Mammalian cell-seeded hydrogel microarrays printed via dip-pin technology

Although significant advances have been made in the development of DNA and protein microarrays, less effort has been put toward developing mammalian cell microarrays. Such cellular microarrays may be useful in examining the effects of biological or chemical agents on cells, particularly in drug development and toxicological applications. Here, mammalian cell-seeded hydrogel microarrays were created using two different commercial microarrayers, with four different pin types. Human dermal fibroblasts were used here as a model cell type, seeded within polyethylene glycol-based hydrogels similar to those under investigation as tissue engineering scaffolds, which serve as synthetic extracellular matrices for the cells. Spot sizes of the hydrogels were found to vary with pin type. Multiple touches on a slide following a single dip in the reservoir print solution led to decreasing spot size with each touch; therefore, subsequent microarrays were printed with single touches after a dip. Individual pins of the same type and tip diameter had significantly different spot sizes, likely due to wear of the pins at the tip. However there was high run-to-run reproducibility between subsequent microarrays. Cell viability varied with pin type, and the number of cells per spot varied with cell density in the print solution, as expected.