Here we present an ex-vivo mixed monolayer culture system for the study of human glioma cell (hGC) migration in real-time. This model provides the ability to observe interactions between hGCs and both myelinated and non-myelinated axons within a compartmentalized chamber.
Glioblastoma is one of the most aggressive human cancers due to extensive cellular heterogeneity and the migration properties of hGCs. In order to better understand the molecular mechanisms underlying glioma cell migration, an ability to study the interaction between hGCs and axons within the tumor microenvironment is essential. In order to model this cellular interaction, we developed a mixed culture system consisting of hGCs and dorsal root ganglia (DRG) axon-oligodendrocyte co-cultures. DRG cultures were selected because they can be isolated efficiently and can form the long, extensive projections which are ideal for migration studies of this nature. Purified rat oligodendrocytes were then added on purified rat DRG axons and induced to myelinate. After confirming the formation of compact myelin, hGCs were finally added to the co-culture and their interactions with DRG axons and oligodendrocytes was monitored in real-time using time-lapse microscopy. Under these conditions, hGCs form tumor-like aggregate structures that express GFAP and Ki67, migrate along both myelinated and non-myelinated axonal tracks and interact with these axons through the formation of pseudopodia. Our ex vivo co-culture system can be used to identify novel cellular and molecular mechanisms of hGC migration and could potentially be used for in vitro drug efficacy testing.
Glioblastoma is one of the most aggressive and lethal tumors of the human brain. The current standard of care includes surgical resection of the tumor followed by radiation1 plus concomitant and adjuvant administration of temozolomide2. Even with this multi-therapeutic approach, tumor recurrence is inevitable3. This is partly due to the extensive migratory nature of the tumor cells, which invade the brain parenchyma creating multiple finger-like projections within the brain4 that make complete resection unlikely.
In recent years, it has become evident that the aggressiveness of glioblastoma is due, in part, to the presence of a population of cancer stem cells within the tumor mass5,6, which exhibit high migratory potential7,8, resistance to chemotherapy and radiation9,10 and the ability to form secondary tumors11. GSCs are capable of recapitulating original polyclonal tumors when xenografted to nude mice5.
Despite the wealth of knowledge regarding the genetic background of glioblastomas, studies on glioma cell (GC) migration are currently hindered by a lack of efficient in vitro or in vivo migration models. Notably, while glioma cell-axonal interactions modulated by cellular and environmental factors are a core component of glioma invasion, to our knowledge there is currently no experimental system with the ability to model these interactions12,13,14. To address this deficiency, we developed an ex vivo culture system of primary hGCs co-cultured with purified DRG axon-oligodendrocytes that results in elevated expression of differentiated tumor markers as well as extensive migration and interaction of hGCs with myelinated and non-myelinated fibers. This ex vivo platform, due to its compartmentalized layout, is suitable for testing the effects of novel therapeutics on hGC migration patterns.,
Migration studies for hGCs may be performed by using Boyden chamber systems or scratch assays. However, while these experiments fail to give any information regarding the interactions of tumor cells with other surrounding tissues, the present system can recapitulate GC interactions with myelinated and non-myelinated fibers. Furthermore, to study tumor formation and end-point migration, organotypic slice cultures of the rodent brain or in vivo implantation of glioma cells into the rodent brain or flank have previously bee…
The authors have nothing to disclose.
This work was supported by internal funds of the Department of Neurosurgery, Brown University to N.T.
100 mm Suspension Culture Dish | Corning | 430591 | |
2.5S NGF | ENVIGO | B.5025 | |
60 mm Suspension Culture Dish | Corning | 430589 | |
ACK Lysing Buffer | Thermo Fisher | A1049201 | |
Ammonium Hydroxide Solution | Fisher Scientific | A669-500 | Concentrated |
Animal-Free Recombinant Human EGF | Peprotech | AF-100-15 | |
Animal-Free Recombinant Human FGF-basic (154 a.a.) | Peprotech | AF-100-18B | |
Anti-A2B5 MicroBeads, human, mouse, rat | Miltenyi Biotec | 130-093-392 | |
Antibiotic-Antimycotic (100X) | Thermo Fisher | 15240062 | |
AutoMACS Rinsing Solution (PBS, pH 7.2) | Miltenyi Biotec | 130-091-222 | |
B27 Supplement | Thermo Fisher | 17504044 | |
B27 Supplement, minus vitamin A | Thermo Fisher | 12587001 | |
Bacteriological Plate | BD Falcon | 351029 | |
Biotin | Sigma | B4639 | |
BSA | Sigma | A9418 | |
Campenot Chamber | Tyler Research | CAMP-10 | |
Cell Culture Dish | Corning | 430165 | 35mm X 10mm |
Cell Strainer | BD Falcon | 352350 | 70 uM, Nylon |
Cell Strainer | BD Falcon | 352340 | 30 uM, Nylon |
Collagenase/Dispase | Roche | 11097113001 | |
Cultrex Rat Collagen I | Trevigen | 3440-100-01 | |
D-Glucose | Sigma | G5146 | |
DMEM | Thermo Fisher | 10313021 | |
DNase I | Sigma | D7291 | |
Dow Corning High-Vacuum Grease | Fisher Scientific | 14-635-5D | |
Dumont #5 Forceps | Roboz | RS-5045 | |
E16 Timed Pregnant Sprague Dawley Rat | |||
EBSS | Sigma | E7510 | |
EGTA | Sigma | E3889 | |
FBS | Hyclone | SH30070.02 | |
FUDR | Sigma | F0503 | |
GlutaMAX Supplement | Thermo Fisher | 35050061 | |
Ham's F-12 Nutrient Mix | Thermo Fisher | 11765054 | |
HBSS | Thermo Fisher | 14175095 | |
Hemostatic Forceps | Roboz | RS-7035 | |
Heparin Sodium Salt, 0.2% in PBS | Stem Cell Technologies | 07980 | |
Hypodermic Needle, 18G | BD | 511097 | |
Insulin-Transferrin-Selenium G | Thermo Fisher | 41400045 | |
L-Cysteine | Sigma | C7477 | |
L-Glutamine | Thermo Fisher | 25030081 | |
Leibovitz's L-15 Medium | Thermo Fisher | 11415064 | |
MACS BSA Stock Solution | Miltenyi Biotec | 130-091-376 | |
MACS MultiStand | Miltenyi Biotec | 130-042-303 | |
MEM | Thermo Fisher | 1190081 | |
Mg2SO4 | Sigma | M2643 | |
MiniMACS Separator | Miltenyi Biotec | 130-042-102 | |
MS Columns plus tubes | Miltenyi Biotec | 130-041-301 | |
NAC | Sigma | A8199 | |
NaHCO3 | Sigma | S5761 | |
Neurobasal Medium | Thermo Fisher | 21103049 | |
Neurobasal-A Medium | Thermo Fisher | 10888022 | |
Ordinary forceps | |||
P2 Sprague Dawley Rat Pups | |||
Papain | Worthington | LS003126 | |
Penicillin-Streptomycin | Thermo Fisher | 15140148 | |
Pin Rake | Tyler Research | CAMP-PR | |
Progesterone | Sigma | P8783 | |
StemPro Accutase Cell Dissociation Reagent | Thermo Fisher | A1110501 | |
Syrine Grease Applicator | Tyler Research | CAMP-GLSS | |
Transferrin | Sigma | T2036 | |
Uridine | Sigma | U3003 |