| Objective:To study if microbubble destruction with ultrasound can stimulate endogenous vascular endothelial growth factor (VEGF) secretion to promote angiogenesis and wound healing in rats,and hope to develop a new therapy candidate for clinical treatment.Methods:1.Totally 96 SD rats were randomly divided into four groups: microbubble destruction with ultrasound (US+MB), microbubble (MB), ultrasound (US) and control group. They all subsequently accepted one rounded whole-layer skin incision on back each other after anesthetized with intraperitoneal chloral hydrate.Iodophor and disinfection on skin of back. All of the skin incisions were topically applied with coupling agent. Rats in US+MB group were injected with 0.5ml microbubble contrast agent via tail vein,and then ultrasound irradiated for 3 minutes immediately. MB group were injected with 0.5ml microbubble contrast agent. US group were injected with 0.5ml physiological saline, an then ultrasound irradiated for 3 minutes immediately under the same condition. Control group were injected with 0.5ml physiological saline.Feeding each rat in single cage with the incision exposed to the air after all treatments.2. Observed the general condition, wound infection and granulation tissues of the rats daily.3. On day 1,3,5,7,14 and 21 after wound creation,4 animals in each group were selected randomly,fixed after anesthetized and determined the percentage of wound contraction.4. Detected and recorded margin of blood flow signal at the above time points.5. Sacrificed the rats at different time points and analyzed the excised wound tissues were analyzed by histology.6.Analyzed VEGF expression in wounds at above time points by immunohistochemistry.7. Statistical analysis:Count data was expressed as mean±standard deviation, and analyzed by one-way ANOVA, measurement data were analyzed by Non-parametric test for independent samples using the SPSS version 16.0 software. p value less than 0.05 was considered as statistically significant.Results:1. General observation:On day 5,7 and 14, the percent of wound contraction of US+MB group was higher as compared with other 3 groups (day5,14 p<0.05, day7 p<0.01).2.CDFI:The blood flow signal were most abundant on day 3,and there was no significant difference between every two groups at all time points (p>0.05).3. Histological examination of excised tissues (HE staining):On day 7, wounds of US+MB group displayed the most accumulation of granulation tissue and all new capillaries were perpendicular to the wound surface,but the new capillaries of other 3 groups were disordered. On day 14, collagen fibers of US+MB group were arranged regularly, and regenerated hair follicle and sebaceous gland could be seen by histological examination, butother 3 groups were arranged less neatly and there were fewer regenerated hair follicles and sebaceous glands.4. Immunohistochemical examination of VEGF expression:the peak expression appeared on day 3 in US+MB group, other 3 groups were on day 5 to day 7.The expression of VEGFof US+MB group were higher than other 3 groups on day 3,5,7(day3 p<0.05, day5,7 p<0.01).Conclusions:1. US+MB treatment could improve the rate and quality of wound healing compared with MB, US treated alone or control group.2. Granulation tissues of US+MB treatment were maturated earlier than MB,US treatment and control group,which could accelerate wound healing.3. Cavitation induced by microbubble destruction with ultrasound could stimulate the secretion of endogenous VEGF,which may be the mechanism of promoting angiogenesis and wound healing. |
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