A
targeted, nanoparticle gelatin-based clot-busting treatment dissolved
significantly more blood clots than a currently used drug in an animal
study of acute coronary syndrome presented at the American Heart
Association’s Scientific Sessions 2011.

The
new drug-delivery system used gelatin to deactivate the clot-busting
drug tissue plasminogen activator, or tPA, to treat acute coronary
syndrome. Soundwaves were then used to reactivate tPA once it reached
the blood clot. It is considered a stealth approach because tPA doesn’t
act until it has reached its target.

“When
tPA is mixed with gelatin and administered in the form of
nanoparticles, it reduces tPA activity. Inactivation of tPA during
circulation is very important to reduce bleeding complications,” said
Yoshihiko Saito, M.D., senior author and professor and cardiologist at
Nara Medical University in Kashihara, Japan.

This gelatin-based drug-delivery system could potentially treat patients with chest pain en route to the hospital via ambulance.

Traditionally,
tPA is administered in the hospital, injected through a vein in the arm
or a catheter inserted into the groin and guided directly into the
blocked vessel.

Prompt
clot-busting therapy, or thrombolysis, restores blood flow to the heart
and can often prevent death. When a clot completely blocks a blood
vessel, the recommended treatment is emergency angioplasty, when a tiny
metal mesh tube is inserted into the artery to prop it open. However,
about half of the patients who die from acute coronary syndrome do not
reach the hospital in time to receive appropriate therapy.

“This
drug delivery system aims to quickly restore blood flow. Restoring
blood flow reduces tissue damage and improves the prognosis,” Saito
said.

The
body naturally produces tPA, which helps prevent blood clots by
inhibiting certain proteins involved in the clotting process. Gelatin
also binds these proteins—in particular the von Willebrand factor, which
in this study responded to gelatin combined with tPA, but not to tPA
alone.

Tracking
the drug using radioactive tPA, scientists analyzed blood clots in
animals and found three times more nanoparticle tPA than regular
isolated tPA. Thirty minutes after administering drugs in a different
animal model, blood flow was partially or completed restored in:

10% with tPA alone;

40% with tPA and ultrasound; and

90% with drug-delivery system of tPA /nanoparticle and ultrasound.

Acute
coronary syndrome—when blood flow to the heart decreases
abruptly—affects up to 1.2 million Americans each year. This includes
chest pain and heart attacks.            

http://newsroom.heart.org/pr/aha/gelatin-based-nanoparticle-treatment-217783.aspx