To evaluate the effect of chyle fat on hypertrophic scar of human transplanted under the back of nude mice.

Eighteen BALB/c nude mice were selected. Fat granule cells were collected from the abdominal and later thigh fat suction operations and hypertrophic scar tissue excised from the face and neck in the Department of Burns and Plastic Surgery, Fourth Medical Center of PLA General Hospital. Fat granule cells were processed into nano-transformed heads to make chyle fat. Each human hypertrophic scar tissue were cut into small pieces. Four skin incisions were made on the back of each nude mice with scissors. These specimens were implanted into the backs of the mice with 4 pieces per nude mouse. Eighteen nude mice were divided into 3 groups: control group, triamcinolone acetonide group and chyle fat group according to the random number table method, 6 nude mice and 24 scar tissues per group. One week after transplantation, the control group was injected with 0.9% sodium chloride solution into each transplanted scar tissue(0.05 mL/g); triamcinolone acetonide was injected into the triamcinolone acetonide group (0.05 mL/g); chyle fat group was injected with chyle fat (0.05 mL/g); and then injected once a week. Comparison of pre-transplant hypertrophic scar tissue weight and percentage change in weight of hypertrophic scar tissue 4 weeks after transplantation was calculated. After hematoxylin-eosin staining and Masson staining, histomorphological changes under biological microscope were observed. Masson staining semi-quantitative analysis of positive area (sky blue) as a percentage of total field of view was compared. Immunohistochemical staining was performed to detect the expression of decorin. Data were processed with One-way ANOVA and Dunnett-t test.

Before transplantation, there were no significant differences in the weight of hypertrophic scar tissue among the 3 groups (F=26.230, P=0.119). At 4 weeks after transplantation, the percentage change of weight of hypertrophic scar tissue in the chyle fat group, triamcinolone acetonide group and control group was (73.2±15.9)%, (79.5±8.6)%, (87.0±14.9)%, respectively. The difference was statistically significant (F=16.680, P=0.042). The percentage change of weight of hypertrophic scar tissue in the chyle fat group was compared with the control group and triamcinolone acetonide group, the differences were statistically significant (t=14.130, 1.228, P=0.010, 0.099). Histological observations showed that hematoxylin-eosin staining was consistent with the overall trend of Masson staining. The results of hematoxylin-eosin staining were: large amount of collagen fibers and fibroblasts and disorder of collagen fibers were seen in the dermis of the control group; the dermis of the triamcinolone acetonide group were found in coarse collagen fibers, and the continuity and uniformity were generally; the number of collagen fibers in the dermis of the chyle fat group was small and arranged. Semi-quantitative analysis of Masson staining: the percentages of the positive area(sky blue) of the chyle fat group, triamcinolone acetonide group were accounted for (74.3±13.5)%, (80.9±9.0)%, (91.2±4.5)%, respectively. Comparative differences were statistically significant (F=1.708, P=0.025). The chyle fat group was significantly different from the triamcinolone acetonide group and the control group (t=13.130, 7.806; P=0.027, 0.019). Immunohistochemical analysis of decorin in hypertrophic scar: under the optical microscope, the triamcinolone acetonide group and the chyle fat group showed positive results of decorin, and the chyle fat group staining was stronger than that of the triamcinolone acetonide group. However, the control group showed extremely low expression point and patchy decorin staining. The expression levels of decorin in the chyle fat group, triamcinolone acetonide group and control group were 0.021±0.010, 0.025±0.012 and 0.088±0.058, respectively. The difference was statistically significant (F=32.160, P=0.034). The expression levels of decorin in the chyle fat group was compared with the triamcinolone acetonide group and the control group, there were statistically significant (t=8.016, 1.224; P=0.048, 0.027).

Injecting chyle fat into hypertrophic scar can reduce the density and quantity of fibroblasts, promote the normalization of collagen arrangement, quantity and shape, and improve histological features such as collagen accumulation.