Docosahexaenoic Acid Promotes Dopaminergic Differentiation in Induced Pluripotent Stem Cells and Inhibits Teratoma Formation in Rats with Parkinson-Like Pathology

Recent updates on allogeneic CAR-T cells in hematological malignancies

CAR-T cell therapy is known as an effective therapy in patients with hematological malignancies. Since 2017, several autologous CAR-T cell (auto-CAR-T) drugs have been approved by the US Food and Drug Administration (FDA) for the treatment of some kinds of relapsed/refractory hematological malignancies. However, some patients fail to respond to these drugs due to high manufacturing time, batch-to-batch variation, poor quality and insufficient quantity of primary T cells, and their insufficient expansion and function. CAR-T cells prepared from allogeneic sources (allo-CAR-Ts) can be an alternative option to overcome these obstacles. Recently, several allo-CAR-Ts have entered into the early clinical trials. Despite their promising preclinical and clinical results, there are two main barriers, including graft-versus-host disease (GvHD) and allo-rejection that may decline the safety and efficacy of allo-CAR-Ts in the clinic. The successful development of these products depends on the starter cell source, the gene editing method, and the ability to escape immune rejection and prevent GvHD. Here, we summarize the gene editing technologies and the potential of various cell sources for developing allo-CAR-Ts and highlight their advantages for the treatment of hematological malignancies. We also describe preclinical and clinical data focusing on allo-CAR-T therapy in blood malignancies and discuss challenges and future perspectives of allo-CAR-Ts for therapeutic applications.

Omega-3 polyunsaturated fatty acids and Parkinson's disease: A systematic review of animal studies

Parkinson's disease (PD) is the second most common neurodegenerative disorder. The primary pathological features of PD include the presence of α-synuclein aggregates and Lewy bodies, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Recently, omega-3 fatty acids (ω-3 PUFAs) have been under investigation as a preventive and/or therapeutic strategy for PD, primarily owing to their antioxidant and anti-inflammatory properties. Therefore, the objective of this study was to conduct a systematic review of the literature, focusing on studies that assessed the effects of ω-3 PUFAs in rodent models mimicking human PD. The search was performed using the terms "Parkinson's disease," "fish oil," "omega 3," "docosahexaenoic acid," and "eicosapentaenoic acid" across databases PUBMED, Web of Science, Science Direct, Scielo, and Google Scholar. Following analysis based on predefined inclusion and exclusion criteria, 39 studies were included. Considering behavioral parameters, pathological markers of the disease, quantification of ω-3 PUFAs in the brain, as well as anti-inflammatory, antioxidant, and anti-apoptotic effects, it can be observed that ω-3 PUFAs exhibit a potential neuroprotective effect in PD. In summary, this systematic review presents significant scientific evidence regarding the effects and mechanisms underlying the neuroprotective properties of ω-3 PUFAs, offering valuable insights for the development of future clinical investigations.

Neuroprotective effects of DHA-derived peroxidation product 4(RS)-4-F4t-neuroprostane on microglia

The abundance of docosahexaenoic acid (DHA) in brain membrane phospholipids has stimulated studies to explore its role in neurological functions. Upon released from phospholipids, DHA undergoes enzymatic reactions resulting in synthesis of bioactive docosanoids and prostanoids. However, these phospholipids are also prone to non-enzymatic reactions leading to more complex pattern of metabolites. A non-enzymatic oxidized product of DHA, 4(RS)-4-F_4t-Neuroprostane (44FNP), has been identified in cardiac and brain tissues. In this study, we examined effects of the 44FNP on oxidative and inflammatory responses in microglial cells treated with lipopolysaccharide (LPS). The 44FNP attenuated LPS-induced production of reactive oxygen species (ROS) in both primary and immortalized microglia (BV2). It also attenuated LPS-induced inflammation through suppressing NFκB-p65 and levels of iNOS and TNFα. In addition, 44FNP also suppressed LPS-induced mitochondrial dysfunction and upregulated the Nrf2/HO-1 antioxidative pathway. In sum, these findings with microglial cells demonstrated neuroprotective effects of this 44FNP and shed light into the potential of nutraceutical therapy for neurodegenerative diseases.

Neuroprotective Effect of Dioscin against Parkinson’s Disease via Adjusting Dual-Specificity phosphatase 6(DUSP6)-Mediated Oxidative Stress

Exploration of lead compounds against Parkinson’s disease (PD), a neurodegenerative disease, is of great important. Dioscin, a bioactive natural product, shows various pharmacological effects. However, the activities and mechanisms of dioscin against PD have not been well investigated. In this study, the tests on 6-hydroxydopamine (6-OHDA)-induced PC12 cells and rats were carried out. The results showed that dioscin dramatically improved cell viability, decreased reactive oxygen species (ROS) levels, improved motor behavior and tyrosine hydroxylase(TH) levels and restored the levels of glutathione (GSH) and malondialdehyde (MDA) in rats. Mechanism investigation showed that dioscin not only markedly increased the expression level of dual- specificity phosphatase 6 (DUSP6) by 1.87-fold in cells and 2.56-fold in rats, and decreased phospho-extracellular regulated protein kinases (p-ERK) level by 2.12-fold in cells and 2.34-fold in rats, but also increased the levels of nuclear factor erythroid2-related factor 2 (Nrf2), hemeoxygenase-1 (HO-1), superoxide dismutase (SOD) and decreased the levels of kelch-1ike ECH-associated protein l (Keap1) in vitro and in vivo. Furthermore, DUSP6 siRNA transfection experiment in PC12 cells validated the protective effects of dioscin against PD via regulating DUSP6 to adjust the Keap1/Nrf2 pathway. Our data supported that dioscin has protection against PD in regulating oxidative stress via DUSP6 signal, which should be considered as an efficient candidate for the treatment of PD in the future.

Functionalized Nanocellulose Drives Neural Stem Cells toward Neuronal Differentiation

Transplantation of differentiated and fully functional neurons may be a better therapeutic option for the cure of neurodegenerative disorders and brain injuries than direct grafting of neural stem cells (NSCs) that are potentially tumorigenic. However, the differentiation of NSCs into a large population of neurons has been a challenge. Nanomaterials have been widely used as substrates to manipulate cell behavior due to their nano-size, excellent physicochemical properties, ease of synthesis, and versatility in surface functionalization. Nanomaterial-based scaffolds and synthetic polymers have been fabricated with topology resembling the micro-environment of the extracellular matrix. Nanocellulose materials are gaining attention because of their availability, biocompatibility, biodegradability and bioactivity, and affordable cost. We evaluated the role of nanocellulose with different linkage and surface features in promoting neuronal differentiation. Nanocellulose coupled with lysine molecules (CNC-Lys) provided positive charges that helped the cells to attach. Embryonic rat NSCs were differentiated on the CNC-Lys surface for up to three weeks. By the end of the three weeks of in vitro culture, 87% of the cells had attached to the CNC-Lys surface and more than half of the NSCs had differentiated into functional neurons, expressing endogenous glutamate, generating electrical activity and action potentials recorded by the multi-electrode array.

