The main goals of our research are to establish an experimental protocol for coaxing embryonic stem cells into inner ear sensory cells (sensory hair cells). This work has implications on future treatment of hearing loss and balance disorders, for which no current treatment exist. We began with using mouse embryonic stem cells to explore specific experimental conditions that lead to cell differentiation in direction of the inner ear. In the last funding period, we were able to increase the efficacy of this procedure by approximately 10-fold. At the same time, we were able to cut the time needed for a guidance experiment from 2-3 months to 8 days. We have now begun testing whether human embryonic stem cells are also able to follow the same guidance protocol and we found that human cells can also coaxed toward the inner ear lineage with a slightly modified protocol. The efficiency with human cells is comparable to the efficiency experienced with the mouse cells. The time needed for initial differentiation of the human cells into early inner ear is not very much different from the time needed for differentiating mouse cells, but we still need to verify this preliminary result.
In addition to in vitro guidance tests, we have begun with assessing the in vivo potential of mouse and human inner ear precursor cells, which were derived from mouse and human embryonic stem cells. Toward this goal, we have begun to establish a coculture system in which we culture the mouse and human cells inside the developing inner ear of chicken embryos. Before starting with the more complicated in ovo experiments, we decided to first establish a culture system in vitro, which will allow us to perform more pilot tests in a more controlled cell culture environment. Establishment and initial assays in this regard have been conducted in the past funding period and we are optimistic that we will be able to assess the potential of mouse and human embryonic stem cell-derived inner ear cell types using the established in vitro tests in the upcoming funding period.