“Characterisation of mouse and human dental pulp cells for auditory regeneration”

Modern-day regenerative medicine is constantly exploring the development and application of stem cells for cell-based therapies in many conditions and diseases. One of such conditions is deafness, which affects over 360 million people worldwide, frequently caused by irreversible damage to the sensory cells. Therapies which could replace dead or damaged spiral ganglion neurons in deafness are sought as alternatives to the currently limited approaches. In this regard, stem cells from human dental pulp cells (hDPCs) are proposed to be intrinsically neurogenic due to their neural crest origin. Nevertheless, hDPCs have been poorly investigated in the context of auditory nerve regeneration. In the present work, we aimed to obtain a neurogenic population from hDPCs which could be differentiated into auditory neurons. We included mouse incisor dental pulp cells in our experiments, which allowed us to identify conditions that promote a neurogenic phenotype. We established hDPC cultures in serum-free, defined media as a basal condition for growth and propagation, providing pre-clinical advantages to the standard condition containing foetal bovine serum. The specific activity in an auditory regeneration system was tested co-culturing the hDPCs together with denervated cochlear explants ex-vivo. Our results have shown that dental pulp cells cultures can be established in serum-free neurogenic conditions; expressing basal levels of markers related to neural progenitor-, neural- and neural crest cells. Particularly, growing hDPCs as sphere aggregates showed and enhanced neural crest molecular signature and showed differentiation into spiral ganglion-like neurons when co-cultured with cochlear explants. Therefore, we present a comprehensive characterisation of human dental pulp cells under standard and defined culture conditions, their ability to express a neural crest stem signature and provided evidence, for the first time, of their potential to differentiate into spiral ganglion-like neurons in an ex-vivo model of auditory nerve regeneration.