Estradiol Facilitates Functional Integration of iPSC-Derived Dopaminergic Neurons into Striatal Neuronal Circuits via Activation of Integrin α5β1

For cell transplantation therapy for Parkinson's disease (PD) to be realized, the grafted neurons should be integrated into the host neuronal circuit to restore the lost neuronal function. Here, using wheat-germ agglutinin-based transsynaptic tracing, we show that integrin α5 is selectively expressed in striatal neurons that are innervated by midbrain dopaminergic (DA) neurons. In addition, we found that integrin α5β1 was activated by the administration of estradiol-2-benzoate (E2B) in striatal neurons of adult female rats. Importantly, we observed that the systemic administration of E2B into hemi-parkinsonian rat models facilitates the functional integration of grafted DA neurons derived from human induced pluripotent stem cells into the host striatal neuronal circuit via the activation of integrin α5β1. Finally, methamphetamine-induced abnormal rotation was recovered earlier in E2B-administered rats than in rats that received other regimens. Our results suggest that the simultaneous administration of E2B with stem cell-derived DA progenitors can enhance the efficacy of cell transplantation therapy for PD. [Display omitted] •Integrin α5 is expressed in striatal neurons innervated by nigral DA neurons•Administration of E2B activates integrin α5β1 in the rat striatum•E2B facilitates integration of grafted iPSC-derived DA neurons into host striatum Takahashi and colleagues reveal that administration of estradiol-2-benzoate promotes functional integration of iPSC-derived DA neurons into host striatal neuronal circuit via activation of integrin α5 and behavioral recovery of 6-OHDA-lesioned rats. These findings strongly suggest that this therapeutic strategy is advantageous for realizing efficient cell transplantation therapy for Parkinson's disease patients.