Objective: To investigate the effects of local
transplantation of autologous adipose-derived mesenchymal stem cells (ADSCs) on the formation of hyperplastic
scar on rabbit ears. Methods: ADSCs were isolated from inguinal fat of six New Zealand rabbits and then sub-cultured. ADSCs of the third passage of each rabbit were used in the following experiments. Six full-thickness skin defect
wounds with diameter of 6 mm on the ventral surface of every rabbit ear were made. Wound healing and local-tissue proliferation were observed, and complete epithelization time of
wounds and formation time of hyperplastic
scar were recorded. The
wounds on left ears were selected as group ADSCs, and the
wounds on right ears were selected as control group, with 36
wounds in each group. After the complete epithelization of
wounds (post injury day 25), 0.2 mL
bromodeoxyuridine (
BrdU) labeled autologous ADSCs with the concentration of 5×106 per milliliter were injected into each
wound of the rabbit of group ADSCs, while the same amount of
phosphate buffer solution was injected into each
wound of the rabbit of control group. The frequency of injection was once every 5 days, totally for 3 times, and the latter 2 times were injected into
scars generated from healed
wound. Hyperplastic
scars of rabbits of two groups were harvested on the fifth day after the third injection, then the morphology was observed by HE staining, and the arrangement of
collagen in hyperplastic
scar was observed by VG staining. The distribution of
BrdU-labeled ADSCs in the hyperplastic
scar was observed with fluorescence microscope. The
protein content of type Ⅰ
collagen, type Ⅲ
collagen,
transforming growth factor β1 (TGF-β1), and
decorin in hyperplastic
scar were detected by
enzyme-linked
immunosorbent assay, and the
mRNA expression of
decorin and TGF-β1 in hyperplastic
scar were tested by real-time fluorescent quantitative reverse transcription-polymerase chain reaction. Data were processed with paired t test. Results: (1) The complete epithelization time of
wounds of rabbits' ears was (20.0±2.0) d post injury, and hyperplastic
scars were formed on post injury day 35.0±2.2. On post injury day 40, hyperplastic
scars of rabbits of control group were still obvious, while those of group ADSCs became smaller, flat, soft, and light colored. (2) Compared with those in control group, epithelial cell layers and the number of nucleated cells in corium layer of hyperplastic
scars of rabbits of group ADSCs were increased, and epithelium foot like and dermal papilla like structures were observed. The
collagen density of hyperplastic
scars of rabbits of control group was tight and arranged disorderly, while that of group ADSCs were decreased significantly and arranged regularly as compared with that of control group. (3) On post injury day 40,
BrdU-labeled ADSCs were still observed in the hyperplastic
scars of rabbits of group ADSCs. (4) The
protein content of type Ⅰ
collagen, type Ⅲ
collagen, TGF-β1, and
decorin in hyperplastic
scars of rabbits of group ADSCs were respectively (1.40±0.04) and (8.18±0.23) μg/L, (25.1±0.7) ng/L, and (4.872±0.101) ng/mL, and those in hyperplastic
scars of rabbits of control group were respectively (2.29±0.05) and (12.20±0.38) μg/L, (37.2±1.1) ng/L, and (4.143±0.024) ng/mL. Compared with those in control group, the
protein content of type Ⅰ
collagen, type Ⅲ
collagen, and TGF-β1 in hyperplastic
scars of rabbit of group ADSCs were significantly decreased (with t values from -33.66 to -22.84, P values below 0.001), while the
protein content of
decorin were significantly increased (t=10.41, P<0.001). (5) Compared with those in control group, the
mRNA expression of TGF-β1 in hyperplastic
scars of rabbits of group ADSCs was significantly decreased (t=4.45, P<0.01), while the
mRNA expression of
decorin was significantly increased (t=5.61, P<0.01). Conclusions:
Autologous transplantation of ADSCs into
scar of rabbit at the early stage can inhibit the formation of hyperplastic
scar, promote the quality of wound healing, and the mechanism may relate to the down-regulation of TGF-β1, type Ⅰ
collagen, and type Ⅲ
collagen and the up-regulation of
decorin induced by ADSCs.