The advance by a team at UCLA could mitigate against the complications associated with chemotherapy and radiotherapy.
The research was co-led by Richard Wirz, a professor of mechanical and aerospace engineering at the UCLA Samueli School of Engineering; and former UCLA bioengineering professor Zhen Gu, who is now the dean of the College of Pharmaceutical Sciences at Zhejiang University in China. The team’s work is detailed in Science Advances.
Ionised gas, or plasma, is most often experienced as lightning, which is said to have inspired the plasma-generation technique for this new technology. The research team built a handheld, air-fed cold atmospheric plasma – aCAP - device that uses ambient air as its feed gas.
The patent-pending aCAP device uses tiny plasma arcs that require less than a trillionth of the gigajoule power of a natural atmospheric electrostatic discharge. The system generates near-room-temperature plasma – or cold plasma - with these arcs ionising a jet of ambient air by stripping away some of the electrons from the air molecules. It is safe to touch, feeling like a cool breeze across the skin or static electricity at higher powers.
In medicine, cold atmospheric plasma is emerging as a promising technology for wound healing, sterilisation, dentistry and other applications. More recently, researchers turned their attention toward using the advance to destroy cancer cells, noting that cold plasmas have already been shown to kill bacteria in several ways — such as eliminating their cell membranes, cell walls, and DNA and RNA, as well as unravelling proteins.
The team first tested the technology in vitro on breast cancer tumour cells and melanoma cells, showing its effectiveness in killing the target cells while leaving healthy cells intact. They then tested on mice with tumours that were surgically removed. In a statement, UCLA said that compared to the control group, a significant percentage of the mice that treated with the cold plasma showed no signs of tumour regrowth and no visible adverse reaction. There had been an increase in the activity of T cells also.
According to the researchers, another advantage of aCAP is that it only requires air-intake through a small inlet fan, which avoids the high costs and complexity of conventional cold plasma devices that depend on specialised systems for feed gases, such as argon or helium.
The researchers are now in the process of optimising the design of the device and conducting tests on larger animals to better simulate human conditions.