Organoid cultures prior to time course experiments
Organoids are cultured in 50 µl/well of 1:1 Matrigel/culture maintenance medium mix within wells of 24 well-plates and in the presence of 500 µl of culture maintenance medium. Organoids are split mechanically every 5-7 days.
Organoid time course experiment from single cells
Sample preparation and single cell seeding
1. Remove the medium from the wells and collect Matrigel droplets containing organoids with ice cold PBS into a falcon tube (use 0.5 ml of PBS per well). Centrifuge the tube for 5 min at 400 rcf and 4°C to pellet the organoids
Note:Number of wells to collect depends on the type of experiment conducted (number of replicates and number of plates to prepare). For a normal time course experiment, we usually collect between 12 and 24 wells
2. Discard supernatant and re-suspend pellet in Tryple (add 100 µl of Tryple with 10 µM of Rock inhibitor for each collected well)
3. Incubate 20 min at 37°C with harsh pipetting every five minutes
4. AddDMEM/F-12 (~3 times the amount of used Tryple) and centrifugefor 5 min at 400 rcf and 4°C
5. Discard supernatant and re-suspend in 0.5 ml of cold PBS (PBS plus 10 µM Rock inhibitor)
6. Filter cell suspension through a 30 µm cell strainer directly into a FACS sorting tube
7. Keep samples on ice until sorting (ideally this should be done within 30 min)
8. Prepare a 1.5 ml Eppendorf tube with 200 µl of ENR medium (add 10 µM Rock inhibitor to ENR medium) to collect the sample (collection tube, store on ice)
9. FACS sort single alive cells into prepared collection tube
10.After sorting, centrifuge collection tube for 5 min at 800 rcf and 4°C
11. Discard supernatant carefully, re-suspend in 1:1 ratio of ENR medium and Matrigel
Note:Dilute pellet with a 1:1 ratio of ENR medium and Matrigel to obtain a final concentration of ~3000 cells/5 µl droplet. Depending on batch to batch variability of the medium compounds, organoid forming efficiency can show some variation. For this reason, adjustment of seeding densities might help (usually in a range between 2500 and 5000 cells/5 µl droplet). A final density of 100-200 organoid/well represents a good number for further analysis
12. Seed 5 µl droplet of the prepared cell suspension for each well of a 96 well-plate
Note:Number of plates and number of wells per plate to prepare depends on the experiment. Usually we prepare 6 plates with multiple wells containing organoids which we fix after 3h, 24h, 48h, 72h, 96h and 120h after plating
13. Incubate the plate for 15-20 min at 37°Cin an incubator to let the droplets solidify.
14. Add 100 µl/well of ENR medium supplemented with 20% Wnt3a-CM, 10µM of Rock inhibitor and 3µM of CHIR99021
Remark: If FACS sorting is not possible, after step 6, count the cells and continue with step 10 to seed them. However, FACS sorting ensures that only single alive cells are in the starting population
15a. For experiments without perturbations:
1. After 24h replace medium with 100 µl of ENR medium with addition of 20% Wnt3a-CM and 10µM of Rock inhibitor
2. After 72h replace medium with 100 µl of ENR medium only
15b. For experiments with perturbation by small compounds:
Note: Depending of the experiment compounds can either by added directly after seeding or at later time points
Verteporfin treatment:
1. Remove ENR medium
2. Add 100 µl/well of 5 µM Verteporfin or DMSO diluted in ENR medium at time point of interest
3. Change medium daily adding fresh compound and supplement as under 15a until fixation
Inducible hYap1 overexpression:
1. Remove ENR medium
2. Add 100 µl/well of 0.05 µg/ml Doxycycline hyclate or ddH2O diluted in ENR medium at time point of interest
3. Change medium daily adding fresh compound or ddH20 and supplement as under 15a until fixation
Inducible Lats1/2 double knock-out:
1. 24 h before single cell isolation culture organoids growing in a 24-well plate in 500 µl/well of 1 µg/ml 4-Hydroxytamoxifen or DMSO diluted in ENR medium
2. Grow single cells in normal ENR medium as described in 15a until fixation
DAPT treatment:
1. Remove ENR medium
2. Add 100 µl/well of 10 µM DAPT or DMSO in ENR medium at the time point of interest
3. Change medium daily adding fresh compound and supplement as under 15a until fixation
Ly411575 or MK-0752 treatment:
1. Remove ENR medium
2. Add 100 µl/well of 0.5 µM Ly411575 or MK-0752 or DMSO in ENR medium
3. Change medium daily adding fresh compound and supplement as under 15a until fixation
CHIR99021 or IWP-2 treatment:
1. Remove ENR medium
2. Add 100 µl/well of 5 µM CHIR99021 or 2 µM IWP-2 or respectively 5 and 2 µM DMSO diluted in ENR at time point of interest
3. Change medium daily adding fresh compound and supplement as under 15a until fixation
EREG treatment:
1. Remove ENR medium
2. Add 100 µl/well of 0.5 µg/ml EREG or PBS diluted in ENR at time point of interest
3. Change medium daily adding fresh compound and supplement as under 15a until fixation
Fixation
1. Spin the 96-well plate at 3000 rpm for 10 min in a pre-cooled centrifuge at 10°C prior to fixation
2. Wash each well once with 100 µl of PBS before adding 100 µl of 4% PFA (diluted in in PBS) for 45 min at room temperature
3. Wash 3 x with PBS (100 µl/well)
Note: After fixation, plates can be stored for weeks in the fridge (add 200 µl of PBS into each well). Plates should be sealed with Parafilm to prevent evaporation of PBS
(General) Immunostaining: After fixation
