(418h) Proteomics Analysis of Extracellular Matrix Derived from Pluripotent Stem Cell Aggregates

The characterization of proteins in the extracellular matrix of pluripotent stem cells is of value in analyzing the paracrine signaling in which the cultured cells are engaged in.  Proteomics analysis based on liquid chromatography–mass spectrometry was used to analyze the proteins secreted in the extracellular matrix by three different types of murine embryonic stem cell cultures: undifferentiated aggregates, embryoid bodies, and neural progenitor cells derived from the murine stem cells.  Undifferentiated aggregates are able to proliferate extensively and maintain the pluripotency.  Embryoid bodies are aggregate-like structures that contain the cells from three germ layers.  Neural progenitor cells were derived through the embryoid body formation treated by retinoic acid.  These different cellular systems secrete distinct composition of extracellular matrix shown in the proteomics analysis.  Data analysis was performed using Scaffold proteome software and the Ensemble database.  Data sets were filtered using gene ontology classification for cellular components based on the terms “extracellular proteins”.  Different proteins were identified in various subsets of the three groups which may be responsible for the tissue development of different cellular systems of pluripotent stem cells.  The proteomics analysis performed in this study provides the knowledge and the understanding on the differentially expressed proteins found in the extracellular matrix of pluripotent stem cells which experienced different developmental paths.