Effect of adipose-derived stem cells stimulated by direct current electric field on refractory wound healing in diabetic rats
Zhang Rui, Liu Lan, Xie Defu, Lin Yingxi, Ren Hongjing, Yan Hong
Department of Plastic and Burn Surgery, Affiliated Hospital of Southwest Medical University, National Key Clinical Construction Specialty, Wound Repair and Regeneration Laboratory, Luzhou 646000, Sichuan Province, China
Abstract: BACKGROUND: Adipose-derived stem cells have a great potential in wound healing and regeneration and we have proven that a direct-current electric-field can promote the proliferation of human adipose-derived stem cells without changing biological characteristics.
OBJECTIVE: To investigate the effect of rat adipose-derived stem cells stimulated by a direct-current electric-field on refractory wound healing in diabetic rats.
METHODS: (1) Rat adipose-derived stem cells were obtained. After identification, they were pretreated with 100 mV/mm or 0 mV/mm of direct-current electric-field stimulation, with a frequency of 1 h/d, for 3 days. (2) Diabetic refractory wound models were constructed and randomly divided into three groups, with 7 rats in each group, totaling 21 rats. Animals in the electric-field-rat adipose-derived stem cell and rat adipose-derived stem cell groups were injected with 1 mL of electric-field-rat adipose-derived stem cells or normal rat adipose-derived stem cells, respectively, at multiple points of the wound, with a cell concentration of 1×109 cells/L. The PBS group was given the same amount of PBS. (3) At 3, 7, and 14 days after model establishment, the degree of wound healing was observed. Laser speckle contrast imaging was used to record the blood perfusion of rat wounds. The histological changes of wound healing were evaluated by hematoxylin and eosin staining. Microvessels were counted. The expression of vascular endothelial growth factor in the wound tissue was observed by immunohistochemistry. The expression of CD31 was observed by immunofluorescence.
RESULTS AND CONCLUSION: (1) Compared the normal rat adipose-derived stem cells and PBS groups, wounds in the electric-field-rat adipose-derived stem cell group were nearly completely healed on day 14, and the wound-healing speed was significantly accelerated (P < 0.05). (2) In the electric-field-rat adipose-derived stem cell group, wound epithelization began on day 3. On day 14, the epidermal structure was more complete and continuous in the electric-field-rat adipose-derived stem cell group than those of the other two groups; moreover, the wound angiogenesis was increased (P < 0.05) and the expression levels of vascular endothelial growth factor and CD31 were significantly greater (P < 0.05). (3) The wound blood perfusion of the three groups gradually reached a peak and retreated with the progression of time. The blood perfusion of the electric-field-rat adipose-derived stem cell group was significantly higher than that of the PBS group at different time points after treatment (P < 0.05) and was significantly higher than that of the normal rat adipose-derived stem cell group on day 7 (P < 0.05). (4) The results showed that rat adipose-derived stem cells stimulated by direct-current electric-field exposure could accelerate the healing process of diabetic refractory wounds. The potential mechanism here may be related to the ability of rat adipose-derived stem cells to increase blood perfusion, promote vascular endothelial growth factor expression, and increase the rate of angiogenesis, which provides a new idea for culturing adipose-derived stem cells in vitro and accelerating the actual clinical transformation.
Key words: direct-current electric field, adipose-derived stem cell, cell proliferation, wound healing, diabetes, rat