Effects of pulsed Nd:Yag laser at molecular and cellular level a study on the basis of Hilterapia®

Lasers have been widely applied in many different fields of medicine, proving their effectiveness in the treatment of a wide range of diseases. In spite of the great amount of literature, it is difficult to understand the molecular and cellular mechanisms at the basis of the systemic effects induced by laser irradiation because of different kinds of laser used, operative conditions, variety of biological targets and responses. The application of high power lasers in physiotherapy is quite recent. It is due to the development of instruments which allow the control of photothermal and photomechanical processes so as to obtain therapeutic effects without tissue damage. In particular, pulsed Nd:YAG laser has proved hisversatility and efficacy in the treatment of many different musculoskeletal diseases and it is believed to have anti-inflammatory, anti-oedema, analgesic and also reparative effects. The aim of the studies here presented was to contribute in understanding the molecular mechanisms and cellular processes at the basis of the systemic effects produced by pulsed Nd:YAG laser irradiation. Owing to the lack of chromophores efficiently absorbing Nd:YAG radiation (wavelength 1064 nm) in cells and tissues, we hypothesized that, rather than photochemical processes, aspecific mechanisms probably due to combined photothermal and photomechanical interactions could be responsible for the above mentioned effects of pulsed Nd:YAG laser. The finding suggestthat cells “sense” pulsed ND:YAG laser irradiation and respond to it through mechanotransduction machinery. We hypothesize that the interaction between tissue and laser radiation alters the mechanics of cell microenvironment, thus acting on the cells as a mechanical stress.