I'm hoping to get a single, confluent epithelial layer of hacat cells growing on top of a layer of matrigel. I can find people culturing hacat cells IN matrigel, but not a smooth layer of each.
HaCaT cells are interesting. For best results and to mimic their natural physiology, I would advise to grow them in a stratified multilayer format upon a stroma (Matrigel) containing fibroblasts so that the full cell-cell interactions and signalling can occur. They are also very fastidious for particular media and supplements. Note, HaCaT do not keratinise easily after differentiation. Clearly, this all depends on the type of assay being utilised and research question you are are intending to answer. Good luck.