Proteomic Analysis of the Pericyte Derived Extracellular Matrix

Pericytes (PC) line the post capillary venules and deposit extracellular matrix (ECM) proteins that provide vascular integrity during angiogenesis and regulatory signals during inflammation. Here we describe the characterization of soluble and structural ECM proteins that are deposited by PC. ECM components in PC-derived ECM were qualitatively and quantitatively analyzed via liquid chromatography/tandem mass spectrometry LC/MS-MS, while Western blot analysis was used to confirm the presence of commonly investigated matrix proteins. Functional annotation was used to categorize specific types of proteins, including structural collagens, glycoproteins, proteoglycans, ancillary angiogenic and inflammatory proteins. Further, the functional ability of PC derived ECM to support endothelial cell tubule formation, neutrophil adhesion, polarization and chemotaxis were evaluated. Our findings indicate that PC ECM is compositionally distinct to smooth muscle cell (SMC) ECM, and functionally supports vasculogenesis and neutrophil adhesion as well as SMC ECM. While differences in neutrophil polarization and cell ruffling were seen between PC ECM and SMC ECM adherent neutrophils, no difference in migratory velocities were observed. This first characterization of PC derived ECM provides insight into its potential use as a component of implantable engineered scaffolds and for investigations of basic cellular response to the microvascular basement membrane.