In vitro engineering of a microvascular network

Microvasculature plays a central role in the metabolism of tissues as a supplier of nutrients and oxygen, and is the loci of a number of diseases, such as inflammation and infection. In vitro, an artificial microvasculature can serve as a model to study inflammatory and angiogenic responses to physiological stimuli, and vascular dysfunction such as ischemia. The development of a microvascular network is also necessary for sustaining of other engineered tissue constructs before implantation.; This work uses the strategy of engineering biological gels (collagen type I gel in particular) and controlling localization of vascular cells at micro-meter scale to synthesize a microvascular network in vitro. As compared to existing methods of fabricating synthetic polymers or inducing self-assembly of cells in an amorphous bulk of gel, the strategy in this work combines the advantages of engineering at micro-meter scale and the innate properties of biological materials.; A number of new methods for engineering microstructures of gels have been developed: surface treatment for distortion-free separation of stamps from gels enables application of soft lithographic techniques to micro-molding of gels; enzymatic digestion of sacrificial gels allows the engineering of micro-meter scale cavities in gels; perturbant-induced gel bonding permits engineering of multi-layered structures that sustain physiological flow pressures. Finally, this work presents an in vitro microvascular network of collagen gels with human microvascular endothelial cells at the inner surfaces that mimics the geometry of an in vivo microvasculature. Future work will determine flow conditions (e.g. shear stress, transmural pressures) that enable the as-seeded construct to mature into a network that exhibits normal barrier function. We envision that this matured in vitro microvascular network can be used as a model to study inflammatory and angiogenic responses of the microvasculature.