Microvascular Structure and Function in Vitro

Vascular structure — a network of convective paths — is a ubiquitous element in multicellular, living systems. The key function of vascular structure in animals and plants is mediation of convective mass transfer over macroscopic distances; this transfer allows an organism to monitor and control the chemical state of its tissues. In our laboratory, we are developing methods to embed and operate microfluidic systems within tissue-like materials in order to capture this function for both biological and non-biological applications. I will present two examples to illustrate our efforts: 1) Capillary beds for the culture of mammalian cells in three-dimensions. In this section, I will discuss the development of methods both to fabricate synthetic capillary beds and to grow them directly out of endothelial cells. I will highlight how simple ideas from continuum mechanics and material science have guided our efforts. 2) Synthetic xylem networks that allow for the transpiration of water at large negative pressures. I will point out the unusual thermodynamic and transport phenomena that are involved in the transpiration process in plants. I will then present our perspectives on the design criteria for systems — synthetic and biological — that mediate this process. Finally, I will describe our experiments with “synthetic trees” in which we have reproduced the main features of transpiration. I will conclude with perspectives on applications and generalizations of both these classes of vascularized materials.