5、Bioenergetic and Functional Consequences of Bone Marrow–Derived Multipotent Progenitor Cell Transplantation in Hearts With Postinfarction Left Ventricular Remodeling
梗死后骨髓多能前体细胞移植后的左室重建以及生物能量学和功能学后果
Background— The present study examined whether transplantation of adherent bone marrow–derived stem cells, termed pMultistem, induces neovascularization and cardiomyocyte regeneration that stabilizes bioenergetic and contractile function in the infarct zone and border zone (BZ) after coronary artery occlusion.
背景：本研究验讫了移植黏着的骨髓来源的干细胞，定义为pMultistem，是否能够诱导新生血管形成和心肌细胞再生，从而稳定冠脉闭塞后梗死区和边缘区的生物能量和收缩功能。
Methods and Results— Permanent left anterior descending artery occlusion in swine caused left ventricular remodeling with a decrease of ejection fraction from 55±5.6% to 30±5.4% (magnetic resonance imaging). Four weeks after left anterior descending artery occlusion, BZ myocardium demonstrated profound bioenergetic abnormalities, with a marked decrease in subendocardial phosphocreatine/ATP (31P magnetic resonance spectroscopy; 1.06±0.30 in infarcted hearts [n=9] versus 1.90±0.15 in normal hearts [n=8; P<0.01]). This abnormality was significantly improved by transplantation of allogeneic pMultistem cells (subendocardial phosphocreatine/ATP to 1.34±0.29; n=7; P<0.05). The BZ protein expression of creatine kinase–mt and creatine kinase–m isoforms was significantly reduced in infarcted hearts but recovered significantly in response to cell transplantation. MRI demonstrated that the infarct zone systolic thickening fraction improved significantly from systolic "bulging" in untreated animals with myocardial infarction to active thickening (19.7±9.8%, P<0.01), whereas the left ventricular ejection fraction improved to 42.0±6.5% (P<0.05 versus myocardial infarction). Only 0.35±0.05% donor cells could be detected 4 weeks after left anterior descending artery ligation, independent of cell transplantation with or without immunosuppression with cyclosporine A (with cyclosporine A, n=6; no cyclosporine A, n=7). The fraction of grafted cells that acquired an endothelial or cardiomyocyte phenotype was 3% and 2%, respectively. Patchy spared myocytes in the infarct zone were found only in pMultistem transplanted hearts. Vascular density was significantly higher in both BZ and infarct zone of cell-treated hearts than in untreated myocardial infarction hearts (P<0.05).
方法和结果：永久性冠脉左前降支闭塞导致猪的左心室重建，同时伴有55±5.6%到30±5.4%的射血分数减少（磁共振显像）。左前降支闭塞后四周，边缘区心肌表现出明显的生物能量学异常情况，伴有内膜下磷酸肌酸/ATP的明显减少（磁共振波谱成像；梗死心肌的1.06±0.30 [n=9] VS 正常心肌的1.90±0.15 [n=8; P<0.01]）。移植同种异体的pMultistem细胞后这种异常有明显的改善（内膜下磷酸肌酸/ATP增加至1.34±0.29; n=7; P<0.05）。边缘区本来肌酸激酶mt和甲酸激酶m的表达明显增加，但经过细胞移植后得到明显的改善。MRI显示增厚的梗死区的收缩分数与梗死后未经处理的膨出的梗死区的射血分数相比，有明显的改善(19.7±9.8%, P<0.01)，然而左室射血分数的改善达到42.0±6.5% (P<0.05 与梗死心肌相比)。仅仅0.35±0.05%供体细胞在左前降支结扎四周后可以检测得到，移植后使用环胞素A进行免疫抑制或不使用的独立结果分别为(使用组, n=6; 不使用组, n=7).获得内皮细胞或心肌细胞表型的抑制细胞的分数分别为3% and 2%。梗死区斑片样获救的细胞仅在pMultistem细胞移植后的心脏内被检测到。细胞治疗组的梗死区和边缘区的血管密度明显高于未治疗的梗死心脏。
Conclusions— Thus , allogeneic pMultistem improved BZ energetics, regional contractile performance, and global left ventricular ejection fraction. These improvements may have resulted from paracrine effects that include increased vascular density in the BZ and spared myocytes in the infarct zone.
结论：因此，同种异体pMultistem移植可以改善边缘区能量，局部收缩表现以及总的左室射血分数。这些改善，包括边缘区血管密度的增加以及保存梗死区的心肌细胞，来自于旁分泌效应。
Key Words: cells • heart failure • hypertrophy • magnetic resonance imaging • metabolism • myocardial contraction • myocardial infarction
Molecular Cardiology:
6、Targeted Cardiac Overexpression of A20 Improves Left Ventricular Performance and Reduces Compensatory Hypertrophy After Myocardial Infarction
靶向心脏过表达A20改善左室工作效应和减少梗死后的代偿性心肌肥大
background— A20 was originally characterized as a tumor necrosis factor–inducible gene in human umbilical vein endothelial cells. As an inhibitor of nuclear factor-B signaling, A20 protects against apoptosis, inflammation, and cardiac hypertrophy. In the present study, we tested the hypothesis that cardiac-specific overexpression of A20 could protect the heart from myocardial infarction.
