April 28, 2010 - Infusing tiny, melanin-covered nanoparticles into patients may protect bone marrow from the harmful effects of radiation therapy, according to scientists at Albert Einstein College of Medicine of Yeshiva University in New York City.
The study, which is described in the current issue of the International Journal of Radiation Oncology, Biology and Physics, was tested on mouse models. Melanin naturally shields the skin from the damaging effects of sunlight and has been shown to protect against radiation. This technique for shielding normal cells from radiation damage could allow doctors to administer higher doses of radiation to tumors, making the treatment more effective.
Ekaterina Dadachova, Ph.D., associate professor of nuclear medicine and of microbiology and immunology and the Sylvia and Robert S. Olnick faculty scholar in cancer research at Einstein, led the study. Dadachova and her colleagues focused on packaging melanin in particles so small that they would not get trapped by the lungs, liver or spleen. They created melanin nanoparticles by coating tiny (20 nanometers in diameter) silica particles with several layers of melanin pigment that they synthesized in their laboratory.
The researchers found that these particles successfully lodged in bone marrow after being injected into mice. Then, in a series of experiments, they investigated whether their nanoparticles would protect the bone marrow of mice treated with two types of radiation.
One group of mice was injected with nanoparticles and a second group was not. Three hours later, both groups were exposed to whole-body radiation. The levels of white cells and platelets dropped in those receiving melanin nanoparticles before radiation exposure. Ten days after irradiation, platelet levels had fallen by only 10 percent in mice that had received nanoparticles compared with a 60 percent decline in untreated mice. The levels of white blood cells and platelets returned to normal much more quickly than in the control mice.
Clinical trials testing whether melanized nanoparticles might protect cancer patients undergoing radiation therapy could begin in two to three years.
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 involved in the study are Ekaterina Revskaya, Ph.D., Peter Chu, B.Sc., Matthew Friedman, Joshua D. Nosanchuk, M.D., Sean Cahill, Ph.D., and Susana Frases, Ph.D., all from Einstein, and Valeria Pazo, M.D., of Jacobi Medical Center.
For more information: www.redjournal.org/article/S0360-3016%2810%2900254-3/abstract
