<P> In terms of injury repair and tissue engineering, the extracellular matrix serves two main purposes . First, it prevents the immune system from triggering from the injury and responding with inflammation and scar tissue . Next, it facilitates the surrounding cells to repair the tissue instead of forming scar tissue . </P> <P> For medical applications, the ECM required is usually extracted from pig bladders, an easily accessible and relatively unused source . It is currently being used regularly to treat ulcers by closing the hole in the tissue that lines the stomach, but further research is currently being done by many universities as well as the U.S. Government for wounded soldier applications . As of early 2007, testing was being carried out on a military base in Texas . Scientists are using a powdered form on Iraq War veterans whose hands were damaged in the war . </P> <P> Not all ECM devices come from the bladder . Extracellular matrix coming from pig small intestine submucosa are being used to repair "atrial septal defects" (ASD), "patent foramen ovale" (PFO) and inguinal hernia . After one year 95% of the collagen ECM in these patches is replaced by the normal soft tissue of the heart . </P> <P> Extracellular matrix proteins are commonly used in cell culture systems to maintain stem and precursor cells in an undifferentiated state during cell culture and function to induce differentiation of epithelial, endothelial and smooth muscle cells in vitro . Extracellular matrix proteins can also be used to support 3D cell culture in vitro for modelling tumor development . </P>

Cell that secretes protein components of extracellular fibers