2.24 Hydrogels of decellularized matrix

The extracellular matrix (ECM) is a highly complex mixture of structural and functional proteins and other biomolecules. The ECM provides tissue-specific molecular and mechanical cues that contribute to the maintenance of cellular homeostasis, promote optimal tissue function and if required, mediate wound healing and tissue repair. ECM bioscaffolds prepared from decellularized tissues have been used to facilitate constructive and functional tissue remodeling in a variety of clinical applications. The discovery that these ECM materials could be solubilized and subsequently manipulated to form hydrogels expanded their potential in vitro and in vivo utility; ie, as in vitro culture substrates and as injectable materials that fill irregularly-shaped defects. The mechanisms by which ECM hydrogels direct cell behavior and influence remodeling outcomes are only partially understood, but likely include structural and biological signals retained from the native source tissue. This article describes the utility, formation, and physical and biological characterization of ECM hydrogels. Recent applications of ECM hydrogels in the gastrointestinal tract are presented to demonstrate in vivo utility of ECM hydrogels. Finally, new research directions of ECM hydrogels are discussed.