BackgroundPreclinical models of pediatric cancers are essential for testing new
chemotherapeutic combinations for clinical trials. The most widely used
genetic model for preclinical testing of neuroblastoma is the TH-MYCN mouse.
This neuroblastoma-prone mouse recapitulates many of the features of human
neuroblastoma. Limitations of this model include the low frequency of bone
marrow metastasis, the lack of information on whether the gene expression
patterns in this system parallels human neuroblastomas, the relatively slow
rate of tumor formation and variability in tumor penetrance on different
genetic backgrounds. As an alternative, preclinical studies are frequently
performed using human cell lines xenografted into immunocompromised mice,
either as flank implant or orthtotopically. Drawbacks of this system include
the use of cell lines that have been in culture for years, the inappropriate
microenvironment of the flank or difficult, time consuming surgery for
orthotopic transplants and the absence of an intact immune system.Principal FindingsHere we characterize and optimize both systems to increase their utility for
preclinical studies. We show that TH-MYCN mice develop tumors in the
paraspinal ganglia, but not in the adrenal, with cellular and gene
expression patterns similar to human NB. In addition, we present a new
ultrasound guided, minimally invasive orthotopic xenograft method. This
injection technique is rapid, provides accurate targeting of the injected
cells and leads to efficient engraftment. We also demonstrate that tumors
can be detected, monitored and quantified prior to visualization using
ultrasound, MRI and bioluminescence. Finally we develop and test a
“standard of care” chemotherapy regimen. This protocol, which is
based on current treatments for neuroblastoma, provides a baseline for
comparison of new therapeutic agents.SignificanceThe studies suggest that use of both the TH-NMYC model of neuroblastoma and
the orthotopic xenograft model provide the optimal combination for testing
new chemotherapies for this devastating childhood cancer.
Optical methods using phosphorescence quenching by oxygen are suitable for sequential monitoring and non-invasive measurements for oxygen concentration (OC) imaging within cells. Phosphorescence intensity measurement is widely used with phosphorescent dyes. These dyes are ubiquitously but heterogeneously distributed inside the whole cell. The distribution of phosphorescent dye is a major disadvantage in phosphorescence intensity measurement. We established OC imaging system for a single cell using phosphorescence lifetime and a laser scanning confocal microscope. This system had improved spatial resolution and reduced the measurement time with the high repetition rate of the laser. By the combination of ubiquitously distributed phosphorescent dye with this lifetime imaging microscope, we can visualize the OC inside the whole cell and spheroid. This system uses reversible phosphorescence quenching by oxygen, so it can measure successive OC changes from normoxia to anoxia. Lower regions of OC inside the cell colocalized with mitochondria. The time-dependent OC change in an insulin-producing cell line MIN6 by the glucose stimulation was successfully visualized. Assessing the detailed distribution and dynamics of OC inside cells achieved by the presented system will be useful to understanding a physiological and pathological oxygen metabolism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.