Co-Culture in Millicell Cell Culture Inserts Protocol
A. Day 1
- Coat T-75 flasks with 10 mL of 0.1% gelatin in DPBS and incubate for at least 30 minutes at 37°C.
- Thaw PMEF vial (s) quickly in a 37°C water bath, transfer to 15 mL tube already containing 10 mL warm medium. Gently invert tube, and pellet cells at 4°C, ~1000 rpm for approximately 4–5 minutes.
- Remove supernatant, resuspend cells, remove gelatin from plates/flasks, and aliquote feeder cell suspension per densities recommended below.
- Remove excess gelatin from flask prior to seeding.
- Seed flask with MEF feeder cell suspension: approximately 1.5 × 105 cells per mL MEF should result in 95% confluence within 24 hours.
- Incubate at 37°C overnight.
B. Day 2
- Coat T-75 flasks with 10 mL of 0.1% gelatin in DPBS and incubate for at least 30 minutes at 37°C.
- Thaw PMEF vial (s) quickly in a 37°C water bath, transfer to 15 mL tube already containing 10 mL warm medium. Gently invert tube, and pellet cells at 4°C, ~1000 rpm for approximately 4–5 minutes.
- Remove supernatant, resuspend cells, remove gelatin from plates/flasks, and aliquote feeder cell suspension per densities recommended below.
- Remove excess gelatin from flask prior to seeding.
- Seed flask with MEF feeder cell suspension: approximately 1.5 × 105 cells per mL MEF should result in 95% confluence within 24 hours.
- Incubate at 37°C overnight.
C. Day 3
- Feed ESC on MEF feeder layer with fresh ESC media.
D. Day 4-8
- Feed ESC on MEF feeder layer with fresh ESC media or pass cells, at a 1:2 ratio, if required. (After thawing ESC, 2–3 passages are preferred before seeding onto a Millicell-24 or Millicell 96-well plate. Both cell types are lifted at once and passed on to a new T-75 containing inactivated MEF.) ESC colonies grown on Millicell-96 cell culture insert 1.0 PET membrane, stained for alkaline phosphatase activity, after culturing via indirect co-culture with ESC in apical well, at a 200 cell per well seeding density, and MEF in the single-well feeder tray.
E. Day 9
- Feed ESC on MEF feeder layer with fresh ESC media.
- Coat Millicell-24 or Millicell-96 single-well feeder tray with approximately 5–10 mL of 25 µg/mL fibronectin in DPBS and incubate for 45 minutes at room temperature.
- Remove excess fibronectin from single-well tray.
- Thaw MEF using protocol from Day 1, section A.
- Seed fibronectin coated single-well tray with MEF cell suspension: approximately 1.67 × 106 MEF cells per single-well tray will result in 95% confluence within 24 hours.
- Cover with lid and incubate single-well tray at 37°C overnight.
F. Day 10
- Lift ESC and MEF feeder cells from T-75 flasks:
- Wash flasks 2X with 10 mL of pre-warmed DPBS (incubate 1–2 minutes per wash).
- Remove DPBS and add 3 mL TrypLE and incubate at room temp for 2–3 minutes.
- Monitor detachment of cells with an inverted microscope and add ESC media to inactivate TrypLE.
- Mix well and wash flask wall to remove all cells from flask.
- Separate ESC from MEF feeder cells:
- Transfer ESC/MEF cell suspension to a new T-75 flask and incubate at 37°C for 45 minutes.
- Remove non-adherent cells (ESC) and transfer to another new T-75 flask and incubate at 37°C for 45 minutes.
- Remove non-adherent cells (ESC) again and seed cell culture filter plate wells with ESC suspension.
- Seed apical wells of the cell culture plates with ESC. Seed approximately 200–500 cells per well in 100 µL ESC media for Millicell-96 plates
- and approximately 1000–1500 cells per well in 400 µL ESC media for Millicell-24 plates.
- Remove media from the MEF seeded single-well trays and replace with approximately 28–32 mL ESC media.
- Combine ESC seeded cell culture filter plates to MEF seeded single-well trays.
- Incubate assembly at 37°C overnight.
G. Day 12 and Day 14
- Feed ESC and MEF indirect co-culture with ESC media.
H. Day 16
- Analyze alkaline phosphatase activity to demonstrate that ESC is undifferentiated with an alkaline phosphatase detection kit.
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