Figure 7: Characterization of iDA neurons.

(a–l) Co-staining of iDA neurons with antibodies against TH and dopaminergic markers AADC (a), ALDH1A1 (b), DAT (c), VMAT2 (d), Pitx3 (e) and Nurr1 (f), or midbrain neuronal markers FoxA2 (g) and engrailed 1 (En1) (h), or synaptic markers PSD95 (i) and syntaxin 1 (j), or markers for mature neurons MAP2 (k) and NeuN (l). Scale bar, 10 μm. (m) The amount of endogenous dopamine in the iDA neurons and the original fibroblasts. *P<0.01, unpaired, two-tailed Student’s t-tests versus fibroblast; n=6 wells from 3 independent experiments. (n) Dopamine release from iDA neurons in Hank’s balanced salt solution (HBSS), HBSS with KCl (56 mM) or Ca²⁺-free HBSS with KCl (56 mM). *P<0.01, unpaired, two-tailed Student’s t-tests versus HBSS without KCl; n=6 wells from 3 independent experiments. (o) KCl-induced dopamine release in the absence or presence of the dopamine D2-class agonist quinpirole (Q, 1 μM). *P<0.01, unpaired, two-tailed Student’s t-tests; n=6. (p) Dopamine uptake by iDA neurons for 5 min in the absence or presence of the selective DAT inhibitor nomifensine (10 μM) or GBR12909 (10 μM). *P<0.01, unpaired, two-tailed Student’s t-tests versus DA alone; n=6 wells from 3 independent experiments. (q, r) Dopamine content (q) or KCl-induced dopamine release (r) in iDA neurons generated with various factors and with or without serum withdrawal. FBS, fetal bovine serum. *P<0.01, unpaired, two-tailed Student’s t-tests versus corresponding condition with FBS; n=6 wells from 3 independent experiments. (s) Voltage-gated Na⁺ and K⁺ currents. (t) Response to current injections. (u) Spontaneous action potentials. (v) Spontaneous excitatory postsynaptic currents. Days indicated were from the start of serum withdrawal.