BACKGROUND:Preclinical studies have shown the therapeutic potential of VEGF-B (vascular endothelial growth factor B) in revascularization of the ischemic myocardium, but the associated cardiac hypertrophy and adverse side effects remain a concern. To understand the importance of endothelial proliferation and migration for the beneficial versus adverse effects of VEGF-B in the heart, we explored the cardiac effects of autocrine versus paracrine VEGF-B expression in transgenic and gene-transduced mice.METHODS:We used single-cell RNA sequencing to compare cardiac endothelial gene expression in VEGF-B transgenic mouse models. Lineage tracing was used to identify the origin of a VEGF-B-induced novel endothelial cell population and adeno-associated virus–mediated gene delivery to compare the effects of VEGF-B isoforms. Cardiac function was investigated using echocardiography, magnetic resonance imaging, and micro-computed tomography.RESULTS:Unlike in physiological cardiac hypertrophy driven by a cardiomyocyte-specific VEGF-B transgene (myosin heavy chain alpha-VEGF-B), autocrine VEGF-B expression in cardiac endothelium (aP2 [adipocyte protein 2]-VEGF-B) was associated with septal defects and failure to increase perfused subendocardial capillaries postnatally. Paracrine VEGF-B led to robust proliferation and myocardial migration of a novel cardiac endothelial cell lineage (VEGF-B-induced endothelial cells) of endocardial origin, whereas autocrine VEGF-B increased proliferation of VEGF-B-induced endothelial cells but failed to promote their migration and efficient contribution to myocardial capillaries. The surviving aP2-VEGF-B offspring showed an altered ratio of secreted VEGF-B isoforms and developed massive pathological cardiac hypertrophy with a distinct cardiac vessel pattern. In the normal heart, we found a small VEGF-B-induced endothelial cell population that was only minimally expanded during myocardial infarction but not during physiological cardiac hypertrophy associated with mouse pregnancy.CONCLUSIONS:Paracrine and autocrine secretions of VEGF-B induce expansion of a specific endocardium-derived endothelial cell population with distinct angiogenic markers. However, autocrine VEGF-B signaling fails to promote VEGF-B-induced endothelial cell migration and contribution to myocardial capillaries, predisposing to septal defects and inducing a mismatch between angiogenesis and myocardial growth, which results in pathological cardiac hypertrophy.

中文翻译：

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VEGF-B 诱导的心内膜内皮细胞谱系在生理性与病理性心脏肥大中的作用

背景：临床前研究已显示 VEGF-B（血管内皮生长因子 B）在缺血心肌血运重建中的治疗潜力，但相关的心脏肥大和不良副作用仍然令人担忧。为了了解内皮增殖和迁移对 VEGF-B 在心脏中的有益与不利影响的重要性，我们探讨了转基因和基因转导小鼠中自分泌与旁分泌 VEGF-B 表达对心脏的影响。细胞 RNA 测序比较 VEGF-B 转基因小鼠模型中的心脏内皮基因表达。谱系追踪用于鉴定 VEGF-B 诱导的新型内皮细胞群的起源和腺相关病毒介导的基因传递，以比较 VEGF-B 亚型的影响。使用超声心动图、磁共振成像和微型计算机断层扫描来研究心脏功能。 结果：与心肌细胞特异性 VEGF-B 转基因（肌球蛋白重链 α-VEGF-B）驱动的生理性心脏肥大不同，自分泌 VEGF-B 表达心脏内皮细胞（aP2 [脂肪细胞蛋白 2]-VEGF-B）与隔膜缺陷和出生后心内膜下毛细血管灌注失败相关。旁分泌 VEGF-B 导致心内膜起源的新型心脏内皮细胞谱系（VEGF-B 诱导的内皮细胞）的强劲增殖和心肌迁移，而自分泌 VEGF-B 增加 VEGF-B 诱导的内皮细胞的增殖，但未能促进它们的迁移和对心肌毛细血管的有效贡献。幸存的 aP2-VEGF-B 后代表现出分泌的 VEGF-B 同种型的比例发生改变，并出现了具有独特心脏血管模式的大规模病理性心脏肥大。在正常心脏中，我们发现了一小部分 VEGF-B 诱导的内皮细胞群，该细胞群仅在心肌梗塞期间出现轻微扩张，但在与小鼠妊娠相关的生理性心脏肥大期间则没有。 结论：VEGF-B 的旁分泌和自分泌会诱导内皮细胞群的扩张。具有独特血管生成标记的特定心内膜来源的内皮细胞群。然而，自分泌 VEGF-B 信号传导无法促进 VEGF-B 诱导的内皮细胞迁移和对心肌毛细血管的贡献，容易出现间隔缺损并诱导血管生成和心肌生长之间的不匹配，从而导致病理性心脏肥大。