Novel biofabrication technologies to recapitulate in vivo geometries in collagen hydrogels.

摘要

Tissue engineering and regenerative medicine aims to restore form and function to tissues that have been lost or damaged due to disease, congenital defect, or trauma. Biomaterials suitable to restore these complex tissues need to provide a balance between chemical and mechanical properties, providing accurate cell-matrix interaction and induce in vivo behaviors such as proliferation, differentiation and migration. It also requires that physical and chemical cues be presented to the body in the proper temporal and spatial pattern. The extracellular matrix exerts forces that are transmitted through focal adhesion causing changes in the cell behavior. The hypothesis for this dissertation work was that by using the ideal substrate composition, the geometrical features and the proper elasticity of the substrate, we can recapitulate the microenviroments of the in vivo niche and control cell behavior.;The self renewal capabilities of muscle stem cells, satellite cells, are lost once they are culture in a rigid environment where they commit to become skeletal myocytes. In our studies, we tuned the elasticity of a collagen hydrogel to their in vivo elastic modulus and we maintain the quiescence phenotype. We developed reaction electrospinning, which is a technique that combines two processes: electrospinning and fibrillogenesis. For the first time in literature, we show that as we spin collagen monomers and microfibrils using benign solvents, they undergo fibrillogenesis resulting in fibrous collagen scaffolds. Also, we developed a sacrificial material, BSA rubber, which can deliver specific geometrical templates to a collagen material, recapitulating the internal three-dimensional architectures. Our prototype consist of a 3D branched architecture using type I collagen.;Overall, we developed fabrication techniques that allow us to tune the elasticity of the matrix, create fibrous scaffolds, and incorporate the geometrical features into an in vitro collagen scaffold. These techniques combine state of the art imaging, micromachining and selective enzymatic activity to create three dimensional biomaterials. The overall goal of this work is to fabricate custom made tissue scaffolds that replicate in vivo tissue composition, architecture, and cell population for broad application in tissue engineering. These new biomaterials will enable the modulation of cell potential, and thus, accelerate discovery in the field of regenerative medicine.