Melanin-covered nanoparticles may aid cancer patients in radiation therapy by Aarti Kapoor 

Bronx, NEW YORK — Radiation therapy is often used to kill cancer cells and shrink tumors, but the amount of radiation must be limited due to its negative side-effects — one of them being the destruction of bone-marrow stem cells. Melanin — the naturally occurring pigment that gives skin and hair its color — has been shown to protect against radiation. However, due to its insoluble nature, it has been a challenge to get melanin into the bone marrow of patients — until now.   

Scientists at Albert Einstein College of Medicine of Yeshiva University recently found that it may be possible for melanin to be delivered to the bone marrow by intravenously administering melanin-covered nanoparticles into cancer patients.

“Physicians will (now) be able to give higher radiation doses to patient's tumors as their bone marrow is protective,” said Ekaterina Dadachova, Ph.D., associate professor of nuclear medicine and of microbiology & immunology and the Sylvia and Robert S. Olnick Faculty Scholar in Cancer Research at Einstein, as well as senior author of the study that was recently published in the International Journal of Radiation Oncology, Biology and Physics.

“For patients, it means better chances of cure and also less side effects such as tiredness, immunosuppression which can cause various opportunistic infections and other undesirable consequences,” she added.

The research

In the study, Dadachova and her colleagues synthesized melanin-nanoparticles by covering silica nanocores with melanin. After a series of tests aimed at confirming that the pigment formed on the surface of the nanocores is really melanin and that the size of the particles is still below 100 nanometers, the nanoparticles were introduced into mice via intravenous injection and their protective effect on the bone marrow was tested by subjecting the mice either to whole body external radiation or to internally administered radionuclides in the form of radiolabeled antibodies.

Through their experiments, the researchers not only found that melanin nanoparticles protected bone marrow, but the nanoparticles did not interfere with radiation therapy’s effectiveness on tumors. 

Silica nanocores – any toxicity issues?

As to whether introducing the silica nanocores into the body presented any concerns relating to toxicity, Dadachova said, “Silica is extremely inert material … plus the nanoparticles will be with time removed from the bone marrow by phagocytic cells. However, we are planning in future work to use biodegradable nanocores for covering them with melanin.”

Other potential applications

Dadachova mentioned other potential applications that may arise as a result of this study: “Such radioprotective nanoparticles could be potentially administered to anyone who will be exposed to high doses of radiation  from nuclear industry workers to military personnel and astronauts,” she said.

Future plans

The team’s future plans for research in this area include optimizing the nanoparticles to make them more radioprotective, and investigating whether the amount of administered doses of these nanoparticles can be increased to improve radioprotection of bone marrow even further. Clinical trials are likely to begin in two to three years. 

More information: The paper, “Melanin-covered nanoparticles for protection of bone marrow during radiation therapy of cancer,” was published in the April 26 online issue of the International Journal of Radiation Oncology, Biology and Physics. Other researchers in the study are Arturo Casadevall, M.D., Ph.D., Andrew D. Schweitzer, M.D., Ekaterina Revskaya, Ph.D., Peter Chu, B.Sc., Valeria Pazo, M.D., Matthew Friedman, Joshua D. Nosanchuk, M.D., Sean Cahill, Ph.D., and Susana Frases, Ph.D. 

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