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Due to its ability to permeate the dense cartilage matrix, peptidic nanoparticles
appears to a promising approach for effective OA treatment.
At least 27 million people in the United States are
affected by osteoarthritis and at least
12 percent of osteoarthritis cases arises from earlier injuries.
Over-the-counter (OTC) painkillers, like anti-inflammatory drugs, help reduce
pain but do not cease unrelenting cartilage destruction. Hence, pain associated with the condition only gets worse.
The
researchers at Washington University School of Medicine in St. Louis have
revealed in mice that they can inject nanoparticles into an injured joint and
conquer inflammation soon after an injury, lowering the destruction
of cartilage. These findings are described online in the Proceedings of
the National Academy of Sciences.
According
to senior author Christine Pham, MD, an associate professor of medicine,"I
see a lot of patients with osteoarthritis, and there's really no treatment. We
try to treat their symptoms, but even when we inject steroids into an arthritic
joint, the drug only remains for up to a few hours, and then it's cleared.
These nanoparticles remain in the joint longer and help prevent cartilage
degeneration."
An
osteoarthritis patient has persistently suffered an earlier injury - a torn
meniscus or ACL injury in the knee, a fall, car accident or other trauma.
Inflammation is followed after such injuries as a result of body's natural
response. Some commonly used drugs like acetaminophen and ibuprofen, and
injections of steroids (worst cases of pain) also can provide pain relief to
the patients, although their effects are short-lived.
The
nanoparticles were injected shortly after an injury, and within 24 hours in the
study mentioned here. The nanoparticles were at work taming inflammation in the
joint. The particles remained in
cartilage cells in the joints for weeks unlike steroid injections that are
quickly removed.
These
nanoparticles penetrate deeply into the tissues as they are more than 10 times
smaller than a red blood cell. The particles carry a peptide derived from a
natural protein- melittin. It has been altered to enable it to bind to a
molecule called small interfering RNA (siRNA). The melittin transfers siRNA to
the damaged joint, obstructing with inflammation in cells. The co-investigators Hua Pan, PhD, an assistant
professor of medicine, and Samuel Wickline, MD, the James R. Hornsby Family
Professor of Biomedical Sciences formulated the peptide-based nanoparticle.
As
per Wickline," The nanoparticles are injected directly into the joint, and
due to their size, they easily penetrate into the cartilage to enter the
injured cells. Previously, we've delivered nanoparticles through the
bloodstream and shown that they inhibit inflammation in a model
of rheumatoid arthritis. In this study, they were injected locally into
the joint and given a chance to penetrate into the injured cartilage."
To
avert the cartilage breakdown after injury, the nanoparticles were injected
immediately. Whether such a technique will work years after an injury, when
osteoarthritis is initiated and there is severe cartilage loss, still needs to
be estimated. But the results point out that the nanoparticles, if given soon
after joint injuries occur, could assist in maintaining cartilage viability and
hinder the progression to osteoarthritis.
Linda
J. Sandell, PhD, the Mildred B. Simon Research Professor of Orthopaedic Surgery
and director of Washington University's Center for Musculoskeletal Research
said that
"The inflammatory molecule that we're targeting not only causes problems after an injury, but it's also responsible for a great deal of inflammation in advanced cases of osteoarthritis. So we think these nanoparticles may be helpful in patients who already have arthritis, and we're working to develop experiments to test that idea."
Proceedings of the National Academy of Sciences
Nanoparticle injections may be future of osteoarthritis treatment
Jason M. Beneciuk et al.
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