PLA2G6 mutations cause motor dysfunction phenotypes of young-onset dystonia-parkinsonism type 14 and can be relieved by DHA treatment in animal models

Parkinson's disease (PD), the most common neurodegenerative motor disorder, is currently incurable. Although many studies have provided insights on the substantial influence of genetic factors on the occurrence and development of PD, the molecular mechanism underlying the disease is largely unclear. Previous studies have shown that point mutations in the phospholipase A2 group VI gene (PLA2G6) correlate with young-onset dystonia-parkinsonism type 14 (PARK14). However, limited information is available regarding the pathogenic role of this gene and the mechanism underlying its function. To study the role of PLA2G6 mutations, we first used zebrafish larvae to screen six PLA2G6 mutations and revealed that injection of D331Y, T572I, and R741Q mutation constructs induced phenotypes such as motility defects and reduction in dopaminergic neurons. The motility defects could be alleviated by treatment with L-3, 4-dihydroxyphenylalanine (L-dopa), indicating that these mutations are pathological for PARK14 symptoms. Furthermore, the injection of D331Y and T572I mutation constructs reduced phospholipase activity of PLA2G6 and its lipid metabolites, which confirmed that these two mutations are loss-of-function mutations. Metabolomic analysis revealed that D331Y or T572I mutation led to higher phospholipid and lower docosahexaenoic acid (DHA) levels, indicating that reduced DHA levels are pathological for defective motor functions. Further, a dietary DHA supplement relieved the motility defects in PLA2G6^D331Y/D331Y knock-in mice. This result revealed that the D331Y mutation caused defective PLA2G6 phospholipase activity and consequently reduced the DHA level, which is the pathogenic factor responsible for PARK14. The results of this study will facilitate the development of therapeutic strategies for PARK14.

Tributyltin Alters Calcium Levels, Mitochondrial Dynamics, and Activates Calpains Within Dorsal Root Ganglion Neurons

Tributyltin (TBT) remains a global health concern. The primary route of human exposure to TBT is either through ingestion or skin absorption, but TBT's effects on the peripheral nervous system have still not been investigated. Therefore, we exposed in vitro sensory dorsal root ganglion (DRG) neurons to TBT at a concentration of 50-200 nM, which is similar to the observed concentrations of TBT in human blood samples. We observed that TBT causes extensive axon degeneration and neuronal death in the DRG neurons. Furthermore, we discovered that TBT causes an increase in both cytosolic and mitochondrial calcium levels, disrupts mitochondrial dynamics, decreases neuronal ATP levels, and leads to the activation of calpains. Additional experiments demonstrated that inhibition of calpain activation prevented TBT-induced fragmentation of neuronal cytoskeletal proteins and neuronal cell death. Thus, we conclude that calpain activation is the key executioner of TBT-induced peripheral neurodegeneration.

Docosahexaenoic and Arachidonic Acids as Neuroprotective Nutrients throughout the Life Cycle

The role of docosahexaenoic acid (DHA) and arachidonic acid (AA) in neurogenesis and brain development throughout the life cycle is fundamental. DHA and AA are long-chain polyunsaturated fatty acids (LCPUFA) vital for many human physiological processes, such as signaling pathways, gene expression, structure and function of membranes, among others. DHA and AA are deposited into the lipids of cell membranes that form the gray matter representing approximately 25% of the total content of brain fatty acids. Both fatty acids have effects on neuronal growth and differentiation through the modulation of the physical properties of neuronal membranes, signal transduction associated with G proteins, and gene expression. DHA and AA have a relevant role in neuroprotection against neurodegenerative pathologies such as Alzheimer's disease and Parkinson's disease, which are associated with characteristic pathological expressions as mitochondrial dysfunction, neuroinflammation, and oxidative stress. The present review analyzes the neuroprotective role of DHA and AA in the extreme stages of life, emphasizing the importance of these LCPUFA during the first year of life and in the developing/prevention of neurodegenerative diseases associated with aging.

Evaluating Novel RXR Agonists That Induce ApoE and Tyrosine Hydroxylase in Cultured Human Glioblastoma Cells

There is considerable interest in identifying effective and safe drugs for neurodegenerative disorders. Cell culture and animal model work have demonstrated that modulating gene expression through RXR-mediated pathways may mitigate or reverse cognitive decline. However, because RXR is a dimeric partner for several transcription factors, activating off-target transcription is a concern with RXR ligands (rexinoids). This off-target gene modulation leads to unwanted side effects that can include low thyroid function and significant hyperlipidemia. There is a need to develop rexinoids that have binding specificity for subsets of RXR heterodimers, to drive desired gene modulation, but that do not induce spurious effects. Herein, we describe experiments in which we analyze a series of novel and previously reported rexinoids for their ability to modulate specific gene pathways implicated in neurodegenerative disorders employing a U87 cell culture model. We demonstrate that, compared to the FDA-approved rexinoid bexarotene (1), several of these compounds are equally or more effective at stimulating gene expression via LXREs or Nurr1/NBREs and are superior at inducing ApoE and/or tyrosine hydroxylase (TH) gene and protein expression, including analogs 8, 9, 13, 14, 20, 23, and 24, suggesting a possible therapeutic role for these compounds in Alzheimer's or Parkinson's disease (PD). A subset of these potent RXR agonists can synergize with a presumed Nurr1 ligand and antimalarial drug (amodiaquine) to further enhance Nurr1/NBREs-directed transcription. This novel discovery has potential clinical implications for treatment of PD since it suggests that the combination of an RXR agonist and a Nurr1 ligand can significantly enhance RXR-Nurr1 heterodimer activity and drive enhanced therapeutic expression of the TH gene to increase endogenous synthesis of dopamine. These data indicate that is it possible and prudent to develop novel rexinoids for testing of gene expression and side effect profiles for use in potential treatment of neurodegenerative disorders, as individual rexinoids can have markedly different gene expression profiles but similar structures.

