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Researchers put safety of magic anti-cancer bullet to test

A group of MIPT researchers together with their colleagues from Moscow,
Nizhny Novgorod, Australia and the Netherlands have carried out the
first systematic study analyzing the safety of so-called upconversion
nanoparticles that may be used to treat skin cancer and other skin
diseases. This study is one of the most important steps on the path to
new, safe and effective methods to diagnose and treat cancer.

It was back in 1908 that the German naturalist and doctor Paul Ehrlich
came up with the idea of a “magic bullet”- a drug that would fight only
pathogenic microbes or cancer cells, without affecting the healthy
cells. One century later chemists and physicians are closer than ever
before to turning this idea into reality, thanks to nanotechnology.
Entering the body, the nanoparticles of certain substances may
accumulate in the tumor cells, “ignoring” the healthy ones. It’s
possible to attach the molecules of drugs or diagnostic agents to such
nanoparticles to find cancer cells and destroy them without damaging the
other cells in the body.
For this purpose, researchers use nanoparticles of gold and
ferromagnetic materials, heating them with high frequency electric
currentsso that they kill cancer cells from the inside. One of the most
promising types of nanoparticles for diagnosing and treating cancer is
so-called upconversion nanoparticles (UCNPs). 
They convert near-infrared
radiation, which can penetrate deep into human tissue, in visible
light, making it possible to detect cancerous cells in body tissues,
change them and monitor the progress of treatment. UCNP scan be
configured so that they will release drugs with the help of light.

However, before developing therapeutic methods based on the use of
nanoparticles, it must be determined whether they can cause any harm to
healthy cells or not – that is the subject of the research done by Elena
Petersen and Inna Trusova of MIPT and their colleagues from Moscow,
Nizhny Novgorod, Australia and the Netherlands.
“Despite the fact that there’re a large number of studies on the
cytotoxicity of UCNPs, all of them are circumstantial in a way, because
the study of this problem was peripheral for their authors,” says
Petersen, the head of the Laboratory of Cellular and Molecular
Technologies at MIPT. “We’ve done the first systematic study of the
effects of nanoparticles on cells.”
The researchers studied the properties of one of the most common
types of UCNPs, which is derived from sodium yttrium fluoride (Na[YF4])
doped with the rare-earth elements erbium and ytterbium. The group
tested how these nanoparticles are absorbed by fibroblasts (the cells of
human connective tissue)and keratinocytes (epidermal cells), and
studied how nanoparticles affect these cells’ viability.

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The results show that the cytotoxicity of UCNPs depends on the cell
type. They are not toxic for dermal fibroblasts and slightly toxic for
keratinocytes. However, the toxicity for keratinocytes depends on the
concentration of the nanoparticles, meaning that these cells can be used
as a biological indicator for evaluating the safety of different types
of UCNPs.
In addition to the “naked” nanoparticles, there searchers tested
several modifications of polymer-coated nanoparticles. In these cases,
the difference between the response of fibroblasts and keratinocytes was
even higher, for example, the particles coated with polyethylenimine
interfered with the intracellular metabolism of the keratinocytes, but
had no effect on the fibroblasts. The group identified the types of
polymer coating that made the nanoparticles as safe as possible.
“This study is an important step towards beginning to use UCNPs to
diagnose and treat skin cancer and other skin diseases,” says Petersen.
According to her, there are already studies of the use of nanoparticles
for the treatment of skin diseases, but to utilize them on a large scale
it is necessary to prove that they are safe and efficient.
Source: MIPT