An Ultrathin Coating of Microcapsules Enhances the Function of Encapsulated Hepatocyte Spheroids

Maintaining the differentiated phenotype and function of primary hepatocytes in vitro and in vivo represents a distinct challenge. Our paper describes microcapsules comprised of a bioactive polymer and overcoated with an ultrathin film as a means of maintaining the function of entrapped hepatocytes for at least two weeks. We previously demonstrated that heparin (Hep)-based microcapsules improved the function of entrapped primary hepatocytes by capturing and releasing cell-secreted inductive signals, including hepatocyte growth factor (HGF). Further enhancement of hepatic function could be gained by loading exogenous HGF into microcapsules. In this study, we demonstrate that an ultrathin coating of tannic acid (TA) further enhances endogenous HGF signaling for entrapped hepatocytes and increases by 2-fold the rate of uptake of exogenous HGF by Hep microcapsules. Hepatocytes in overcoated microcapsules exhibited better function and hepatic gene expression than in capsules without a TA coating. Our study showcases the potential application of ultrathin coatings to modulate the bioactivity of microcapsules and may enable the use of encapsulated hepatocytes for modeling drug toxicity or treating liver diseases.