Figure 1.

The need for more relevant in vitro models. Traditional tools for biological study fall on a spectrum of increasing physiological relevance. At one end of the spectrum, traditional in vitro systems, such as 2D or 3D cell culture, are low cost, high-throughput, and enable researchers to isolate specific interactions. At the other end of the spectrum, in vivo mouse models offer greater physiological relevance but can be time consuming and costly, and it is more difficult to isolate specific interactions. There is a need for engineered in vitro tissue models with increased physiological relevance to complement and bridge the gap between these systems. Bottom inset: volume-rendered image showing a HUVEC-lined lumen through a collagen I hydrogel in the center channel of a microfluidic device with 2 medium reservoirs on either side. Cells are stained for CD31 (green) and nuclei (red). Scale bar = 100 μm.