Cell-cell contacts are crucial in a myriad of biological settings including cancer progression,
embryonic development, and immune system function. Understanding such processes requires
examining cellular communication in its native context. Optical imaging tools are ideally suited
for this purpose.
The most commonly employed optical imaging technology is fluorescence. While
fluorescent tools are useful at the microscopic level, issues of autofluorescence and the
requirement for incident light limit their utility at larger length scales. This leaves a gap in our
ability to “see” at the macroscopic level.
A complementary strategy, bioluminescence, circumvents these issues allowing chemically
generated light from a luciferase enzyme to illuminate cellular movement. Bioluminescence has
been employed to monitor both intracellular and extracelluar events, from gene expression to
Despite its versatility, bioluminescence has not easily transitioned to monitoring direct cell
contacts. This is due, in part, to a lack of tools that can illuminate celllular interactions at the
microscopic level. Moreover, there are a limited number of luciferase probes useful for cell
tracking. My work was aimed at filling this gap by developing new bioluminescent tools for
studying cell populations.
To enable visualization of cell contacts, I employed a split-reporter strategy wherein the
luciferase halves were tethered to separate cells. This method enabled light emission to be linked
with the microscopic process of cell contacts. It could be used to monitor immune and cancer
cell interactions during disease progression.
To develop new cell tracking tools, I exploited an enzymatic chemical attachment method to
append bioluminescent enzymes to small molecules and proteins. Furthermore, this method was
used to directly label cell surfaces with luciferases. Such tools will facilitate the monitoring cells
recalcitrant to genetic manipulation, including stem cells and primary cells, as well as tracking
endogenous cell populations, such as metastatic tumor cells.
My work will enable the study of cellular contacts as well as non-genetically encodable cell
populations in vivo and noninvasively. Future work from our lab will use these methodologies to
further diversify bioluminescent imaging techniques and use the tools I have developed to
monitor stem cell and cancer cell migration in mouse models.