Repurposing arsenic in a way that benefits the body
In order to understand the function of nanobins, it is necessary to understand the biology of tumor growth. In order to survive and grow, cancer cells need sources of oxygen and nutrients. Through angiogenesis, which is a process that involves the formation of new blood vessels from pre-existing vessels, the tumors emit signals to trigger the growth of these vessels in and around the tumor. The new blood vessels that are formed are leaky, with numerous gaps and holes. They do not leak red blood cells, as they are too large to move through the gaps and holes, but the nanobins can slip through the leaky vasculature. “The tumors start collecting the nanobins in ways that normal tissue doesn’t, building up the concentration of these arsenic-loaded liposomes in the tumor,” said O’Halloran.
Once inside the tumor, how is arsenic released? Since cancer cells process nutrients and make energy, they are somewhat more acidic than normal cells. It is their acidity that helps to dissolve the arsenic found inside the nanobins, thus releasing the drug inside the tumor. “The acidic character of the tumor helps it grow and proliferate, which is something we can take advantage of with nanobins,” explained O’Halloran.
As a result, O’Halloran and his research team have found a unique way to repurpose arsenic as a potential treatment for cancer – the leakiness of the new blood vessels helps the nanobins to collect within the tumor, while the acidic interior of the tumor triggers the release of the arsenic found within the nanobins.