Abstract: Objective To investigate the inhibition effect and mechanism of intra-cicatrix injection of adipose derived stem cells on hypertrophic scar in rabbit ear. Methods Twelve New Zealand white rabbits were used for establishing scar model and were randomly divided into 3 groups. Two weeks after the operation, all the right ears were injected DMEM as internal control while left ears of group 1, 2 were injected ADSCs, ADSCs-CM respectively. Left ears in the third group were remained untouched. Photos and ultrasonography were taken before and 1, 2, 3 weeks after injection. Histochemical and genetic detection were used 3 weeks after the rabbits were sacrificed for offering scar tissue. Results All wounds were re- epithelized 2 weeks after the injection. Wounds injected DMEM and untouched gradually grew thick, red and stiff which are the symptoms of hypertrophic scars, while ADSCs and ADSCs-CM injected ones showed no sign of growing hypertrophic. HE and Masson＇s staining showed collagen deposit and irregularly arrangement in the DMEM injection and untouched scars, while much less and better arranged collagen deposit were shown in both ADSCs and ADSCs-CM treated ones. Genetic detection showed lower expression of α-SMA, Collagen I in ADSCs and ADSCs-CM injection scars, compared with DMEM treated and untreated ones. Dil label staining showed a larger amount of ADSCs in the scar tissue of ADSCs treated group. Conclusion Intra-cicatrix injection of ADSCs can inhibit hypertrophic scar through ameliorating collagen deposit by down regulate the expression of α-SMA, Collagen I.

Key words: Adipose derived stem cells, Hypertrophic scar, Intra-cicatrix injection