Effects Of Fractional Laser Combined With Focused-radiofrequency To The Dermal Collagen Fiber Of Mouse

Objective:To observe and evaluate the influence of CO₂ fractional laser and focused-radiofrequency to the skin collagen of Kunming mouse,and to provide a theoretical basis for clinical practice.Methods:Selecting eighteen female Kunming mice with weight 30±g,divided the back skins into four regions:section A（blank control section）,section B（focused-radiofrequency）,section C（CO₂ fractional laser）,section D（CO₂ fractional laser and focused-radiofrequency）.Randomly executing three mice in batches and cutting out their back skins from four regions to perform HE staining,Masson staining and immunohistochemical staining,after 0-week,4-week,8-week,12-week,16-week,and 20-week after laser rradiation.Use statistical software SPSS25.0 to analyze and process the data.Results:（1）Compared with the blank control section（section A）,the collagen fibers of the three treatment sections（section B,section C,section D）showed a more regular and tight histology.Arranged,the combined treatment section（D section）has the most significant effect.（2）In the fourth week of the experiment,the dermal thickness and the proportion of collagen fibers of each treatment section（section B,section C,and section D）reached the maximum,（Dermal thickness:A:18.202± 3.211um,B:21.701±5.713um,C:26.194±8.947um,D:42.108±16.096um;collagen fiber ratio:A:17.226±1.255,B:21.121±4.523,C:24.119±4.225,D:32.438±2.085）.（3）From 4-week to 20-week,the ratio of dermal thickness and collagen fibers in the combined treatment section（section D）was higher than that in the blank control section（section A）（P<0.05）.The thickness of dermis and the same area in section D in each time period The proportion of collagen fibers is the largest.（4）From 4-week to 12-week,the expression of TGFβ1 in the joint intervention area was higher than that in the blank control area（P<0.05）.At 16-week and 20-week,although the value of the joint intervention area（area D）was still greater than that of the other groups,but among the groups There was no statistically significant difference in the expression of TGFβ1（P>0.05）;MMP1 in the combined intervention area at 4-week and 12-week was lower than that in the blank control area（P<0.05）,and there was no significant difference in the expression of MMP1 in the other weeks（P>0.05）;In the 4-week and 8-week of the experiment,the expression of VEGF in the dot-matrix laser area and the combined intervention area was higher than that in the blank control area（P<0.05）,and VEGF in the 16-week and 20-week did not show between the groups There was a statistical difference（P>0.05）.Conclusion:Both CO₂ laser and focused radiofrequency can promote the proliferation of collagen fibers in the skin of mice.However,the effect of CO₂ laser combined with focused radiofrequency on collagen fiber proliferation is more obvious,and the effect is lasting and stable.In the early stage,the increase of TGFβ1 and VEGF expression and the decrease of MMP1 expression may be the cause of the increase of dermal collagen fiber synthesis caused by the CO₂ fractional laser combined with focused-radiofrequency.