H. S. Lee

Protein-based human iPS cells efficiently generate functional dopamine neurons and can treat a rat model of Parkinson disease

Parkinson disease (PD) involves the selective loss of midbrain dopamine (mDA) neurons and is a possible target disease for stem cell-based therapy. Human induced pluripotent stem cells (hiPSCs) are a potentially unlimited source of patient-specific cells for transplantation. However, it is critical to evaluate the safety of hiPSCs generated by different reprogramming methods. Here, we compared multiple hiPSC lines derived by virus- and protein-based reprogramming to human ES cells (hESCs). Neuronal precursor cells (NPCs) and dopamine (DA) neurons delivered from lentivirus-based hiPSCs exhibited residual expression of exogenous reprogramming genes, but those cells derived from retrovirus- and protein-based hiPSCs did not. Furthermore, NPCs derived from virus-based hiPSCs exhibited early senescence and apoptotic cell death during passaging, which was preceded by abrupt induction of p53. In contrast, NPCs derived from hESCs and protein-based hiPSCs were highly expandable without senescence. DA neurons derived from protein-based hiPSCs exhibited gene expression, physiological, and electrophysiological properties similar to those of mDA neurons. Transplantation of these cells into rats with striatal lesions, a model of PD, significantly rescued motor deficits. These data support the clinical potential of protein-based hiPSCs for personalized cell therapy of PD.

Prolonged Membrane Depolarization Enhances Midbrain Dopamine Neuron Differentiation via Epigenetic Histone Modifications

Understanding midbrain dopamine (DA) neuron differentiation is of importance, because of physiological and clinical implications of this neuronal subtype. We show that prolonged membrane depolarization induced by KCl treatment promotes DA neuron differentiation from neural precursor cells (NPCs) derived from embryonic ventral midbrain (VM). Interestingly, the depolarization‐induced increase of DA neuron yields was not abolished by L‐type calcium channel blockers, along with no depolarization‐mediated change of intracellular calcium level in the VM‐derived NPCs (VM‐NPCs), suggesting that the depolarization effect is due to a calcium‐independent mechanism. Experiments with labeled DA neuron progenitors indicate that membrane depolarization acts at the differentiation fate determination stage and promotes the expression of DA phenotype genes (tyrosine hydroxylase [TH] and DA transporter [DAT]). Recruitment of Nurr1, a transcription factor crucial for midbrain DA neuron development, to the promoter of TH gene was enhanced by depolarization, along with increases of histone 3 acetylation (H3Ac) and trimethylation of histone3 on lysine 4 (H3K4m3), and decreases of H3K9m3 and H3K27m3 in the consensus Nurr1 binding regions of TH promoter. Depolarization stimuli on differentiating VM‐NPCs also induced dissociation of methyl CpG binding protein 2 and related repressor complex molecules (repressor element‐1 silencing transcription factor corepressor and histone deacetylase 1) from the CpG sites of TH and DAT promoters. Based on these findings, we suggest that membrane depolarization promotes DA neuron differentiation by opening chromatin structures surrounding DA phenotype genes and inhibiting the binding of corepressors, thus allowing transcriptional activators such as Nurr1 to access DA neuron differentiation gene promoter regions. STEM CELLS 2011;29:1861–1873

Subphrenic bronchogenic cyst mimicking a juxtahepatic solid lesion

AbstractMost bronchogenic cysts occur in the mediastinum. However, they may be found near any organ derived from the embryonic foregut, even in the extrathoracic region. We report a case of subphrenic bronchogenic cyst that was initially confused with a solid lesion because of its unusual location and atypical appearance on ultrasonography, computed tomography, and magnetic resonance imaging. n

GABA mediates the network activity‐dependent facilitation of axonal outgrowth from the newborn granule cells in the early postnatal rat hippocampus

Neural network activity regulates the development of hippocampal newborn granule cells (GCs). Excitatory GABAergic input is known to be a key player in this regulation. Although calcium signaling is thought to be a downstream mediator of GABA, GABA‐induced calcium signaling in newborn GCs is not well understood. We investigated Ca2+ signaling and its regulatory role in axon and dendrite outgrowth in newborn GCs identified in the organotypic slice culture of early postnatal rat hippocampus. Here, we report that hippocampal network activity can induce calcium transients (CaTs) in newborn GCs during the first post‐mitotic week via GABAergic inputs. The GABA‐induced CaTs were mediated mainly by L‐type Ca2+ channels. Furthermore, we found that inhibiting any step in the signaling pathway, network activity → GABA → L‐type Ca2+ channels, selectively suppressed the axonal outgrowth and pruning of newborn GCs, but not dendritic outgrowth. The GABAA receptor blocker bicuculline significantly suppressed axonal outgrowth, despite increasing network activity, thus indicating an essential role of GABAergic inputs. Therefore, we conclude that network activity‐dependent GABAergic inputs open L‐type Ca2+ channels and promote axonal outgrowth in newborn GC during the first post‐mitotic week.

