Human Clinical-Grade Parthenogenetic ESC-Derived Dopaminergic Neurons Recover Locomotive Defects of Nonhuman Primate Models of Parkinson's Disease

Abstract

Clinical application of stem cell derivatives requires clinical-grade cells and sufficient preclinical proof of safety and efficacy, preferably in primates. We previously successfully established a clinical-grade human parthenogenetic embryonic stem cell (hPESC) line, but the suitability of its subtype-specific progenies for therapy is not clear. Here, we compared the function of clinical-grade hPESC-derived midbrain dopaminergic (DA) neurons in two canonical protocols in a primate Parkinson's disease (PD) model. We found that the grafts did not form tumors and produced variable but apparent behavioral improvement for at least 24 months in most monkeys in both groups. In addition, a slight DA increase in the striatum correlates with significant functional improvement. These results demonstrated that clinical-grade hPESCs can serve as a reliable source of cells for PD treatment. Our proof-of-concept findings provide preclinical data for China's first ESC-based phase I/IIa clinical study of PD (ClinicalTrials.gov number NCT03119636).

Keywords: Parkinson's disease; cell therapy; dopaminergic neuron; embryonic stem cell; monkey; nonhuman primate.

Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Figures

Graphical abstract

Figure 1

In Vitro Neural Induction of Clinical-Grade hPESC Q-CTS-hESC-1 (A) Immunofluorescence images of neural markers on days 10, 15, and 42 using EB protocol. n = 3 independent experiments. Scale bars, 50 μm. (B) Quantification of the markers presented in (A). H9 was used as a control. Error bars indicate SEM; n = 3 independent experiments. (C) Immunofluorescence images of neural markers on days 10, 15, and 42 using the FP protocol. n = 3 independent experiments. Scale bars, 50 μm. (D) Quantification of the markers presented in (C). In (B) and (D), data are presented as mean ± SEM (compared with H9, Student's t test); n = 3 independent experiments. (E–H) Electrophysiological analyses of DA neurons on day 70; n = 12 independent experiments. (E) A representative example of Na+ and K+ currents recorded from hPESC-derived neurons. (F) Na+ currents were blocked by 1 μM tetrodotoxin (TTX). (G) Representative action potentials recorded from hPESC-derived neurons in current-clamp mode. (H) A representative trace of spontaneous action potentials sensitive to TTX treatment. See also Figures S1 and S2; Table S1.

Figure 2

The Long-Term Surviving Transplants of hPESC-Derived DA Neurons Exhibited No Tumorigenicity (A) Magnetic resonance imaging (MRI) scans of monkeys #051120 (control group), #061127 (EB-DA group), and #051133 (FP-DA group) implanted with day-42 FP-DA after MPTP lesion (left), 1 week post grafting (middle), and 9 months post grafting (right). The arrows indicate the grafts. (B) Changes in the graft volumes of monkeys (#051120, #061127, and #051133) after cell transplantation for 1 week and 9 months estimated by MRI. Data are presented as mean ± SEM, n = 3. ∗∗p < 0.01 (Student's t test). (C) Monkey brain tissues were obtained for biopsy analysis 9 months post transplantation. The arrows indicate the injection sites. (D) Gross appearance of brain slice. SPIO-labeled grafts can be observed in striatum. The arrows indicate the injection sites. (E) Histological analyses of brain slices with H&E staining. Scale bars, 500 μm. (F) Blood examination results of all the monkeys pre-MPTP lesion, pre-grafting, and 9 months after grafting. ALT, alanine aminotransferase; AST, aspartate aminotransferase; BUN, blood urea nitrogen; CRE, creatinine; LDH, lactate dehydrogenase; NSE, neuron-specific enolase; AFP, α-fetoprotein; CEA, carcinoembryonic antigen. See also Tables S2 and S3.

Figure 3

Phenotypes of Grafted hPESC-Derived DA Neurons 9 Months Post Grafting in MPTP-Induced PD Monkey Hosts (A) Grafted neurons were labeled by Perl's Prussian blue staining. Robust survival and migration of dopamine neurons in the host brains were observed. The boxed area in each image is shown at a higher magnification on the right. Arrowheads indicate grafted neurons. Scale bar, 20 μm. (B) Histological analysis using DAB-developed immunohistochemistry for tyrosine hydroxylase (TH) revealed numbers of TH+ neurons dispersed throughout the graft, which is indistinguishable between the EB-DA and FP-DA groups. Scale bar, 200 μm. (C and D) Expression of TH (C, green; scale bar, 20 μm) and human-specific neural marker NCAM (D, green; scale bar, 50 μm) co-localized with rhodamine (Rho, red). (E) The number of hNCAM+ cells and TH+ cells surviving in each monkey. Data are presented as mean ± SEM, n = 3. (F) Immunostaining for TH (red) and co-expression (green) with GIRK2. Scale bar, 20 μm. (G) The percentage of GIRK2+ cells per TH+ DA neuron. Data are presented as mean ± SEM, n = 3. See also Figure S3.

Figure 4

Behavioral Evaluation in Monkeys after Transplantation of EB-DA and FP-DA Neurons (A) Time course of changes in motor symptom scores of the monkeys injected with culture medium (control group, n = 3), EB-DA neurons (EB-DA group, n = 4), and FP-DA neurons (FP-DA group, n = 3) from MPTP administration to 8 months after transplantation. (B) Behavioral improvement rate of the three groups after transplantation (0–24 months), which revealed a significant increase in the two groups that received EB-DA or FP-DA neurons. Dotted lines are pre-transplantation baseline scores 11 months after MPTP treatment. Significance compared with control group (Student's t test): ∗p < 0.05. Data are represented as means ± SEM (n = 3 animals for the control and FP-DA groups, 4 animals for the EB-DA group). See also Figure S4.

Figure 5

In Vivo Functional Characterization of Grafted Neurons in Putamen and Caudate Nucleus Measured by HPLC Left panels: MRI images of the monkey brains (051131, A and B, and 051133, C and D) at 9 months. The red dots represent the graft. The yellow dashed lines delineate the putamen and caudate nucleus. Right panels: Levels of DA in the putamen (P) and caudate nucleus (CN). 5-Hydroxytryptamine (5-HT) was measured as a control (n = 3 repeated experiments). The rostral and caudal injection sites are shown in the anterior and posterior slices, respectively. Data are represented as means ± SEM (n = 3 repeated experiments). See also Figure S5.