TH and Parkinson disease: By whichever approach, mDANs need to: (i) co-express neuronal (e.g., TUBB3/βIII-tubulin/TUJ1), dopaminergic (e.g., TH [tyrosine hydroxylase]), and midbrain (e.g., FOXA2, LMX1A) markers; (ii) be able to survive in vitro, and elongate axons with evidence of synapses; (iii) be able to synthesize dopamine; (iv) display evidence of electrical activity; (v) have the capability to reverse PD-like symptoms in animal models without side effects if to be used for cell-based therapies [38].