Bidirectional Signaling of Neuregulin-2 Mediates Formation of GABAergic Synapses and Maturation of Glutamatergic Synapses in Newborn Granule Cells of Postnatal Hippocampus.

Expression of neuregulin-2 (NRG2) is intense in a few regions of the adult brain where neurogenesis persists; however, little is understood about its role in developments of newborn neurons. To study the role of NRG2 in synaptogenesis at different developmental stages, newborn granule cells in rat hippocampal slice cultures were labeled with retrovirus encoding tetracycline-inducible microRNA targeting NRG2 and treated with doxycycline (Dox) at the fourth or seventh postinfection day (dpi). The developmental increase of GABAergic postsynaptic currents (GPSCs) was suppressed by the early Dox treatment (4 dpi), but not by late treatment (7 dpi). The late Dox treatment was used to study the effect of NRG2 depletion specific to excitatory synaptogenesis. The Dox effect on EPSCs emerged 4 d after the impairment in dendritic outgrowth became evident (10 dpi). Notably, Dox treatment abolished the developmental increases of AMPA-receptor mediated EPSCs and the AMPA/NMDA ratio, indicating impaired maturation of glutamatergic synapses. In contrast to GPSCs, Dox effects on EPSCs and dendritic growth were independent of ErbB4 and rescued by concurrent overexpression of NRG2 intracellular domain. These results suggest that forward signaling of NRG2 mediates GABAergic synaptogenesis and its reverse signaling contributes to dendritic outgrowth and maturation of glutamatergic synapses. SIGNIFICANCE STATEMENT The hippocampal dentate gyrus is one of special brain regions where neurogenesis persists throughout adulthood. Synaptogenesis is a critical step for newborn neurons to be integrated into preexisting neural network. Because neuregulin-2 (NRG2), a growth factor, is intensely expressed in these regions, we investigated whether it plays a role in synaptogenesis and dendritic growth. We found that NRG2 has dual roles in the development of newborn neurons. For GABAergic synaptogenesis, the extracellular domain of NRG2 acts as a ligand for a receptor on GABAergic neurons. In contrast, its intracellular domain was essential for dendritic outgrowth and glutamatergic synapse maturation. These results imply that NRG2 may play a critical role in network integration of newborn neurons.

Automated Information Retrieval for Hazard Identification in Construction Sites

The repetitive occurrence of similar accident in construction disasters is one of the prevalent features. Similar accident cases provide direct information for determining the risk of scheduled activities and planning safety countermeasure. Researchers have developed many systems in order to retrieve and use past accident cases. Although the developed systems have a clear and limited target, most of them were developed under a retrieval methods based on ad-hoc systems which can cause inconvenience for users in using the retrieval system. To overcome these limitations, this study proposes an automated information retrieval system that can search for and provide similar accident cases. The retrieval system extracts building information modeling objects and composes a query set by combining BIM objects with a project management information system. Based on the results of this study, the users can excessively reduce query generation. Furthermore, they can easily avoid risks by receiving similar past accident cases that can happen while they work.

Localization and coexistence of calcium-binding proteins and neuropeptides in the vagal ganglia of the goat.

This study was performed to investigate the neurochemical characteristics of the vagal ganglia of the goat by immunohistochemical methods using calbindin D‐28k (CB), calretinin (CR), parvalbumin (PA), substance P (SP), calcitonin gene‐related peptide (CGRP) and galanin (GAL) antibodies. In the proximal vagal ganglia (jugular ganglia), CGRP‐ (57.1%), SP‐ (48.2%), GAL‐ (8.6%), PA‐ (8.7%), CB‐ (8.5%) and CR‐like (5.3%) immunoreactive cells were observed. In the distal vagal ganglia (nodose ganglia), CGRP‐ (40.5%), SP‐ (30.2%), CB‐ (22.0%) and CR‐like (18.1%) immunoreactive cells were present. The double immunohistochemical study showed, that in the proximal vagal ganglia, CGRP immunoreactivity was co‐localized in SP‐ (84.8%), GAL‐ (100%), CB‐ (5.6%) and CR‐ (5.7%) immunoreactive cells; SP immunoreactivity was co‐localized in the CGRP‐ (80.0%), GAL‐ (100%), CB‐ (5.3%) and CR‐ (5.6%) immunoreactive cells; GAL immunoreactivity coexisted in the CGRP‐ (4.4%) and SP‐ (19.8%) immunoreactive cells, but not in calcium‐binding proteins (CBP)‐immunoreactive cells; PA immunoreactivity was absent in the CGRP‐ and SP‐immunoreactive cells; CB and CR immunoreactivities were seen in the CGRP‐ (0.8%) and SP‐immunoreactive (0.9%) cells. On the other hand, in the distal vagal ganglia, CGRP immunoreactivity appeared in SP‐ (66.6%), CB‐ (1.0%) and CR‐ (1.2%) immunoreactive cells; SP immunoreactivities were observed in the CGRP‐ (44.1%), CB‐ (1.0%) and CR‐ (1.2%) immunoreactive cells; CB immunoreactivities were present in the CGRP‐ (0.5%) and SP‐ (0.8%) immunoreactive cells; CR immunoreactivities were contained in the CGRP‐ (0.5%) and SP‐ (0.8%) immunoreactive cells. These findings indicate that the goat is distinct from other mammalian species in the distribution and localization of neurochemical substances in the vagal ganglia, and suggest that these differences may be related to physiological characteristics, particular those of the ruminant digestive system.

