Cell sheet patterning using photo-cleavable polymers

We have found that poly (4-vinylpyridine) (P₄VP) and poly (methylmethacrylate) thin films can be etched with ultraviolet A (UVA) radiation. Furthermore, we also found that dermal fibroblasts could be cultured successfully on the P₄VP polymer, with a doubling time comparable to tissue culture Petri dish standards. Consequently, we were able to grow tissue on P₄VP substrates, this could easily be lifted using UVA radiation. The cell sheets that were removed were then re-plated at a lower density and a series of assays was performed at 3 and 6 days. Although only a small amount of damage was discernable at day 3 nearly complete recovery was observed at day 6. The technique was used to pattern areas within the tissue, where other types of cells could be inserted. To demonstrate the technique, a hybrid tissue layer was produced, in which the dermal fibroblasts in a circular area at the center of the sample were removed by exposure through a mask. A keratinocyte layer was inserted, which adhere to the fibroblast layer forming a tissue with integrated layers of two distinct cell types.