Spontaneous differentiation of porcine neural progenitors in vitro

The pig is the non-primate species that is immunologically closest to humans, and has been considered as an alternative source to human allografts for transplantation. In fact, there has been recent interest in identifying and culturing porcine neural progenitor cells (PNPCs) in vitro, but the long-term culturing has not yet been characterized. Here, we reported the spontaneous differentiation of PNPCs into neuronal and glial cells. For in vitro cultures, the primary cells of the subventricular zone of the forebrain striatum were cultured in the presence of epidermal growth factor and basic fibroblast growth factor to allow the growth of spherical masses that exhibit sustained growth and self-renewal capacity. After growth factor removal, the neurospheres with 10 and 130 days of culture spontaneously differentiated into Tuj1-positive neurons and GFAP-positive astrocytes as seen by double immunocytofluorescence. Molecular characterization using reverse transcription-polymerase chain reaction showed that neurospheres expressed nestin, neuron-specific enolase, and glial fibrillary acidic protein (GFAP). In addition, after cultured in the differentiation medium for 3 months, the growth of neurosphere became slow and displayed cystic structures with the same morphology as that of embryonic bodies derived from embryonic stem cells. It is concluded that PNPCs have the ability to provide an expandable source of neural cells that can develop into neuronal and glial subtypes.