ABSTRACT
The extracellular matrix (ECM) is a complex mixture of structural and functional proteins, glycoproteins, and proteoglycans arranged in a unique, tissue specific three-dimensional ultrastructure. The structure and the composition of the ECM are both a product of the cells that populate the matrix and a determining factor in the phenotype of these cells. A “dynamic reciprocity” exists between the cells and the ECM that is in part dependent upon the local environment of each tissue. 1-3 Age, mechanical loading and microenvironment are all factors that can affect the ligands that reside within the ECM and in turn affect behavior of the resident cell population including gene expression. The resultant three dimensional ultrastructure of each tissue ECM is, therefore, likely distinctive and specific. The ECM that surrounds undifferentiated progenitor cell populations is poorly understood and existing knowledge is largely an extension of what has been learned from in vitro studies and the reported effects of selected growth substrates upon embryonic stem cell (ESC) differentiation patterns. The present chapter will briefly review the composition and function of the ECM that surrounds mature cells and organs, developing embryonic cells, and the relationship of selected ECM components to the growth and differentiation of such embryonic stem cells.
