Coupled myovascular expansion directs growth and regeneration of the neonatal mouse heart

ABSTRACTInnate heart regeneration in zebrafish and neonatal mammals requires multiple cell types, such as epicardial cells, nerves, and macrophages, to enable proliferation of spared cardiomyocytes (CMs). How these cells interact to create growth niches is unclear. Here we profile proliferation kinetics of cardiac endothelial cells (CECs) and CMs in the neonatal mouse heart and find that CM and CEC expansion is spatiotemporally coupled. We show that coupled myovascular expansion during cardiac growth or regeneration is dependent upon VEGF-VEGFR2 signaling, as genetic deletion of Vegfr2 from CECs or inhibition of VEGFA abrogates both CEC and CM proliferation. Repair of cryoinjury, a model of incomplete regeneration, displays poor spatial coupling of CEC and CM proliferation. Boosting CEC density in the border zone by injection of virus encoding Vegfa enhances CM proliferation and the efficacy of heart regeneration, suggesting that revascularization strategies to increase CEC numbers may be an important adjunct for approaches designed to promote CM proliferation after injury. Finally, we use a human Mendelian randomization study to demonstrate that circulating VEGFA levels are positively associated with higher myocardial mass among healthy individuals, suggesting similar effects on human cardiac growth. Our work demonstrates the importance of coupled CEC and CM expansion for cardiomyogenesis and reveals the presence of a myovascular niche that underlies cardiac growth and regeneration.

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Abstract 15756: Vascular Guidance of Cardiomyocyte Proliferation During Growth and Regeneration

Circulation ◽

10.1161/circ.142.suppl_3.15756 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Paige DeBeneditts ◽

Anish Karpurapu ◽

Kyla Brezitski ◽

Michael C Thomas ◽

Ravi - Karra

Keyword(s):

Large Scale ◽

Nearest Neighbor ◽

Critical Role ◽

Cell Types ◽

Neonatal Mouse ◽

Angiogenic Factor ◽

Heart Regeneration ◽

Cardiomyocyte Proliferation ◽

Cardiac Growth ◽

Multiple Cell

Introduction: Stimulating cardiomyocyte (CM) proliferation is a major strategy for achieving therapeutic heart regeneration. However, heart regeneration requires coordinated interactions of multiple cell types. Because a hallmark of advanced heart failure is vascular rarefaction, the requirement of cardiac endothelial cells (CECs) for cardiac growth and regeneration is of particular importance. Hypothesis: We hypothesized that CECs are required for CM proliferation during growth and regeneration. Methods and Results: We performed a large-scale histologic assessment of neonatal mouse hearts and found the rate of CEC proliferation to shadow CM proliferation over the first 10 days of life. Using a nearest neighbor analysis, we found the fraction of proliferating CECs to be significantly enriched around cycling CMs compared to non-cycling CMs, suggesting that CEC and CM expansion are coupled within a myovascular niche. Single cell sequencing of neonatal mouse hearts after cryoinjury revealed that a majority of these proliferating CECs also express Vegfr2 . To functionally link CEC and CM proliferation, we generated Cdh5-CreER T2 ; Vefgr2 flox/flox mice to genetically delete Vegfr2 from CECs. Compared to mice with intact Vegfr2 , loss of Vegfr2 from CECs in neonatal mice leads to loss of CECs and severely dampens CM proliferation by 4 days (7.01±0.88% vs 0.39±0.35%, p = 7.4x10-4, n = 9),. Interestingly, CM proliferation is attenuated when Vegfr2 is deleted from CECs despite an increase of hypoxia indicators in CMs, signifying that hypoxia-induced CM proliferation is dependent on CECs. In contrast to CEC depletion, treatment of cryoinjured neonatal hearts with AAV encoding the master angiogenic factor, Vegfa can enhance heart regeneration with increased CM cycling in the borderzone (12.6±2.2% vs 5.4±0.4%, p = 0.02, n = 8), reduced scarring of the left ventricle (3.4±1.4% vs 7.6±1.2%, p = 03, n = 16), and improved fractional shortening (51.7±2.5% vs 36.7±4.3%, p = 0.007, n = 14). Conclusions: CEC and CM expansion are spatiotemporally coupled in a myovascular niche during cardiac growth. CECs play a critical role to support CM proliferation and are likely to provide instructive cues that may be leveraged for therapeutic heart regeneration.

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Runx1 promotes scar deposition and inhibits myocardial proliferation and survival during zebrafish heart regeneration

10.1101/799163 ◽

2019 ◽

Author(s):

Jana Koth ◽

Xiaonan Wang ◽

Abigail C. Killen ◽

William T. Stockdale ◽

Helen G. Potts ◽

...

