Overview
Spheroids are a type of 3D cell culture model used to more accurately represent a cell’s environment compared to 2D cell culture monolayer models. In the example protocol, we will see scientists generate spheroids from a colorectal cancer cell line and apply live-cell imaging to track the spheroids’ growth.
Protocol
1. Generation of Spheroids from Colorectal Cancer Cell Line
- Wash HCT 116 (stably transduced to express Cluster of Differentiation 19 (CD19) and Green Fluorescence Protein (GFP)) cell monolayers with phosphate buffered saline (PBS; 5 mL for a 25 cm2 or 10 mL for a 75 cm2 flask). Add trypsin (0.5 mL for a 25 cm2 or 1 mL for a 75 cm2 flask) and incubate cells at 37 °C for 5 min.
- Check cell detachment under a microscope and neutralize cell dissociation enzyme with complete Roswell Park Memorial Institute 160 medium (RPMI 1640) (RPMI 1640 + 10% FCS + Gentamycin; 10 mL for a 25 cm2 or 20 mL for a 75 cm2 flask).
- Centrifuge cell suspension at 500 x g for 5 min. Remove supernatant using a pipette and resuspend by pipetting up and down several times with 5 mL of complete RPM1 1640 medium.
- Count cells using Trypan blue exclusion on a compatible cell counter.
- Centrifuge cell suspension at 500 x g for 5 min. Remove supernatant using a pipette and resuspend in RPMI medium to obtain 5 x 103cells/mL.
- Coat a 96-well round bottom plate with 100 µL/well of 100 µg/mL of poly-L-lysine (PLL) in PBS during 1 hour at room temperature. Wash twice with PBS and let the plate dry.
- Transfer the cell suspension to a sterile reservoir and dispense 200 µL/well into the PLL-coated 96-well round bottom plates using a multichannel pipette.
- Transfer the plate to the automated imaging apparatus inside an incubator (37 °C, 5% CO2, 95% humidity).
- Log into the acquisition software, select Schedule To Acquire | Launch Add Vessel | Scan On Schedule | Create Vessel: New.
- Select Scan Type: Spheroid. Select the channels of interest: Phase + Brightfield (to follow spheroids growth), Green (to follow tumor signal, acquisition time 300 ms) and Red (to follow apoptosis, acquisition time 400 ms).
- Select the desired magnification: 10x.
- Pick the plate model and its position in the drawer. Select the position of wells to image. Enter the description of the experiment: name, type of cells, number of cells.
- For the analysis setup, select Defer Analysis Until Later. Right click on the timeline and select Set Selected Scan Group Intervaloption and set Add scans every to 4 h and For a total of to 24 h. Set the desired starting time (at least 1 h after incubation in the automated imaging apparatus).
- Check every 2 days for the growth of spheroids by logging into the imaging software.
- Pick the View Recent Scans option and double-click on the desired experiment. Select Brightfield in the image channels panel and then use the Measure image features tool to measure the diameter of the spheroids. It takes 6 days for a spheroid to reach the desired size: 0.5 mm of diameter. Add 50 µL of complete RPMI medium per well at day 4 to limit medium evaporation effect.
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Materials
Name | Company | Catalog Number | Comments |
Dulbecco’s Phosphate Buffered Saline | SIGMA-ALDRICH | D8537-500ML | Lot Number: RNBG7037 |
75 cm² growth area flasks | VWR | 430639 | Lot Number: 2218002 |
75 cm² growth area flasks | VWR | 734-2705 | Lot Number: 3718006 |
Trypsin-EDTA | SIGM-ALDRICH | T3924-100ml | Lot Number: SLBTO777 |
RPMI 1640 med L-glutamin, 10 x 500 mL | Life Technology (Gibco) | 21875-091 | Lot Number: 1926384 |
Gentamicin | Thermo Fischer | 15750060 | Lot Number: 1904924A |
Trypan Blue Solution, 0.4% | Thermo Fischer | 15250061 | Lot Number: 1886513 |
96 well plate, round bottom | VWR | 734-1797 | Lot Number: 33117036 |
X-VIVO 15 with Gentamicin L-Gln, Phenol Red, 1 L | BioNordika | BE02-060Q | Lot Number: 8MB036 |
Reagent Reservoir | VWR | 89094-672 | Lot Number: 89094-672 |
15 mL tubes | VWR | 734-1867 | Lot Number: 19317044 |
Fetal Bovine Serum | Gibco | 10500064 | Lot Number: 08Q3066K |
HCT 116 Colorectal Carcinoma Line | ATCC | CCL-247 | - |
Incucyte S3 | Essen Bioscience |