Parkinson's disease (PD) is one of neurodegenerative disorders, for which development of a cell transplantation therapy is expected. Recently, new technologies for induction of dopaminergic (DA) neurons from pluripotent stem cells (ESCs/iPSCs) has been innovated toward clinical application. In addition, it is important to form the functional synapse between grafted-iPSC-derived DA neurons and host neurons for successful transplantation therapy. Here, we hypothesize that these host neurons are striatal neurons that are innervated from midbrain DA neurons in normal state. Since, it is to be desired that grafted-DA neurons can be replaced the function of authentic midbrain DA neurons. Therefore, our first aim is characterization of the host neurons that should be formed the functional synapse with grafted-DA neurons. In addition, identification of the cell adhesion molecules to play a role for the functional synaptic formation between midbrain DA neurons and striatal neurons strongly contributes to increase the synaptic formation between grafted-DA neurons and host striatal neurons.
Here, we showed that histological characteristics of striatal neurons that are innervated from midbrain DA neurons in normal mouse brain using trans-synaptic tracer, wheat-germ agglutinin (WGA). WGA+ cell bodies could be observed in several striatal neurons, when WGA was injected into substantia nigra par compact (SNpc). Then, we investigated several neuronal markers that were co-stained with WGA, and calculate the number and ratio of these neurons. Finally, we revealed main populations of striatal neurons that innervated from midbrain DA neurons in normal state.