Neuronal differentiation potential of human mesenchymal stem cells.

Adult mesenchymal stem cells derived from adipose tissue (A-MSC) have the capacity to differentiate in vitro into mesenchymal as well as endodermal and ectodermal cell lineages. We investigated the neuronal differentiation potential of human A-MSC with a protocol which included sphere formation followed by culture in brain-derived neurotrophic factor (BDNF) and retinoic acid (RA). After 30 days, about 57% of A-MSC showed morphological, immunocytochemical and electrophysiological evidence of initial neuronal differentiation. In fact, A-MSC displayed elongated shape with protrusion of two or three cellular processes, selectively expressed nestin and neuronal molecules (including GABA receptor and tyroxine hydroxilase), but not glial phenotypic markers. Differentiated cells showed negative membrane potential (60 mV), delayed rectifier potassium currents and TTX-sensitive sodium currents. Such changes were stable for at least 7 days after the removal of differentiation medium. In view of these results and the easy accessibility of adipose tissue, A-MSC may be a ready source of adult MSC with neuronal differentiation potential, an useful tool to treat neurodegenerative diseases.