# PDGFbeta Receptor Activation Promotes Atheroprotective Changes in SMC Phenotype

> **NIH NIH R01** · UNIVERSITY OF VIRGINIA · 2020 · $652,024

## Abstract

Atherosclerosis is a progressive disease that is a leading cause of death in the Western world. Remarkably,
despite decades of research, there remain major ambiguities regarding the role of smooth muscle cells (SMC)
in lesion pathogenesis, as well as mechanisms that control plaque stability and the probability of plaque rupture
with possible myocardial infarction (MI) or stroke. The general dogma is that SMC are primarily involved in late
not early stage lesions, and that their primary role is atheroprotective by contributing to formation of a fibrous
cap. However, recent Nature Medicine studies by our lab involving simultaneous SMC-specific lineage tracing
and knockout (KO) of the stem cell pluripotency genes, Oct4 or Klf4 provided compelling evidence that SMC
play a much greater role in lesion pathogenesis than has been generally appreciated. Key findings include our
showing that: 1) >80% of SMC-derived cells within advanced lesions of ApoE-/- mice lack detectable expression
of typical SMC markers; 2) 30-40% of SMC-derived cells within both advanced mouse and human lesions lack
detectable SMC markers and have activated markers of MФs; and 3) SMC can have major beneficial or
detrimental effects on lesion pathogenesis depending on the nature of their phenotypic transitions. Thus, there is
a critical need to identify factors and mechanisms that promote beneficial changes in SMC phenotype. Studies in this
proposal will test the overall hypothesis that PDGFβR-dependent changes in SMC phenotype are atheroprotective and
that augmentation of the PDGFβR signaling pathway should be one of the primary therapeutic targets for treating
advanced atherosclerosis. This hypothesis will be tested in two specific aims. Aim 1 will test the hypothesis that PDGFβR-
dependent transitions in SMC phenotypic play a critical role in the development and progression of atherosclerosis. Aim
1a will extend our initial studies showing that SMC specific conditional PDGFβR KO at 6-8 weeks of age followed by 18
weeks of Western diet (WD) resulted in BCA lesions that were larger but virtually lacking SMC to include rigorous analysis
of indices of plaque stability and mechanisms for reductions in SMC number within lesions. Aim 1b will test the hypothesis
that SMC-specific conditional KO of PDGFβR results in detrimental transitions in SMC phenotype including increased
numbers of SMC-derived Lgals3+ foam cells (SMC-FC) and reduced numbers of SMC derived myofibroblasts (SMC-MF)
within the fibrous cap. Aim 2 will test the hypothesis that PDGFβR-signaling pathways confer atheroprotective effects
within advanced atherosclerotic lesions at least in part through inducing favorable changes in SMC phenotype. Studies
will test how SMC-specific or global genetic or pharmacologic inhibition (Aims 2a-2c) or augmentation (infusion of rPDGF-
DD, Aim 2d) of PDGFβR signaling in Western diet fed ApoE-/- mice with advanced atherosclerotic lesions impacts overall
lesion pathogenesis, indices of plaque...

## Key facts

- **NIH application ID:** 9908167
- **Project number:** 5R01HL132904-04
- **Recipient organization:** UNIVERSITY OF VIRGINIA
- **Principal Investigator:** Gary K Owens
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $652,024
- **Award type:** 5
- **Project period:** 2017-04-01 → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9908167

## Citation

> US National Institutes of Health, RePORTER application 9908167, PDGFbeta Receptor Activation Promotes Atheroprotective Changes in SMC Phenotype (5R01HL132904-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9908167. Licensed CC0.

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