Division of Plastic, Reconstructive & Aesthetic Surgery, Geneva University Hospitals, Geneva CH-1211, Switzerland.
Lab Invest. 2010 Jan;90(1):40-51. doi: 10.1038/labinvest.2009.117. Epub 2009 Nov 9.
Recent findings have attested the protective effects of erythropoietin (EPO) in ischemically challenged organs. We therefore aimed at elaborating the underlying mechanism of EPO-mediated protection in musculocutaneous tissue undergoing persistent ischemia after acute injury. Mice were assigned to five experimental groups equipped with a randomly perfused flap fixed in a dorsal skinfold chamber, whereas the sixth group did not undergo flap preparation: EPO, L-Name, EPO and L-Name, EPO and bevacizumab, untreated flap, and nonischemic chamber (control). Intravital fluorescence microscopic analysis of microhemodynamics, apoptotic cell death, macromolecular leakage and angiogenesis was carried out over a 10-day period. Further, immunohistochemical analysis was used to study the protein expression of endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF). Increased expression of eNOS in EPO-administered mice correlated with significant arteriolar dilation and thus increased blood flow resulting in a maintained functional capillary density (FCD) at day 10. In addition, EPO induced a VEGF upregulation, which was associated with newly formed capillaries. In addition, EPO was able to reduce ischemia-induced apoptotic cell death and finally to significantly reduce flap necrosis. In contrast, coadministration of L-Name abolished EPO-mediated tissue protection by abrogating the dilatory effect resulting in reduced FCD and tissue survival, without counteracting angiogenesis and apoptotic cell death, whereas additional administration of bevacizumab did not influence the beneficial effect of EPO on flap survival despite abrogating angiogenesis. Macromolecular leakage was found to be increased in all treatment groups. This study shows that EPO administration prevents musculocutaneous tissue from ischemic necrosis as a consequence of an eNOS-dependent arteriolar hyperperfusion maintaining capillary perfusion, thus representing a promising approach to pharmacologically protect ischemically challenged tissue.
最近的研究结果证实了促红细胞生成素（EPO）对缺血性器官的保护作用。因此，我们旨在阐述 EPO 在急性损伤后持续缺血的肌肉皮肤组织中介导保护作用的潜在机制。将小鼠分为五个实验组，每个组均配备一个随机灌注的皮瓣，固定在背部皮肤褶皱室中，而第六个组不进行皮瓣准备：EPO、L-Name、EPO 和 L-Name、EPO 和贝伐单抗、未处理的皮瓣和非缺血室（对照）。在 10 天的时间内，通过活体荧光显微镜分析微血液动力学、凋亡细胞死亡、大分子渗漏和血管生成。此外，还使用免疫组织化学分析来研究内皮型一氧化氮合酶（eNOS）和血管内皮生长因子（VEGF）的蛋白表达。在给予 EPO 的小鼠中，eNOS 的表达增加与明显的小动脉扩张相关，从而导致血流增加，导致第 10 天的功能毛细血管密度（FCD）保持不变。此外，EPO 诱导 VEGF 的上调，这与新形成的毛细血管相关。此外，EPO 能够减少缺血诱导的凋亡细胞死亡，最终显著减少皮瓣坏死。相比之下，L-Name 的共同给药通过消除扩张作用消除了 EPO 介导的组织保护作用，导致 FCD 和组织存活率降低，而没有对抗血管生成和凋亡细胞死亡，而贝伐单抗的额外给药尽管消除了血管生成，但并没有影响 EPO 对皮瓣存活的有益作用。发现所有治疗组的大分子渗漏都增加了。这项研究表明，EPO 给药可防止肌肉皮肤组织发生缺血性坏死，这是由于 eNOS 依赖性小动脉过度灌注维持毛细血管灌注所致，因此代表了一种有前途的方法，可以在药理学上保护缺血性组织。
