Deterministic Single-Cell Encapsulation in PEG Norbornene Microgels for Promoting Anti-Inflammatory Response and Therapeutic Delivery of Mesenchymal Stromal Cells.

Abstract

Tissue engineeringat single-cell resolution has enhanced therapeutic efficacy. Droplet microfluidics offers apowerful platform that allows deterministic single-cell encapsulation into aqueous droplets, yet the direct encapsulation of cells into microgels remains challenging. Here, the design of a microfluidic device that is capable of single-cell encapsulation withinpolyethylene glycol norbornene (PEGNB) hydrogelson-chip is reported. Cellsare first ordered in media within a straight microchannelviainertial focusing, followed by the introduction of PEGNB solution from two separate, converging channels. Droplets are thoroughly mixed by passage through a serpentine channel, and microgels are formed by photo-photopolymerization. This platform uniquely enables both single-cell encapsulation and excellent cell viability post-photo-polymerization. More than 90% of singly encapsulated mesenchymal stromal cells (MSCs) remain alive for 7 days. Notably, singly encapsulated MSCs have elevated expression levels in genes that code anti-inflammatory cytokines, for example, IL-10 and TGF-β, thus enhancing the secretion of proteins of interest.Following injection into a mouse model with induced inflammation, singly encapsulated MSCs show a strong retention ratein vivo,reduce overall inflammation, and mitigate liver damage. These translational results indicate that deterministic single-cell encapsulation could find use in a broad spectrum of tissue engineeringapplications.