Low Viscosity Highly Concentrated Dispersions of Stable Protein Nanoclusters for Subcutaneous Injection

Stabilizing proteins in solution at high concentration is of broad interest in science, technology, and human health for the treatment of a wide range of diseases. Proteins have a tendency to undergo irreversible aggregation, gelation or precipitation at high concentrations due to unfolding caused by specific short ranged forces. Herein we create a translucent dispersion of dense equilibrium nanoclusters of conformationally stable proteins which retain their stability in vitro and in vivo. The nanoclusters are formed by adding trehalose as a crowder which leads to an entropic depletion attraction between the protein monomers. This attraction results in increased inter-protein attraction and hence the trehalose concentration can be used to tune the cluster size. The high protein volume fraction within the cluster stabilizes the protein conformation through a self-crowding mechanism and the primarily repulsive electrostatic interactions between the clusters keep them colloidally stable, preventing gelation.  The clusters dissociate into native conformationally stable protein molecules upon dilution in vitro and in vivo (mice). This tunablility of multi-scale interactions , specifically inter-monomer short range attraction and inter-cluster long range repulsion, to produce nanoclusters is not protein-specific. Therefore this nnaocluster concept can be applied to a wide range of therapeutic proteins without the need to engineer modified proteins through changing the amino acid sequence.