Smooth muscle cells orchestrate the endothelial cell response to flow and injury
Author
Balcells Camps, Mercedes
Martorell López, Jordi
Olivé, Carla
Santacana, Marina
Chitalia, Vipul C.
Cardoso, Angelo A.
Edelman, Elazer R.
Other authors
Universitat Ramon Llull. IQS
Publication date
2010-05Abstract
Background—Local modulation of vascular mammalian target of rapamycin (mTOR) signaling reduces smooth muscle cell (SMC) proliferation after endovascular interventions but may be associated with endothelial cell (EC) toxicity. The trilaminate vascular architecture juxtaposes ECs and SMCs to enable complex paracrine coregulation but shields SMCs from flow. We hypothesized that flow differentially affects mTOR signaling in ECs and SMCs and that SMCs regulate mTOR in ECs.
Methods and Results—SMCs and/or ECs were exposed to coronary artery flow in a perfusion bioreactor. We demonstrated by flow cytometry, immunofluorescence, and immunoblotting that EC expression of phospho-S6 ribosomal protein (p-S6RP), a downstream target of mTOR, was doubled by flow. Conversely, S6RP in SMCs was growth factor but not flow responsive, and SMCs eliminated the flow sensitivity of ECs. Temsirolimus, a sirolimus analog, eliminated the effect of growth factor on SMCs and of flow on ECs, reducing p-S6RP below basal levels and inhibiting endothelial recovery. EC p-S6RP expression in stented porcine arteries confirmed our in vitro findings: Phosphorylation was greatest in ECs farthest from intact SMCs in metal stented arteries and altogether absent after sirolimus stent elution.
Conclusions—The mTOR pathway is activated in ECs in response to luminal flow. SMCs inhibit this flow-induced stimulation of endothelial mTOR pathway. Thus, we now define a novel external stimulus regulating phosphorylation of S6RP and another level of EC-SMC crosstalk. These interactions may explain the impact of local antiproliferative delivery that targets SMC proliferation and suggest that future stents integrate design influences on flow and drug effects on their molecular targets.
Document Type
Article
Published version
Language
English
Subject (CDU)
577 - Material bases of life. Biochemistry. Molecular biology. Biophysics
616.1 - Pathology of the circulatory system, blood vessels. Cardiovascular complaints
Keywords
Sang--Circulació
Endoteli
Biologia molecular
Músculs
Pròtesis de Stent
Blood flow
Endothelium
Mammalian target of rapamycin (mTOR)
Molecular biology
Signal transduction
Stents
Pages
8 p.
Publisher
American Heart Association
Is part of
Circulation. Vol.121, n.20 (2010), p.2192–2199
This item appears in the following Collection(s)
Rights
© American Heart Association. Tots els drets reservats