Fig. 1.

Analysis of ‘human’ immature neuronal cells. A The short tandem repeat (STR) patterns of uncultivated male human donor cells isolated by positive magnetic cell sorting. STR loci tested were D5S818 (1), vWA (2), D13S317 (3), THO1 (4), D7S820 (5), TPOX (6), D16S539 (7), CSF1 (8) and amelogenin (X and Y) [37]. A unique human STR pattern without indication of cross-contamination was obtained. B The cultivated cells reacted with antibodies against neuron specific proteins, anti-human bassoon, a large multidomain protein in the presynaptic active zone (green fluorescence) and anti-human CaC, a voltage-gated Ca²⁺ channel protein (P/Q-type, [.alpha]-1A subunit) – red fluorescence). The antibodies were known to cross-react to other mammalian species such as rats. Insert: scanning electron microscopy of cultured cells. C Chromosome analysis of the cultured cells revealed that the cells are not of human origin. The large acrocentric chromosomes (arrows) and the small metacentric chromosomes (arrowheads) suggest a rat karyotype [67], which D was confirmed by PCR analysis of the cultured neurons.