Lectin Staining of Microvascular Glycocalyx in Microfluidic Cancer Cell Extravasation Assays

The endothelial glycocalyx forms the inner-most lining of human microvasculature. It ensures the physiological function of blood vessels and plays a crucial role in the occurrence and progression of microvascular diseases. The present communication aims to highlight the usefulness of high-resolution imaging of lectin (Bandeiraea Simplicifolia) stained endothelial glycocalyx in 3-dimensional microfluidic cell cultures. The microfluidic system allowed visualizing cancer cell extravasation, which is a key event in metastasis formation in cancer pathologies. In brief, microvascular networks were created through spontaneous vasculogenesis. This occurred from 3 dimensional (3D) suspensions of human umbilical vein endothelial cells (HUVECs) in hydrogels confined within microfluidic devices. Extravasation of MDA-MB-231 breast cancer cells from perfusable endothelial lumens was observed with confocal imaging of lectin-stained microvascular networks. The present work provides guidance towards optimizing the methodology used to elucidate the role of the endothelial glycocalyx during cancer cell extravasation. In particular, a high-resolution view of the endothelial glycocalyx at the site of extravasation is presented. The occurrence of glycocalyx defects is well aligned with the contemporary notion in the field that glycocalyx shedding precedes cancer cell extravasation.