Internalization of liposome nanoparticles functionalized with TrkB ligand in rat cochlear cell populations

Objectives: To investigate the targetability of TrkB ligand-functionalized liposome nanoparticles for gene delivery to spiral ganglion cells. Materials and methods: A TrkB affinity peptide was synthesized and coupled to liposome nanoparticles carrying the plasmid pGeneClip™ hMGFP encoding shRNA to transiently silence inhibitor of differentiation and DNA binding-2 (Id2) along with the reporter gene EGFP. Internalization and targetability were analyzed in primary cochlear cell culture, cochlear explants, and live rats. Gene transduction was evaluated in rat cochlear explants. Immunofluorescent staining in combination with confocal microscopy was used for observation. Results: Efficient internalization was observed in primary cochlear cell culture for both peptide-functionalized liposome nanoparticles and blank liposome nanoparticles in a concentration-dependant manner. Both particles showed uptake in spiral ganglion cells and adjacent nerve fibers. Potential targetability with TrkB affinity peptide-functionalized liposome nanoparticles was observed in the adult rat cochlea. More efficient gene expression was seen for the peptide-functionalized liposome nanoparticles, and the function of the shRNA was demonstrated in cochlear explants and adult rat cochleae. Conclusions: Potential targetability of A371-functionalized liposome nanoparticles was observed in the adult rat cochlea. Functionalization of liposome nanoparticles with TrkB ligand did not change cellular internalization, but it did enhance gene expression.