Rapid generation of OPC-like cells from human pluripotent stem cells for treating spinal cord injury.

Remyelination via the transplantation of oligodendrocyte precursor cells (OPCs) has been considered as a strategy to improve the locomotor deficits caused by traumatic spinal cord injury (SCI). To date, enormous efforts have been made to derive OPCs from human pluripotent stem cells (hPSCs), and significant progress in the transplantation of such cells in SCI animal models has been reported. The current methods generally require a long period of time (>2 months) to obtain transplantable OPCs, which hampers their clinical utility for patients with SCI. Here we demonstrate a rapid and efficient method to differentiate hPSCs into neural progenitors that retain the features of OPCs (referred to as OPC-like cells). We used cell sorting to select A2B5-positive cells from hPSC-derived neural rosettes and cultured the selected cells in the presence of signaling cues, including sonic hedgehog, PDGF and insulin-like growth factor-1. This method robustly generated neural cells positive for platelet-derived growth factor receptor-α (PDGFRα) and NG2 (~90%) after 4 weeks of differentiation. Behavioral tests revealed that the transplantation of the OPC-like cells into the spinal cords of rats with contusive SCI at the thoracic level significantly improved hindlimb locomotor function. Electrophysiological assessment revealed enhanced neural conduction through the injury site. Histological examination showed increased numbers of axon with myelination at the injury site and graft-derived myelin formation with no evidence of tumor formation. Our method provides a cell source from hPSCs that has the potential to recover motor function following SCI.

Highly pure and expandable PSA-NCAM-positive neural precursors from human ESC and iPSC-derived neural rosettes.

Homogeneous culture of neural precursor cells (NPCs) derived from human pluripotent stem cells (hPSCs) would provide a powerful tool for biomedical applications. However, previous efforts to expand mechanically dissected neural rosettes for cultivation of NPCs remain concerns regarding non-neural cell contamination. In addition, several attempts to purify NPCs using cell surface markers have not demonstrated the expansion capability of the sorted cells. In the present study, we show that polysialic acid-neural cell adhesion molecule (PSA-NCAM) is detected in neural rosette cells derived from hPSCs, and employ PSA-NCAM as a marker for purifying expandable primitive NPCs from the neural rosettes. PSA-NCAM-positive NPCs (termed hNPC(PSA-NCAM+)) were isolated from the heterogeneous cell population of mechanically harvested neural rosettes using magnetic-based cell sorting. The hNPC(PSA-NCAM+) extensively expressed neural markers such as Sox1, Sox2, Nestin, and Musashi-1 (80∼98% of the total cells) and were propagated for multiple passages while retaining their primitive characteristics in our culture condition. Interestingly, PSA-NCAM-negative cells largely exhibited characteristics of neural crest cells. The hNPC(PSA-NCAM+) showed multipotency and responsiveness to instructive cues towards region-specific neuronal subtypes in vitro. When transplanted into the rat striatum, hNPC(PSA-NCAM+) differentiated into neurons, astrocytes, and oligodendrocytes without particular signs of tumorigenesis. Furthermore, Ki67-positive proliferating cells and non-neural lineage cells were rarely detected in the grafts of hNPC(PSA-NCAM+) compared to those of neural rosette cells. Our results suggest that PSA-NCAM-mediated cell isolation provides a highly expandable population of pure primitive NPCs from hPSCs that will lend themselves as a promising strategy for drug screening and cell therapy for neurodegenerative disorders.

Behavioral improvement after transplantation of neural precursors derived from embryonic stem cells into the globally ischemic brain of adolescent rats.

PURPOSE: We intended to determine whether transplanted neural precursors, derived from mouse embryonic stem (ES) cells, can migrate and differentiate into mature neurons and glial cells in damaged brains and improve functional deficits caused by global cerebral ischemic injury in adolescent rats. METHODS: Global ischemia was induced using the four-vessel occlusion method. ES cells that display enhanced expression of yellow fluorescent protein were co-cultured in N2 supplemented media with PA6 cells that had stromal derived inducing activity. Neural precursor cells were directly transplanted bilaterally into hippocampal C3 areas 2 weeks after induction of global ischemia. Assessments of the Morris water-maze test at eight weeks and, the Open field activity levels at two, four, six and eight weeks after transplantation were carried out according to standard methods. RESULTS: From neural precursors, we were able to generate neural lineages, including neurons and glial cells in vitro. Eight weeks following transplantation, cellular migration as well as generation of neural cells including neurons, astrocytes, and oligodendrocytes developed from the grafted ES cell-derived neural precursors were observed. Cell-transplanted animals exhibited enhanced functional recovery on sensorimotor and behavioral tests, compared to vehicle-treated control animals. CONCLUSION: Therefore, transplantation of mouse ES cell-derived neural precursor cells shows promise for improving recovery after global ischemia in adolescent rats.