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. Author manuscript; available in PMC: 2022 Jan 1.
Published in final edited form as: Adv Drug Deliv Rev. 2020 May 7;168:118–133. doi: 10.1016/j.addr.2020.05.001

Figure 4. Inner ear schematic showing established delivery approaches for CRISPR-Cas9 gene-editing system.

Figure 4

Established approaches of gene delivery into inner ear cells include canalostomy (a), trans-round window membrane (b), and cochleostomy to the scala tympani and scala media (c) [109]. Viral vectors can be used for the delivery of Cas9 DNA or RNA with sgRNA into the inner hair cells, while non-viral vectors can be additionally used for Cas9 protein delivery (d). Viral vectors and non-viral vectors enter cells through membrane fusion and endocytosis, respectively (e). Delivery of either DNA or mRNA can lead to the expression of Cas9 protein inside the cell, and Cas9 ultimately functions as protein form in genome editing combined with sgRNA (f).