Abstract: BACKGROUND: Although the tension band technique can stimulate skin regeneration to repair skin defects, it has been successfully applied in clinical practice and has achieved satisfactory results, but the most suitable tension intensity for skin regeneration is still inconclusive.  
OBJECTIVE: To discuss the effect of different tension intensities on skin regeneration in rat models of skin defect.
METHODS:  Male SD rats aged 3 months old were selected as experimental animals. The back skin of SD rats was fixed by the 3D printed oval skin fixing device to establish rat models of skin defect wound on the back, and the 3D printed tension band device was fixed on the edge of the skin. The silicone loop was installed on the principle of tying shoelaces, and different tension parameters (0, 0.2, 1 N) of the silicone loop were adjusted by the tension detector. The changes in the area of the skin defect were observed immediately, 3, and 7 days after model establishment. At 7 days after the surgical procedure, histological sections of the skin at the edge of the wound were taken for immunohistochemical staining of CD31 and vascular endothelial growth factor to observe the effect of different tension stimulation on skin regeneration.  
RESULTS AND CONCLUSION: (1) Appropriate tension stimulation could effectively stimulate skin proliferation and healing; skin defect wounds without tension stimulation could expand with the contracture of the skin edge and increase the area of the skin defect, which was not conducive to the treatment of skin defects. (2) Tension stimulation was not the bigger the better. Simultaneously, the wound shrinkage speed of 0.2 N tension group was faster than that of 1 N tension group. In 1 N tension group, the skin around the wound was sclerotic and the elasticity was decreased. It was considered that the larger tension led to skin ischemia. (3) The number of microvessels in the 0.2 N tension group was significantly increased, and the expression of vascular endothelial growth factor was significantly higher than that of the 0 N tension and 1 N tension groups, indicating that tension stimulation could promote the formation of microvessels and increase the expression of vascular endothelial growth factor, but high tension stimulation (1 N in this study) is not conducive to the formation of skin capillaries around the skin defect and is not conducive to wound healing. (4) It is concluded that appropriate tension can cause extensive reconstruction of extracellular matrix in local skin. By inducing angiogenesis, it can improve the supply of nutrients for local cell metabolism and promote the reorganization of cytoskeleton. This process has strict requirements on the size of tension.

Key words: 3D printing, controllable tension band, skin defect, skin regeneration