Is it possible to co-culture 2 different cell lines that require different growth medium (DMEM, and RPMI-1640)? Eg plating the cells on opposite layer (bilayer) of the tissue scaffold.
The problem you are dealing with is most common during co-culture experiments. Since tissue scaffold's one side can't be isolated from other so using different media for separate sides is practically impossible. Ideally you should acclimatize your both cell types to single media which is totally possible or you should try a different media like a-MEM in which both cells show optimum growth. Still if your cells are very specific to grow in these two media then you can try RAFT MEM maintainance media from Lonza. That is suitable to culture most of the cells for co-culture experiments. Rest you can ask the company people.
Disclaimer: I am not intended to promote any company product and the answer provided here is solely based on my personal experience.