OBJECTIVE:We attempted to induce mesenchymal stem cells (MSCs) from human Wharton's jelly (WJ) to differentiate into neuronal progenitor cells, neurons, and auditory hair cells. MATERIALS and METHODS:MSCs were isolated from WJ from human umbilical cords and cultured in medium containing epidermal growth factor and basic fibroblast growth factor. Differentiation into hair cells and neurons was induced using a neurobasal medium containing glial cell-derived neurotrophic factor, brain-derived neurotrophic factor, and neurotrophic factor 3. Fluorescence-activated cell sorting (FACS), immunocytochemistry, and reverse transcription polymerase chain reaction were performed to characterize the differentiated auditory hair cells and neurons. RESULTS:MSCs isolated from human WJ were confirmed by FACS. Double immunocytochemistry confirmed the expression of the hair cell markers myosin VIIA and TRPA1 and the functional marker C-terminal binding protein 2. Differentiation into neurons was revealed using neurofilament and βIII-tubulin markers. Gene expression of neuronal lineage-specific markers confirmed the neuronal differentiation state. CONCLUSION:MSCs from human WJ can be successfully induced to differentiate into auditory hair cells and neurons in vitro.

During brain development, polysialylated (polySia) neural cell adhesion molecules (polySia-NCAMs) modulate cell-cell adhesive interactions involved in synaptogenesis, neural plasticity, myelination, and neural stem cell (NSC) proliferation and differentiation. Our findings show that polySia-NCAM is expressed on NSC isolated from adult guinea pig spiral ganglion (GPSG), and in neurons and Schwann cells after differentiation of the NSC with epidermal, glia, fibroblast growth factors (GFs) and neurotrophins. These differentiated cells were immunoreactive with mAb's to polySia, NCAM, β-III tubulin, nestin, S-100 and stained with BrdU. NSC could regenerate and be differentiated into neurons and Schwann cells. We conclude: (1) polySia is expressed on NSC isolated from adult GPSG and on neurons and Schwann cells differentiated from these NSC; (2) polySia is expressed on neurons primarily during the early stage of neuronal development and is expressed on Schwann cells at points of cell-cell contact; (3) polySia is a functional biomarker that modulates neuronal differentiation in inner ear stem cells. These new findings suggest that replacement of defective cells in the inner ear of hearing impaired patients using adult spiral ganglion neurons may offer potential hope to improve the quality of life for patients with auditory dysfunction and impaired hearing disorders.