Neuronal Differentiation and Exosome Profiling of Dental Pulp Stem Cells: Unveiling Their Potential for Nerve Repair

Peripheral nerve injuries remain a major clinical problem, and cell-free therapies using stem cell-derived bioproducts have emerged as promising alternatives. This study evaluated the influence of neurogenic differentiation and passage number on the secretomic and exosomal profile of human dental pulp stem cells (hDPCSs). Conditioned media from undifferentiated and neurodifferentiated hDPSCs, and exosomes derived from undifferentiated hDPSCs at passages 4 and 7, were analyzed using multiplex immunoassays, RT-PCR, and scanning electron microscopy (SEM). Neurodifferentiated hDPSCs at early passages secreted higher levels of neurotrophic, angiogenic and immunomodulatory factors, including FGF-2, IL-6, IL-8, and PDGF-AA. Exosomes from early-passage undifferentiated cells showed a more abundant and relevant neuroregenerative mRNA cargo in comparison to the later passages. Both cell types and exosomes adhered to the Reaxon^® nerve guidance conduit, confirming the permissive nature of the materials regarding cells and cellular products, allowing adhesion and survival. Neurite outgrowth assays performed on neurodifferentiated hDPSCs confirmed functional neural behavior. In later passages, a decline in secretory and exosomal activity was noted. These results highlight the relevance of early-passage hDPSCs as a source of bioactive factors and support their application in cell-free approaches for peripheral nerve regeneration.