Table 1. Milestones in the development of stem-cell-based therapies for PD.

Year	Cell type	Event
1988	Foetal ventral mesencephalon	First human transplant.
1998	ESCs	Derivation of human ESCs.
2007	iPSCs	First generation of iPSCs.
2008	ESCs	Generation of the first protocol outlining good differentiation into dopaminergic neurons from human ESCs.
2010	iPSCs	First generation of A9 dopaminergic neurons from iPSCs.
	iPSCs	Patient-derived iPSC-derived dopaminergic neurons reduce motor dysfunction in a 6OHDA rat model.
2011	ESCs	Human ESC-derived dopaminergic neurons reverse motor dysfunction in a rodent 6OHDA model.
2014	ESCs	Proof of principle that human ESC-derived dopaminergic progenitors are safe and efficacious in animal models of PD.
2015	Foetal ventral mesencephalon	First TRANSEURO patient grafted.
	Parthenogenetic NSCs	Proof of concept of NSCs in animal models.
2016	Parthenogenetic NSCs	First patient grafted in the ISCO trial.
2017	Parthenogenetic ESCs	First patient grafted with parthenogenetic ESC-derived neural precursors in the Chinese Academy of Sciences trial.
	iPSCs	Proof of principle that iPSC-derived dopaminergic progenitors are safe and efficacious in animal models of PD.
2018	Foetal ventral mesencephalon	Last TRANSEURO patient grafted.
	iPSCs	First CiRA patient grafted with allogenic iPSC-derived dopaminergic progenitors.
	Parthenogenetic ESCs	Publication of proof-of-principle data pertaining to parthenogenetic neural precursors in PD.
2019	Parthenogenetic NSCs	Last patient grafted in the ISCO trial.
2020	iPSCs	First report of safety in a patient grafted with autologous iPSC-derived dopaminergic cells.
In the near future	iPSCs	Start of the SUMMIT for PD Phase-I clinical trial to assess the use of human autologous iPSC-derived dopaminergic progenitors.
	ESCs	Start of the European STEM-PD and NYSTEM-PD Phase-I clinical trial to assess the use of human embryonic stem cell-derived dopaminergic progenitors.