As early as in 2009, the Vienna University of Technology developed a therapy device that is being further developed and marketed by the Viennese company REPULS. Since then, the REPULS deep-penetration radiator has found its way into numerous medical practices. The analgesic and anti-inflammatory effect of light of certain wavelengths has been clinically confirmed. But how exactly can this work?

It is still not fully understood how the light affects the tissue and the body cells it contains. However, this is not because there is a lack of clues. Rather, more and more molecules are being discovered in cells that are affected by light. Studies at LBI Trauma showed that the activity of the mitochondria, the power plants of the cells, and the production of energy (ATP) are stimulated, which favours cell division and makes cell metabolism run faster. In addition, light, especially with short wavelengths, releases nitric oxide, an important messenger substance in the body that, among other things, causes blood vessels to dilate. Furthermore, in a study at LBI Trauma, a whole series of proteins were identified that were either expressed more or less often, i.e. built according to the instructions in the genetic code, after treatment with the light of the REPULS emitters – and here, too, the wavelength played an important role.

The effects within the cells are so manifold that it is often difficult to predict how the cell will react in total. That is why the behaviour of the cells is also being closely examined.

A study led by Dr. Peter Dungel and Dr. Susanne Wolbank was able to show that fat stem cells divide more often and form larger cell colonies after treatment with pulsed light. In addition, their ability to form capillary network-like structures was increased, and they produced more VEGF, a signalling molecule that stimulates vascularisation.

Another study had the aim to prove whether light can stimulate fat stem cells to form cartilage under suitable conditions. This does not work equally well with every cell donor. But if these cells are to be used later to treat cartilage defects, it is important that every patient has a good chance of cartilage formation. It turned out that red light in particular was able to activate cartilage formation – even in cells from donors who were unable to do so without light. An examination of gene expression showed that these cells had previously produced many inflammatory markers (i.e. molecules that trigger inflammatory reactions). After the light therapy, this was no longer the case.

In addition, light has positive properties beyond the cellular level. The multitude of positive effects that can be detected in the laboratory can also be observed in preclinical and clinical applications. A great deal of research has been done at LBI Trauma in the field of wound healing.

Wound healing disorders are on the rise and, in addition to the personal burden, lead to massive costs in the health care system. They often occur in connection with diabetes or long periods of bed confinement. About one percent of the population suffers from a chronic wound. This is where light therapy unfolds its potential as a cost-effective, non-invasive form of therapy for tissue regeneration and wound healing. The improvement of disturbed wound healing through light therapy has already been confirmed in several studies. Tissue necrosis, caused by a lack of oxygen supply to the wound, can be reduced and an improved blood supply to wound areas can be promoted. Cell growth and the formation of networks of endothelial cells, which are responsible for the formation of new blood vessels, can also be stimulated.

Finally, the effect of light can also be combined with special substances (photosensitisers). In the course of this so-called photodynamic therapy, oxygen radicals are formed that have an antibacterial effect, among other things, which has a positive effect on wound healing. Light therapy is therefore particularly promising for chronic wounds.

Another non-invasive form of therapy and already clinically established is extracorporeal shock wave therapy. Already used since the 1980s to break up kidney stones, it was discovered that this therapy can also stimulate the formation of new bone. Studies confirmed: shock wave therapy helps with poorly healing or non-healing bones (pseudoarthrosis) and is already being used clinically there. The emergency hospital Meidling was a pioneer in establishing this therapy worldwide. The influence of extracorporeal shock wave therapy on nerve tissue is currently being investigated at LBI Trauma. It has been shown that it leads to faster bridging of peripheral nerve defects. As part of a Wings for Life project, its use in spinal cord contusions is currently being tested – with promising results.