Elementary Research On Damage Effects And Photobiomodulation Of High Intensity Nd: YAG And KTP Lasers On Fibroblasts

With the development of the theoretical and technical study of laser, the usage of laser in the surgery and medicine is more and more extensive. The lasers used in surgeries, such as ocular surgery, dental surgery, dermatic surgery and medical surgery, are because their functional thermal ablation and melting ablation. Meanwhile, The biomodulation of low intensity laser irradiation was found in many years ago. However there is still little of study focusing on the intersection of the two fields. In fact, the intensity of high power laser beem decreases rapidly when laser is transmissing in bio-tissue and the intensity of the edge of laser beem is so low that photobiomodulation , which might effect the healing process after laser surgery, but not thermal effect might work. In this thesis, monolayer human skin fibroblasts wasused as models to study the damage effect of high intensity laser irradiation and photobiomodulation of marginal irradiation of high intensity laser beam.In the first part of this thesis, the healing processes after mechanical wounded and laser surgery were discussed first. In this section, the thesis showed that the effects, which were thermal effect and photobiomodulation, induced by laser ablation responded to the healing delay. Then the thesis summoned the effects of fibroblasts on wound healing. How to cultivate human skin fibroblasts in vitro was also summaried in this thesis.In the second part, with the help of MTT assay, monolayer human skin fibroblasts were used as models to study the damage effects of Nd:YAG and KTP laser irradiation. In order to understand the relationship between damage effect and,irradiation parameter, polynomial model rd = A + B1 X Epulse + B2 x E2pulse (the rd is damage radius (mm) and the Epulse is pulse energy (mJ)) was used to fit out the damageradius-pulse energy curves. The results showed that the survival rate (damage radius) decreased (increased) with the increase (decrease) of pulse energy or pulse rate immediately after 532nm or 1064 nm laser irradiation, and the survival rate (damage radius) immediately after 532nm laser irradiation was slightly larger (smaller) than the one immediately after 1064 nm laser irradiation at the same pulse energy and pulse rate. The fitness results indicated that coefficient A increased but coefficient Bl decreased with the increase of frequency, regardless the wavelength.Recent advance of effects of low intensity laser irradiation on cells were summarized in this thesis. The effects of low intensity laser irradiation onlymphocyte , macrophage, fibroblasts and the biostimulation effects of low intensitylaser irradiation were included in the third part. Then the biological information model of photobiomodulation (BIMP) was introduced to explain photobiomodulation and the information function of low intensity laser irradiation.Monolayer human skin fibroblasts were used again to study the photobiomodulation of marginal irradiation of high intensity laser beam in the fourth part. The results showed that HSFs proliferation was significantly promoted 24hours/48 hours after 1064 run laser treatment at 100mJ and 150mJ pulse energy, but significantly inhibited 24 hours/48 hours after 532 run laser treatment at lOOmJ pulse energy. These results indicated that when cells were irradiating, the energy of laser not only transformed into heat energy, which responded to the thermal effects, but also modulated the cell function as the photo signal.In conclusion, when high power laser irradiation is used on monolayer cells, thermal effect might works in the central area and the photobiomodulation, which depends on the parameters of the laser output, might works in the rest. The category of laser and the parameters of output are important to laser surgery.