Dataset Information

Consequences of fibroblast ablation in adult murine hearts

ABSTRACT: Fibroblasts produce the majority of collagen in the heart and are thought to regulate extracellular matrix (ECM) turnover. However, the in vivo role of fibroblasts in structuring the basal ECM network is poorly understood. To examine the effects of fibroblast loss on the microenvironment in the adult murine heart, we generated mice with reduced fibroblast numbers and evaluated the tissue microenvironment during homeostasis and after injury. We determined that a 60-80% reduction in fibroblasts numbers did not overtly change the fibrillar collagen network but did alter the distribution and abundance of type VI collagen, a microfibrillar collagen that forms an open network with the basement membrane. In fibroblast ablated mice, myocardial infarction did not result in ventricular wall rupture, and heart function was more effectively preserved during angiotensin II/phenylephrine (AngII/PE) induced fibrosis. Analysis of cardiomyocyte contractility demonstrated weaker contractions and slower calcium release and reuptake in uninjured and AngII/PE infused fibroblast ablated animals. Moreover, fibroblast ablated hearts have a similar gene expression prolife to hearts with exercise-induced and physiological hypertrophy after AngII/PE infusion. These results suggest that hearts are resilient to a significant degree of fibroblast loss and that fibroblasts can directly impact cardiomyocyte function. Furthermore, a reduction in fibroblasts may have cardioprotective effects heart after injury suggesting that manipulation of the number of fibroblasts may have therapeutic value.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Heart

SUBMITTER: Sumit Bhutada

LAB HEAD: Suneel Apte

PROVIDER: PXD021739 | Pride | 2023-03-10

REPOSITORIES: Pride

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Publications

Consequences of PDGFRα<sup>+</sup> fibroblast reduction in adult murine hearts.

Kuwabara Jill T JT Hara Akitoshi A Bhutada Sumit S Gojanovich Greg S GS Chen Jasmine J Hokutan Kanani K Shettigar Vikram V Lee Anson Y AY DeAngelo Lydia P LP Heckl Jack R JR Jahansooz Julia R JR Tacdol Dillon K DK Ziolo Mark T MT Apte Suneel S SS Tallquist Michelle D MD

eLife 20220923

Fibroblasts produce the majority of collagen in the heart and are thought to regulate extracellular matrix (ECM) turnover. Although fibrosis accompanies many cardiac pathologies and is generally deleterious, the role of fibroblasts in maintaining the basal ECM network and in fibrosis in vivo is poorly understood. We genetically ablated fibroblasts in mice to evaluate the impact on homeostasis of adult ECM and cardiac function after injury. Fibroblast-ablated mice demonstrated a substantive reduc ...[more]

PMID: 36149056

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Project description:Cardiac fibrosis is a pathophysiologic hallmark of the aging heart. In the uninjured heart, cardiac fibroblasts exist in the quiescent state, but little is known about how proliferation rates and fibroblast transcriptional programs change throughout the lifespan of the organism from the immediate postnatal period to adult life and old age. Using EdU pulse labeling, we demonstrate that more than 50% of cardiac fibroblasts are actively proliferating in the first day of post-natal life. However, within 4 weeks of birth in the juvenile animal, only 10% of cardiac fibroblasts are proliferating. By early adulthood, the fraction of proliferating cardiac fibroblasts further decreases to approximately 2%, where it so remains throughout the rest of the organism’s life span. Examination of absolute cardiac fibroblast numbers demonstrated concordance with age related changes in fibroblast proliferation with no significant differences in absolute cardiac fibroblast numbers between animals 14 weeks and 1.5 years of age. We demonstrate that the maximal changes in cardiac fibroblast transcriptional programs and in particular collagen expression occur within the first weeks of life from the immediate postnatal to the juvenile period. We show that even though the aging heart exhibits an increase in the total amount of accumulated collagen, transcription of various collagens and ECM genes both in the heart and cardiac fibroblast is maximal in the newly born and juvenile animal and decreases with organismal aging. Examination of DNA methylation changes both in the heart and in cardiac fibroblasts did not demonstrate significant changes in differentially methylated regions between young and old mice. Our observations demonstrate that cardiac fibroblasts attain a stable proliferation rate and transcriptional program early in the life span of the organism and suggest a model of cardiac aging where phenotypic changes in the aging heart are not directly attributable to changes in proliferation rate or altered collagen expression in cardiac fibroblasts.

Project description:Pericytes have been implicated in regulation of inflammatory, reparative, fibrogenic and angiogenic responses in several different organs and pathologic conditions. Although the adult mammalian heart contains abundant pericytes, their fate and involvement in myocardial disease remains unknown. We used NG2Dsred;PDGFRaEGFP pericyte-fibroblast dual reporter mice and inducible NG2CreER mice to study the fate and phenotypic modulation of pericytes in a model of myocardial infarction. The transcriptomic profile of pericyte-derived fibroblasts was studied using PCR arrays. The transcriptomic profile of NG2 lineage cells (pericytes) was studied in control and infarcted hearts using single cell RNA-sequencing analysis. The role of TGF-b signaling in regulation of pericyte phenotype in vivo was investigated using pericyte-specific Tgfbr2 knockout mice. In vitro, the effects of TGF-b were studied in cultured human placental pericytes.In normal mouse hearts, NG2 and PDGFRa identified distinct non-overlapping populations of pericytes and fibroblasts respectively. Following myocardial infarction, a population of cells expressing both pericyte and fibroblast markers emerged. These cells expressed large amounts of extracellular matrix (ECM) genes. Lineage tracing demonstrated that in the infarcted region, a subpopulation of pericytes underwent fibroblast conversion. Single cell RNA-seq experiments demonstrated expansion and diversification of pericyte-derived cells in the infarct, associated with emergence of subpopulations exhibiting accentuated matrix gene synthesis. In vitro studies and the profile of pericyte-derived fibroblasts identified TGF-b as a potentially causative mediator in fibrogenic activation of infarct pericytes. However, pericyte-specific Tgfbr2 disruption had no significant effects on myofibroblast infiltration and collagen deposition in the infarct. Pericyte-specific TGF-b signaling was involved in vascular maturation, mediating formation of a mural cell coat investing infarct neovessels. These reparative effects of infarct pericytes protected the infarcted heart from dilative remodeling.

Dataset Information

Consequences of fibroblast ablation in adult murine hearts

Publications

Consequences of PDGFRα<sup>+</sup> fibroblast reduction in adult murine hearts.

Similar Datasets

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