Inhibiting Effect Of Artesunate On Hypertrophic Scarring In Rabbit Ear Model

Objective To probe into the inhibiting effect of Artesunate on hypertrophic scarring in rabbit ear hypertrophic scar model so as to provide a scientific basis for clinical use. Methods Six New Zealand rabbits were used to establish animal model for hypertrophic scar, six square wounds in size of 1㎝×1㎝ each were created down to bare cartilage on the ventral surface of each ear. In an auto-control paired design, after epithelization of the wounds, the scars on the left ears were taken as Artesunate group receiving sodium Artesunate by local injection in a dose of 60mg/ml solution, 20(l pre scar every two days for 15 days. The scars on the right ears served as control group were treated with 5% sodium bicarbonate by local injection 20(l pre scar. After 15 days of treatment the scars were harvested, Hematoxylin and eosin staining and Van Gieson staining were used to observe the histomorphology of the fibroblasts and collagen fibers. Hypertrophy index of the scar was measured by using light microscope, Mastocyte were counted on Toluidine blue staining slide. Cell apoptosis was analyzed byusing DNA agarose gel electrophoresis and TdT-mediated dUTP nick end labeling. Collagen content of the hypertrophic scars was determinated by using the method of chloraseptine-T. Simultaneously, the activity of the collagenase of the hypertrophic scars was extracted and measured .Results PartⅠAnimal model: 90 percent of the wounds could form hypertrophic scar which was similar to human hypertrophic scar. And the time of the epithelization of the wound was 16~19 days or so. The hypertrophic scar was 4~5 times as height as surrounding normal skin. And the hypertrophy of scar could last three months, then the scar would flatten and soften gradually in our preliminary experiment. In Hematoxylin-eosin staining and Van Gieson staining the epidermis of the scar was integral. And no appendages of skin were found in the scar, the dermis of the scar thickened and contained lots of fibroblasts and collagen fibers. Collagen fibers were in swirls with collagen nodules. Part Ⅱ Experiment: On gross examination the hardness of the scars of the Artesunate group was lower than that of control group. The dermis of the Artesunate group was thinner than that of control group, the collagen was well-arranged in Artesunate group. More fibroblasts and the collagen nodules could be found in control group under microscope in HE and VG staining. The hypertrophy indices(HI) of Artesunate group and control group were 3.56±1.04mm and 4.45±0.81mm respectively,which showed there wassignificant difference between the two groups(P<0.01). In Artesunate group the DNA Ladder was positive in DNA agarose gel electrophoresis, but the control group was negative. Moreover, TUNEL staining showed there was significant difference in apoptosis between the two groups(P<0.01). Under the transmission electron microscope nuclear fragmentation, nuclear concintration, nuclear crescent, apoptotic bodies of fibroblasts could be found in Artesunate group. There were many of lysosomes and swelling mitochondrias in the fibroblasts of the Artesunate group. But in control group the shape of fibroblasts and the organelles were normal, a few swelling mitochondria and expansion of rough endoplasmic reticulums were found, which indicated that the function of the fibroblasts was active. There was significant difference between the two groups in mastocyte counts(P<0.01).The mastocyte count of Artesunate group and control group were 5.27±1.27/HP and 10.67±2.35/HP respectively. There were significant differences in content of collagen and activity of collagenase between Artesunate group and control group(P<0.01).Conclusions: 1. The higher rate of fibroblast apoptosis in Artesunate group shows Artesunate can inhibit fibroblast proliferation by inducing fibroblast apoptosis and reducing mastocyte to reduce collagen synthesis. It also can degrade collagen by increasing the activity of the collagenase. These indicate that Artesunate can inhibit formation of...