Monitoring Immune Cell Function Through Optical Imaging: a Review Highlighting Transgenic Mouse Models

Abstract

Transgenic mouse models have facilitated research of human diseases and validation of therapeutic approaches. Inclusion of optical reporter genes (fluorescent or bioluminescent genes) in the targeting vectors used to develop such models makes in vivo imaging of cellular and molecular events possible, from the microscale to the macroscale. In particular, transgenic mouse models expressing optical reporter genes allowed accurately distinguishing immune cell types from trafficking in vivo using intravital microscopy or whole-body optical imaging. Besides lineage tracing and trafficking of different subsets of immune cells, the ability to monitor the function of immune cells is of pivotal importance for investigating the effects of immunotherapies against cancer. Here, we introduce the reader to state-of-the-art approaches to develop transgenics, optical imaging techniques, and several notable examples of transgenic mouse models developed for immunology research by critically highlighting the models that allow the following of immune cell function.

Keywords: Bioluminescence; Fluorescence; Immune cells; Intravital imaging; Transgenic mouse models.

Fig. 1.

State-of-the-art technologies and approaches for development of transgenic mouse models. Constitutive knock-in mouse models are generated using a target vector carrying gene of interest into the early mouse embryonic cells. Within the mouse genome, the integration of the target vector might occur randomly or through induced homologous recombination. Conditional knock-in mouse models where expression of gene of interest occurs at a specific time or tissue are involved in the majority of cases using the Cre-loxP system. Cyclization recombinase (Cre) recognizes specific DNA recognition sites (LoxP sites) and catalyzes a site-specific recombination event between those two sites.

Fig. 2.

Different optical imaging techniques for in vivo imaging.