Functional cargo delivery into mouse and human fibroblasts using a versatile microfluidic device

Efficient intracellular cargo delivery is a key hurdle for the translation of many emerging stem cell and cellular reprogramming therapies. Recently, a microfluidic-based device constructed from silicon was shown to transduce macromolecules into cells via shear-induced formation of plasma membrane pores. However, the scalability and widespread application of the current platform is limited since physical deformation-mediated delivery must be optimized for each therapeutic application. Therefore, we sought to create a low-cost, versatile device that could facilitate rapid prototyping and application-specific optimization in most academic research labs. Here we describe the design and implementation of a microfluidic device constructed from Polydimethylsiloxane (PDMS) that we call Cyto-PDMS (Cytoplasmic PDMS-based Delivery and Modification System). Using a systematic Cyto-PDMS workflow, we demonstrate intracellular cargo delivery with minimal effects on cellular viability. We identify specific flow rates at which a wide range of cargo sizes (1-70 kDa) can be delivered to the cell interior. As a proof-of-principle for the biological utility of Cyto-PDMS, we show (i) F-actin labeling in live human fibroblasts and (ii) intracellular delivery of recombinant Cre protein with appropriate genomic recombination in recipient fibroblasts. Taken together, our results demonstrate that Cyto-PDMS can deliver small-molecules to the cytoplasm and biologically active cargo to the nucleus without major effects on viability. We anticipate that the cost and versatility of PDMS can be leveraged to optimize delivery to a broad array of possible cell types and thus expand the potential impact of cellular therapies.