Human embryonic stem cells overexpressing dopaminergic transcription factors survive and differentiate in the substantia nigra in vivo

Abstract

Background: Degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) in Parkinson's disease (PD) is responsible for motor and cognitive impairment. Replacing the dopaminergic cell population in the SNpc to restore normal dopamine levels is a potential therapeutic approach. However, improving neuronal integration still requires a reliable cell source for transplantation and a profound understanding of the effects of the local microenvironment on transplanted cells. We have previously shown that embryoid bodies (EBs)-derived cells from mouse embryonic stem cells overexpressing the dopaminergic transcription factor Lmx1a engrafted into SNpc develop tyrosine hydroxylase (TH)-positive phenotype. In the present work, we transplanted EBs-derived cells from genetically engineered human embryonic stem cells (hESCs), overexpressing the dopaminergic transcription factors LMX1A, FOXA2, and OTX2 (hESC-LFO). We determined their potential to differentiate into TH-expressing neurons in the SNpc of an in vivo PD model. Methods: EBs-derived cells from genetically the engineered hESCs-LFO cell line were transplanted, and their neuronal differentiation potential was determined in the SNpc of an in vivo PD model with 6-hydroxy dopamine (6-OHDA). Three rat groups were designed as follows: Untreated (healthy rats), sham (rats administered with saline solution), and 6-OHDA (rats lesioned with 6-OHDA). A one-way ANOVA test was performed for statistical analysis. Results: Neural rosettes, a fundamental developmental hallmark of neuroepithelial tissue, were found at 7 and 15 days post-transplantation (dpt) in ~ 70% of the transplanted brains in all three conditions: Untreated, sham, and 6-OHDA. The majority of the neural rosettes corresponded to the lumen formation stage. In comparison, no graft survival was observed in EB transplants derived from unmodified hESCs. Interestingly, at 30 dpt, hESC-LFO engrafted cells showed neuronal morphology and positive immunolabeling for TH in all the brains exhibiting surviving transplants: 10% 6-OHDA rats, 0% sham, and 100% untreated rats. Conclusions: Overall, our results show that overexpression of LFO factors favors short-term survival while strongly initiating neural differentiation of hESC-derived cells in SNpc surviving grafts by forming neural rosettes and differentiating into TH-positive cells.