Biomimetic, ultrathin and elastic hydrogels regulate human neutrophil extravasation across endothelial-pericyte bilayers

PLoS One. 2017 Feb 24;12(2):e0171386. doi: 10.1371/journal.pone.0171386. eCollection 2017.

Abstract

The vascular basement membrane-a thin, elastic layer of extracellular matrix separating and encasing vascular cells-provides biological and mechanical cues to endothelial cells, pericytes, and migrating leukocytes. In contrast, experimental scaffolds typically used to replicate basement membranes are stiff and bio-inert. Here, we present thin, porated polyethylene glycol hydrogels to replicate human vascular basement membranes. Like commercial transwells, our hydrogels are approximately 10μm thick, but like basement membranes, the hydrogels presented here are elastic (E: 50-80kPa) and contain a dense network of small pores. Moreover, the inclusion of bioactive domains introduces receptor-mediated biochemical signaling. We compare elastic hydrogels to common culture substrates (E: >2GPa) for human endothelial cell and pericyte monolayers and bilayers to replicate postcapillary venules in vitro. Our data demonstrate that substrate elasticity facilitates differences in vascular phenotype, supporting expression of vascular markers that are increasingly replicative of venules. Endothelial cells differentially express vascular markers, like EphB4, and leukocyte adhesion molecules, such as ICAM-1, with decreased mechanical stiffness. With porated PEG hydrogels we demonstrate the ability to evaluate and observe leukocyte recruitment across endothelial cell and pericyte monolayers and bilayers, reporting that basement membrane scaffolds can significantly alter the rate of vascular migration in experimental systems. Overall, this study demonstrates the creation and utility of a new and accessible method to recapture the mechanical and biological complexity of human basement membranes in vitro.

MeSH terms

  • Basement Membrane / chemistry*
  • Basement Membrane / metabolism
  • Basement Membrane / ultrastructure
  • Biomarkers / metabolism
  • Biomimetic Materials / chemistry
  • Biomimetic Materials / metabolism
  • Cell Movement
  • Elastic Modulus
  • Elasticity
  • Endothelial Cells / cytology*
  • Endothelial Cells / metabolism
  • Extracellular Matrix / chemistry
  • Extracellular Matrix / metabolism
  • Gene Expression
  • Humans
  • Hydrogels / chemistry
  • Hydrogels / metabolism
  • Intercellular Adhesion Molecule-1 / genetics
  • Intercellular Adhesion Molecule-1 / metabolism
  • Neutrophils / cytology*
  • Neutrophils / metabolism
  • Pericytes / cytology*
  • Pericytes / metabolism
  • Polyethylene Glycols / chemistry
  • Porosity
  • Primary Cell Culture
  • Receptor, EphB4 / genetics
  • Receptor, EphB4 / metabolism
  • Signal Transduction
  • Tissue Engineering / methods*

Substances

  • Biomarkers
  • Hydrogels
  • ICAM1 protein, human
  • Intercellular Adhesion Molecule-1
  • Polyethylene Glycols
  • Receptor, EphB4