Non-invasive regeneration therapy of dilated cardiomyopathy using G-CSF

在UM-X7.1型仓鼠（人类扩张型心肌病模型）中，心力衰竭逐渐发展，其中一半在30周龄时死亡。我们在超微结构上发现了典型的自噬空泡，包括降解的线粒体、糖原颗粒和髓磷脂样图，并在该模型的许多心肌细胞中过度表达泛素、组织蛋白酶D和Rab7。重要的是，大多数质膜渗漏的心肌细胞组织蛋白酶D阳性，表明自噬变性和细胞死亡之间存在直接联系。心肌细胞凋亡未见明显变化。从15周龄开始，每周5天注射粒细胞集落刺激因子（10 μg/kg/天），持续15周，可改善30周龄仓鼠的存活率（100% vs.未治疗仓鼠的53%，p<0.0001），改善心室功能和重塑，增加心肌细胞大小，减少心肌纤维化，随后显著减少自噬结果。它还导致肿瘤坏死因子-α下调，Akt、转录-3信号转导和激活因子、基质金属蛋白酶活性升高。然而，没有明确的证据表明骨髓细胞向心肌细胞转分化。综上所述，自噬性死亡是心肌病仓鼠心肌细胞损失的重要原因，粒细胞集落刺激因子主要通过抗自噬机制而非抗凋亡或再生机制发挥有益作用。

In UM-X7.1 strain hamsters, a model of human dilated cardiomyopathy, heart failure progressively develops and a half of them die by 30 weeks old. We ultrastructurally found typical autophagic vacuoles including degraded mitochondria, glycogen granules, and myelin-like figures and overexpressed ubiquitin, cathepsin D and Rab7 in many cardiomyocytes of this model. Importantly, most cardiomyocytes with leaky plasma membrane were positive for cathepsin D, suggesting a direct linkage between autophagic degeneration and cell death. Meanwhile, cardiomyocyte apoptosis appeared insignificant. Injection of granulocyte colony-stimulating factor (10 μg/kg/day) 5 days/week for 15 weeks, started at 15 weeks of age, improved survival among 30-week-old hamsters (100% vs. 53% in the untreated hamsters, p<0.0001), ventricular function and remodeling, increased cardiomyocyte size, and reduced myocardial fibrosis, followed by a dramatic reduction in the autophagic findings. It also resulted in downregulation of tumor necrosis factor-α and increase in activities of Akt, signal transducer and activator of transcription-3, and matrix metalloproteinases. However, there was no clear evidence of transdifferentiation from bone marrow cells into cardiomyocytes. In conclusion, autophagic death is important for cardiomyocyte loss in the cardiomyopathic hamster and granulocyte colony-stimulating factor has the beneficial effect mainly via antiautophagic mechanism rather than antiapoptosis or regeneration.