Existing clinical cell therapies, which rely on the use of biological functionalities of living cells, can be further enhanced by conjugating functional particles to the cells to form cell-particle complexes. Disk-shaped microparticles produced by the top-down microfabrication approach possess unique advantages for this application. However, none of the current mechanisms for conjugating the microfabricated microparticles to the cells are principally applicable to all types of cells with therapeutic potentials. On the other hand, membrane intercalation is a well-established mechanism for attaching fluorescent molecules to living cells or for immobilizing cells on a solid surface. This paper reports a study on conjugating disk-shaped microparticles, referred to as micropatches, to living cells through membrane intercalation for the first time. The procedure for producing the cell-micropatch complexes features an unprecedented integration of microcontact printing of micropatches, end-grafting of linear molecules of octadecyl chain and poly(ethylene glycol) to the printed micropatches, and use of gelatin as a temperature-sensitive sacrificial layer to allow the formation and subsequent release of the cell-micropatch complexes. Complexes composed of mouse neuroblastoma cells were found to be stable in vitro, and the micropatch-bound cells were viable, proliferative, and differentiable. Moreover, complexes composed of four other types of cells were produced. The membrane-intercalation mechanism and the corresponding fabrication technique developed in this study are potentially applicable to a wide range of therapeutic cells and thus promise to be useful for developing new cell therapies enhanced by the disk-shaped microparticles.
Keywords: PEG; cell therapy; drug delivery; human mesenchymal stem cells; membrane intercalation; microfabrication; microparticle.