背景：A20原来被认为具有肿瘤坏死因子的特征――人脐静脉内皮细胞内的可诱导基因。作为核因子B信号传导的抑制子，A20具有对凋亡、炎症和心肌肥大的保护作用。在本研究中，我们检验了心脏特异型过表达A20可以保护心脏免于发生心肌梗死。
Methods and Results— We investigated the role of constitutive human A20 expression in acute myocardial infarction using a transgenic model. Transgenic mice containing the human A20 gene under the control of the -myosin heavy chain promoter were constructed. Myocardial infarction was produced by coronary ligation in A20 transgenic mice and control animals. The extent of infarction was then quantified by 2-dimensional and M-mode echocardiography and by molecular and pathological analyses of heart samples in infarct and remote heart regions 7 days after myocardial infarction. Constitutive overexpression of A20 in the murine heart resulted in attenuated infarct size and improved cardiac function 7 days after myocardial infarction. Significantly, we found a decrease in nuclear factor-B signaling and apoptosis, as well as proinflammatory response, cardiac remodeling, and interstitial fibrosis, in noninfarct regions in the hearts of constitutive A20-expressing animals compared with control animals.
方法和结果：我们利用转基因模型研究了心肌梗死中组成性人类A20基因的表达。在肌球蛋白重链启动子的控制下，构建了含有人类A20基因的转基因小鼠。利用冠脉结扎使A20基因小鼠和对照组小鼠产生心肌梗死。随后利用二维超声和M超声对梗死范围进行量化，同时利用分子和病理学手段对梗死7胎天后梗死区和远隔区的心脏样本进行分析。梗死7天后，组成性过表达A20的小鼠心脏梗死范围减少、心功能有所改善。明显的，与对照组相比，在组成性表达A20的动物中我们发现核因子B信号转导、凋亡、促炎反应、心脏重建以及间质纤维化都有所下降。
Conclusions— Cardiac-specific overexpression of A20 improves cardiac function and inhibits cardiac remodeling, apoptosis, inflammation, and fibrosis after acute myocardial infarction.
结论：心脏特异型过表达A20改善心脏功能，抑制急型心肌梗死后的心脏重建、凋亡、炎症和间质纤维化。
Key Words: apoptosis • cardiovascular diseases • fibrosis • gene therapy • hypertrophy • inflammation • remodeling
7、The pH Hypothesis of Postconditioning
Staccato Reperfusion Reintroduces Oxygen and Perpetuates Myocardial Acidosis
Michael V. Cohen, MD; Xi-Ming Yang, MD, PhD; James M. Downey, PhD
后条件的PH假说――断续性再灌注输入氧和长期保持心肌的酸中毒状态
Background— It is unclear how reperfusion of infarcting hearts with alternating cycles of coronary reperfusion/occlusion attenuates infarction, but prevention of
mitochondrial permeability transition pore (MPTP) formation is crucial. Acidosis also suppresses MPTP formation. We tested whether postconditioning protects by maintaining acidosis during early reoxygenation.
背景：梗死心脏再灌注以及伴随的冠脉再灌注/闭塞环的改变如何减轻梗死尚不清楚，但是预防线粒体通透性转换孔(MPTP)的是极为重要的。酸中毒也可以抑制MPTP的形成。我们检验了是否在早期再氧合的过程中，后条件是否具有通过维持酸中苏而对心梗具有保护作用。
Methods and Results— After 30-minute regional ischemia in isolated rabbit hearts, reperfusion with buffer (pH 7.4) caused 34.4±2.2% of the risk zone to infarct, whereas 2 minutes of postconditioning (6 cycles of 10-second reperfusion/10-second occlusion) at reperfusion resulted in 10.7±2.9% infarction. One minute (3 cycles) of postconditioning was not protective. Hypercapnic buffer (pH 6.9) for the first 2 minutes of reperfusion in lieu of postconditioning caused equivalent cardioprotection (15.0±2.6% infarction), whereas 1 minute of acidosis did not protect. Delaying postconditioning (6 cycles) or 2 minutes of acidosis for 1 minute aborted protection. Reperfusion with buffer (pH 7.7) blocked postconditioning protection, but addition of the MPTP closer cyclosporin A restored protection. Reactive oxygen species scavenger N-2-mercaptopropionyl glycine, protein kinase C antagonist chelerythrine, and mitochondrial KATP channel closer 5-hydroxydecanoate each blocked protection from 2 minutes of acidosis as they did for postconditioning.
方法和背景：离体家兔心脏30分钟局部缺血后，用缓冲液(pH 7.4)进行在灌注导致34.4±2.2%的危险区梗死，然而再灌注中两分钟的后条件（6轮10秒钟的灌注/10秒钟的闭塞）仅导致10.7±2.9%的梗死。一分钟（3轮）的后条件并没有保护作用。头两分钟利用高碳酸缓冲液进行再灌注，代替后条件，具有同样的心肌保护作用(15.0±2.6%梗死)，然而1分钟的酸中毒却没有保护作用。延迟后条件或两分钟的酸中毒1分钟使保护作用流产。用缓冲液(pH 7.7)能阻断后条件的保护作用，而增加MPTP关闭剂环胞素A则可以重新恢复保护作用。活性氧簇清道夫N-2硫丙酰甘氨酸、蛋白激酶C拮抗剂白屈菜红碱、线粒体KATP通道关闭剂5-hydroxydecanoate都可以阻断两分钟的酸中毒和后条件的保护作用。
Conclusion— Thus, postconditioning prevents MPTP formation by maintaining acidosis during the first minutes of reperfusion as reoxygenated myocardium produces reactive oxygen species that activate protective signaling to inhibit MPTP formation after pH normalization.
结论：因此，在第一分钟内，后条件通过维持酸中毒来保护MPTP形成；在PH正常后，再氧合心肌产生活性氧簇激活保护性信号通路抑制MTPT形成。
Key Words: acidosis • free radicals • mitochondrial permeability transition pore • myocardial infarction • reperfusion