Conditioned medium from Endothelial Progenitor Cells promotes number of dopaminergic neurons and exerts neuroprotection in cultured ventral mesencephalic neuronal progenitor cells

Transplantation of stem and progenitor cells offers a promising tool for brain repair in the context of neuropathological disorders including Parkinson's disease. There is growing proof that the capacity of adult stem and progenitor cells for tissue regeneration relies rather on the release of paracrine factors than on their cell replacement properties. In line with this notion, we have previously reported that conditioned medium (CM) collected from cultured Endothelial Progenitor Cells (EPC) stimulated survival of striatal neurons. In the present study we investigated whether EPC-CM promotes survival of cultured midbrain progenitor cells. For that purpose primary cultures from fetal rat embryonic ventral mesencephalon (VM) were prepared and grown for 7 days in vitro (DIV). EPC-CM was administered from DIV5-7. First, we found that EPC-CM treatment resulted in significantly increased cell densities of TH-ir neurons. Interestingly, this effect was no longer seen after proteolytic digestion of the EPC-CM. EPC-CM also significantly increased densities of beta-III-tubulin positive neurons and lba-1-ir microglial cells. The effect on dopaminergic neurons was not due to higher cell proliferation as no incorporation of EdU was observed in TH-ir cells. Importantly, EPC-CM exerted neuroprotection against MPP+ induced toxicity as in vitro model of Parkinson's disease. Taken together, our findings identified EPC-CM as a powerful tool to promote survival of cultured VM neurons and further support the importance of paracrine factors in the actions of stem and progenitor cells for brain repair.

Decellularized Wharton's jelly extracellular matrix as a promising scaffold for promoting hepatic differentiation of human induced pluripotent stem cells

Liver tissue engineering as a therapeutic option for restoring of damaged liver function has a special focus on using native decellularized liver matrix, but there are limitations such as the shortage of liver donor. Therefore, an appropriate alternative scaffold is needed to circumvent the donor shortage. This study was designed to evaluate hepatic differentiation of human induced pluripotent stem cells (hiPSCs) in decellularized Wharton's jelly (WJ) matrix as an alternative for native liver matrix. WJ matrices were treated with a series of detergents for decellularization. Then hiPSCs were seeded into decellularized WJ scaffold (DWJS) for hepatic differentiation by a defined induction protocol. The DNA quantitative assay and histological evaluation showed that cellular and nuclear materials were efficiently removed and the composition of extracellular matrix was maintained. In DWJS, hiPSCs‐derived hepatocyte‐like cells (hiPSCs‐Heps) efficiently entered into the differentiation phase (G1) and gradually took a polygonal shape, a typical shape of hepatocytes. The expression of hepatic‐associated genes (albumin, TAT, Cytokeratin19, and Cyp7A1), albumin and urea secretion in hiPSCs‐Heps cultured into DWJS was significantly higher than those cultured in the culture plates (2D). Altogether, our results suggest that DWJS could provide a proper microenvironment that efficiently promotes hepatic differentiation of hiPSCs.

Metabolic studies of synaptamide in an immortalized dopaminergic cell line

INTRODUCTION

Synaptamide, the N-acylethanolamine of docosahexaenoic acid (DHA), is structurally similar to the endocannabinoid N-arachidonoylethanolamine, anandamide. It is an endogenous ligand at the orphan G-protein coupled receptor 110 (GPR110; ADGRF1), and induces neuritogenesis and synaptogenesis in hippocampal and cortical neurons, as well as neuronal differentiation in neural stem cells.

PURPOSE

Our goal was to characterize the metabolic fate (synthesis and metabolism) of synaptamide in a dopaminergic cell line using immortalized fetal mesencephalic cells (N27 cells). Both undifferentiated and differentiating N27 cells were used in this study in an effort to understand synaptamide synthesis and metabolism in developing and adult cells.

METHODS

Radiotracer uptake and hydrolysis assays were conducted in N27 cells incubated with [1-¹⁴C]DHA or with one of two radioisotopomers of synaptamide: [α,β-¹⁴C₂]synaptamide and [1-¹⁴C-DHA]synaptamide.

RESULTS

Neither differentiated nor undifferentiated N27 cells synthesized synaptamide from radioactive DHA, but both rapidly incorporated radioactivity from exogenous synaptamide into membrane phospholipids, regardless of which isotopomer was used. Pharmacological inhibition of fatty acid amide hydrolase (FAAH) reduced formation of labeled phospholipids in undifferentiated but not differentiated cells.

CONCLUSIONS

In undifferentiated cells, synaptamide uptake and metabolism is driven by its enzymatic hydrolysis (fatty acid amide hydrolase; FAAH), but in differentiating cells, the process seems to be FAAH independent. We conclude that differentiated and undifferentiated N27 cells utilize synaptamide via different mechanisms. This observation could be extrapolated to how different mechanisms may be in place for synaptamide uptake and metabolism in developing and adult dopaminergic cells.

The Role of Lipids in Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disease characterized by a progressive loss of dopaminergic neurons from the nigrostriatal pathway, formation of Lewy bodies, and microgliosis. During the past decades multiple cellular pathways have been associated with PD pathology (i.e., oxidative stress, endosomal-lysosomal dysfunction, endoplasmic reticulum stress, and immune response), yet disease-modifying treatments are not available. We have recently used genetic data from familial and sporadic cases in an unbiased approach to build a molecular landscape for PD, revealing lipids as central players in this disease. Here we extensively review the current knowledge concerning the involvement of various subclasses of fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, and lipoproteins in PD pathogenesis. Our review corroborates a central role for most lipid classes, but the available information is fragmented, not always reproducible, and sometimes differs by sex, age or PD etiology of the patients. This hinders drawing firm conclusions about causal or associative effects of dietary lipids or defects in specific steps of lipid metabolism in PD. Future technological advances in lipidomics and additional systematic studies on lipid species from PD patient material may improve this situation and lead to a better appreciation of the significance of lipids for this devastating disease.

Nutritional Regulators of Bcl-xL in the Brain

B-cell lymphoma-extra large (Bcl-xL) is an anti-apoptotic Bcl-2 protein found in the mitochondrial membrane. Bcl-xL is reported to support normal brain development and protects neurons against toxic stimulation during pathological process via its roles in regulation of mitochondrial functions. Despite promising evidence showing neuroprotective properties of Bcl-xL, commonly applied molecular approaches such as genetic manipulation may not be readily applicable for human subjects. Therefore, findings at the bench may be slow to be translated into treatments for disease. Currently, there is no FDA approved application that specifically targets Bcl-xL and treats brain-associated pathology in humans. In this review, we will discuss naturally occurring nutrients that may exhibit regulatory effects on Bcl-xL expression or activity, thus potentially providing affordable, readily-applicable, easy, and safe strategies to protect the brain.

