Hyaluronic Acid Microgels as Intracellular Endosomolysis Reagents.

Hyaluronic acid (HA) microgels were investigated as biocompatible and biodegradable reagents for facilitating endosomolysis in human cells. Employing inverse emulsion templates, HA microgels were prepared by cross-linking aqueous sodium hyaluronate droplets with divinyl sulfone (DVS). Introduction of ether sulfone cross-links was confirmed by infrared (IR) spectroscopy and elemental analysis. The degree of cross-linking of the microgels was estimated using high performance liquid chromatography (HPLC). The size distribution of the water-dispersible HA microgels was studied by laser diffraction analysis, and the gel morphology was investigated using scanning electron microscopy (SEM). Aqueous microgel suspensions were found to be well-tolerated in human cells at concentrations of up to 100 μg/mL. Endosome-rupturing properties of the HA microgels were evaluated in vitro using calcein internalization and Cre protein delivery assays. The results of this study serve as a proof-of-principle for the utility of cross-linked HA microgels as a new class of biocompatible and biodegradable endosomolytic reagents.