Marín-Juez Rubén, Marass Michele, Gauvrit Sebastien, Rossi Andrea, Lai Shih-Lei, Materna Stefan C, Black Brian L, Stainier Didier Y R
Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany;
Department of Developmental Genetics, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany.
Proc Natl Acad Sci U S A. 2016 Oct 4;113(40):11237-11242. doi: 10.1073/pnas.1605431113. Epub 2016 Sep 19.
Zebrafish have a remarkable capacity to regenerate their heart. Efficient replenishment of lost tissues requires the activation of different cell types including the epicardium and endocardium. A complex set of processes is subsequently needed to support cardiomyocyte repopulation. Previous studies have identified important determinants of heart regeneration; however, to date, how revascularization of the damaged area happens remains unknown. Here, we show that angiogenic sprouting into the injured area starts as early as 15 h after injury. To analyze the role of vegfaa in heart regeneration, we used vegfaa mutants rescued to adulthood by vegfaa mRNA injections at the one-cell stage. Surprisingly, vegfaa mutants develop coronaries and revascularize after injury. As a possible explanation for these observations, we find that vegfaa mutant hearts up-regulate the expression of potentially compensating genes. Therefore, to overcome the lack of a revascularization phenotype in vegfaa mutants, we generated fish expressing inducible dominant negative Vegfaa. These fish displayed minimal revascularization of the damaged area. In the absence of fast angiogenic revascularization, cardiomyocyte proliferation did not occur, and the heart failed to regenerate, retaining a fibrotic scar. Hence, our data show that a fast endothelial invasion allows efficient revascularization of the injured area, which is necessary to support replenishment of new tissue and achieve efficient heart regeneration. These findings revisit the model where neovascularization is considered to happen concomitant with the formation of new muscle. Our work also paves the way for future studies designed to understand the molecular mechanisms that regulate fast revascularization.
斑马鱼具有显著的心脏再生能力。高效补充丢失的组织需要激活包括心外膜和心内膜在内的不同细胞类型。随后需要一系列复杂的过程来支持心肌细胞的重新填充。先前的研究已经确定了心脏再生的重要决定因素；然而，迄今为止，受损区域的血管再生是如何发生的仍然未知。在这里，我们表明血管生成芽生进入损伤区域早在损伤后15小时就开始了。为了分析vegfaa在心脏再生中的作用，我们使用了通过在单细胞阶段注射vegfaa mRNA挽救至成年期的vegfaa突变体。令人惊讶的是，vegfaa突变体在损伤后形成冠状动脉并实现血管再生。作为对这些观察结果的一种可能解释，我们发现vegfaa突变体心脏上调了潜在补偿基因的表达。因此，为了克服vegfaa突变体中缺乏血管再生表型的问题，我们构建了表达可诱导显性负性Vegfaa的鱼类。这些鱼在受损区域的血管再生极少。在没有快速血管生成性血管再生的情况下，心肌细胞增殖未发生，心脏无法再生，保留了纤维化瘢痕。因此，我们的数据表明快速的内皮细胞侵入使受损区域能够高效地进行血管再生，这对于支持新组织的补充和实现高效的心脏再生是必要的。这些发现重新审视了新血管形成被认为与新肌肉形成同时发生的模型。我们的工作也为未来旨在理解调节快速血管再生的分子机制的研究铺平了道路。
