Bioluminescence imaging of hollow fibers in living animals: its application in monitoring molecular pathways.

We have applied noninvasive optical imaging technology to the in vivo hollow fiber assay, using tumor cell lines in which optical reporters are expressed in response to activation/inhibition of a specific molecular pathway. In vivo noninvasive imaging of molecular pathways in cells within hollow fibers enables a rapid and accurate evaluation of drug targets and provides useful insights to guide novel drug discovery. In this protocol we show, as an example, that a luciferase reporter, driven by the responsive element of nuclear factor NF-kappaB, was induced in cells within hollow fibers implanted in living mice, and a detailed procedure for in vivo bioluminescence imaging of hollow fibers is described. This approach can, in principle, be applied to image any molecular pathways of interest when appropriate reporter cells are generated. Hollow fiber encapsulation and implantation takes 2 d, and in vivo validation of reporter takes 1-2 weeks.