Effect of low level laser irradiation on expression of cytokines and growth factors involved in wound healing

• Main Author: Sekhejane, Palesa Rose
• Published: 2010
• Subjects: Lasers' therapeutic use; Wound healing
• Online Access: http://hdl.handle.net/10210/3121

M. Tech. === Phototobiomodulation (PBM), also known as low level laser therapy (LLLT) or photobiostimulation, is a non-invasive form of therapy that utilizes low intensity laser light or irradiation to provide healing. However, in order for healing to be successful certain laser parameters need to be taken into consideration i.e. fluence (dosage), wavelength and power density. Laser therapy has been used for various medical applications and fields. Multiple cytokines and growth factors are involved in wound healing including Interleukin (IL)-1, IL-6 and Tumour Necrosis Factor alpha (TNF- a). In diseased state(s) such as diabetes mellitus (DM) or psoriasis, these growth factors or cytokines are either found elevated or decreased depending on various factors and for abnormally prolonged periods. However, inflammatory cytokines are usually elevated. Phototherapy has been reported to accelerate wound healing, attenuate pain and cease inflammation. However, the effect of phototherapy on cytokine modulation has not been explored extensively, especially under various stress mechanisms. Furthermore, the pathway that laser irradiation induces on modulated pro-inflammatory cytokines has not been clearly elucidated as scientists typically report on the up- or down-regulated expression of cytokines. Numerous authors have reported on the efficacy of laser irradiation to enhance the rate of wound healing and proliferation in normal and diabetic cells or tissue; however, literature that has demonstrated the latter on hypoxic insulted cells is inadequate. In this study hypoxic insult was induced as it is one of the factors that usually prolong the healing process in diabetic wounds. Prior to commencing with the main study, a pilot study was done to exclude the effect of osmotic pressure on cells grown in media containing additional glucose, and thus simulating a diabetic model iv in vitro. Mannitol was used as a control since it is not absorbed by the cells. The study involved four groups namely: normal, normal wounded, mannitol wounded and diabetic wounded cells with each group having a non-irradiated control. Mannitol wounded and diabetic wounded cells had a final concentration of 30 mM mannitol and glucose respectively. A wavelength of 636 nm at a fluence of 5 J/cm2 was used on day 1; experiments were repeated four times and all tests were done in duplicate. Cellular responses (Trypan Blue, adenosine triphosphate (ATP) and lactate dehydrogenase (LDH)) and morphological changes were assessed after 1 h incubation post-irradiation in both irradiated and non-irradiated cultures.