Table 1.
A summary of adeno-associated virus (AAV) vectors used in gene therapy for genetic hearing impairments and vestibular dysfunction.
| Gene Name; Deafness Locus |
AAV Vector | Animal Model | Route of Delivery; Age at Delivery |
Target Cells/Outcomes | References |
|---|---|---|---|---|---|
| Vglut3; DFNA25 | AAV1-mVglut3 | Vglut3−/− mice | RWM; P1-P3, P10-P12 | Transduction of almost 100% IHCs, normal ABR thresholds and waveforms at both low and high frequencies, up to 28 weeks post injection. Earlier delivery increases hearing recovery longevity. | [20] |
| Gjb2 (Cx26); DFNB1 | AAv2/1-CB7-Gjb2 AAV2/1-CB7-Gjb2-GFP |
Cx26fl/flFoxg1-Cre+/− mice | Cochleostomy; P0-P1 |
High transduction efficiency of supporting cells, especially outer sulcus cells. Very low transduction of sensory hair cells, but improved hair cells and spiral ganglion neurons survival. No restoration of hearing sensitivity. |
[35] |
| AAV2/5-CMV-Gjb2 | Cx26fl/flP0-Cre mice | RWM; P0, P42 | Transduction of supporting cells, the spiral ligament fibrocytes and the spiral limbus. Preserved structure of OHCs, IHCs, and supporting cells, and improved ABR thresholds at neonatal stage, but not in adult mice. | [86] | |
|
Tmc1; DFNB7/11 Tmc1Bth/+; DFNA36 |
AAV2/1-CBA-Tmc1 AAV2/1-CBA-Tmc2 |
Tmc1−/− and Tmc1Bth mice | RWM; P0-P2 | Restoration of IHCs function. Partial recovery of ABR thresholds in Tmc1−/− mice injected either with either AAV2/1-CBA-Tmc1 or AAV2/1-CBA-Tmc2. No recovery of OHC function, due to low viral transduction rates in OHCs. | [22] |
| AAV2/Anc80L65-CMV-Tmc1-WPRE, AAV2/Anc80L65-CMV-Tmc2-WPRE, AAV2/Anc80L65-CMV-Tmc1EX1-WPRE, AAV2/Anc80L65-CMV-EGFP-WPRE |
Wild-type and Tmc1−/− mice | RWM; P0-P2, P4, P7, P14, and P30 | Cochlea: High transduction of both IHCs and OHCs at neonatal stage. Rescued sensory function in mature hair cells, and enhanced hair cell survival. Partial recovery of ABR thresholds, especially at the low frequencies. Vestibular end-organs: High transduction of vestibular hair cells, and enhanced viability of hair cells. Restoration of vestibular behavior and balance function even at mature stages. |
[75] | |
| Whrn; DFNB31; USH2D | AAV2/8-CMV-Whrn-GFP | Whirler (Whrnwi/wi) mice | RWM; P1-P5 | Transduction of ~15% of IHCs, and any of OHCs. No improvement in hearing sensitivity. Restoration of stereocilia length and hair bundle morphology and increase in IHCs survival. | [87] |
| AAV2/8-CMV-Whrn-GFP | Whirler (Whrnwi/wi) mice | PSCC; P4 | Cochlea: Normal stereocilia bundles morphology. Successful transduction of IHCs, and partial restoration of hearing for at least 4 months. Vestibular end-organs: Efficient transduction of vestibular hair cell. Restoration of utricular hair cells morphology. Normal vestibular behavior and balance function for at least 4 months, and improved vestibular evoked potentials (VsEPs). |
[88] | |
| Pjvk; DFNB59 | AAV2/8-Pjvk-IRES-eGFP AAV8-Pjvk-IRES-eGFP |
Pjvk−/− mice | RWM; P3 | Partial restoration of ABR thresholds, normal ABR waveforms and wave amplitudes. | [21] |
| MsrB3; DFNB74 | rAAV2/1-CMV-MsrB3-GFP | MsrB3−/− mice | Otocysts; E12.5 | High transduction efficiency of both IHCs and OHCs in all cochlear turns. Preserved hair cells, rescued morphology of stereociliary bundles, and normal ABR thresholds at both low and high frequencies at P28. | [89] |
| Clrn1; Ush3A | AAV2/2-CAG-Clrn1-UTRs AAV2/8-CAG-Clrn1-UTRs |
Clrn1−/− and KO-TgAC1 mice (Transgene Atoh1-enhacer-Clrn-1 UTRs) | RWM; P1-P3 | Preserved hair bundle morphology at P100. Normal click-evoked ABR thresholds and waveforms at P100. | [90] |
| AAV2/8-CAG-Clrn1-IRES-eGFP |
Clrn1ex4−/− and Clrn1ex4fl/fl Myo15−Cre+/− mice |
RWM; P1-P3 | High transduction of both IHCs and OHCs. An almost complete rescue of hearing for low and high frequencies in Clrn1ex4fl/flMyo15-Cre+/−mice. Prevention of the synaptic defects and durably preservation of the stereocilia hair bundles morphology up to P12. | [26] | |