1. Add 100 µl of permeabilization buffer, incubate for 1h at room temperature (shake plate at 300 rpm)
2. Wash 3 x with PBS (100 µl/well)
3. Add 100 µl of blocking buffer for 1h at room temperature (shake plate at 300 rpm)
4. Dilute the primary antibody to an appropriate concentration in blocking buffer and add 60 µl/well for 2 h at room temperature or overnight at 4°C depending on the used antibody
5. Wash 3 x with PBS (100 µl/well)
6. Dilute the secondary antibody 1:500 in blocking buffer and add 100 µl/well for 1 h at room temperature (shake plate at 300 rpm)
7. Wash 3 x with PBS (100 µl/well)
8. Stain cell nuclei with 100 µl/well DAPI (20 µg / ml diluted in ddH20) for 15 min at room temperature
9. Wash 3 x with PBS (100 µl/well)
10. To stain cell outlines, add CellTrace dye to the CellTrace buffer (final concentration 1 µg/ml) and immediately add 100 µl/well for 10 min at room temperature
11. Wash 3 x with PBS (100 µl/well)
Note: Plates are now ready for imaging or can be stored in the fridge at 4°C for several weeks. Plates should be sealed with Parafilm to prevent evaporation of PBS and covered with aluminum foil to prevent bleaching of the fluorophores
12. Optional: If confocal z-stacks of organoids are acquired, optical penetration depth ofthe sample can be improved by optical clearing of the sample3. Each well is incubated in 100 µl of optical clearing solution at room temperature for 20 min (sample should become transparent). After incubation, the optical clearing solution is replaced with 100 µl of fresh optical clearing solution and the sample is imaged in optical clearing solution
Note: Optical clearing solution can lead to bleaching of the fluorescence signal over time. For this reason, the solution should be removed after imaging by washing with PBS
(Multiplexed) Immunostaining: After fixation, the 4i (iterative indirect immunofluorescence imaging)2 protocol can be used instead of the (General) Immunostaining protocol
1. Permeabilize with 100/well µl of -20 °C Methanol for 30 min at -20°C
2. Wash 3 x shortly with PBS (100 µl/well) followed by 3 x 10 min washes with PBS (200 µl/well, shake plate at 300 rpm)
3. Add 100 µl/well of multiplexing blocking buffer for 1 h at room temperature (shake plate at 300 rpm)
4. Dilute the primary antibody to an appropriate concentration in multiplexing blocking buffer and add 60 µl/well for 2 h at room temperature or overnight at 4°C depending on the used antibody
5. Wash 3 x with PBS (100 µl/well)
6. Dilute the secondary antibody with a concentration of 1:500 in multiplexing blocking buffer and add 100 µl/well for 1 h at room temperature (shake plate at 300 rpm)
7. Wash 3 x with PBS (100 µl/well)
8. Stain cell nuclei with 100 µl/well of DAPI (20 µg / ml diluted in ddH20) for 15 min at room temperature
9. Wash 3 x with PBS (100 µl/well)
10. To stain cell outlines, add CellTrace dye to the CellTrace buffer (final concentration 1µg/ml) and immediately add 100 µl into each well for 10 min at room temperature
11. Wash 3 x with PBS (100 µl/well)
Note: Plates are now ready for imaging of the first round or can be stored in the fridge at 4°C for several weeks
12. Imaging: Add 200 µl/well of imaging buffer and image
13. Antibody Elution: Wash3 x 10 min with elution buffer (100 µl/well) at room temperature (shake plate at 300 rpm)
14. Wash 3 x shortly with PBS (100 µl/well) followed by 3 x 10 min washes with PBS (200 µl/well, shake plate at 300 rpm)
15. Re-block the plate by adding 100 µl/well of multiplexing blocking buffer for 1 h at room temperature (shake plate at 300 rpm)
16. Staining for next round of imaging:Dilute next set of antibodies to appropriate concentration in multiplexing blocking buffer and apply for 2 h at room temperature or overnight at 4°C depending on the used antibody (add 60 µl/well)
17. Wash 3 x with PBS (100 µl/well)
18. Dilute the secondary antibody with a concentration of 1:500 in multiplexing blocking buffer and add 100 µl/well for 1h at room temperature (shake plate at 300 rpm)
19. Wash 3 x with PBS (100 µl/well)
20. Re-stain nuclei by adding 100 µl/well of DAPI (20 µg/ml diluted in ddH20) for 15 min at room temperature
21. Wash 3 x with PBS (100 µl/well)
22. Imaging: Add 200 µl/well of imaging buffer
Note: Steps 13-22 can be repeated iteratively for multiple rounds with new antibodies
Imaging, segmentation and feature extraction
Code to automatically segment and extract features for organoids stained and imaged as described under Immunostainingcan be found under https://github.com/fmi-basel/glib-nature2018-materials. We recommend to use a spinning disk confocal microscope for acquisition of maximum intensity projections together with z-stack images for each organoid.
RNA extraction for bulk RNA sequencing
For sample preparation follow: Sample preparation and single cell seeding.
Note: for each time point plate 5000 cell/well in 30 wells of a 96-well plate.
1. Remove the culture medium and wash the wells with 100 µl of PBS
2. Scrape the cells embedded in Matrigel with 100 µl/well of Buffer RL + b-mercaptoethanol (10 µl b-mercaptoethanol for each 1 ml of Buffer RL required) and collect them in a 15 ml falcon tube
3. Add 30 µl/well of ethanol 97% to the lysate and mix by vortexing
4. Follow the protocol of the Single Cell RNA Purification Kit from Section 2. Total RNA Purification from All Types of Lysate
a. Note: DNase treatment is an Optional step described in Appendix A
b. Note: Elute RNA in 20 µl of Elution Solution A