"That is a very hard thing to do. Drugs typically will get cleared before they are able to move through much of the cartilage," Brett Geiger, an MIT graduate student, is the lead author of the paper, told MIT News. "When you start to think about translating this technology from studies in rats to larger animals and someday humans, the ability of this technology to succeed depends on its ability to work in thicker cartilage."

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3D printing might save your life one day. It's transforming medicine and health care.

What can 3D printing do for medicine? The "sky is the limit," says Northwell Health researcher Dr. Todd Goldstein.

Northwell Health
Sponsored by Northwell Health
  • Medical professionals are currently using 3D printers to create prosthetics and patient-specific organ models that doctors can use to prepare for surgery.
  • Eventually, scientists hope to print patient-specific organs that can be transplanted safely into the human body.
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An organism found in dirt may lead to an anxiety vaccine, say scientists

Can dirt help us fight off stress? Groundbreaking new research shows how.

University of Colorado Boulder
Surprising Science
  • New research identifies a bacterium that helps block anxiety.
  • Scientists say this can lead to drugs for first responders and soldiers, preventing PTSD and other mental issues.
  • The finding builds on the hygiene hypothesis, first proposed in 1989.

Are modern societies trying too hard to be clean, at the detriment to public health? Scientists discovered that a microorganism living in dirt can actually be good for us, potentially helping the body to fight off stress. Harnessing its powers can lead to a "stress vaccine".

Researchers at the University of Colorado Boulder found that the fatty 10(Z)-hexadecenoic acid from the soil-residing bacterium Mycobacterium vaccae aids immune cells in blocking pathways that increase inflammation and the ability to combat stress.

The study's senior author and Integrative Physiology Professor Christopher Lowry described this fat as "one of the main ingredients" in the "special sauce" that causes the beneficial effects of the bacterium.

The finding goes hand in hand with the "hygiene hypothesis," initially proposed in 1989 by the British scientist David Strachan. He maintained that our generally sterile modern world prevents children from being exposed to certain microorganisms, resulting in compromised immune systems and greater incidences of asthma and allergies.

Contemporary research fine-tuned the hypothesis, finding that not interacting with so-called "old friends" or helpful microbes in the soil and the environment, rather than the ones that cause illnesses, is what's detrimental. In particular, our mental health could be at stake.

"The idea is that as humans have moved away from farms and an agricultural or hunter-gatherer existence into cities, we have lost contact with organisms that served to regulate our immune system and suppress inappropriate inflammation," explained Lowry. "That has put us at higher risk for inflammatory disease and stress-related psychiatric disorders."

University of Colorado Boulder

Christopher Lowry

This is not the first study on the subject from Lowry, who published previous work showing the connection between being exposed to healthy bacteria and mental health. He found that being raised with animals and dust in a rural environment helps children develop more stress-proof immune systems. Such kids were also likely to be less at risk for mental illnesses than people living in the city without pets.

Lowry's other work also pointed out that the soil-based bacterium Mycobacterium vaccae acts like an antidepressant when injected into rodents. It alters their behavior and has lasting anti-inflammatory effects on the brain, according to the press release from the University of Colorado Boulder. Prolonged inflammation can lead to such stress-related disorders as PTSD.

The new study from Lowry and his team identified why that worked by pinpointing the specific fatty acid responsible. They showed that when the 10(Z)-hexadecenoic acid gets into cells, it works like a lock, attaching itself to the peroxisome proliferator-activated receptor (PPAR). This allows it to block a number of key pathways responsible for inflammation. Pre-treating the cells with the acid (or lipid) made them withstand inflammation better.

Lowry thinks this understanding can lead to creating a "stress vaccine" that can be given to people in high-stress jobs, like first responders or soldiers. The vaccine can prevent the psychological effects of stress.

What's more, this friendly bacterium is not the only potentially helpful organism we can find in soil.

"This is just one strain of one species of one type of bacterium that is found in the soil but there are millions of other strains in soils," said Lowry. "We are just beginning to see the tip of the iceberg in terms of identifying the mechanisms through which they have evolved to keep us healthy. It should inspire awe in all of us."

Check out the study published in the journal Psychopharmacology.

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