Cell culture on a thermo-responsive polymer surface.

We have used a thermo-responsive polymer, poly-N-isopropyl acrylamide (PNI-PAAm), as a substratum for the culture of human dermal fibroblasts by conjugating it with collagen. The cells attached well, spread, and grew on the substratum, indicating that the polymer has no toxicity towards the cells. PNIPAAm is insoluble in water over the lower critical solution temperature (LCST; about 32 degrees C) and reversibly solubilized below the LCST. Taking advantage of this conversion, monolayered fibroblasts cultured on the substratum containing the PNIPAAm over the LCST, were completely detachable from the substratum by simply lowering the temperature below the LCST, without the use of conventional detaching agents such as trypsin and EDTA. The detached cell sheet gradually aggregated and finally formed a multicellular spheroid. This polymer may provide a convenient and potentially useful technology for cell culture.