Mesenchymal Stem Cells from Nucleus Pulposus and Neural Differentiation Potential: a Continuous Challenge

Mesenchymal stem cells (MSCs) are well-characterized adult stem cells, recently isolated from human nucleus pulposus of degenerate and non-degenerate intervertebral disc. The attention to this source is linked to its embryologic history and cells may conserve a stronger aptitude to neuronal differentiation than other MSCs. Here, MSCs from nucleus pulposus (NP-MSCs) were successfully isolated and characterized for morphology, proliferation, and expression of selected genes. Subsequently, the neuronal differentiation was induced by 10 days of culture with a neuronal medium. NP-MSCs subjected to neural differentiation media (NP-MSCs-N) showed a morphological and biochemical modifications. NP-MSCs-N displayed elongated shape with protrusion, intermediate filaments, microtubules, and electron dense granules and the ability to form neurospheres. Even if they expressed neural markers such as NESTIN, β-TUBULIN III, MAP-2, GAP-43, and ENOLASE-2, the neural differentiated cells did not show neither spontaneous nor evoked intracellular calcium variations compared to the undifferentiated cells, suggesting that cells do not have electric functional properties. Further studies are required in order to get a better understanding and characterization of NP-MSCs and analyzed the molecular mechanisms that regulate their neural differentiation potential.