title: Multimodality imaging methods for assessing retinoblastoma orthotopic xenograft growth and development.
abstract: Genomic studies of the pediatric ocular tumor retinoblastoma are paving the way for development of targeted therapies. Robust model systems such as orthotopic xenografts are necessary for testing such therapeutics. One system involves bioluminescence imaging of luciferase-expressing human retinoblastoma cells injected into the vitreous of newborn rat eyes. Although used for several drug studies, the spatial and temporal development of tumors in this model has not been documented. Here, we present a new model to allow analysis of average luciferin flux ([Formula: see text]) through the tumor, a more biologically relevant parameter than peak bioluminescence as traditionally measured. Moreover, we monitored the spatial development of xenografts in the living eye. We engineered Y79 retinoblastoma cells to express a lentivirally-delivered enhanced green fluorescent protein-luciferase fusion protein. In intravitreal xenografts, we assayed bioluminescence and computed [Formula: see text], as well as documented tumor growth by intraocular optical coherence tomography (OCT), brightfield, and fluorescence imaging. In vivo bioluminescence, ex vivo tumor size, and ex vivo fluorescent signal were all highly correlated in orthotopic xenografts. By OCT, xenografts were dense and highly vascularized, with well-defined edges. Small tumors preferentially sat atop the optic nerve head; this morphology was confirmed on histological examination. In vivo, [Formula: see text] in xenografts showed a plateau effect as tumors became bounded by the dimensions of the eye. The combination of [Formula: see text] modeling and in vivo intraocular imaging allows both quantitative and high-resolution, non-invasive spatial analysis of this retinoblastoma model. This technique will be applied to other cell lines and experimental therapeutic trials in the future.
authors.affiliation: Eugene and Marilyn Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, Indiana, United States of America.
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Corson
authors.affiliation: Eugene and Marilyn Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Samuels
authors.affiliation: Eugene and Marilyn Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Andrea A
authors.initials: AA
authors.lastname: Wenzel
authors.affiliation: Eugene and Marilyn Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Eastern University, St. Davids, Pennsylvania, United States of America.
authors.forename: Anna J
authors.initials: AJ
authors.lastname: Geary
authors.affiliation: Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Amanda A
authors.initials: AA
authors.lastname: Riley
authors.affiliation: Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Brian P
authors.initials: BP
authors.lastname: McCarthy
authors.affiliation: Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, Indiana, United States of America; Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Herman B Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health, Indianapolis, Indiana, United States of America.
authors.forename: Helmut
authors.initials: H
authors.lastname: Hanenberg
authors.affiliation: Herman B Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health, Indianapolis, Indiana, United States of America.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Bailey
authors.affiliation: Indiana Center for Vascular Biology and Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Pamela I
authors.initials: PI
authors.lastname: Rogers
authors.affiliation: Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, Indiana, United States of America; Herman B Wells Center for Pediatric Research, Department of Pediatrics, Section of Pediatric Hematology/Oncology, Riley Hospital for Children at Indiana University Health, Indianapolis, Indiana, United States of America.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Pollok
authors.affiliation: Eugene and Marilyn Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America; Indiana Center for Vascular Biology and Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Gangaraju
authors.initials: G
authors.lastname: Rajashekhar
authors.affiliation: Department of Radiology and Imaging Sciences, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Territo
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D005134:Eye Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008163:Luminescent Measurements; D011859:Radiography; D051381:Rats; D012175:Retinoblastoma / Q000000981:diagnostic imaging / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014183:Transplantation, Heterologous
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins