The Effects Of Ultrapulsed Fractional CO₂ Laser Combined Multi-polar RF On SD Rat Skin

Part I The effects of ultrapulsed fractional CO2 laser with different density and energy on SD rat skin collagenObjective:To further improve the effect of ultrapulsed CO₂ fractional laser on skin aging in SD rats under different energy densities and scanning densities.Methods:Forty six SD rats were randomly divided into laser intervention group（n=40）and blank control group（n=6）.In the laser intervention group,each SD rat was divided into left and right sides with the midline of the dorsal skin.According to the different scanning density,the left side was group A（scanning density 25MTZs/cm²）,the right side was group B（scanning density 100MTZs/cm²）.A1,A2,A3,A4,B1,B2,B3,B4 were set in order to set the energy density of group A and group B with energy values of30m J/cm²,60m J/cm²,120m J/cm²,150m J/cm²;blank control group for the C group,no laser intervention.Twelve samples were randomly selected at2W,4W,8W and 12W after laser intervention.HE staining and Masson staining were performed.After laser intervention,the ratio of dermal thickness and dermal collagen fiber was measured at 12W.Results:Macroscopic observation:laser interference in immediately there was the damage area array samples,mild skin redness,we can be observed normal skin between MTZs apparently in group A,can,t be observed normal skin between MTZs in group B;The 2^nd w after laser interference:every group have taken off scabs completely,reddish,haveing concave dots;The 8^th w after laser interference,dotted concave dots disappeared.The immediately after HE staining:laser interference in group A,A1 MTZs epidermal necrosis,scabby,damage depth of dermal shallow,MTZs interval is apparently normal skin structure,A2,A3,A4 with the increase of the energy density,the deeper the damage depth;Laser interference in group B,B1MTZs epidermal necrosis,scabby,damage degree is lighter than A1,tissue coagulation staining shallow,MTZs interval smaller between normal skin structure,B2,B3,B4 with the increase of the energy density,deep into tissue coagulation,interval normal skin began to structure is not clear or basic piece,damage depth deepening continuously,the dermis is obvious cranny.The 2^ndW after laser interference,each skin full A2,A3,A4,B2,B3,B4 the new collagen fiber around the hair follicles,sebaceous glands;The 8^thw after laser interference,the dermal newborn collagen fiber gradually strip of repair,can cover the area that not was irradiated by laser;The 12^thw after laser interference measuring thickness dermis found:A2,A3,A4,B2,B3,B4 compared with group C,the difference was statistically significant（P<0.05）;Each leather thickness in group A were 734.95±30.66μm,761.10±26.93μm,782.21±21.23μm,823.02±18.19μm,to compare two all P<0.05;Each leather thickness in group B were 729.03±36.43μm,770.84±14.64μm,811.52±16.25μm,841.85±31.65μm,to compare two all P<0.05;Multivariate analysis of variance found that the energy density,the density of scanning effect on uniform thickness dermis（F=13.67,P=0.000;F=6.25;P=0.023;P<0.05）,the influence of the energy density is more significant.The 12^th W after laser interference measurement dermal collagen fibers than two-dimensional space found:A2,A3,A4,B2,B3,B4 compared with blank group,the difference was statistically significant（P<0.05）,comparison of A3 and A4,comparison of B3 and B4,there was no statistically significant difference（P>0.05）.Conclusion:Different energy density and scanning density of super-pulsed CO2 lattice laser have the synergistic effect on the synthesis of dermal collagen fibers,and the stronger the energy density and the scanning density are,the stronger the energy density is than the effect of scanning density on the synthesis of dermal collagen fibers Significantly.Part II The effects of ultrapulsed fractional CO2 laser combined Multi-polar RF on SD rat skinObjective: to investigate the effects of ultrapulsed fractional CO2 laser combined multipolar radiofrequency on SD rat skin.Methods: SD rats back after hair removal,it can be divided into four areas: group A（blank control group）,group B（ultrapulsed fractional CO2 laser group）,group C（Multi-polar RF group）and group D（ultrapulsed fractional CO2 laser combined Multi-polar RF group）.Biopsies were taken at 2W,4W,8W and 12 W after interference,to hematoxylin and eosinstaining（HE）,Masson staining,type III collagen immunohistochemical and VEGF immunohistochemical.Results: Macroscopic observation: The 2nd w after the interference: Group B and group D have taken off scabs completely,reddish,haveing concave dots;The 8th w after the interference,dotted concave dots disappeared.HE staining: the number of fibroblasts in the skin of the group B,C and D had increased significantly compared to group A on 8,12 week after irradiationin,group D was the most obvious thickening（P < 0.05）;Masson staining: the 8th week and 12 th week,group D collagen fiber was more compact thangroup A,B and C（P < 0.05）;Immunohistochemical type III collagen fiber: III collagen synthesis was increasing,in the group B,C and D compared with group A on 2 week after irradiationin;group C and D continued to increase on 4 week after irradiationin,group D more obvious than group C（P < 0.05）.Immunohistochemical VEGF: The average optical density of VEGF in the skin of group B,C,D group had increased significantly compared to that in the on group A on 8,12 week after irradiationin（P < 0.05）,and group D was more significant（P < 0.05）.Group C,group D VEGF positive expression is still better than group A on 12 week after treatment（all P < 0.05）.Conclusion: Ultrapulsed fractional CO2 laser combined Multi-polar RF was more to generate new collagen fibers than only ultrapulsed fractional CO2 laser or only Multi-polar RF;Multi-polar RF was more obvious than ultrapulsed fractional CO2 laser;Multi-polar radiofrequency and Ultrapulsed fractional CO2 laser combined Multi-polar RF therapeutic can keep the skin expression of VEGF long time at a high level than ultrapulsed fractional CO2 laser,and thecombined was more obvious.