Liver Ischemia Contributes to Early Islet Failure Following Intraportal Transplantation: Benefits of Liver Ischemic-Preconditioning

Early graft failure following intraportal islet transplantation (IPIT) represents a major obstacle for successful islet transplantation. Here, we examined the role of islet emboli in the induction of early graft failure and utilized a strategy of ischemic-preconditioning (IP) to prevent early islet destruction in a model of syngeneic IPIT in STZ-induced diabetic mice. Numerous focal areas of liver necrosis associated with the islet emboli were observed within 24 h post-IPIT. Pro-inflammatory cytokines, IL-1beta and IL-6, were significantly increased 3 h after IPIT, while TNF-alpha was elevated for up to 5 days post-IPIT. Caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling positive cells were observed in the transplanted islets trapped in areas of necrotic liver at 3 h and 1 day post-IPIT. Hyperglycemia was corrected immediately following IPIT of 200 islets, but recurrence of hyperglycemia was observed within 14 days associated with a poor response to glucose challenge. IP, a procedure of pre-exposure of the liver to transient ischemia and reperfusion, protected the liver from embolism-induced ischemic injury and prevented early islet graft failure. These data suggest that islet embolism in the portal vein is a major cause of functional loss following IPIT that can be prevented by liver IP.     

缺血预处理对大鼠肝脏缺血再灌注损伤的保护作用

目的 探讨缺血预处理(IPC)对肝脏缺血再灌注(I/R)损伤中细胞凋亡和Fas蛋白表达的影响.方法 60只SD大鼠随机分成正常对照组(N组)、缺血再灌注对照组(I/R组)、缺血预处理组(IPC组).比较各组血清AST、ALT和LDH水平,肝组织中凋亡细胞及细胞凋亡指数,肝组织Fas蛋白的表达情况.结果 IP组血清AST、ALT和LDH水平、细胞凋亡指数、Fas蛋白表达低于I/R组.IPC组血清ALT水平高于N组.结论 缺血预处理对肝脏缺血再灌注损伤有保护作用,可能与抑制Fas蛋白高表达、减少细胞凋亡有关.     

冠状动脉血管成形术中药物性预适应的应用

预适应的概念发现以来,发现它是对抗心肌缺血的有效机制之一,经皮经腔冠脉成形术中反复球囊扩张是探讨预适应现象的最好的临床模型,也可以用于对预适应模拟药物作用的研究,如腺苷、尼可地尔、缓激肽、氨茶碱、硝酸甘油、尼索地平等。模拟预适应药物的应用可对抗心肌缺血,减少梗死面积,改善预后。