THOR Low Level Laser Therapy for Wound Healing

Physiological Changes
The physiological effects have been studied extensively by one of the world's most eminent biologists and editor of Gray's Anatomy, Prof. Mary Dyson.

The effects of low level or low intensity laser therapy (LLLT or LILT) on the three overlapping phases of wound healing, i.e. inflammation, proliferation and remodelling, are such that acute injuries heal more rapidly and that healing can be induced in chronic lesions such as venous ulcers/ pressure sores and diabetic ulcers. The duration of acute inflammation can be reduced by LLLT, the proliferative phase of repair, during which granulation tissue is formed, beginning earlier . The rate of wound contraction can be altered and angiogenesis increased. Healing involves the interaction and activity of many different cell types. Research has been carried out on the effects of LLLT on keratinocytes, mast cells, macrophages and fibroblasts. Keratinocyte and fibroblast proliferation can be stimulated directly and also indirectly through growth factors released from irradiated macrophages.

Professor Mary Dyson PhD FCSP(Hon) FAIUM(Hon) LHD(Hon) Former Editor Grays Anatomy Former Head, Tissue Repair Research Unit, UMDS, Guys Hospital

The effect on keratinocytes is particularly marked when the cells are maintained in adverse conditions similar to those produced by injury. The mast cell content of both intact and injured skin increases following irradiation, but only in injured skin is mast cell degranulation increased. This suggests that the sensitivity of mast cells to stimuli such as light is increased in injured tissues. Some of the materials released when mast cells degranulate can initiate the inflammatory response of the skin to injury, whereas others stimulate later processes such as angiogenesis. Work on cells involved in repair, namely endothelial cells, pericytes and lymphocytes is in progress.

References

Steinlechner C, Dyson M: The effect of low level laser therapy on the proliferation of keratinocytes. Low Level Laser Therapy. 1993; 5 (2): 65.

Steinlechner C, Dyson M: The effect of low level laser therapy on the proliferation of keratinocytes. Low Level Laser Therapy; 1993; 5(2): 65.

Dyson M, Young S: Effect of Laser Therapy on Wound Contraction and Cellularity in Mice. Lasers in Medical Science. 1986; 1: 125.

Dyson M: Cellular and subcellular aspects of low level laser therapy. Progress in low level laser therapy. Eds. T. Ohshiro and R.G. Calderhead, John Wiley & Sons, England. 1991, p. 221

Bolton P A, Young S R, Dyson M: Macrophage responsiveness to light therapy. A dose response study. Low Level Laser Therapy. 1990; 2: 101-106.

Bolton P A, Dyson M, Young S R: The effect of polarised light on the release of growth factors from the U-937 macrophage-like cell line. Low Level Laser Therapy. 1992; 4: 33- 42.

Cheetham M J, Young R S, Dyson M. Histological effects of 820 nm laser irradiation on the healthy growth plate of the rat. Low Level Laser Therapy 1992; 2: 59.

Bolton P, Young S, Dyson M. The direct effect of 860 nm light on cell proliferation and on succinic dehydrogenase activity of human fibroblasts in vitro. Low Level Laser Therapy. 1995; 7: 55-60.

el Sayed S O, Dyson M. Effect of laser pulse repetition rate and pulse duration on mast cell number and degranulation. Laser in Surgery and Medicine. 1996; 19 (4): 433-437.

Nicolopoulos N, Dyson M et al. The use of laser surgery in the subtotal meniscectomy and the effect of low-level laser therapy on the healing potential of rabbit meniscus: an experimental study. Lasers Med Sci. 1996; 11 (2): 109-115.

Steinlechner C, Dyson M: The effect of low level laser therapy on the proliferation of keratinocytes. Low Level Laser Therapy. 1993; 5 (2): 65.

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