Keyword(s):

Plasminogen Activator Inhibitor ◽

Cell Types ◽

Degradation Pathway ◽

Heart Regeneration ◽

Injury Site ◽

Heart Repair ◽

Multiple Cell ◽

Collagen Genes ◽

Zebrafish Heart ◽

Activator Inhibitor

Runx1 is a transcription factor that plays a key role in determining the proliferative and differential state of multiple cell-types, during both development and adulthood. Here, we report how runx1 is specifically upregulated at the injury site during zebrafish heart regeneration, but unexpectedly, absence of runx1 results in enhanced regeneration. Using single cell sequencing, we found that the wild-type injury site consists of Runx1-positive endocardial cells and thrombocytes that induce expression of smooth muscle and collagen genes without differentiating into myofibroblasts. Both these populations are absent in runx1 mutants, resulting in a less collagenous and fibrinous scar. The reduction in fibrin in the mutant is further explained by reduced myofibroblast formation and by upregulation of components of the fibrin degradation pathway, including plasminogen receptor Annexin 2A as well as downregulation of plasminogen activator inhibitor serpine1 in myocardium and endocardium, resulting in increased levels of Plasminogen. In addition, we find enhanced myocardial proliferation as well as increased myocardial survival in the mutant. Our findings suggest that Runx1 controls the regenerative response of multiple cardiac cell-types and that targeting Runx1 is a novel therapeutic strategy to induce endogenous heart repair.

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Abstract 148: Neonatal Mouse Heart Regeneration is Dependent on Mononuclear Diploid Cardiomyocytes and Paracrine IGF2 Signaling

Circulation Research ◽

10.1161/res.125.suppl_1.148 ◽

2019 ◽

Vol 125 (Suppl_1) ◽

Author(s):

Hua Shen ◽

Michaela Patterson ◽

Peiheng Gan ◽

Henry M Sucov

Keyword(s):

Neonatal Mouse ◽

Mouse Heart ◽

Heart Regeneration

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Transplantation of embryonic stem cells into the infarcted mouse heart: formation of multiple cell types

Journal of Molecular and Cellular Cardiology ◽

10.1016/j.yjmcc.2005.09.001 ◽

2006 ◽

Vol 40 (1) ◽

pp. 195-200 ◽

Cited By ~ 120

Author(s):

Dinender K. Singla ◽

Timothy A. Hacker ◽

Lining Ma ◽

Pamela S. Douglas ◽

Ruth Sullivan ◽

...

Keyword(s):

Stem Cells ◽

Embryonic Stem Cells ◽

Embryonic Stem ◽

Cell Types ◽

Mouse Heart ◽

Multiple Cell ◽

Heart Formation

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Cardiac cell type-specific responses to injury and contributions to heart regeneration

Cell Regeneration ◽

10.1186/s13619-020-00065-1 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Weijia Zhang ◽

Jinxiu Liang ◽

Peidong Han

Keyword(s):

Cell Types ◽

Scar Tissue ◽

Experimental Models ◽

Heart Regeneration ◽

Cell Type ◽

Cell Behaviors ◽

Epicardial Cells ◽

Injured Area ◽

Fibrotic Scar ◽

Cell Type Specific

AbstractHeart disease is the leading cause of mortality worldwide. Due to the limited proliferation rate of mature cardiomyocytes, adult mammalian hearts are unable to regenerate damaged cardiac muscle following injury. Instead, injured area is replaced by fibrotic scar tissue, which may lead to irreversible cardiac remodeling and organ failure. In contrast, adult zebrafish and neonatal mammalian possess the capacity for heart regeneration and have been widely used as experimental models. Recent studies have shown that multiple types of cells within the heart can respond to injury with the activation of distinct signaling pathways. Determining the specific contributions of each cell type is essential for our understanding of the regeneration network organization throughout the heart. In this review, we provide an overview of the distinct functions and coordinated cell behaviors of several major cell types including cardiomyocytes, endocardial cells, epicardial cells, fibroblasts, and immune cells. The topic focuses on their specific responses and cellular plasticity after injury, and potential therapeutic applications.

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Characterization of a common progenitor pool of the epicardium and myocardium

Science ◽

10.1126/science.abb2986 ◽

2021 ◽

pp. eabb2986

Author(s):

Richard C. V. Tyser ◽

Ximena Ibarra-Soria ◽

Katie McDole ◽

Satish A. Jayaram ◽

Jonathan Godwin ◽

...

Keyword(s):

Cardiac Development ◽

Cell Types ◽

Trophic Factors ◽

Mouse Heart ◽

Genetic Lineage ◽

Cardiac Cell ◽

Embryonic Mouse ◽

Cardiac Progenitors ◽

Multiple Cell ◽

Definition Of

The mammalian heart is derived from multiple cell lineages; however, our understanding of when and how the diverse cardiac cell types arise is limited. We mapped the origin of the embryonic mouse heart at single-cell resolution using a combination of transcriptomic, imaging, and genetic lineage labeling approaches. This provided a transcriptional and anatomic definition of cardiac progenitor types. Furthermore, it revealed a cardiac progenitor pool that is anatomically and transcriptionally distinct from currently known cardiac progenitors. Besides contributing to cardiomyocytes, these cells also represent the earliest progenitor of the epicardium, a source of trophic factors and cells during cardiac development and injury. This study provides detailed insights into the formation of early cardiac cell types, with particular relevance to the development of cell-based cardiac regenerative therapies.

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