Dedifferentiation of human uterine polyp stem cells into embryo-like cells during inducing pluripotency

By introduction of Oct4, Sox2, Klf4 and cMyc, human adult somatic cells can be reprogrammed into embryonic stem cell capable of pluripotent differentiation. In several lines of human endometrial polyp- and cervical polyp-mesenchymal stem cells (EPMSCs and CPMSC), we showed introduction of the four transcription factors led to a dedifferentiation of these cells into early embryo-like cells in three days, ranging from one-cell, two-cell, four-cell embryos, and morula to blastocyst. These early embryo-like cells resembled human early embryo derived from in vitro fertilization (IVF) in morphology, and hatching activity. These cells also expressed hypoblast (GATA4) and trophoblast (Cdx2) markers. After culturing the embryo-like cells for one month, the induced pluripotency stem cells (iPSC) could be formed (proved by pluripotency gene expression, by in vitro and in vivo differentiation). C/EBPα expression was also increased in uterine polyps. In contrast, MSCs derived from normal endometrium could not be induced to dedifferentiation to such early embryo-like cells. We conclude that EPMSCs and CPMSCs could be dedifferentiated to early embryo-like cells by the iPSC cocktail. This suggests that polyps of the organ derived from Mullerian duct may harbor epigenetic markers making them vulnerable to reprogramming to the earliest developmental stage. This study provides a simple model to derive early human embryo-like cells by in vitro.

Promoting Induced Pluripotent Stem Cell-driven Biomineralization and Periodontal Regeneration in Rats with Maxillary-Molar Defects using Injectable BMP-6 Hydrogel

Periodontal disease may cause considerable destruction of alveolar bone, periodontal ligaments (PDLs) and cementum and even lead to progressive oral dysfunction. Periodontal tissue regeneration is the ultimate goal of periodontal disease treatment to reconstruct both structures and functions. However, the regenerative efficiency is low, possibly due to the lack of a proper periodontal microenvironment. In this study, we applied an injectable and thermosensitive chitosan/gelatin/glycerol phosphate hydrogel to provide a 3D environment for transplanted stem cells and to enhance stem cell delivery and engraftment. The iPSCs-BMP-6-hydrogel complex promoted osteogenesis and the differentiation of new connective tissue and PDL formation. In animal models of maxillary-molar defects, the iPSCs-BMP-6-hydrogel-treated group showed significant mineralization with increased bone volume, trabecular number and trabecular thickness. Synergistic effects of iPSCs and BMP-6 increased both bone and cementum formation. IPSCs-BMP-6-hydrogel-treated animals showed new bone synthesis (increased ALP- and TRAP-positive cells), new PDL regeneration (shown through Masson’s trichrome staining and a qualification assay), and reduced levels of inflammatory cytokines. These findings suggest that hydrogel-encapsulated iPSCs combined with BMP-6 provide a new strategy to enhance periodontal regeneration. This combination not only promoted stem cell-derived graft engraftment but also minimized the progress of inflammation, which resulted in highly possible periodontal regeneration.

A post-transcriptional program coordinated by CSDE1 prevents intrinsic neural differentiation of human embryonic stem cells

While the transcriptional network of human embryonic stem cells (hESCs) has been extensively studied, relatively little is known about how post-transcriptional modulations determine hESC function. RNA-binding proteins play central roles in RNA regulation, including translation and turnover. Here we show that the RNA-binding protein CSDE1 (cold shock domain containing E1) is highly expressed in hESCs to maintain their undifferentiated state and prevent default neural fate. Notably, loss of CSDE1 accelerates neural differentiation and potentiates neurogenesis. Conversely, ectopic expression of CSDE1 impairs neural differentiation. We find that CSDE1 post-transcriptionally modulates core components of multiple regulatory nodes of hESC identity, neuroectoderm commitment and neurogenesis. Among these key pro-neural/neuronal factors, CSDE1 binds fatty acid binding protein 7 (FABP7) and vimentin (VIM) mRNAs, as well as transcripts involved in neuron projection development regulating their stability and translation. Thus, our results uncover CSDE1 as a central post-transcriptional regulator of hESC identity and neurogenesis.

Unlike transcriptional regulation of hESC identity, little is known post-transcriptionally. Here, the authors show that the RNA binding protein CSDE1 regulates core components of hESC identity, neurectoderm commitment and neurogenesis to maintain pluripotency and prevent neural differentiation.

Docosahexaenoic acid (DHA) enhances the therapeutic potential of neonatal neural stem cell transplantation post-Traumatic brain injury

Traumatic Brain Injury (TBI) is a major cause of death and disability worldwide with 1.5 million people inflicted yearly. Several neurotherapeutic interventions have been proposed including drug administration as well as cellular therapy involving neural stem cells (NSCs). Among the proposed drugs is docosahexaenoic acid (DHA), a polyunsaturated fatty acid, exhibiting neuroprotective properties. In this study, we utilized an innovative intervention of neonatal NSCs transplantation in combination with DHA injections in order to ameliorate brain damage and promote functional recovery in an experimental model of TBI. Thus, NSCs derived from the subventricular zone of neonatal pups were cultured into neurospheres and transplanted in the cortex of an experimentally controlled cortical impact mouse model of TBI. The effect of NSC transplantation was assessed alone and/or in combination with DHA administration. Motor deficits were evaluated using pole climbing and rotarod tests. Using immunohistochemistry, the effect of transplanted NSCs and DHA treatment was used to assess astrocytic (Glial fibrillary acidic protein, GFAP) and microglial (ionized calcium binding adaptor molecule-1, IBA-1) activity. In addition, we quantified neuroblasts (doublecortin; DCX) and dopaminergic neurons (tyrosine hydroxylase; TH) expression levels. Combined NSC transplantation and DHA injections significantly attenuated TBI-induced motor function deficits (pole climbing test), promoted neurogenesis, coupled with an increase in glial reactivity at the cortical site of injury. In addition, the number of tyrosine hydroxylase positive neurons was found to increase markedly in the ventral tegmental area and substantia nigra in the combination therapy group. Immunoblotting analysis indicated that DHA+NSCs treated animals showed decreased levels of 38kDa GFAP-BDP (breakdown product) and 145kDa αII-spectrin SBDP indicative of attenuated calpain/caspase activation. These data demonstrate that prior treatment with DHA may be a desirable strategy to improve the therapeutic efficacy of NSC transplantation in TBI.

