Researchers are able to produce medicine encapsulated in
nanoparticles the size of viruses, but new research has shown another great
challenge in nanomedicine—the immune system—and the importance of the coating
polymers on the nanoparticle surface.
Researchers have over time been able to
show that medicine designed at nanoscale offers unprecedented opportunities for
targeted treatment of serious diseases such as cancer. However, now research
also shows that the body’s immune system plays a significant part in the drug
delivery process.
“Researchers today are able encapsulate
medicine in nanoparticles the size of viruses. The nanoparticles are effective
for drug delivery because they can very precisely find diseased cells and carry
the medicine to them. This means that you can suffice with less dosage and
thereby fewer side effects,” explains Professor Moein Moghimi from the Faculty
of Pharmaceutical Sciences at the Univ.
of Copenhagen.
Professor Moghimi has along with colleagues
at the Univ. of Brighton and the Technical Univ. of
Denmark published a landmark paper in ACS
Nano regarding the immune system’s attack on nanoparticles.
A water disguise
The new research has shown that the coating of the nanoparticle
surface has great influence on the activation of the immune system—the
particle’s polymer coating can be designed in various ways, and the form can
change the body’s immune response.
“Drug delivery with nanoparticles
camouflaged as water soluble polymers has proven very effective. One way of
delivering drugs safely to diseased sites in the body is to encapsulate them in
small polymeric particles in similar size to viruses. However, when injected
into the blood these particles are intercepted by the body’s defense system.
This can be overcome by camouflaging the surface of these nanocarriers with
water soluble polymers. This makes the surface ‘water-like’ and less visible to
the immune system,” says Professor Moghimi.
Significance of changing the coating
polymers
Professor Moghimi works at the Department of
Pharmaceutics and Analytical Chemistry where he heads the Centre for
Pharmaceutical Nanotechnology and Nanotoxicology, which is supported by the
Danish Agency for Science, Technology and Innovation. This work was done as
part of ongoing research at the Centre.
Professor Moghimi’s main focus is
nanotoxicology—and the possible consequences of drug delivery with
nanoparticles.
“Our newest research indicates that we
should be very cautious when designing the surface of the nanoparticles.
Remarkably, changing the conformation of the coating polymers on nanoparticle
surface from a ‘mushroom-type’ to a ‘brush-type’ appearance can switch
complement activation from one pathway to another,” explains Professor Moghimi.
The research demonstrates difficulty in
design and surface engineering of polymeric nanoparticles such that it is
hydrophilic enough to be compatible with biological fluids and yet prevent
complement activation. This is also very important from clinical perspectives
since complement activation may induce adverse reactions in some patients.
