Microfabrication of Physiologically Representative Blood Vessels into Hydrogels

Abstract

The microcirculation is a dynamic and significant component of the peripheral human circulatory system. It is comprised of an extensive network of sub millimetre blood vessels: arterioles, capillaries, and venules. The cells and structures of the microcirculation are responsible for a number of essential functions, such as convective mass transport, gaseous exchange for tissues, biochemical signalling, nutrient transport, immune response, and even assisting in the regulation of blood pressure and temperature. Due to the important functions of the microvasculature, its dysfunction can result in a multitude of pathologies such as arteriosclerosis, atherosclerosis and fibromusclular displasia, which may lead to stroke, aneurysms and vasculitis, to name a few. Many researchers have developed theoretical models and developed experimental platforms to study the microcirculation, in particular its roles in disease and health. Better methods to construct in vitro microenvironments, which are better representations of the in vivo microenvironment, are important to cell culture studies, in particular studies into the cells which reside and pass thorugh the microvasculature In this thesis, a novel protocol is presented to fabricate physiologically representative microcirculatory networks within collagen hydrogel and Histogel scaffolding for use in perfusion based cell culture studies of the microvasculature. Specifically laser and soft-lithography fabrication techniques were developed to pattern and assemble microfluidic channels with approximately circular and semicircular profiles into both collagen hydrogels and Histogel hydrogels. In addition, the ability to align separately micromolded hydrogels using a custom fabricated flow chamber and a novel semi-automatic alignment technique is demonstrated. Perfusion of the microfluidic network was demonstrated; further refinements to this protocol would enable application in more advanced cell culture studies. The alignment technique developed is believed to have far reaching applications in applications requiring semi-automatic alignment of multiple functional layers.