Compact MRI for the detection of teratoma development following intrathecal human embryonic stem cell injection in NOD-SCID mice

Stem cells are emerging as a promising new treatment modality for a variety of central nervous system disorders. However, their use is hampered by the potential for the development of teratomas and other tumors. Therefore, there is a crucial need for the development of methods for detecting teratomas in preclinical safety studies. The aim of the current study is to assess the ability of a compact Magnetic Resonance Imaging (MRI) system to detect teratoma formation in mice. Five NOD-SCID mice were injected intrathecally with human embryonic stem cells (hESCs), with two mice serving as controls. In vivo MRI was performed on days 25 and 48, and ex vivo MRI was performed after scheduled euthanization (day 55). MRI results were compared to histopathology findings. Two animals injected with hESCs developed hind-limb paresis and paralysis, necessitating premature euthanization. MRI examination revealed abnormal pale areas in the spinal cord and brain, which correlated histopathologically with teratomas. This preliminary study shows the efficacy of compact MRI systems in the detection of small teratomas following intrathecal injection of hESCs in a highly sensitive manner. Although these results should be validated in larger studies, they provide further evidence that the use of MRI in longitudinal studies offers a new monitoring strategy for preclinical testing of stem cell applications.

Generation of Osteosarcomas from a Combination of Rb Silencing and c-Myc Overexpression in Human Mesenchymal Stem Cells

Osteosarcoma (OS) was a malignant tumor occurring with unknown etiology that made prevention and early diagnosis difficult. Mesenchymal stem cells (MSCs), which were found in bone marrow, were claimed to be a possible origin of OS but with little direct evidence. We aimed to characterize OS cells transformed from human MSCs (hMSCs) and identify their association with human primary OS cells and patient survival. Genetic modification with p53 or retinoblastoma (Rb) knockdown and c-Myc or Ras overexpression was applied for hMSC transformation. Transformed cells were assayed for proliferation, differentiation, tumorigenecity, and gene expression profile. Only the combination of Rb knockdown and c-Myc overexpression successfully transformed hMSCs derived from four individual donors, with increasing cell proliferation, decreasing cell senescence rate, and increasing ability to form colonies and spheres in serum-free medium. These transformed cells lost the expression of certain surface markers, increased in osteogenic potential, and decreased in adipogenic potential. After injection in immunodeficient mice, these cells formed OS-like tumors, as evidenced by radiographic analyses and immunohistochemistry of various OS markers. Microarray with cluster analysis revealed that these transformed cells have gene profiles more similar to patient-derived primary OS cells than their normal MSC counterparts. Most importantly, comparison of OS patient tumor samples revealed that a combination of Rb loss and c-Myc overexpression correlated with a decrease in patient survival. This study successfully transformed human MSCs to OS-like cells by Rb knockdown and c-Myc overexpression that may be a useful platform for further investigation of preventive and target therapy for human OS. Stem Cells Translational Medicine 2017;6:512-526.

Nurr1-Based Therapies for Parkinson's Disease

Previous studies have documented that orphan nuclear receptor Nurr1 (also known as NR4A2) plays important roles in the midbrain dopamine (DA) neuron development, differentiation, and survival. Furthermore, it has been reported that the defects in Nurr1 are associated with Parkinson's disease (PD). Thus, Nurr1 might be a potential therapeutic target for PD. Emerging evidence from in vitro and in vivo studies has recently demonstrated that Nurr1-activating compounds and Nurr1 gene therapy are able not only to enhance DA neurotransmission but also to protect DA neurons from cell injury induced by environmental toxin or microglia-mediated neuroinflammation. Moreover, modulators that interact with Nurr1 or regulate its function, such as retinoid X receptor, cyclic AMP-responsive element-binding protein, glial cell line-derived neurotrophic factor, and Wnt/β-catenin pathway, have the potential to enhance the effects of Nurr1-based therapies in PD. This review highlights the recent progress in preclinical studies of Nurr1-based therapies and discusses the outlook of this emerging therapy as a promising new generation of PD medication.

Human induced pluripotent stem cells in Parkinson's disease: A novel cell source of cell therapy and disease modeling

Human induced pluripotent stem cells (hiPSCs) and human embryonic stem cells (hESCs) are two novel cell sources for studying neurodegenerative diseases. Dopaminergic neurons derived from hiPSCs/hESCs have been implicated to be very useful in Parkinson's disease (PD) research, including cell replacement therapy, disease modeling and drug screening. Recently, great efforts have been made to improve the application of hiPSCs/hESCs in PD research. Considerable advances have been made in recent years, including advanced reprogramming strategies without the use of viruses or using fewer transcriptional factors, optimized methods for generating highly homogeneous neural progenitors with a larger proportion of mature dopaminergic neurons and better survival and integration after transplantation. Here we outline the progress that has been made in these aspects in recent years, particularly during the last year, and also discuss existing issues that need to be addressed.

Association of Nurr1 gene mutations with Parkinson's disease in the Han population living in the Hubei province of China

Nurr1 defects could in part underlie Parkinson's disease pathogenesis, and Nurr1 gene polymorphism has been found in Caucasian patients with Parkinson's disease. In this study, heteroduplex technology was applied to compare the DNA sequences of eight exons of Nurr1 among 200 sporadic Parkinson's disease patients and 200 healthy controls in the Han population in the Hubei province, China. One allele amplified from exon 3 of Nurr1 was polymorphic in five Parkinson's disease patients (2.5%, 5/200), and two individuals had a polymorphic allele amplified from exon 2 (1%, 2/200). The anomalous electrophoresis fragment in exon 3 of Nurr1 gene contained a 709C/A missense mutation, and a polymorphic single nucleotide polymorphism at 388G/A was identified in exon 2. Compared with the control group, the Nurr1 gene expression level in the Parkinson's disease group was decreased, and the Nurr1 gene expression levels in Parkinson's disease patients carrying the polymorphisms at exons 2 and 3 were significantly decreased. Our data indicate that the single nucleotide polymorphism 388G/A in exon 2 and the 709C/A missense mutation in exon 3 of the Nurr1 gene in the Chinese population might affect the pathogenesis of Parkinson's disease.

