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Cellular mechanisms of oligoclonal vascular smooth muscle cell expansion in cardiovascular disease.

Published version
Peer-reviewed

Type

Article

Change log

Authors

Worssam, Matt D 
Taylor, James Ck 
Taylor, Annabel L 

Abstract

AIMS: Quiescent, differentiated adult vascular smooth muscle cells (VSMCs) can be induced to proliferate and switch phenotype. Such plasticity underlies blood vessel homeostasis and contributes to vascular disease development. Oligoclonal VSMC contribution is a hallmark of end-stage vascular disease. Here we aim to understand cellular mechanisms underpinning generation of this VSMC oligoclonality. METHODS AND RESULTS: We investigate the dynamics of VSMC clone formation using confocal microscopy and single cell transcriptomics in VSMC-lineage-traced animal models. We find that activation of medial VSMC proliferation occurs at low frequency after vascular injury and that only a subset of expanding clones migrate, which together drives formation of oligoclonal neointimal lesions. VSMC contribution in small atherosclerotic lesions is typically from one or two clones, similar to observations in mature lesions. Low frequency (<0.1%) of clonal VSMC proliferation is also observed in vitro. Single-cell RNA-sequencing revealed progressive cell state changes across a contiguous VSMC population at onset of injury-induced proliferation. Proliferating VSMCs mapped selectively to one of two distinct trajectories and were associated with cells showing extensive phenotypic switching. A proliferation-associated transitory state shared pronounced similarities with atypical SCA1+ VSMCs from uninjured mouse arteries and VSMCs in healthy human aorta. We show functionally that clonal expansion of SCA1+ VSMCs from healthy arteries occurs at higher rate and frequency compared to SCA1- cells. CONCLUSION: Our data suggest that activation of proliferation at low frequency is a general, cell-intrinsic feature of VSMCs. We show that rare VSMCs in healthy arteries display VSMC phenotypic switching akin to that observed in pathological vessel remodelling and that this is a conserved feature of mouse and human healthy arteries. The increased proliferation of modulated VSMCs from healthy arteries suggests that these cells respond more readily to disease-inducing cues and could drive oligoclonal VSMC expansion.

Description

Keywords

Vascular smooth muscle cells, Lineage tracing, Single-cell transcriptomics, Clonal dynamics

Journal Title

Cardiovasc Res

Conference Name

Journal ISSN

0008-6363
1755-3245

Volume Title

Publisher

Oxford University Press (OUP)
Sponsorship
British Heart Foundation (CH/2000003)
British Heart Foundation (CH/2000003/12800)
British Heart Foundation (FS/19/54/34889B)
British Heart Foundation (PG/19/6/34153)
British Heart Foundation (FS/15/38/31516)
British Heart Foundation (None)
British Heart Foundation (RE/18/1/34212)
Wellcome Trust (208363/Z/17/Z)