Metabolic optimization of cell therapy

摘要 2型糖尿病是发生心力衰竭的独立危险因素。它有助于不利的 心脏重塑并增加心力衰竭死亡率。虽然细胞疗法为治疗心脏病提供了希望 尽管在非糖尿病患者中细胞治疗失败，但在糖尿病心脏中细胞治疗的功效仍然不确定。我们的初步 研究表明，糖尿病损害心脏祖细胞（CPC）的生长、存活和分化， 从糖尿病心脏分离的CPC不能促进心肌梗死（MI）后的心肌恢复。我们发现 CPCs表达Glut 1，在细胞外存在高浓度Glut 1时， 葡萄糖，独立于胰岛素。此外，从糖尿病小鼠中分离的CPC表现出显著和持续的 有氧糖酵解增加，伴随着6-磷酸果糖-2-激酶/果糖-2，6- 双磷酸酶3-已知维持高糖酵解速率的磷酸果糖激酶2同种型。我们的研究 还表明，糖尿病CPC中糖酵解活性的增加与葡萄糖衍生碳的减少有关， 通过戊糖磷酸和己糖胺生物合成途径的通量，但通过 甘油脂生物合成途径。这些结果表明，CPC中的高糖酵解速率改变了其活性， 葡萄糖代谢的辅助途径，这是重要的生物合成反应，维持氧化还原 平衡和抗压力。葡萄糖代谢的这种变化影响CPC功能， 我们的观察表明，增加PFK步骤的糖酵解足以降低CPC 体外增殖。根据这些观察，我们怀疑CPC的糖尿病功能障碍至少是 部分是由葡萄糖代谢失调引起的，纠正这种代谢缺陷将是 优化糖尿病心脏细胞治疗的可行方法。我们打算检验糖尿病 导致CPC糖酵解活性增加，从而减少通过关键辅助途径的通量， 葡萄糖代谢这种代谢失调降低了CPC的增殖、存活和分泌活性， 并损害CPC促进心肌修复的能力。为了验证这一假设，我们将：（1）检查 糖尿病如何影响CPC的能力和治疗;（2）阐明葡萄糖代谢在介导 糖尿病中CPC功能障碍;（3）确定挽救葡萄糖代谢缺陷是否能改善细胞 糖尿病心脏的治疗该项目的成功完成将使人们对 调节干/祖细胞功能的代谢途径以及它们如何影响细胞的结果 治疗心力衰竭这些发现将有助于优化细胞治疗方案，并为细胞治疗提供信息。 正在进行和未来的细胞疗法试验，用于治疗非糖尿病和糖尿病患者的心力衰竭。

ABSTRACT Type 2 diabetes is an independent risk factor for the development of heart failure. It contributes to adverse cardiac remodeling and it increases heart failure mortality. While cell therapy offers promise for treating heart failure in nondiabetic patients, the efficacy of cell therapy in diabetic hearts remains uncertain. Our preliminary studies show that diabetes impairs cardiac progenitor cell (CPC) growth, survival and differentiation and that CPCs isolated from diabetic hearts fail to promote myocardial recovery after myocardial infarction (MI). We find that CPCs express Glut1 and that their rate of glucose utilization increases in the presence of high extracellular glucose, independently of insulin. Moreover, CPCs isolated from diabetic mice exhibit a marked and sustained increase in aerobic glycolysis, accompanied by an elevated level of 6-phophofructo-2-kinase/fructose-2,6- bisphosphatase 3—a phosphofructokinase 2 isoform known to sustain high rates of glycolysis. Our studies also show that increased glycolytic activity in diabetic CPCs is associated with lower glucose-derived carbon flux through the pentose phosphate and hexosamine biosynthetic pathways, but higher flux through the glycerolipid biosynthetic pathway. These results indicate that high rates of glycolysis in CPCs alter the activity of ancillary pathways of glucose metabolism, which are important for biosynthetic reactions, maintaining redox balance, and for resistance to stress. That such changes in glucose metabolism affect CPC function is indicated by our observation that increasing glycolysis at the PFK step is sufficient to decrease CPC proliferation in vitro. Informed by these observations, we suspect that diabetic dysfunction in CPCs is, at least in part, caused by a dysregulation of glucose metabolism and that correcting this metabolic defect will be a viable approach to optimize cell therapy for the diabetic heart. We propose to test the hypothesis that diabetes leads to an increase in the glycolytic activity in CPCs, which diminishes flux through key ancillary pathways of glucose metabolism. This metabolic dysregulation decreases CPC proliferation, survival, and secretory activity, and impairs the capacity of CPCs to promote myocardial repair. To test this hypothesis, we will: (1) examine how diabetes affects CPC competence and therapy; (2) elucidate the role of glucose metabolism in mediating CPC dysfunction in diabetes; and (3) determine whether rescuing defects in glucose metabolism improves cell therapy in the diabetic heart. Successful completion of the project will provide new understanding of the metabolic pathways that regulate stem/progenitor cell function and how they affect the outcomes of cell therapy for heart failure. These findings would facilitate the optimization of cell therapy protocols and inform ongoing and future cell therapy trials for the treatment of heart failure in both nondiabetic and diabetic patients.