Molecular mechanisms of dopaminergic subset specification: fundamental aspects and clinical perspectives

Dopaminergic (DA) neurons in the ventral mesodiencephalon control locomotion and emotion and are affected in psychiatric and neurodegenerative diseases, such as Parkinson's disease (PD). A clinical hallmark of PD is the specific degeneration of DA neurons located within the substantia nigra (SNc), whereas neurons in the ventral tegmental area remain unaffected. Recent advances have highlighted that the selective vulnerability of the SNc may originate in subset-specific molecular programming during DA neuron development, and significantly increased our understanding of the molecular code that drives specific SNc development. We here present an up-to-date overview of molecular mechanisms that direct DA subset specification, integrating our current knowledge about subset-specific roles of transcription factors, signaling pathways and morphogenes. We discuss strategies to further unravel subset-specific gene-regulatory networks, and the clinical promise of fundamental knowledge about subset specification of DA neurons, with regards to cell replacement therapy and cell-type-specific vulnerability in PD.

Induced pluripotent stem cells without c-Myc ameliorate retinal oxidative damage via paracrine effects and reduced oxidative stress in rats

PURPOSE

To investigate the efficacy and mechanisms of non-c-Myc induced pluripotent stem cell (iPSC) transplantation in a rat model of retinal oxidative damage.

METHODS

Paraquat was intravitreously injected into Sprague-Dawley rats. After non-c-Myc iPSC transplantation, retinal function was evaluated by electroretinograms (ERGs). The generation of reactive oxygen species (ROS) was determined by lucigenin- and luminol-enhanced chemiluminescence. The expression of brain-derived neurotrophic factor, ciliary neurotrophic factor, basic fibroblast growth factor (bFGF), stromal cell-derived factor (SDF)-1α, and CXCR4 was measured by immunohistochemistry and ELISA. An in vitro study using SH-SY5Y cells was performed to verify the protective effects of SDF-1α.

RESULTS

Transplantation of non-c-Myc iPSCs effectively promoted the recovery of the b-wave ratio in ERGs and significantly ameliorated retinal damage. Non-c-Myc iPSC transplantation decreased ROS production and increased the activities of superoxide dismutase and catalase, thereby reducing retinal oxidative damage and apoptotic cells. Moreover, non-c-Myc iPSC transplantation resulted in significant upregulation of SDF-1α, followed by bFGF, accompanied by a significant improvement in the ERG. In vitro studies confirmed that treatment with SDF-1α significantly reduced apoptosis in a dose-dependent manner in SH-SY5Y cells. Most transplanted cells remained in the subretinal space, with spare cells expressing neurofilament M markers at day 28. Six months after transplantation, no tumor formation was seen in animals with non-c-Myc iPSC grafts.

CONCLUSIONS

We demonstrated the potential benefits of non-c-Myc iPSC transplantation for treating oxidative-damage-induced retinal diseases. SDF-1α and bFGF play important roles in facilitating the amelioration of retinal oxidative damage after non-c-Myc iPSC transplantation.

Nanoengineered Platforms to Guide Pluripotent Stem Cell Fate

Tissue engineering utilizes cells, signaling molecules, and scaffolds towards creating functional tissue to repair damaged organs. Pluripotent stem cells (PSCs) are a promising cell source due to their ability to self-renewal indefinitely and their potential to differentiate into almost any cell type. Great strides have been taken to parse the physiological mechanisms by which PSCs respond to their microenvironment and commit to a specific lineage. The combination of physical cues and chemical factors is thought to have the most profound influence on stem cell behavior, therefore a major focus of tissue engineering strategies is scaffold design to incorporate these signals. One overlooked component of the in vivo microenvironment researchers attempt to recapitulate with three dimensional (3D) substrates is the nanoarchitecture formed by the fibrillar network of extracellular matrix (ECM) proteins. These nanoscale features have the ability to impact cell adhesion, migration, proliferation, and lineage commitment. Significant advances have been made in deciphering how these nanoscale cues interact with stem cells to determine phenotype, but much is still unknown as to how the interplay between physical and chemical signals regulate in vitro and in vivo cellular fate. This review dives deeper to investigate nanoscale platforms for engineering tissue, as well use the use of these nanotechnologies to drive pluripotent stem cell lineage determination.

Dopaminergic-like neurons derived from oral mucosa stem cells by developmental cues improve symptoms in the hemi-parkinsonian rat model

Achieving safe and readily accessible sources for cell replacement therapy in Parkinson’s disease (PD) is still a challenging unresolved issue. Recently, a primitive neural crest stem cell population (hOMSC) was isolated from the adult human oral mucosa and characterized in vitro and in vivo. In this study we assessed hOMSC ability to differentiate into dopamine-secreting cells with a neuronal-dopaminergic phenotype in vitro in response to dopaminergic developmental cues and tested their therapeutic potential in the hemi-Parkinsonian rat model. We found that hOMSC express constitutively a repertoire of neuronal and dopaminergic markers and pivotal transcription factors. Soluble developmental factors induced a reproducible neuronal-like morphology in the majority of hOMSC, downregulated stem cells markers, upregulated the expression of the neuronal and dopaminergic markers that resulted in dopamine release capabilities. Transplantation of these dopaminergic-induced hOMSC into the striatum of hemi-Parkinsonian rats improved their behavioral deficits as determined by amphetamine-induced rotational behavior, motor asymmetry and motor coordination tests. Human TH expressing cells and increased levels of dopamine in the transplanted hemispheres were observed 10 weeks after transplantation. These results demonstrate for the first time that soluble factors involved in the development of DA neurons, induced a DA phenotype in hOMSC in vitro that significantly improved the motor function of hemiparkinsonian rats. Based on their neural-related origin, their niche accessibility by minimal-invasive procedures and their propensity for DA differentiation, hOMSC emerge as an attractive tool for autologous cell replacement therapy in PD.

Omega-3 polyunsaturated fatty acids protect neural progenitor cells against oxidative injury

The omega-3 polyunsaturated fatty acids (ω-3 PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), derived mainly from fish oil, play important roles in brain development and neuroplasticity. Here, we reported that application of ω-3 PUFAs significantly protected mouse neural progenitor cells (NPCs) against H₂O₂-induced oxidative injury. We also isolated NPCs from transgenic mice expressing the Caenorhabditis elegans fat-1 gene. The fat-1 gene, which is absent in mammals, can add a double bond into an unsaturated fatty acid hydrocarbon chain and convert ω-6 to ω-3 fatty acids. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining showed that a marked decrease in apoptotic cells was found in fat-1 NPCs after oxidative injury with H₂O₂ as compared with wild-type NPCs. Quantitative RT-PCR and Western blot analysis demonstrated a much higher expression of nuclear factor erythroid 2-related factor 2 (Nrf2), a master transcriptional factor for antioxidant genes, in fat-1 NPCs. The results of the study provide evidence that ω-3 PUFAs resist oxidative injury to NPCs.

