Molecular imaging aims at following molecules of medical interest in living patients or tissue. Those molecules can be either naturally found in organisms or be synthetic ones directly injected in patients. The great advantage of molecular imaging is the possibility to noninvasively monitor biochemical processes in patients or other live organisms.
For optical applications, various methods can be used based on absorption and fluorescent or bioluminescent biomarkers. For instance, fluorescent probes based on near-infrared fluorophores have been widely used in near-infrared imaging of cancer tissue.
Multiple applications of molecular imaging techniques have been developed for medicine or research purposes:
iUPS nanoprobes target both acidic pH and tumor vasculature with broad tumor specificity. Intravital fluorescent images show complementary pattern of spatial activation of cRGD-UPSi-RhoG (green) and UPSe-TMR (red) inside tumor vasculature and parenchyma, respectively. From A nanoparticle-based strategy for the imaging of a broad range of tumours by nonlinear amplification of microenvironment signals, Nat Mater, 2014
Reporter gene imaging of CSCs (Cardiac Stem Cells) fate after transplantation
(A) A representative animal injected with 5×105 CSCs shows significant bioluminescence activity at day 2, which decreases progressively over the following 8 weeks. (B) Detailed quantitative analysis of signals from all animals transplanted with CSCs. Signal activity is expressed as photons/sec/cm2/sr. (C) Estimation of percent donor cell survival plotted as % signal activity (normalized to day 2) over the 8 week period following transplantation.
From Imaging Survival and Function of Transplanted Cardiac Resident Stem Cells, J Am Coll Cardiol. 2009
Generation of stable GFP-LC3 expressing HCC cell line.
(A, C) Highly metastatic HCCLM3 cell line stably expressing GFP-LC3 reporter gene (HCCLM3-GFP-LC3) was generated via lentivirus-mediated GFP-LC3 overexpression. The HCCLM3-GFP-LC3 cells exhibited a large number of GFP-LC3 dots after rapamycin treatment (+Rapa). (B, C) HCCLM3 stably expressing GFP (HCCLM3-GFP) served as Control. The HCCLM3-GFP cells displayed no GFP-LC3 dots after rapamycin treatment (+Rapa). (D) Western blot analysis of LC3 showed that rapamycin induced intense autophagy in both HCCLM3-GFP-LC3 and HCCLM3-GFP.
From Promoting Colonization in Metastatic HCC Cells by Modulation of Autophagy, Plos One, 2013
Generation of stable GFP
Example of a reporter gene assay using the GFP to describe hydrophobic interactions required for P-granule integrity in c. elegans. (A) Top, dissected GLH-1::GFP gonads exposed to hexanediol (HD), hexanetriol (HT), or egg buffer (Control).
From P granules extend the nuclear pore complex environment in the C. elegans germ line, J Cell Biol, 2011.