Elastic protein-based materials in tissue reconstruction.
In natural tissues, cells form multiple attachment sites to their extracellular matrix. By means of those attachments, cells deform as the tissue deforms in response to the natural mechanical stresses and strains that the tissue must sustain during function. These mechanical forces are the energy input that instruct the cells to produce the extracellular matrix sufficient to sustain those forces. Thus, an ideal artificial material should have both the attachment sites for the natural cells and a compliance that matches the natural tissue. Elastic protein-based polymers have been designed to provide both cell attachment sites and to exhibit the required elastic modulus of the tissue to be replaced. Thus, this introduces the potential to design a temporary functional scaffolding that will be remodeled, while functioning, into a natural tissue. A feasibility study applies this concept to the problem of urinary bladder reconstruction in terms of the filling and emptying of a simulated bladder comprised of an elastic protein-based matrix containing cell attachment sites with human urothelial cells growing out onto the dynamic matrix. Furthermore, the elastic protein-based materials themselves have been designed to perform the set of energy conversions that occur in living organisms and, in particular, to convert mechanical energy into chemical energy with the result of chemical signals of the sort that could provide the stimuli to turn on the genes for producing the required extracellular proteins.