| AAV2/9.PHP.B-CBA-Clrn1-eGFP | Clrn−/−mice | RWM; P0-P1, P30 | Cochlea: High transduction of both IHCs and OHCs at neonatal stage. Almost all IHCs from apex to base transduced, but no OHC transduction at adult stage. Robust hearing rescue at low frequencies. Vestibular end-organs: Robust transduction of vestibular hair cells |
[27] | |
| Ush1c; DFNB18 | AAV2/Anc80L65-CMV-Harma1 AAV2/Anc80L65-CMV-Harmb1 |
Ush1c c.216G>A knockin mice (Acadian mutation) | RWM; P0-P1, P10-P12 | Cochlea: High transduction efficiency of both IHCs and OHCs. Normal ABR thresholds in mice injected with harmonin-b1 alone or harmonin-a1/b1 together, particularly at low frequencies. Normal hair bundle morphology along the entire organ of Corti at 6 weeks of age. Vestibular end-organs: Restoration of balance behaviors |
[25] |
| Sans; USH1G | AAV2/1-CAG-Sans-eGFP AAV2/2-CAG-Sans-eGFP AAV2/5-CAG-Sans-eGFP AAV2/8-CAG-Sans-eGFP |
Ush1g−/− mice | RWM; P2.5 | Cochlea: AAV2/1 and AAV2/2 and AAV2/5 injections mostly transduced supporting cells of the organ of Corti. AAV2/8 injection transduced IHCs with greater efficiency at the apex of the cochlea than at the base, whereas OHCs were transduced with roughly the same efficiency at the base and at the apex. Restoration of hair bundle morphology, and improved hearing thresholds. Vestibular end-organs: AAV2/8 transduced the vast majority of vestibular hair cells, restored morphology of stereociliary bundles, and durably rescued balance defects. |
[23] |
| Lhfpl5; DFNB66/67 | Exo-AAV1-CBA-GFP Exo-AAV1-CBA-HA-Lhfpl5 |
Wild-type and Lhfpl5−/− mice | RWM; Cochleostomy; P0-P1 | Cochlea: Both RWM and cochleostomy injection transduced with high efficiently both IHCs and OHCs. Cochleostomy also transduced spiral ganglion neurons and supporting cells. Improved hearing thresholds at frequencies from 4 to 22 kHz. Vestibular end-organs: Robust transduction of vestibular hair cells via both RWM and cochleostomy injections. Restoration of balance behaviors. | [36] |
| Otof; DFNB9 | Dual vector: AAv2/quadY-F-smCBA-Otof N term-AA1-816-SD and AAv2/quadY-F-smCBA-Otof C term-AA817-1992-SA-pA. ALK bridge 3′ to SD and 5′ to SA, respectively. |
Otof−/− mice | RWM; P10, P17, and P30 | High transduction efficiency of IHCs. Durable restoration of otoferlin expression in transduced inner hair cells. Normal ABR thresholds for both click and tone-burst stimuli in treated mice. Restoration of ABR wave I latency, and partial recovery of ABR wave I amplitude. | [73] |
| Dual 5′-AAv2/6-TS and 5′-AAV2/6-hybrid: hbA-CMVe-eGFP-P2A, 5′-Otof CDS-exon 1-21-SD. Dual-3′AAV2/6-TS and 3′-AAV2/6-hybrid: SA-3′Otof CDS-exon 22-46-WPRE-pA. ALK bridge 3′ to SD and 5′ to SA, respectively |
Otof−/− mice | RWM; P6-P7 | Highly efficient transduction of IHCs, supporting cells, and spiral ganglion neurons. Full recovery of fast exocytosis in Otof−/− IHCs. Normal click-evoked ABR thresholds and waveforms (particularly, waves II-V), and increased ABR wave amplitudes. | [74] | |
| Slc26a4; DFNB4 | rAAV2/1-CMV-Slc26a4-tGFP | Slc26a4−/− and Slc26a4tm1Dontuh/tm1Dontuh mice | Otocysts; endolymphatic sac; E12.5 | Cochlea: Restoration of hearing function, but variable hearing phenotype between injected mice. Preservation of both OHCs and IHCs at 5 weeks of age. Vestibular end-organs: Transient pendrin expression prevented enlargement of the membranous labyrinth but failed to restore otoconia formation and the acquisition vestibular function. |
[91] |
RWM, round window membrane; PSCC, posterior semicircular canal; IHCs, inner hair cells; OHCs, outer hair cells: ABR, auditory-evoked brainstem response; CBA, chicken β-actin; SD, splice donor site; SA, acceptor site; TS, trans-splicing; CDS, coding sequences; hbA, human beta-actin promoter; CMVe, cytomegalovirus enhancer; pA, polyadenylation signal; WPRE, woodchuck hepatitis virus post-transcriptional regulatory element; ALK, Alkaline Phosphatase; tGFP, turbo green fluorescent protein.