Understanding the extracellular matrix

Tissue engineering deals with the growth and regeneration techniques of connective tissues or organs from a combination of cells and a scaffold to produce a functional organ. The engineering techniques therefore begin with an implantation of artificial materials, providing a proper environment for cells or tissues to be grown and functionalized. The scaffolds are often formulated with biodegradable polymer, extracellular matrix, and growth factors, serving as a skeleton to be filled up with cells, and eventually grow into three-dimensional tissues. With the importance of the intercellular connection in the field of tissue engineering, considerable efforts have been made to design an artificial extracellular matrix in vitro: to achieve a three-dimensional network in its architecture and effective ingredients for its chemical composition. Another important aspect, however, that I would like to emphasize, is understanding how sophisticated the interaction is between the extracellular matrix network and cyto-skeletal networks in cells. The cytoskeletal network in most eukaryotic cells is a combination of polymeric networks made of actin filaments, microtubules, and intermediate filaments. These networks play an essential role in determining not only the shape and mechanics of a cell, but more importantly, cell motility. In particular, an orchestrated movement of cells in particular directions to specific locations is essentially required during any tissue development in nature. These cellular migrations are often explained by a cytoskel-etal model; the spontaneous cycling of polymerization and depolymerization of cytoskel-etal filaments leads the cellular motility at the cell's front, where a tight interface with the extracellular network occurs. The concept of symmetry breaking is helpful for understanding the cytoskeletal mech