Adult subventricular zone neural stem cells as a potential source of dopaminergic replacement neurons

Clinical trials engrafting human fetal ventral mesencephalic tissue have demonstrated, in principle, that cell replacement therapy provides substantial long-lasting improvement of motor impairments generated by Parkinson's Disease (PD). The use of fetal tissue is not practical for widespread clinical implementation of this therapy, but stem cells are a promising alternative source for obtaining replacement cells. The ideal stem cell source has yet to be established and, in this review, we discuss the potential of neural stem cells in the adult subventricular zone (SVZ) as an autologous source of replacement cells. We identify three key challenges for further developing this potential source of replacement cells: (1) improving survival of transplanted cells, (2) suppressing glial progenitor proliferation and survival, and (3) developing methods to efficiently produce dopaminergic neurons. Subventricular neural stem cells naturally produce a dopaminergic interneuron phenotype that has an apparent lack of vulnerability to PD-mediated degeneration. We also discuss whether olfactory bulb dopaminergic neurons derived from adult SVZ neural stem cells are a suitable source for cell replacement strategies.

Nanotechnology in the regulation of stem cell behavior

Stem cells are known for their potential to repair damaged tissues. The adhesion, growth and differentiation of stem cells are likely controlled by the surrounding microenvironment which contains both chemical and physical cues. Physical cues in the microenvironment, for example, nanotopography, were shown to play important roles in stem cell fate decisions. Thus, controlling stem cell behavior by nanoscale topography has become an important issue in stem cell biology. Nanotechnology has emerged as a new exciting field and research from this field has greatly advanced. Nanotechnology allows the manipulation of sophisticated surfaces/scaffolds which can mimic the cellular environment for regulating cellular behaviors. Thus, we summarize recent studies on nanotechnology with applications to stem cell biology, including the regulation of stem cell adhesion, growth, differentiation, tracking and imaging. Understanding the interactions of nanomaterials with stem cells may provide the knowledge to apply to cell-scaffold combinations in tissue engineering and regenerative medicine.

Tracing synaptic connectivity onto embryonic stem cell-derived neurons

Transsynaptic circuit tracing using genetically modified rabies virus (RV) is an emerging technology for identifying synaptic connections between neurons. Complementing this methodology, it is now possible to assay the basic molecular and cellular properties of neuronal lineages derived from embryonic stem cells (ESCs) in vitro, and these properties are under intense investigation toward devising cell replacement therapies. Here, we report the generation of a novel mouse ESC (mESC) line that harbors the genetic elements to allow RV-mediated transsynaptic circuit tracing in ESC-derived neurons and their synaptic networks. To facilitate transsynaptic tracing, we have engineered a new reporter allele by introducing cDNA encoding tdTomato, the Rabies-G glycoprotein, and the avian TVA receptor into the ROSA26 locus by gene targeting. We demonstrate high-efficiency differentiation of these novel mESCs into functional neurons, show their capacity to synaptically connect with primary neuronal cultures as evidenced by immunohistochemistry and electrophysiological recordings, and show their ability to act as source cells for presynaptic tracing of neuronal networks in vitro and in vivo. Together, our data highlight the potential for using genetically engineered stem cells to investigate fundamental mechanisms of synapse and circuit formation with unambiguous identification of presynaptic inputs onto neuronal populations of interest.

Genetic strategies to investigate neuronal circuit properties using stem cell-derived neurons

The mammalian brain is anatomically and functionally complex, and prone to diverse forms of injury and neuropathology. Scientists have long strived to develop cell replacement therapies to repair damaged and diseased nervous tissue. However, this goal has remained unrealized for various reasons, including nascent knowledge of neuronal development, the inability to track and manipulate transplanted cells within complex neuronal networks, and host graft rejection. Recent advances in embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) technology, alongside novel genetic strategies to mark and manipulate stem cell-derived neurons, now provide unprecedented opportunities to investigate complex neuronal circuits in both healthy and diseased brains. Here, we review current technologies aimed at generating and manipulating neurons derived from ESCs and iPSCs toward investigation and manipulation of complex neuronal circuits, ultimately leading to the design and development of novel cell-based therapeutic approaches.

Stem cells and regenerative therapies for Parkinson's disease

Currently the mainstay of Parkinson's disease (PD) therapy is the pharmacological replacement of the loss of the dopaminergic nigrostriatal pathway using drugs such as dopamine agonists and levodopa. Whilst these drugs effectively ameliorate some of the motor features of PD, they do not improve many of the nonmotor features that arise secondary to pathology outside of this system, nor do they slow the progressive neurodegeneration that is a characteristic of the disease. Regenerative therapies for PD seek to fill this therapeutic gap, with cell transplantation being the most explored approach to date. A number of different cell sources have been used in this therapeutic approach, but to date, the most successful has been the use of fetal ventral mesencephalic (VM) tissue that contains within it the developing nigral dopaminergic cells. Cell transplantation for PD was pioneered in the 1980-1990s, with several successful open-label trials of fetal VM transplantation in patients with relatively advanced PD. Whilst these findings were not replicated in two subsequent double-blind sham-surgery controlled trials, there were reasons to explain this outside of the one drawn at the time that these therapies are ineffective. Indeed all these studies have provided evidence that following the transplantation of fetal VM tissue, dopaminergic cells can survive long term, produce dopamine, and bring about clinical improvements in younger patients over many years. The use of fetal tissue, irrespective of its true efficacy, will never become a widely available therapy for PD for a host of practical and ethical reasons, and thus much work has been put in recently to exploring the utility of stem cells as a source of nigral dopaminergic neurons. In this respect, the advent of embryonic stem cell and induced pluripotent cells has heralded a new era in cell therapy for PD, and several groups have now demonstrated that these cells can form dopaminergic neurons which improve functional deficits in animal models of PD. Whilst encouraging, problems with respect to the immunogenicity and tumorigenicity of these cells means that they will need to be used in the clinic cautiously. Other regenerative therapies in PD have been tried over the years and include the use of trophic factors. This has primarily involved glial cell line-derived neurotrophic factor (GDNF) and again has produced mixed clinical effects, and in order to try and resolve this, a new trial of intraputamenal GDNF is now being planned. In addition, a new trial for platelet derived growth factor as a treatment for PD has just completed recruitment, and PYM50028 (Cogane) an oral agent shown in animal models to reduce the effects of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) lesioning by the induction of growth factors is currently under investigation in a multicentre Phase II trial. Overall, there are a number of promising new regenerative therapies being developed and tested in PD, although the true long-term efficacy of any of these in large numbers of patients is still not known.

