低强度脉冲超声对大鼠急性肌腱损伤早期血管生成的影响及机制

背景:越来越多研究表明,低强度脉冲超声可以促进急性肌腱损伤的愈合,但其具体机制尚不清楚。目的:观察低强度脉冲超声对急性肌腱损伤后早期血管生成的影响,并检测与血管内皮生长因子相关信号通路的调控关系,进而揭示其潜在作用机制。方法:8-12周龄SPF级雄性SD大鼠局部注射Ⅰ型胶原酶3 d建立急性跟腱损伤动物模型,随机分为超声组和对照组。超声组每日使用有效辐射面积为1 cm^(2)的超声小探头垂直于跟腱部位进行低强度脉冲超声治疗,对照组不干预。治疗2周后进行超声影像学检查,观察肌腱早期愈合情况;治疗1,2周后行苏木精-伊红染色和CD31免疫组织化学染色观察组织血管数量变化,Western blot和qRT-PCR检测跟腱组织中血管内皮生长因子相关信号通路分子的表达。结果与结论:①灰阶超声显示:超声组较对照组跟腱更为连续,回声强度更低且较为均匀,肌腱厚度明显降低(P<0.05);②苏木精-伊红染色和CD31免疫组织化学结果一致显示:治疗2周后,超声组的新生血管数量明显较同期对照组增多(P<0.05);③Western blot和qRT-PCR结果显示:治疗2周后超声组跟腱中血管内皮生长因子、Yes相关蛋白、血管生成素2、富含半胱氨酸的血管生成素诱导物61的蛋白和mRNA表达均显著高于对照组(P<0.05);④结果表明:低强度脉冲超声通过上调血管内皮生长因子表达显著增加了急性肌腱损伤早期血管生成数量,加速了肌腱愈合。

Effect and mechanism of low intensity pulsed ultrasound on early angiogenesis in rats with acute tendon injury

BACKGROUND: In recent years, increasing studies have shown that low-intensity pulsed ultrasound can promote the healing of acute tendon injuries, but the specific mechanism is still unclear. OBJECTIVE: To observe the effect of low-intensity pulsed ultrasound on early angiogenesis after acute tendon injury, and to detect the regulatory relationship of low-intensity pulsed ultrasound with vascular endothelial growth factor-related signaling pathways, so as to reveal its potential mechanism of action. METHODS: Animal models of acute Achilles tendon injury were established using local injection of type I collagenase for 3 days in SPF male Sprague-Dawley rats aged 8-12 weeks, and were then randomly divided into ultrasound group and control group. In the ultrasound group, low-intensity pulsed ultrasound was treated daily with a small ultrasonic probe with an effective radiation area of 1 cm2 perpendicular to the Achilles tendon. No intervention was performed in the control group. Ultrasound imaging examination was performed 2 weeks later to observe the early healing of the tendon. Hematoxylin-eosin staining and CD31 immunohistochemical staining were performed to observe the changes in the number of blood vessels in the tissues after 1 and 2 weeks of treatment. The expression of vascular endothelial growth factor-related signaling pathway molecules in Achilles tendon tissues was detected by western blot or qRT-PCR. RESULTS AND CONCLUSION: Compared with the control group, the Achilles tendon in the ultrasound group was more continuous, the echo intensity was lower and more uniform, and the tendon thickness was significantly reduced (P < 0.05). Hematoxylin-eosin staining and CD31 immunohistochemical staining results showed that after 2 weeks of treatment, the number of new vessels in the ultrasound group was significantly increased compared with the control group (P < 0.05). Western blot and qRT-PCR results showed that after 2 weeks of continuous ultrasound intervention, the protein or mRNA expressions of vascular endothelial growth factor, Yes-associated protein, angiopoietin-2 and cysteine-rich angiogenic inducer 61 in the Achilles tendon of the ultrasound group were significantly higher than those of the control group (P < 0.05). These finding indicate that low-intensity pulsed ultrasound significantly increases the number of blood vessels in the early stage of acute tendon injury and accelerate tendon healing by up-regulating vascular endothelial growth factor expression. © 2024, Publishing House of Chinese Journal of Tissue Engineering Research. All rights reserved.