Survival of human embryonic stem cells implanted in the guinea pig auditory epithelium

Abstract

Hair cells in the mature cochlea cannot spontaneously regenerate. One potential approach for restoring hair cells is stem cell therapy. However, when cells are transplanted into scala media (SM) of the cochlea, they promptly die due to the high potassium concentration. We previously described a method for conditioning the SM to make it more hospitable to implanted cells and showed that HeLa cells could survive for up to a week using this method. Here, we evaluated the survival of human embryonic stem cells (hESC) constitutively expressing GFP (H9 Cre-LoxP) in deaf guinea pig cochleae that were pre-conditioned to reduce potassium levels. GFP-positive cells could be detected in the cochlea for at least 7 days after the injection. The cells appeared spherical or irregularly shaped, and some were aggregated. Flushing SM with sodium caprate prior to transplantation resulted in a lower proportion of stem cells expressing the pluripotency marker Oct3/4 and increased cell survival. The data demonstrate that conditioning procedures aimed at transiently reducing the concentration of potassium in the SM facilitate survival of hESCs for at least one week. During this time window, additional procedures can be applied to initiate the differentiation of the implanted hESCs into new hair cells.

Potential of Gene and Cell Therapy for Inner Ear Hair Cells

“…These two techniques were used in HeLa cells [ 84 ], which are more robust than stem cells and survived for at least 7 days following treatment. While the successful survival of human embryonic stem cells was also reported, it was not maintained for >1 day [ 85 ]. More favorable outcome was shown to be feasible when an additional conditioning procedure, the addition of sodium caprate, was included [ 86 , 87 ].…”

“…Sodium caprate results in a temporary disruption of the tight junctions of the auditory epithelium. When used together with a potassium-lowering method, sodium caprate supported transplanted stem cell survival for at least seven days [ 85 ].…”

Severe streptomycin ototoxicity in the mouse utricle leads to a flat epithelium but the peripheral neural degeneration is delayed

“…The slow degeneration of neural components may benefit the re-innervation of new HCs. Feasibility for implanting exogenous cells has been demonstrated for the auditory FE (Lee et al, 2017; Park et al, 2014) and might also be developed for the vestibular organs. It may still be necessary to follow stem cell transplantation with protocols for inducing the transdifferentiation of exogenous cells into vestibular HCs and SCs.…”

Stem Cell-Based Therapeutic Approaches to Restore Sensorineural Hearing Loss in Mammals

“…Lee et al address this issue by preconditioning the scala media to reduce the potassium concentration before implanting the hESCs in the deaf guinea pig cochlea. Their results showed the increased survival of hESCs in the cochlea; however, some stem cells lose their pluripotency and differentiation ability as noted by the lower expression of the Oct3/4 marker [78]. The primary objective of this study is to figure out whether the hESCs survived after implantation in the animal model.…”

“…Therefore, it is important to adopt the methods that create a more hospitable environment in the cochlea. There are few strategies to do so, such as replacing the scala media fluid with the more hostile media to stem cells, systemic administration of loop diuretic drug to lower the potassium concentration, and the use of sodium caprate that disrupts the tight junctions in the cochlea [ 77 , 78 ].…”