Russian scientists at the Moscow Institute of Physics and Technology (MIPT), the Joint Institute for High Temperatures of the Russian Academy of Sciences (JIHT RAS), and Gamaleya Research Centre of Epidemiology and Microbiology found that treating cells with cold plasma leads to their regeneration and rejuvenation. This result can be used to develop a plasma therapy program for patients with non-healing wounds.
The paper has been published in the Journal of Physics D: Applied Physics.
Non-healing wounds make it more difficult to provide effective treatment to patients and are therefore a serious problem faced by doctors. These wounds can be caused by damage to blood vessels in the case of diabetes, failure of the immune system resulting from an HIV infection or cancers, or slow cell division in elderly people. Treatment of non-healing wounds by conventional methods is very difficult and in some cases impossible.
Cold atmospheric-pressure plasma refers to a partially ionized gas (the proportion of charged particles in the gas being close to 1?%) with a temperature below 100,000 K. Its application in biology and medicine has been made possible by the advent of plasma sources generating jets at 30–40?°C.
An earlier study established the bactericidal properties of low-temperature plasma, as well as the relatively high resistance of cells and tissues to its influence. The results of plasma treatment of patients with non-healing wounds varied from positive to neutral. The authors’ previous work prompted them to investigate the possibility that the effect of plasma treatment on wound healing could depend on application pattern (the interval between applications and the total number of applications).
Two types of cells were used in this study, viz. fibroblasts (connective tissue cells) and keratinocytes (epithelial cells). Both play a central role in wound healing.
The effect of plasma treatment on cells was measured. In fibroblast samples, the number of cells increased by 42.6?% after one application (A) and by 32.0?% after two applications (B), as compared to the untreated controls. While no signs of DNA breaks were detected following plasma application, an accumulation of cells in the active phases of the cell cycle was observed, alongside a prolonged growth phase (30 hours). This means that the effect of plasma could be characterized as regenerative, as opposed to harmful.
The proliferation of cells that had been treated daily over a period of three days (group C) was reduced by 29.1?% relative to the controls. Keratinocytes did not show noticeable changes in proliferation.
The researchers also performed an assay of the senescence-associated ?-galactosidase, which is measured at pH 6.0. The concentration of this enzyme in a cell increases with age. Plasma treatment significantly reduced the content of this substance in the samples. This, together with a prolonged exponential growth phase of the culture, suggests a functional activation of cells—their rejuvenation.
‘The positive response to plasma treatment that we observed could be linked to the activation of a natural destructive mechanism called autophagy, which removes damaged organelles from the cell and reactivates cellular metabolic processes,’ says Elena Petersen, a co-author of the paper and the head of the Laboratory of Cellular and Molecular Technologies at MIPT.
The scientists are planning additional research into the molecular mechanisms underlying the effects of plasma on cells. They also aim to determine the influence of a patient’s age on the effectiveness of plasma therapy.
Learn more: Cold plasma will heal non-healing wounds
Tuning cold plasma can either promote or inhibit bone formation
Cold plasma looks like the glow from the “Star Wars” blue light saber but this beam of energy, made of electrons that change polarity at micro-second or nanosecond speeds, could help bones heal faster, according to a study published August 11th in the Journal of Tissue Engineering and Regenerative Medicine.
Most people interact with plasma every day. It’s in our TVs, fluorescent lights, lightning, the aurora borealis, and the sun. However, these are all examples of hot or “thermal” plasmas. Since the discovery of cold plasma, about 20 years ago, it has been used in agriculture to sterilize the surface of fruit without damaging the delicate edibles. More recently, scientists have been performing experiments treating living animal cells and tissues with cold plasma to learn more about its potential applications in medicine.
“We’ve previously studied how different applications of cold plasma can either directly kill cells, such as in skin cancer, or help them grow, as in developing bones. In this study, we asked how cold plasma would affect the area surrounding cells, known as the extracellular matrix,” says lead author Theresa Freeman, Ph.D., Associate Professor in the Department of Orthopedic Surgery in the Sidney Kimmel Medical College at Thomas Jefferson University. The extracellular matrix around cells is made of collagen and other proteins that interact with the cells and can influence their growth and behavior. For example, the extracellular matrix can either promote or inhibit bone formation or cancer cell growth and metastasis.
“We showed that matrix treated with cold plasma generated using microsecond pulsing can promote differentiation of cells into cartilage and increase bone formation,” says Dr. Freeman. “Conversely, we showed matrix treated with nanosecond-pulsed cold plasma inhibited cell differentiation and bone formation.”
The study demonstrates that cold plasma may be “tuned” to either promote or inhibit cell/matrix interactions by chemically altering the matrix.
The researchers started their experiments by exposing a commercially available extracellular matrix, (Matrigel) to either nanosecond or microsecond pulsed cold plasma at different frequencies. When microsecond cold plasma-treated Matrigel was inserted into a mouse, cells entered the gel and began the process of bone formation. However, far fewer cells entered the nanosecond plasma-treated Matrigel, and bone formation was stunted. Using an in vitro assay, Dr. Freeman and colleagues showed that cells grown on microsecond plasma-treated collagen had higher levels of focal adhesion kinase activation, indicating better cell/matrix attachments which helps initiate bone formation. There were also higher levels of anti-apoptotic proteins, suggesting better cell viability than in nanosecond-cold plasma treated collagen.
“As research into medical applications of cold plasma expands, it will be important to study various plasma types and conditions in tissue models, rather than isolated cells,” says Dr. Freeman, “Because cold plasma affects each cell type and matrix protein to produce variable physiological effects,” says Dr. Freeman, “it’s important to study not just how each cell behaves when exposed, but how they react together within the tissue and organismal environment.”