MEDILIGHT Blue light for chronic wound healing
In the biological part of the MEDILIGHT project, the proliferative and anti-proliferative effects of different light schedules have been tested in-vitro and in-vivo. For in-vitro studies, varying dosages, wavelengths and number of light cycles have been investigated using different skin cell types like keratinocytes and fibroblasts. Besides cell metabolism and proliferation gene expression profiles, signal cascades have been monitored at different time points after illumination to obtain a time curve of the light effects. In addition, scratch tests have been performed to provide an in-vitro indicator for wound healing. The in-vitro studies have been completed by irradiating different bacterial strains, such as Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneu-moniae showing a frequent occurrence in infected wounds. An impact of the chosen irradiation schedule is now tested on the skin of healthy and diabetic rats and will then pass to the final clinical proof of concept by treating healthy and diabetic individuals. Blue light is known for its anti-microbial, anti-proliferative and anti-inflammatory effects without damaging the tissue as compared to hazardous UV light as well as its low penetration depth [1-3]. Therefore, in the first stages of the wound healing process, blue light irradiation is applied, inhibiting the formation of bacterial colonies on the one hand and preventing an overshooting epidermisation by growing keratinocytes leading to a premature wound closure. For later wound healing stages, after the wound is “disinfected”, it was planned to apply red light to stimulate an accelerated cell growth [4] of inactivated cells being located in deeper skin layers like fibroblasts or stem cells. So far, in-vitro studies using infra-/red light have not shown the desired effects, which is not in agreement with most of the studies published so far (Data not shown). In contrast, biological data obtained for blue light indicate promising results for the development of a system used for an improved wound healing process through light stimulation. Furthermore, one of the aims set for blue light, preventing an overshooting epidermisation in premature healing stages by slowing down the cell metabolism of especially keratinocytes, could be achieved for longer blue light irradiations with a maximum effect at 30min [5]. Fluorescent-activated cell sorting (FACS) was performed after 24h of 30min blue light irradiation confirming the anti-proliferative effect of blue light and excluding apoptotic events at the same time [6]. Also in-vitro studies treating different bacterial strains with blue light revealed bacteriostatic and even bactericidal effects (Data not shown). References 1. Dai, T., et al., Blue light for infectious diseases: Propionibacterium acnes, Helicobacter pylori, and beyond? Drug Resist Updat, 2012. 15(4): p. 223-36 2. Avci, P., et al., Low-level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring. Semin Cutan Med Surg, 2013. 32(1): p. 41-52 3. Teuschl, A., et al., Phototherapy with LED light modulates healing processes in an in vitro scratch-wound model using 3 different cell types. Dermatol Surg, 2015. 41(2): p. 261-8 4. Vinck, E.M. et al., Increased fibroblast proliferation induced by light emitting diode and low power laser irradi-ation. Lasers Med Sci, 2003. 18(2): p. 95-9 5. Becker, A., Sticht, C., Dweep, H., van Abeelen, F. A., Gretz, N., Oversluizen, G.: Impact of blue LED irradiation on proliferation and gene expression of cultured human keratinocytes. In: SPIE (Ed.) SPIE BiOS. San Francisco, In-ternational Society for Optics and Photonics, 2015 pp 930909-930909-930912 6. Becker, A., Klapczynski, A., Kuch, N., Arpino, F., Simon-Keller, K., De La Torre, C., Sticht, C., van Abeelen, F. A., Oversluizen, G., Gretz, N.: Gene expression profiling reveals aryl hydrocarbon receptor as a possible target for photobiomodulation when using blue light. In: Sci. R
Keywords
Chronic wounds, light therapy, smart system
Countries
Switzerland, Cyprus, Czechia, Germany, France, United Kingdom