Host-to-graft propagation of inoculated α-synuclein into transplanted human induced pluripotent stem cell-derived midbrain dopaminergic neurons

Serina Gima; Kazuya Oe; Kaneyasu Nishimura; Takashi Ohgita; Haruka Ito; Hiroyuki Kimura; Hiroyuki Saito; Kazuyuki Takata

doi:10.1016/j.reth.2023.12.019

Host-to-graft propagation of inoculated α-synuclein into transplanted human induced pluripotent stem cell-derived midbrain dopaminergic neurons

Regen Ther. 2024 Jan 6:25:229-237. doi: 10.1016/j.reth.2023.12.019. eCollection 2024 Mar.

Authors

Serina Gima¹, Kazuya Oe¹, Kaneyasu Nishimura^{1

2}, Takashi Ohgita³, Haruka Ito¹, Hiroyuki Kimura^{4

5}, Hiroyuki Saito⁶, Kazuyuki Takata¹

Affiliations

¹ Joint Research Laboratory, Division of Integrated Pharmaceutical Science, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan.
² Laboratory of Functional Brain Circuit Construction, Graduate School of Brain Science, Doshisha University, Kyotanabe 610-0394, Japan.
³ Center for Instrumental Analysis, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan.
⁴ Department of Analytical and Bioinorganic Chemistry, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan.
⁵ Division of Probe Chemistry for Disease Analysis/Central Institute for Radioisotope Science, Research Center for Experimental Modeling of Human Disease, Kanazawa University, Kanazawa 920-8640, Japan.
⁶ Laboratory of Biophysical Chemistry, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan.

Abstract

Introduction: Cell therapeutic clinical trials using fetal mesencephalic tissue provided a proof-of-concept for regenerative therapy in patients with Parkinson's disease. Postmortem studies of patients with fetal grafts revealed that α-synuclein⁺ Lewy body (LB)-like inclusions emerged in long-term transplantation and might worsen clinical outcomes even if the grafts survived and innervated in the recipients. Various studies aimed at addressing whether host-derived α-synuclein could be transferred to the grafted neurons to assess α-synuclein⁺ inclusion appearance in the grafts. However, determining whether α-synuclein in the grafted neurons has been propagated from the host is difficult due to the intrinsic α-synuclein expression.

Methods: We induced midbrain dopaminergic (mDA) neurons from human induced pluripotent stem cells (hiPSCs) and transplanted them into the striatum of immunodeficient rats. The recombinant human α-synuclein preformed fibrils (PFFs) were inoculated into the cerebral cortex after transplantation of SNCA^-/- hiPSC-derived mDA neural progenitors into the striatum of immunodeficient rats to evaluate the host-to-graft propagation of human α-synuclein PFFs. Additionally, we examined the incorporation of human α-synuclein PFFs into SNCA^-/- hiPSC-derived mDA neurons using in vitro culture system.

Results: We detected human α-synuclein-immunoreactivity in SNCA^-/- hiPSC-derived mDA neurons that lacked endogenous α-synuclein expression in vitro. Additionally, we observed host-to-graft α-synuclein propagation into the grafted SNCA^-/- hiPSC-derived mDA neurons.

Conclusion: We have successfully proven that intracerebral inoculated α-synuclein PFFs are propagated and incorporated from the host into grafted SNCA^-/- hiPSC-derived mDA neurons. Our results contribute toward the basic understanding of the molecular mechanisms related to LB-like α-synuclein deposit formation in grafted mDA neurons.

Keywords: Cell transplantation; Dopaminergic neurons; Human induced pluripotent stem cells; α-synuclein.