2010 CBIS Seed Grant Recipients
Colin Carpenter, PhD
Radiation Oncology
Project: Tri-modality Molecular Surgical Guidance Integrated into a Laparoscope
Summary
In this seed grant, we will build an intra-operative laparoscope that is sensitive to multiple contrast mechanisms that are currently used in the clinic, such as optical and radio-emission probes, as well as a newly developed imaging modality, X-ray luminescence imaging. The end-result of this 1-year project will be:
- the fabrication of a custom laparoscope
- the characterization of this system
- initial proof-of-principle animal studies to demonstrate its potential for surgical guidance.
Mark Cutkosky, PhD
Mechanical Engineering
Project: Development and testing of tools with opto-thermal actuation for MRI-guided interventions
Michael Hsieh, MD, PhD
Urology
Project: Single Cell Magnetic Resonance Imaging of Infections Using Bacterial Magnetite
Summary
The aims of this study are to: optimize the magnetotactic properties of uropathogenic bacteria, analyze the temporal and spatial kinetics of intracellular bacterial community (IBC) formation in the bladder and during ascending infection, and define how biofilm-related genes modulate IBC formation at the single cell level.
Figure 1. Intracellular bacterial community formation by uropathogenic E. coli. Adapted from Rosen et al.
Figure 2. MR detection of single micron-sized iron oxide particle (MPIO)-labeled MDA-MB-231BR/EGFP (human breast carcinoma) cells at day 0. In vivo (100 × 100 × 200 
m3) MRI of mouse brain demonstrates the presence of discrete signal voids (black arrow) throughout the brain of a mouse injected with 30,000 MPIO-labeled MDA-MB-231BR/EGFP cells. Adapted from Heyn et al.
Figure 3. AMB-1, a magnetotactic bacterium, produces positive contrast in tumor xenografts following systemic delivery. T1-weighted, axial-slice magnetic resonance images of a mouse tumor before injection (A) as well as 2 (B) and 6 d post injection (C, through tail vein with 1 × 109 AMB-1 suspended in 100 μL Magnetospirillum growth medium). The color column shows normalized signal intensity within the gradient maps. Adapted from Benoit et al.
Anita Koshy, MD
Internal Medicine
Project: Using imaging to determine how and why Toxiplasma gondii injects rhoptry proteins it does not invade
Summary
The overall goal of my research is to better understand the interaction between Toxoplasma gondii, an obligate intracellular parasite, and parenchymal cells of the central nervous system where it establishes a latent infection. This is of great interest as such infection has the remarkable ability to avoid immune clearance (infections in humans are typically life-long) and because of data indicating effects of chronic infection on the behavior of rodents. I recently discovered that Toxoplasma injects a Cre-recombinase fusion protein both into cells it invades and some it does not. This suggests that the parasite can commandeer an even larger number of cells than just the ones it infects, perhaps to facilitate its persistence and effects on behavior. The objects of this seed grant will be to use multiple imaging modes to confirm that uninfected cells are injected both in vitro and in vivo, and then to understand at a molecular level what effect this has on the infected animal.
Uninfected host cells show evidence of secretion of Toxoplasma proteins. Live Toxoplasma parasites that carry an enzyme (β-lactamase) fused to a Toxoplasma protein are allowed to contact and invade host cells for 2 hours. The host cells are then loaded with a substrate that fluoresces green if it is not cleaved by β-lactamase or blue if it is. Thus, one can distinguish uninfected cells (green), infected cells (blue with a pink parasite in it), or injected but uninfected cells (blue without a parasite in the cells). The red highlighted square shows an uninfected, injected cell.
Michael Lin, MD, PhD
Pediatrics and BioEngineering
Project: Chemistry-based engineering of autocatalytic fluorescent proteins for whole-animal imaging in the optical window
Summary
Our long-term goal is to develop FPs (FPs) that allow imaging in whole mice with high sensitivity. The most suitable region of the optical spectrum for whole animal imaging is the “optical window” from 600 to 1000nm, where tissue is most transparent to light. We propose to tune fluorescent proteins for improved excitation in the optical window with the following objectives: (1) To improve FPs for enhanced detection in the optical window by optimizing chromophore interactions known to influence wavelength tuning, and (2) To engineer substantially wavelength-shifted FPs for whole animal imaging by chemistry-based design of novel genetically encoded chromophore structures.
