| Objective: Micro plasma has been successfully used in the treatment of hypertrophic scar.However,there are few reports about the effect of collagen remodeling in hypertrophic scar.In this experiment,the hyperplastic scar of rabbit ears was irradiated by plasma,and the distribution of collagen fibers and the ratio of type ? and ? collagen in scar tissue was observed.The effect of Plasma on hypertrophic scar and the therapeutic effect in different period were studied so as to provide the theoretical basis for the determination of the optimal period of hypertrophic scars.Methods: Six male New Zealand white rabbits weighing 2.5 ± 0.18 kg were used to make hypertrophic scars.Six full-thickness round skin defects were made with depth of 8 mm and interval of 1.0cm along the longitudinal axis of rabbit ears,totally 72 round wounds.The hypertrophic scars of rabbit ears were randomly divided into 6 groups: laser treatment and control group:1 Proliferative phase treatment group(n=12):rabbits in the proliferative phase were treated with plasma irradiation for 30 days(proliferative phase)after model establishment.Plasma parameters: fixed point TIP,diameter 12 mm,dot pitch 1 mm,no casing treatment head,0.6ms,80 w,repeated scanning4 times.Plasma treatment was performed 21 days after surgery.2 Regression phase treatment group(n=12): plasma irradiation therapy was performed 60 days after modeling(regression phase).Treatment parameters and drawing time were the same with the first group.3 Maturation phase treatment group(n=12): plasma irradiation treatment was performed 90 days after modeling(mature phase).Treatment parameters and drawing time were the same with the first group.4 Proliferative phase control group(n=12): as a blank control group without any treatment,and drawn at the same time with the first group5 Regression phase control group(n=12): as the blank control group without any treatment,and drawn at the same time with the second group.6 Maturation phase control group(n=12): as the blank control group without any treatment,and drawn at the same time with the third group.The specimens were embedded in paraffin wax after dehydration,then the sections were sectioned with the thickness of 5.0?m.Hematoxylin-eosin staining(HE),Masson and Sirius red staining were used to observe the distribution of collagen fibers in the hypertrophic scar tissue of rabbit ears.The picric acid-Sirius red polarized light and the image analysis technique were used to measure the ratio of type?and type ?collagen fibers in hypertrophic scar tissue of each experimental group to reflect the effect of Plasma on hypertrophic scar.The proportion of type ? collagen in the hypertrophic scar tissue of the experimental group and the control group was statistically analyzed.The data were expressed by mean ± standard deviation.SPSS13.0 software was used to analyze the data.Randomized two-factorial experiment design and ANOVA was used to analyze the data.The data was defined statistically significant as P <0.01.Results:1 Histomorphological changesControl groupProliferative stage : The scar tissue was hard,red,prominent in the skin surface.In the scope of the original surgical field,proliferative microvessels and a large number of proliferation,disordered,thick shaped,and spiral-like structure collagen fibers could be seen under light microscopy.Regression stage: The scar tissue had shrunk,but still prominent in the skin surface.The color faded,and texture was hard.Reduced microvessels and thicker,further disordered,collagen-deficient collagen fibers could be seen under light microscopy.Maturation stage: Scar tissue atrophied,became flat,of which the central part was white.The texture was harder than the surrounding normal skin.Asmall amount of microvascular and thinner,disordered,dense,collagen-free collagen fibers could be seen under light microscopy.Treatment groupProliferative stage: The color of the scar tissue was lighter than that of the control group,and the texture was slightly soft.Under light microscope,the collagen fibers in the scar tissue were lighter than those in the control group,and the fibers were fine and the collagen was ordered.Regression stage: The color of scar tissue was lighter than that of the control group,the texture was soft and the elasticity increased.Under the light microscope,the color of collagen fibers in the scar tissue was lighter than that in the control group,and the fibers were thin and the collagen arrangement was evacuated.Maturation stage: The color and texture of the scar tissue were improved compared with the control group,which was closer to the surrounding normal skin.Collagen fibers could be seen arranged consistently and loosely under the light microscope.2 Observation and image analysis by polarizing microscopeControl groupProliferative phase: Visible thick yellow collagen ?fiber bundles were cluster-like distributed,uneven-density,disorganized,counting for about 57%of the entire view.collagen? distributed sparsely in slender green ? type collagen which accounted for about 43%.Regression phase: A large number of large,aggregated into blocks,arranged further disorders of type? collagen fibers,accounting for 83% of total field of vision,type ? collagen ratio of less than 17%.Maturation phase: Visible bamboo-like,more chaotic arranged type ?collagen fibers,accounted for more than 92%,while the proportion of type ?collagen was less than 8%.Treatment groupProliferative phase: Compared with the control group,improvement arrangement of collagen fibers was visible and the proportion of type ?collagen has increased,accounting for about 47%.Regression phase: The arrangement of collagen fibers was significantly higher than that of the control group,accounting for 31% of the collagen fibers.Maturation phase: The collagen fibers arranged in the control group were similar to those in the control group,and the proportion of type ? collagen fibers was significantly higher than that of the control group accounting for about 25%.3 Statistical analysisThe results showed that the proportion of type ? collagen in different period of hypertrophic scar was different(F=307.038,P=0.000 <0.01),and the proportion of type ? collagen in different groups was different.Plasma laser treatment can increase the proportion of type ? collagen in scar tissue(F=142.806,P=0.000<0.01),and the degree of increase is closely related to the period of scar treatment(F=16.214,P=0.000<0.01).Compared with the control group,the increase degree was proliferative phase(4%)<regression phase(14%)<maturation phase(17%).According to statistical results,the treatment effects of micro-plasma(Plasma)treatment on hypertrophic scar hypertrophy in rabbits was proliferative phase < regression phase <maturation phase.Conclusion:1 After Plasma treatment,the scar tissue texture improved significantly,and the tough texture became soft and flexible.The ratio of type ? and ?collagen in scar tissue is decreased,which is close to the proportion of normal skin.Collagen fiber morphology also tends to normal skin collagen fibers,which may be one of the mechanisms of micro-plasma treatment of hypertrophic scar.2 The treatment effects of Plasma for different periods of hypertrophic scar is different.Plasma treatment on hypertrophic scar of proliferative stage is effective,but not obvious.The healing effect of healing scar is better than that of proliferative phase.The maturation period is the best and the most obvious. |
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