The Role of Lmx1a in the Differentiation of Human Embryonic Stem Cells into Midbrain Dopamine Neurons in Culture and After Transplantation into a Parkinson's Disease Model

Abstract

Recent studies have provided important insight into the homeoprotein LIM homeobox transcription factor 1␣ (Lmx1a) and its role in the commitment of cells to a midbrain dopamine (mDA) fate in the developing mouse. We show here that Lmx1a also plays a pivotal role in the mDA differentiation of human embryonic stem (hES) cells. Thus, as indicated by small interfering RNA experiments, the transient early expression of Lmx1a is necessary for the coordinated expression of all other dopamine (DA)-specific phenotypic traits as hES cells move from multipotent human neural progenitor cells (hNPs) to more restricted precursor cells in vitro. Moreover, only Lmx1a-specified hNPs have the potential to differentiate into bona fide mDA neurons after transplantation into the 6-hydroxydopamine-treated rat striatum. In contrast, cortical human neuronal precursor cells (HNPCs) and mouse subventricular zone cells do not express Lmx1a or become mDA neurons even when placed in an environment that fosters their DA differentiation in vitro or in vivo. These findings suggest that Lmx1a may be critical to the development of mDA neurons from hES cells and that, along with other key early DA markers (i.e., Aldh1a1), may prove to be extremely useful for the selection of appropriately staged and suitably mDA-specified hES cells for cell replacement in Parkinson's disease. STEM

Autologous mesenchymal stem cell–derived dopaminergic neurons function in parkinsonian macaques

“…We confirmed the coexpression of FOXA2 and GIRK2 in SNc tissue that contains A9 dopaminergic neurons but not in the VTA, which contains A10 dopaminergic neurons. GIRK2/FOXA2 double-positive cells have not been induced from other stem cell sources using existing protocols (44)(45)(46), except for one that manipulates both the sonic hedgehog and WNT signaling pathways (43,47). Recent studies of fetal tissue engrafting in patients with PD or PD model rats have shown that A9 dopaminergic neurons are determinants of successful functional recovery (16,48) and decreased dyskinesia (49) and that they are associated with well-organized synaptic connectivity (16).…”

Human Amniotic Fluid Stem Cells Do Not Differentiate Into Dopamine Neurons In Vitro or After Transplantation In Vivo

“…Brains sections were cut at 30 μm on a freezing microtome and processed for immunocytochemistry as described previously [6,14]. Antibodies were used as above except for the following differences: (β-tubulin III; 1:200), HNA (1:40); GFAP from Chemicon (1:200) and mouse monoclonal anti-CD11 from BD Biosciences (1:25).…”

“…As described previously [14,18], 12 Fischer 344 rats (Taconic) were made Parkinsonian for these studies. Briefl y, rats were anesthetized with sodium pentobarbital [30 mg/kg, intraperitoneally (i.p.…”

“…While adult human bone marrow stromal stem cells (hMSCs) are capable of acquiring some dopaminergic traits, they do not fully trans-differentiate into dopamine (DA) neurons nor do they survive long term transplantation into the brain [3]. Greater success has instead been achieved using human embryonic stem (hES) cells that can be differentiated into neurons of a DA phenotype in vitro and in vivo, and which can ameliorate motor defi cits after transplantation into an animal model of PD [4][5][6][7][8][9][10][11][12][13][14].…”

Induced Pluripotent Stem Cell Technology and Direct Conversion: New Possibilities to Study and Treat Parkinson’s Disease

“…The combination of the three neurodevelopmental factors (BAM) with factors known to be crucially involved in the embryonic development of mDA neurons as well as for their beneficial effect for DA differentiation of ESCs [63][64][65][66][67][68] seem to specifically boost the transdifferentiation towards DA-like neurons. Even though these findings provide a proof of principle for the amazing possibility to directly transdifferentiate/convert somatic cells just by simple forced expression of a specific set of transcription factors, also for iDA neurons a very thorough characterization would be necessary before one could seriously consider their clinical application.…”