Experiment study on the effects of rabbit autologous dermal fibroblasts on hypertrophic scar

Objective To investigate the effect of local autologous dermal fibroblasts transplantation on hypertrophic scar formation and wound healing quality in early scar formation. To explore the feasibility of fibroblasts for prevention and treatment of hypertrophic scar. Methods Dermal fibroblasts were isolated from the dorsal skin tissue of New Zealand white rabbits by mechanical method combined with enzyme digestion. Passage 3 cells were induced to differentiate into osteoblasts and adipocytes. The complete epithelialization time and hypertrophic scar formation after full-thickness skin defect were confirmed by pre-experiment study. In the experiment, 6 rabbits were used, left ear as experimental group and right ear as control group. In the experimental group, the passage 4 dermal fibroblasts labeled with 5-bromodeoxyuridine (5-BrdU) were injected subcutaneously around the wound and hypertrophic scar on 20 d (day 2 after epithelialization) and 30 d (most obvious scar hyperplasia) after surgery. As a control group, physiological saline was injected following the same protocol. On 37 days after surgery, the hypertrophic scar tissue were harvested and assessed by gross view and histological examination. The transplanted cells were detected by immunofluorescence staining, transforming growth factor beta 1 (TGF-β1) and decorin(DCN) mRNA expression were assayed by real-time fluorescence polymerase chain reaction (RT-PCR), and the protein expression of TGF-β1、DCN、Collagen type Ⅰ and type Ⅲ were tested by enzyme linked immunosorbent assay(ELISA). Results Compared with the control group, the scar in the experimental group was flatter and softer, the color was slightly lighter, and the volume was reduced. The histological results showed that compared with the control group, the number of fibroblasts and inflammatory cells in the superficial dermis was reduced, the proliferation of connective tissue and collagen deposition were reduced, and the basal cells and collagen fibers were arranged in order in the experimental group. The results of RT-PCR showed that TGF-β1 mRNA expression level in the hypertrophic scar tissue reduced significantly and DCN increased significantly in the experimental group, compared with the control group (P<0.01). ELISA results showed that TGF-β1, type Ⅰ and Ⅲ collagen contents in hypertrophic scar tissue were significantly lower than that in the control group, while the DCN expression was significantly increased (P<0.01). Conclusions The rabbit dorsal dermal fibroblasts significantly inhibited the hypertrophic scar in rabbit ears. The mechanism may be related to the up-regulation of DCN expression and down-regulation of TGF-β1 expression, reduction of type Ⅰ and Ⅲ collagen synthesis and extracellular matrix deposition, in the hypertrophic scar tissue. Key words: Hyperplastic scar; Fibroblast; Cell transplantation; The rabbit ear scar model