Tracking Egress of Doubly Encapsulated Cells

Abstract

Droplet-based microfluidics can be used to enhance stem cell-based therapy by creating cell-laden hydrogel encapsulations to increase engraftment and retention while providing protection from immune responses caused by the host environment. Current research involves gaining better control over therapeutic mechanisms and one focus is to understand the mechanisms behind cell egress. Control over egress is vital to determining how long cells remain in proximity to the therapeutic target. We propose a microfluidic platform capable of encapsulating cells in two subsequent steps in order to create a double emulsion structure around the cell. In this project, hydrogel-in-hydrogel microdroplets are successfully manufactured without the presence of an intermediate oil layer and are used to observe model NIH 3T3 cell egress. In studying cell egress from singly or doubly encapsulated microcapsules, we are able to better understand the mechanisms that drive egress. Specifically, we hypothesize that cells egress when close to the edge of the microcapsule. In a double emulsion, cells are naturally located away from the edge and closer to the center. Results show that double emulsion microdroplets significantly reduce cell egress but do not eliminate it.