Identification of Extracellular Matrix Proteins Supportive of Endothelial Differentiation

Abstract

Efficient differentiation of pluripotent stem cells into endothelial cells represents one potential means of resolving vascularization issue in the field of tissue engineering. Recently, extracellular matrix proteins (ECM) have been shown potent stimulators of differentiation, including endothelial differentiation. Unclear is how the ECM can exhibit varying signaling stimuli over the course of a 14-day differentiation time scale. Here we test the possibility that an ECM deposited by cells over time could provide the temporal cues needed for endothelial differentiation. Mass spectrometry was employed as a means of measuring changes in deposition of ECM by cells and remodeling with ECM-triggered endothelial differentiation. As a start, the workflow for attaining accurate quantification was optimized. Then temporal dynamics of ECM expression were represented as a heat map and linear graphs of those ECM proteins with unique temporal shifts relative to control cultures. Collagen XVIII, Fibrilin 2, Fibulin 1, Galectin 9, Laminin subunit 5, Nidogen 2 fulfill these criteria and support the possibility that endothelial differentiation spurred by exogenously provided ECM is brought to completion by an evolving ECM composite.