Nanotechnological Regeneration of Spiral Ganglion Neurons with Human Stem Cells

Specific Aim #1: To establish a method for the controlled generation of functional hESC-derived SGNs using diffusible ligands and overexpression of relevant human transcription factors. Approach: We will use extensive molecular profiling and biochemical/electrophysiological analyses to define developmental progression at each stage of differentiation and confirm the identity of hESC-derived cells. Impact: Establishing a method for the controlled generation of fully functional hESC-derived SGNs will provide us with a solid basis for subsequent in vivo experiments in an animal model with the eventual goal of developing human therapies. In addition, the protocol for generating SGNs from hESCs will provide vital information for reprogramming human iPSCs into SGNs. Human iPSCs can be generated from fibroblasts readily harvested from a patient's skin and present no ethical concerns for use in humans. Specific Aim #2: To develop an appropriate stem cell niche for hESC-derived SGNs using a combined biophysical and biochemical approach involving nanotechnology and neurotrophic factors. Approach: We will supply hESC-derived otic neuronal progenitors with neurotrophic factors such as brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) using a bioactive nanofiber gel. Such bioactive nanofiber gels have been shown to promote neurite outgrowth as well as the differentiation of neural progenitor cells into neurons. Cell survival assays, axonal growth assays, and immunohistochemistry will be performed to assess the rates of neuronal differentiation and neurite outgrowth. Impact: Development of a supportive stem cell niche in vitro will provide an ideal local host environment for transplanted stem cells to survive and proliferate in the cochlea. We argue that the use of appropriately differentiated hESC-derived otic neuronal progenitors provided with an ideal niche will be the key to the achievement of safe and successful stem cell-based therapies to regenerate SGNs