National Synchrotron Light Source Lunch Time Seminar

Nature places structural material in the path of high loads where it persists. Indeed, multicelled plants and animals must resist dissipation at multiple scales to survive. However, it is not yet clear precisely how highly-organized, load-bearing structures are produced in biological systems. Traditionally, control of fibrillar organization has been attributed to cells, which are thought to directly place components in the extracellular matrix. However, we have developed a working hypothesis which suggests that nature has evolved a set of structural molecules whose interaction profoundly simplifies the production of anisotropic materials (suitable for load-bearing). Among these, collagen, defined most simply as Gly-X-Y, is the structural molecule of choice and most abundant protein in vertebrates, comprising 25% of total body protein. Collagen arose approximately 700 MYA and appears to have played a major role both in metazoan radiation and evolutionary success. Fibrillar collagens can be found in arteries, bone, ligament, tendon, skin, cornea, anulus fibrosus and cartilage. It seems that wherever there are difficult mechanical design criteria, collagen is employed. Our laboratory has been compiling evidence which suggests that fibrillar collagen (and other associated ECM moieties) comprise the basis of a smart, adaptable structural system. We are currently developing a “smart matrix theory” which posits that the development and growth of collagenous matrix proceeds by three mechanisms: 1) spontaneous formation of highly-organized tissue rudiments from concentrated solutions (~50-400 mg/ml) of collagen monomers, 2) strain-driven load-adaptation of the rudiments and 3) strain-driven growth of the rudiments through preferential polymerization.