Microrheology and ROCK Signaling of Human Endothelial Cells Embedded in a 3D Matrix

• Published in: Biophysical journal 2006-11, Vol.91 (9), p.3499-3507
• Main Authors: Panorchan, Porntula, Lee, Jerry S.H., Kole, Thomas P., Tseng, Yiider, Wirtz, Denis
• Format: Article
• Language: English
• Subjects: Biophysics; Cell Biophysics; Cell Culture Techniques - methods; Cells; Cells, Cultured; Cellular biology; Elasticity; Endothelial Cells - cytology; Endothelial Cells - drug effects; Endothelial Cells - physiology; Extracellular Matrix - drug effects; Extracellular Matrix - physiology; Humans; Intracellular Signaling Peptides and Proteins - metabolism; Mechanical properties; Microfluidics - methods; Nanoparticles; Protein-Serine-Threonine Kinases - metabolism; Rheology; rho-Associated Kinases; Signal Transduction - drug effects; Signal Transduction - physiology; Stress, Mechanical; Vascular Endothelial Growth Factor A - pharmacology
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1529/biophysj.106.084988

Cell function is profoundly affected by the geometry of the extracellular environment confining the cell. Whether and how cells plated on a two-dimensional matrix or embedded in a three-dimensional (3D) matrix mechanically sense the dimensionality of their environment is mostly unknown, partly because individual cells in an extended matrix are inaccessible to conventional cell-mechanics probes. Here we develop a functional assay based on multiple particle tracking microrheology coupled with ballistic injection of nanoparticles to measure the local intracellular micromechanical properties of individual cells embedded inside a matrix. With our novel assay, we probe the mechanical properties of the cytoplasm of individual human umbilical vein endothelial cells (HUVECs) embedded in a 3D peptide hydrogel in the presence or absence of vascular endothelial growth factor (VEGF). We found that VEGF treatment, which enhances endothelial migration, increases the compliance and reduces the elasticity of the cytoplasm of HUVECs in a matrix. This VEGF-induced softening response of the cytoplasm is abrogated by specific Rho-kinase (ROCK) inhibition. These results establish combined particle-tracking microrheology and ballistic injection as the first method able to probe the micromechanical properties and mechanical response to agonists and/or drug treatments of individual cells inside a matrix. These results suggest that ROCK plays an essential role in the regulation of the intracellular mechanical response to VEGF of endothelial cells in a 3D matrix.