Ischemic stroke causes brain damage and neuronal cell death by depriving oxygen and nutrients and releasing excessive levels of glutamate and intracellular calcium. Epigallocatechin gallate (EGCG) is a polyphenolic compound present in green tea. It has antioxidant, anti-inflammatory, and neuroprotective effects. Hippocalcin is a calcium binding protein that regulates calcium concentration, neuronal differentiation, neuronal excitability, and neuronal cell death. In this study, we investigated whether EGCG regulates the expression of hippocalcin in neurons and astrocytes after focal cerebral ischemia. Cerebral ischemia was induced by meddle cerebral artery occlusion (MCAO). EGCG (50 mg/kg) or PBS was injected into the abdominal cavity just before MCAO surgery. Neurobehavioral tests were performed to evaluate the effect of EGCG on neurological behavioral deficits 24 h after MCAO surgery. Immunofluorescence staining was performed to evaluate the positive response to hippocalcin in the cerebral cortex after MCAO surgery. We also detected the positive reactions of neuronal nuclear protein (NeuN) and glial fibrillary acidic protein (GFAP) as markers of neuron and astrocyte, respectively. MCAO caused severe neurological impairment and EGCG treatment attenuated these impairments. MCAO damage reduced the number of NeuN-positive cells and increased the number of GFAP-positive cells. This result indicates a decrease in neurons and an increase in astrocytes. However, EGCG alleviated these changes caused by MCAO damage. MCAO reduced the number of hippocalcin-positive cells in neurons and astrocytes, and EGCG treatment attenuated these reductions. Hippocalcin exerts neuroprotective effect through regulating intracellular calcium concentration. In conclusion, EGCG regulates the expression of hippocalcin in neurons and astrocytes and has neuroprotective effects in focal cerebral ischemia.

Introducing lineage-specific transcription factors (TFs) into somatic cells enables the induction of distinct cellular identities without the need to first pass through a pluripotent stem cell (PSC) state. We and others have demonstrated the direct conversion of somatic cells into adult stem cells or progenitor cells, such as angioblast-like progenitor cells, hematopoietic stem cells, and neural stem cells. The process underlying direct conversion is known to be relatively simpler and faster than that of induced pluripotent stem cell (iPSC) generation. Furthermore, directly converted cells have been shown to exhibit therapeutic potential following transplantation into respective disease models without obvious evidence for tumor formation. Thus, TF-mediated direct conversion technology has been considered as an alternative to iPSC technology for patient-specific cell- and tissue-replacement therapies. Here we show our recent findings describing the robust direct conversion of differentiated somatic cells into distinct cellular identities. Furthermore, we also show the recent 3D organoid technology for generating brain tissues from human pluripotent stem cells.

One of the most extensively studied populations of multipotent adult stem cells are mesenchymal stem cells (MSCs). MSCs derived from the human umbilical cord vein (HUC-MSCs) are morphologically and immunophenotypically similar to MSCs isolated from bone marrow. HUC-MSCs are multipotent stem cells, differ from hematopoietic stem cells and can be differentiated into neural cells. Since neural tissue has limited intrinsic capacity of repair after injury, the identification of alternate sources of neural stem cells has broad clinical potential. We isolated mesenchymal-like stem cells from the human umbilical cord vein, and studied transdifferentiation-promoting conditions in neural cells. Dopaminergic neuronal differentiation of HUC-MSCs was also studied. Neural differentiation was induced by adding bFGF, EGF, dimethyl sulfoxide (DMSO) and butylated hydroxyanisole (BHA) in N2 medium and N2 supplement. The immunoreactive cells for -tubulin III, a neuron-specific marker, GFAP, an astrocyte marker, or Gal-C, an oligodendrocyte marker, were found. HUC-MSCs treated with bFGF, SHH and FGF8 were differentiated into dopaminergic neurons that were immunopositive for tyrosine hydroxylase (TH) antibody. HUC-MSCs treated with DMSO and BHA rapidly showed the morphology of multipolar neurons. Both immunocytochemistry and RT-PCR analysis indicated that the expression of a number of neural markers including NeuroD1, -tubulin III, GFAP and nestin was markedly elevated during this acute differentiation. While the stem cell markers such as SCF, C-kit, and Stat-3 were not expressed after neural differentiation, we confirmed the differentiation of dopaminergic neurons by TH/-tubulin III positive cells. In conclusion, HUC-MSCs can be differentiated into dopaminergic neurons and these findings suggest that HUC-MSCs are alternative cell source of therapeutic treatment for neurodegenerative diseases.

손상된 뇌신경조직내에서 신경줄기세포로부터 새로운 신경세포로의 분화가 상당히 제한되어 있어 이것이 손상된 뇌신경조직의 복구가 잘 이루어지지 않는 원인이라 여겨지고 있다. 본 연구에서는 세포배양을 통해 지방조직 중간엽 줄기세포를 도파민성 신경세포와 콜린성 신경세포로 분화를 유도하였다. 중간엽 줄기세포를 신경세포로 분화시키기 위해 N2배양액에 bFGF, EGF, dimethyl sulphoxide (DMSO)와 butylated hydroxyanisole (

Embryonic stem (ES) cells proliferate extensively in the undifferentiated state and have the potential to differentiate into a variety of cell types in response to various environmental cues. The generation of functional dopaminergic neurons from ES cells is promising for cell replacement therapy to treat Parkinson's disease. We compared the in vitro differentiation potential of pluripotent human embryonic stem (hES, MB03) cells induced with basic fibroblast growth factor (bFGF) or retinoic acid (RA). Both types of treatment resulted in similar neural cell differentiation patterns at the terminal differentiation stage, specifically, 75% neurons and 11% glial cells. Additionally, treatment of hES cells with brain derived neurotrophic factor (BDNF) or transforming growth factor (TGF)- during the terminal differentiation stage led to significantly increased tyrosine hydroxylase (TH) expression, compared to control (P<0.05). In contrast, no effect was observed on the rate of mature or glutamic acid decarboxylase-positive neurons. Immunostaining and HPLC analyses revealed the higher levels of TH (20.3%) and dopamine in bFGF and TGF- treated hES cells than in RA or BDNF treated hES cells. The results indicate that TGF- may be successfully used in the bFGF induction protocol to yield higher numbers of functional dopaminergic neurons from hES cells.