An\nUltrathin Coating\nof Microcapsules Enhances the\nFunction of Encapsulated Hepatocyte Spheroids

Maintaining the differentiated phenotype\nand function\nof primary\nhepatocytes <i>in vitro</i> and <i>in vivo</i> represents a distinct challenge. Our paper describes microcapsules\ncomprised of a bioactive polymer and overcoated with an ultrathin\nfilm as a means of maintaining the function of entrapped hepatocytes\nfor at least two weeks. We previously demonstrated that heparin (Hep)-based\nmicrocapsules improved the function of entrapped primary hepatocytes\nby capturing and releasing cell-secreted inductive signals, including\nhepatocyte growth factor (HGF). Further enhancement of hepatic function\ncould be gained by loading exogenous HGF into microcapsules. In this\nstudy, we demonstrate that an ultrathin coating of tannic acid (TA)\nfurther enhances endogenous HGF signaling for entrapped hepatocytes\nand increases by 2-fold the rate of uptake of exogenous HGF by Hep\nmicrocapsules. Hepatocytes in overcoated microcapsules exhibited better\nfunction and hepatic gene expression than in capsules without a TA\ncoating. Our study showcases the potential application of ultrathin\ncoatings to modulate the bioactivity of microcapsules and may enable\nthe use of encapsulated hepatocytes for modeling drug toxicity or\ntreating liver diseases.