Collagen, a major protein component of the ECM, provides support to tissues like skin, cartilage, bones, blood vessels and ligaments and is thus considered a model scaffold or matrix for tissue engineering due to its properties of biocompatibility, biodegradability and ability to promote cell binding. This ability allows chitosan to control distribution of cells inside the polymeric system. Thus, Type-I collagen obtained from animal tissues is now successfully being used commercially as tissue engineered biomaterial for multiple applications. Collagen has also been used in nerve repair and bladder engineering.  Immunogenicity has limited the applications of collagen. Gelatin has been considered as an alternative for that reason.