Collagen Fibril Orientation In Vitro: From Formation to Advanced Biomaterial Development

Extracellular matrix proteins have a complex assembly in tissue and it is believed that not only the chemical structure, but also their location, plays an important role in cellular functions. Collagen is one of the main components of the extracellular matrix and the oriented arrangement of collagen fibrils in tissues such as bone, cartilage, tendons, and cornea has a significant impact on various tissue functions. In the body, the orientation of extracellular matrix proteins is determined by cells. Oriented collagen fibrils can not only promote directed cell migration, but also stimulate cells to secrete an extracellular matrix with an oriented structure. However, the creation of collagen fibrils with an oriented structure in vitro is still associated with a number of limitations. Such limitations are primarily because the mechanisms regulating cellular functions in the orientation of extracellular matrix proteins, including collagen, are still unknown. Currently, only physical ways of organizing collagen fibrils in a certain direction are known. We hope that the description of the orientation of collagen fibrils in this review will allow readers to better understand the processes that occur with molecules. The study of methods and conditions for obtaining oriented collagen fibrils can help to obtain tissue biomimetic materials with complex properties identical to native tissues. Therefore, we discuss here various methods and conditions for obtaining oriented collagen fibrils in vitro using mechanical, electric, magnetic, and other fields. The prospects of application in tissue engineering and scientific problems of oriented collagen fibrils are also described.