Premium
Rapid Increases in Fluid Shear Stress Elicit Local Lamellipodia and Elevate Microvascular Endothelial Barrier Function
Author(s) -
Spampinato Sara G,
Breslin Jerome W
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.950.2
Subject(s) - shear stress , barrier function , lamellipodium , biophysics , piezo1 , endothelial stem cell , endothelium , chemistry , shear (geology) , materials science , cell , microbiology and biotechnology , ion channel , cell migration , mechanosensitive channels , composite material , medicine , biology , biochemistry , in vitro , receptor
The microvascular endothelium serves as a barrier that controls exchange of fluid and solutes between the blood and tissues. This semipermeable barrier reacts to changes in frictional shear stress from the plasma as it flows over the luminal surfaces of endothelial cells. We tested the hypothesis that step increases in shear stress strengthen endothelial barrier function, due to spreading of endothelial cell membrane near junctions. We also tested the role of the shear stress‐sensing calcium channel Piezo1 in both baseline and mediating shear‐dependent changes in barrier function. An electrical cell substrate impedance sensor (ECIS) was used to determine the barrier function of cultured human cardiac microvascular endothelial cell (HCMEC) monolayers, with transendothelial electrical resistance (TER) serving as an index of barrier integrity. Shear stress was stepped from either 0 or 1 dynes/cm 2 up to 10 dynes/cm 2 using a computer‐controlled peristaltic pump system. Time‐lapse microscopic images of confluent HCMEC monolayers were obtained to observe junctions and spreading behavior of cells. The number of local lamellipodia per 100 microns of junctional distance over time, before and after step increases in shear stress, was quantified. The Piezo1 inhibitor, GSMTx4 was applied at 1.25 mM for at least 30 min under no‐flow conditions prior to testing step increases in shear stress. The results show that step increases in shear stress cause an increase in TER, that correlates with a robust increase in local lamellipodia. GSMTx4 caused a significant decrease in TER within the first few minutes of application. Step increases in shear stress applied after GSMTx4 still caused increases in TER, but usually not up to the level observed prior to GSMTx4 treatment. Combined, the data shows that rapid changes in fluid shear stress elicit a quick rise in the number of local lamellipodia that protrude from endothelial cells, that appear to tighten the junctions between cultured endothelial cells. The results also suggest that the Piezo1 channel has a role in maintaining basal barrier function of endothelial cells. However, endothelial cells can still enhance their barrier function when Piezo1 is blocked using GSMTx4. Because a compromised endothelial barrier is common in many diseases and after injury, our future goal will be to identify mechanisms that promote local lamellipodia as potential therapeutic targets. Support or Funding Information Supported by NIH Grant R01HL098215‐S1