METHODBOOK

Collagen gel containing 3T3 fibroblasts (dermal equivalent for raft culture)

Ingredients for 6 x collagen matrices in a 6-well plate;

• Roughly 3x10⁶ J2-3T3s (a fully confluent T75?)
• 1.5mL 10x reconstitution buffer
• 1.5mL 10x DMEM
• 12mL rat tail type 1 collagen (>3.8mg/mL)
• 10N NaOH
• Glacial acetic acid (in case)

Method

Pre-chill pipettes, keep collagen on ice

The collagen solidifies above 8ºC

Mix 1.5mL of 10x DMEM with 1.5mL of 10x reconstitution buffer, keep on ice.
Count J2-3T3s and pellet required number in a universal.
Add the 3mL of [1:1, 10x DMEM and 10x reconstitution buffer] and swirl to resuspend the cells, keep on ice

The J2-3T3s seem to survive this somehow

Using chilled pipette, add the 12mL of collagen gently to the cells and tilt to mix, avoiding bubbles as far as possible.

Everything is kept cold to avoid the collagen solidifying
Avoid bubbles

Add 10N NaOH to bring the pH up to 7

Judge the pH visually by the phenol red in the DMEM
Maybe 30–60mL will be necessary
Don't go too far, use the glacial AcCOOH if you have to, but the more mixing the more bubbles.

Pipette 2–2.5mL into each well and incubate O/N
In the morning, add 2mL raft media on top of each matrix.
Use within 1 week, change media every 2 days.

Buffers

10x DMEM

Dissolve DMEM powder into 0.1 volume of H₂O.
Filter sterilise and store at 20ºC in working aliquots. (It looks yellow and doesn't dissolve completely).

10x reconstitution buffer

Dissolve 2.2g sodium bicarbonate and 4.8g HEPES in 100mL H₂O.
Filter sterilise and store at 20ºC in working aliquots.

Suppliers

Collagen

Collaborative Biomedical Products (part of Becton Dickinson) Cat # 354236
Telephone (UK) 01865 781615
It comes in vials of 100mg dissolved in 0.02N HCl at roughly 4mg/mL (ie 25ml).
Try to get a batch of at least 3.8mg/mL. If it is stronger than 4mg/mL then dilute it to 4mg/mL with 0.02N acetic acid.