Project description:Early postnatal myofibroblasts are a key cell type involved in postnatal alveolarization. The majority of these cells undergo apoptosis post-alveolarization. However, some dedifferntaite and persist in the adult lung. We utilized single cell RNA seq. to understand transcriptomics of these persisted myofibroblasts.
Project description:Cardiac fibroblasts convert to myofibroblasts with injury to mediate healing after acute myocardial infarction and to mediate long-standing fibrosis with chronic disease. Myofibroblasts remain a poorly defined cell-type in terms of their origins and functional effects in vivo. Methods: Here we generate Postn (periostin) gene-targeted mice containing a tamoxifen inducible Cre for cellular lineage tracing analysis. This Postn allele identifies essentially all myofibroblasts within the heart and multiple other tissues. Results: Lineage tracing with 4 additional Cre-expressing mouse lines shows that periostin-expressing myofibroblasts in the heart derive from tissue-resident fibroblasts of the Tcf21 lineage, but not endothelial, immune/myeloid or smooth muscle cells. Deletion of periostin+ myofibroblasts reduces collagen production and scar formation after myocardial infarction. Periostin-traced myofibroblasts also revert back to a less activated state upon injury resolution. Conclusions: Our results define the myofibroblast as a periostin-expressing cell-type necessary for adaptive healing and fibrosis in the heart, which arises from Tcf21+ tissue-resident fibroblasts. Fluidigm C1 whole genome transcriptome analysis of lineage mapped cardiac myofibroblasts
Project description:Lung myofibroblasts are necessary for early postnatal alveolar growth. The unique contributions of individual myofibroblast lineages to alveolar development is unresolved by existing genetic tools. We generated a Stc1CreERT2 mouse line that labels the developmentally transient secondary crest myofibroblasts (SCMFs), distinguishing them from alveolar duct myofibroblasts (DMF) and smooth muscle. SCMFs expand through clonal proliferation of Stc1-expressing progenitors and are cleared by apoptosis. Deleting the apoptosis effectors Bax and Bak1 in the Stc1-lineage prevented SCMF clearance during alveologenesis. Single-cell RNA sequencing showed that surviving Stc1-lineage cells lose myofibroblast identity while coexpressing SCMF and DMF markers. Embryonic lineage tracing identified distinct progenitors for SCMFs and DMFs, and genetic activation of Hedgehog (Hh) or Wnt signaling pathways failed to interconvert these lineages. These findings establish Stc1-lineage SCMFs as a discrete, developmentally divergent population, and define their life cycle independent of other myofibroblast lineages.
Project description:Alveolarization ensures sufficient lung surface area for gas exchange, and during bulk alveolarization in mice (postnatal day [P] 4.5-14.5), alpha-smooth muscle actin (SMA)+ myofibroblasts accumulate, secrete elastin, and lay down alveolar septum. Herein, we delineate the dynamics of the lineage of early postnatal SMA+ myofibroblasts during and after bulk alveolarization and in response to lung injury. SMA+ lung myofibroblasts first appear at ∼ P2.5 and proliferate robustly. Lineage tracing shows that, at P14.5 and over the next few days, the vast majority of SMA+ myofibroblasts downregulate smooth muscle cell markers and undergo apoptosis. Of note, ∼8% of these dedifferentiated cells and another ∼1% of SMA+ myofibroblasts persist to adulthood. Single cell RNA sequencing analysis of the persistent SMA- cells and SMA+ myofibroblasts in the adult lung reveals distinct gene expression profiles. For instance, dedifferentiated SMA- cells exhibit higher levels of tissue remodeling genes. Most interestingly, these dedifferentiated early postnatal myofibroblasts re-express SMA upon exposure of the adult lung to hypoxia or the pro-fibrotic drug bleomycin. However, unlike during alveolarization, these cells that re-express SMA do not proliferate with hypoxia. In sum, dedifferentiated early postnatal myofibroblasts are a previously undescribed cell type in the adult lung and redifferentiate in response to injury.
Project description:VSMCs expressing SCA1 have increased proliferative capacity (Dobnikar et al, 2018; Worssam et al, 2022; Pan et al, 2020). We therefore, mapped chromatin accessibility changes using bulk ATAC-seq for SCA1+ and SCA1- lineage traced VSMCs.
Project description:Stem cells are defined by two cardinal properties: limitless self-renewal and multipotency. We have serendipitously found that non-haematopoietic DNGR-1 lineage traced cells residing in the ependymal cell layer of the central nervous system display the two cardinal properties of stem cells, both in vitro and in vivo. However, whether these properties were a feature of all DNGR-1-traced cells or were confined to a particular subset of these is unclear. To address the potential heterogeneity of DNGR-1-traced ependymal cells and caractherise their putative stem cell compartment we conducted single-cell RNA sequencing of DNGR-1-traced cells isolated from uninjured spinal cords.
Project description:Using CD133 as a pan-ependymal cell marker, we wished to understand whether CD133+ DNGR-1 traced cells constituted a distinct subset of ependymal cells by comparing these at the single cell level with CD133+ non-traced cells purified from spinal cords of DNGR-1 lineage tracer mice.
Project description:Cardiac fibroblasts convert to myofibroblasts with injury to mediate healing after acute myocardial infarction and to mediate long-standing fibrosis with chronic disease. Myofibroblasts remain a poorly defined cell-type in terms of their origins and functional effects in vivo. Methods: Here we generate Postn (periostin) gene-targeted mice containing a tamoxifen inducible Cre for cellular lineage tracing analysis. This Postn allele identifies essentially all myofibroblasts within the heart and multiple other tissues. Results: Lineage tracing with 4 additional Cre-expressing mouse lines shows that periostin-expressing myofibroblasts in the heart derive from tissue-resident fibroblasts of the Tcf21 lineage, but not endothelial, immune/myeloid or smooth muscle cells. Deletion of periostin+ myofibroblasts reduces collagen production and scar formation after myocardial infarction. Periostin-traced myofibroblasts also revert back to a less activated state upon injury resolution. Conclusions: Our results define the myofibroblast as a periostin-expressing cell-type necessary for adaptive healing and fibrosis in the heart, which arises from Tcf21+ tissue-resident fibroblasts.