Magnetic force-based cell patterning using Arg-Gly-Asp (RGD) peptide-conjugated magnetite cationic liposomes

Micropatterning of target cells is highly desired for tissue engineering and cell biology. Although recent progress in surface chemistry has enabled the spatial control of cell adhesion onto substrates, conventional methods usually require specialized devices and time-consuming processes to fabricate the substrate. In this study, we demonstrate a simple and rapid cell-patterning procedure using magnetite nanoparticles and magnetic force. To label the target cells magnetically, magnetite nanoparticles were encapsulated in cationic liposomes (magnetite cationic liposomes; MCLs). To promote cell attachment, an Arg-Gly-Asp (RGD)-motif-containing peptide was coupled to the phospholipid of MCLs (RGD-MCLs). A human keratinocyte cell line, HaCaT, which has a high anchorage dependency, was used as a model. The RGD-MCLs were added to an ultralow-attachment plate, whose culture surface is modified with a covalently bound hydrogel layer that is hydrophilic and neutrally charged, and then HaCaT cells were seeded to the plates. The RGD-MCLs induced cell adhesion, spreading, cytoskeletal organization, and fibronectin expression. When steel plates with a 200 microm width placed on a magnet were set under a culture surface, magnetically labeled cells aligned on the surface where the steel plate was positioned, resulting in cell patterning. Furthermore, various cell patterns using a computer-aided design were successfully fabricated. These results suggest that cell patterning using RGD-MCLs is a promising approach to tissue engineering and studies in cell biology.