Immunohistochemical localization of substance P, calcitonin gene-related peptide, galanin and calcium-binding proteins in trigeminal ganglia of goat (Capra hircus)

The objectives of this study was to provide a quantitative analysis of calcium‐binding proteins, calbindin (CB), parvalbumin (PA), substance P (SP), calcitonin gene‐related peptide (CGRP) and galanin (GAL), in trigeminal ganglia of goats, to establish whether they exhibit coexistence relationships between each other, and to examine possible colocalization with SP, CGRP and GAL, which have been well characterized according to their distributions in an abundance of large and/or small neurones. CB (12.78%), PA (31.91%), SP (24.63%), CGRP (44.44%) and GAL (3.29%) immunoreactive (IR) cells were observed. About 38.37, 8.7 and 0.73% of CGRP‐IR neurones in the trigeminal ganglion were also immunoreacted with SP, GAL and CB, respectively. Almost all SP‐IR cells are labelled with CGRP (approximately 92.52%), whereas only 16.02 and 0.44% of SP‐IR neurones colocalized with GAL and CB. Approximately 4.65 and 1.10% of the CB‐IR cells were found to contain CGRP and SP immunoreactivity, respectively. Conversely, no CB‐IR cell exhibited GAL immunoreactivity. In addition, all the GAL‐IR cells showed CGRP and SP immunoreactivity. The number of CB‐, PA‐, SP‐, CGRP‐ and GAL‐IR neurones in goat trigeminal ganglion are abundant than that of other animals. These results elucidate that the goat differs from other mammalian species in the distribution and localization of neurochemical substances in trigeminal ganglia, and suggest that this difference may be relevant to the morphological characteristics of cerebral vasculatures such as epidural rete mirabile of goat.

The Coexistence of Calcitonin Gene-Related Peptide and Substance P in Pericellular Arborization and Satellite Cell of Goat Trigeminal and Nodose Ganglia

Pericellular arborization is reported to be the self‐regulating structure in sensory ganglia. Although the calcitonin gene‐related peptide (CGRP) or substance P (SP) immunoreactive pericellular arborization appeared in the sensory ganglia, there was no available information that CGRP and SP colocalize in this structure. As the attempts to resolve the question described above, the present study was undertaken to identify the coexistence of CGRP and SP in pericellular arborizations of the goat nodose and trigeminal ganglia by double immunohistochemistry. As the results show, CGRP immunoreactivity was present in every pericellular arborization containing SP immunoreactivity in trigeminal ganglia, however, pericellular network containing CGRP or SP immunoreactivity was not present in nodose ganglia. Unexpectedly, a few small satellite elements were observed to contain intense CGRP and SP immunoreactivity at the periphery of CGRP and SP immunoreactive neurones in nodose ganglia. Therefore, these results suggest that CGRP and SP coexsit in pericellular arborizations, and that satellite cell as well as pericellular arborization may be involved in intraganglionic regulation of goat sensory ganglia.

The Enhanced Expression of c‐Jun Immunoreactivity in the Adrenalectomized Gerbil Hippocampus

Recent in vitro and in vivo studies have shown that glucocorticoids have a profound influence on the survival of hippocampal neurones, and that the depletion of glucocorticoids as a result of adrenalectomy (ADX) reduces nerve growth factor levels in the hippocampus. It is also believed that ADX is associated with the seizure susceptibility of the Mongolian gerbil. In the present study, the choronological changes of c‐jun immunoreactivity were investigated after ADX in the hippocampal formations in the seizure‐prone gerbil model. In the sham hippocampus, c‐jun immunoreactivity was not observed in the neurones of the hippocampus proper and dentate gyrus. C‐jun immunoreactive neurones appeared 3u2003h after ADX in the neurones of the CA1 area and dentate gyrus, and these immunoreactivities peaked 24u2003h after ADX and then gradually decreased. These results suggest that, in the adrenalectomized gerbil, c‐jun may be expressed in the neurones of the hippocampus in compensation for glucocorticoid deficit. The result of enhanced c‐jun expression of the hippocampal formation provides anatomical support for the hypothesis that c‐jun may play a role in the reduction of seizure activity.