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Updated: Oct 19, 2026

Isolation of Primary Patient-specific Aortic Smooth Muscle Cells and Semiquantitative Real-time Contraction Measurements In Vitro
08:28

Isolation of Primary Patient-specific Aortic Smooth Muscle Cells and Semiquantitative Real-time Contraction Measurements In Vitro

Published on: February 15, 2022

Vascular smooth muscle cell growth arrest on blockade of thrombospondin-1 requires p21(Cip1/WAF1)

D Chen1, K Guo, J Yang

  • 1Department of Medicine (Cardiology), St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02135, USA.

The American Journal of Physiology
|September 14, 1999
PubMed

Insights

Thrombospondin-1 (TSP1) regulates vascular smooth muscle cell (VSMC) proliferation. Blocking TSP1 with an antibody increases p21 expression, inhibiting cell growth, suggesting p21 mediates TSP1

Area of Science:

  • Vascular biology
  • Cell cycle regulation
  • Molecular mechanisms of disease

Background:

  • Vascular smooth muscle cell (VSMC) proliferation is key in atherosclerosis and restenosis.
  • Thrombospondin-1 (TSP1), an extracellular matrix protein, is implicated in VSMC mitogenesis.

Purpose of the Study:

  • To elucidate the molecular mechanisms of TSP1-mediated VSMC growth regulation.
  • To investigate the role of p21 in TSP1-dependent VSMC proliferation.

Main Methods:

  • Used neutralizing anti-TSP1 antibody (A4.1) to study VSMC proliferation.
  • Assessed cyclin-dependent kinase 2 (cdk2) activity and S-phase entry.
  • Measured p21(Cip1/WAF1) (p21) expression and its binding to cdk2.
  • Utilized p21-deficient mouse embryonic fibroblasts (MEFs) for validation.

Main Results:

  • Anti-TSP1 antibody inhibited cdk2 activity and S-phase entry in VSMCs.
  • TSP1 blockade led to increased p21 expression and its binding to cdk2.
  • Anti-TSP1 antibody reduced [(3)H]-thymidine incorporation in wild-type MEFs but not in p21-deficient MEFs.

Conclusions:

  • TSP1 blockade induces VSMC growth arrest, potentially mediated by the cyclin-dependent kinase inhibitor p21.
  • p21 plays a crucial role in TSP1-dependent control of cellular proliferation.
  • Findings offer insights into therapeutic strategies for vascular proliferative diseases.

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