Feb 4 2016
A new technique to restrict the growth of cancerous tumors has been developed by a group of engineers from the Washington University in St. Louis. The group used nanoparticles from the core ingredient in the commonly used antacid tablets.
A common over-the-counter drug, chopped down into nanoparticle size, stopped growth in a cancer tumor.
The team was headed by Avik Som, an MD/PhD student, and Samuel Achilefu, PhD, professor of radiology and of biochemistry & molecular biophysics in the School of Medicine and of biomedical engineering in the School of Engineering & Applied Science. They worked together with the two labs in the School of Engineering & Applied Science.
Two unique techniques were used by the researchers to develop nanoparticles from calcium carbonate. These nanoparticles were later injected into a mouse model to examine its efficiency in treating solid tumors. The outcome of this method was that the pH in the tumor environment was changed from acidic to more alkaline by the compound, preventing the growth of the cancerous tumor.
Through this research, the team proved that it is possible to modify pH present in solid tumors, using nanoparticles that have been specifically designed for this research work. Results of this work were published in the online journal, Nanoscale.
Cancer kills because of metastasis. The pH of a tumor has been heavily correlated with metastasis. For a cancer cell to get out of the extracellular matrix, or the cells around it, one of the methods it uses is a decreased pH.
Avik Som, MD/PhD Student, Washington University
Fighting cancer cells with calcium carbonate
The team wanted to discover new methods to increase the pH of the tumor, only in the tumor environment. In water the pH present in calcium carbonate raises to almost 9. However, when it is injected into the body, the calcium carbonate increases the pH to only 7.4, which is the normal pH in an individual’s body. The researchers experienced some challenges while working with calcium carbonate.
Calcium carbonate doesn’t like to be small. Calcium carbonate crystals are normally 10 to 1,000 times bigger than an ideal nanoparticle for cancer therapy. On top of that, calcium carbonate in water will constantly try to grow, like stalactites and stalagmites in a cave.
Avik Som, MD/PhD Student, Washington University
To solve this problem, Som developed two novel solutions with researchers in the School of Engineering & Applied Science. Teaming up with researchers in the lab of Pratim Biswas, PhD, the Lucy & Stanley Lopata Professor and chair of the Department of Energy, Environmental & Chemical Engineering, they came up with a technique using polyethyleneglycol-based diffusion to synthesize 20- and 300-nanometer-sized calcium carbonate.
Another technique was developed by the researchers, who also worked with Srikanth Singamaneni, PhD, assistant professor of materials science. The team aimed to use this new technique to form 100-nanometer-sized calcium carbonate through the ethanol-assisted diffusion process. The researchers formed a new solvent using albumin to prevent the growth of the calcium carbonate nanoparticles, making it possible to inject them into the human body.
Nanoparticles are generally developed with silver and gold that do not exist in the body. However, there is still concerns about the accumulation of both silver and gold in the human body.
Calcium and carbonate are both found heavily in the body, and they are generally non-toxic. When calcium carbonate dissolves, the carbonate becomes carbon dioxide and is released through the lungs, and calcium is often incorporated into the bones.
Avik Som, MD/PhD Student, Washington University
The team, headed by Som, regularly injected the calcium carbonate nanoparticles into the mouse fibrosarcoma model to prevent the growth of the tumor. However, the tumor continued to grow again once the injecting of nanoparticles into the body was stopped.
In the future, the researchers aim to determine an appropriate dose to avoid the occurrence of metastasis, treating the tumors in a more enhanced manner, and examining the possibility of using the dose of nanoparticles with drugs used for chemotherapy.