Adult human olfactory epithelial-derived progenitors: a potential autologous source for cell-based treatment for Parkinson's disease

Human adult olfactory epithelial-derived neural progenitors (hONPs) can differentiate along several neural lineages in response to morphogenic signals in vitro. A previous study optimized the transfection paradigm for the differentiation of hONPs to dopaminergic neurons. This study engrafted cells modified by the most efficient transfection paradigm for dopaminergic neural restriction and pretransfected controls into a unilateral neurotoxin, 6-hydroxydopamine-induced parkinsonian rat model. Approximately 35% of the animals engrafted with hONPs had improved behavioral recovery as demonstrated by the amphetamine-induced rotation test, as well as a corner preference and cylinder paw preference, over a period of 24 weeks. The pre- and post-transfected groups produced equivalent responses, indicating that the toxic host environment supported hONP dopaminergic differentiation in situ. Human fibroblasts used as a cellular control did not diminish the parkinsonian rotational deficits at any point during the study. Increased numbers of tyrosine hydroxylase (TH)-positive cells were detected in the engrafted brains compared with the fibroblast-implanted and medium-only controls. Engrafted TH-positive hONPs were detected for a minimum of 6 months in vivo; they were multipolar, had long processes, and migrated beyond their initial injection sites. Higher dopamine levels were detected in the striatum of behaviorally improved animals than in equivalent regions of their nonrecovered counterparts. Throughout these experiments, no evidence of tumorigenicity was observed. These results support our hypothesis that human adult olfactory epithelial-derived progenitors represent a unique autologous cell type with promising potential for future use in a cell-based therapy for patients with Parkinson's disease.

Small molecules greatly improve conversion of human-induced pluripotent stem cells to the neuronal lineage

Efficient in vitro differentiation into specific cell types is more important than ever after the breakthrough in nuclear reprogramming of somatic cells and its potential for disease modeling and drug screening. Key success factors for neuronal differentiation are the yield of desired neuronal marker expression, reproducibility, length, and cost. Three main neuronal differentiation approaches are stromal-induced neuronal differentiation, embryoid body (EB) differentiation, and direct neuronal differentiation. Here, we describe our neurodifferentiation protocol using small molecules that very efficiently promote neural induction in a 5-stage EB protocol from six induced pluripotent stem cells (iPSC) lines from patients with Parkinson's disease and controls. This protocol generates neural precursors using Dorsomorphin and SB431542 and further maturation into dopaminergic neurons by replacing sonic hedgehog with purmorphamine or smoothened agonist. The advantage of this approach is that all patient-specific iPSC lines tested in this study were successfully and consistently coaxed into the neural lineage.

Induced pluripotent stem cells without c-Myc attenuate acute kidney injury via downregulating the signaling of oxidative stress and inflammation in ischemia-reperfusion rats

Induced pluripotent stem (iPS) cells have potential for multilineage differentiation and provide a resource for stem cell-based treatment. However, the therapeutic effect of iPS cells on acute kidney injury (AKI) remains uncertain. Given that the oncogene c-Myc may contribute to tumorigenesis by causing genomic instability, herein we evaluated the therapeutic effect of iPS cells without exogenously introduced c-Myc on ischemia-reperfusion (I/R)-induced AKI. As compared with phosphate-buffered saline (PBS)-treated group, administration of iPS cells via intrarenal arterial route into kidneys improved the renal function and attenuated tubular injury score at 48 h after ischemia particularly at the dose of 5 × 10(5) iPS cells. However, a larger number of iPS cells (5 × 10(7) per rat) diminished the therapeutic effects for AKI and profoundly reduced renal perfusion detected by laser Doppler imaging in the reperfusion phase. In addition, the green fluorescence protein-positive iPS cells mobilized to the peritubular area at 48 h following ischemia, accompanied by a significant reduction in infiltration of macrophages and apoptosis of tubular cells, and a remarkable enhancement in endogenous tubular cell proliferation. Importantly, transplantation of iPS cells reduced the expression of oxidative substances, proinflammatory cytokines, and apoptotic factors in I/R kidney tissues and eventually improved survival in rats of ischemic AKI. Six months after transplantation in I/R rats, engrafted iPS cells did not result in tumor formation in kidney and other organs. In summary, considering the antioxidant, anti-inflammatory, and antiapoptotic properties of iPS cells without c-Myc, transplantation of such cells may be a treatment option for ischemic AKI.

Enhanced differentiation of three-gene-reprogrammed induced pluripotent stem cells into adipocytes via adenoviral-mediated PGC-1α overexpression

Induced pluripotent stem cells formed by the introduction of only three factors, Oct4/Sox2/Klf4 (3-gene iPSCs), may provide a safer option for stem cell-based therapy than iPSCs conventionally introduced with four-gene iPSCs. Peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) plays an important role during brown fat development. However, the potential roles of PGC-1α in regulating mitochondrial biogenesis and the differentiation of iPSCs are still unclear. Here, we investigated the effects of adenovirus-mediated PGC-1α overexpression in 3-gene iPSCs. PGC-1α overexpression resulted in increased mitochondrial mass, reactive oxygen species production, and oxygen consumption. Microarray-based bioinformatics showed that the gene expression pattern of PGC-1α-overexpressing 3-gene iPSCs resembled the expression pattern observed in adipocytes. Furthermore, PGC-1α overexpression enhanced adipogenic differentiation and the expression of several brown fat markers, including uncoupling protein-1, cytochrome C, and nuclear respiratory factor-1, whereas it inhibited the expression of the white fat marker uncoupling protein-2. Furthermore, PGC-1α overexpression significantly suppressed osteogenic differentiation. These data demonstrate that PGC-1α directs the differentiation of 3-gene iPSCs into adipocyte-like cells with features of brown fat cells. This may provide a therapeutic strategy for the treatment of mitochondrial disorders and obesity.

The retinoid X receptors and their ligands

This chapter presents an overview of the current status of studies on the structural and molecular biology of the retinoid X receptor subtypes α, β, and γ (RXRs, NR2B1-3), their nuclear and cytoplasmic functions, post-transcriptional processing, and recently reported ligands. Points of interest are the different changes in the ligand-binding pocket induced by variously shaped agonists, the communication of the ligand-bound pocket with the coactivator binding surface and the heterodimerization interface, and recently identified ligands that are natural products, those that function as environmental toxins or drugs that had been originally designed to interact with other targets, as well as those that were deliberately designed as RXR-selective transcriptional agonists, synergists, or antagonists. Of these synthetic ligands, the general trend in design appears to be away from fully aromatic rigid structures to those containing partial elements of the flexible tetraene side chain of 9-cis-retinoic acid. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).