Characterization of proliferating cells isolated from human adult spinal cord. A: Phase contrast photograph of cells (passage 4) isolated from the human spinal cord. Most cells display a mesenchymal morphology. Scale bar = 10 μm. B: Proliferation rate of adherent human cells. Y axis represents the cumulative number of doublings measured at each passage. C, D: QPCR analysis of gene expression in spinal cord cells (red bars) and human fetal brain neural stem cells cultured for 3 passages in serum-containing spinal cord cell medium (blue bars). Y axis represents the expression ratio between the indicated messenger and TBP (TATA binding protein) mRNA. C: Mesenchymal and neural markers. D: Mesenchymal and neural transcription factors. Mes: mesenchymal. NSC: neural stem cells. Neu: neurons. Astro: astrocytes. Oligo: oligodendrocytes. N.D: Not detected.