I wonder how you explore the pattern of miRNA or gene alterations in a "cell-cell contact" co-culture model (not a transwell). I mean how to know the changes come from the cell type you focus on.
It depends upon the question you are asking. If one is studying expression pattern of one gene reporter assays are a good choice. For whole transcriptome profiling, one can employ cell sorting for individual cells in the culture or alternatively a micro-manipulator can be used to pick cell of interest from the culture. Once a cell of interest is separated, it is available for genomic, epigenomic, or transcriptomics.