Sub-micron poly(N-isopropylacrylamide) particles as temperature responsive vehicles for the detachment and delivery of human cells

We describe the first example of particulate materials that can detach cultured cells and then release them intact in a temperature controlled manner. Topologically open microgels composed of water swollen highly branched polymers prepared from poly(N-isopropylacrylamide) (PNIPAM) were modified with a cell-adhesive peptide (GRGDS) to produce particles for gently detaching and then transferring cultured cells to new substrates. The particles bind to cell surface integrins on both dermal fibroblasts and endothelial cells and at temperatures above the lower critical solution temperature (34 °C) remove cells from their normal culture substrates. Brief (45 min) cooling of the resultant particle–cell dispersion to beneath 34 °C releases the cells to grow on new substrates. This avoids the need for trypsinisation to detach cells or centrifugation to collect cells post-detachment and offers a flexible approach to cell detachment and transport which is compatible with normal cell culture methodologies.