There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

中枢神経系疾患の治療は正常細胞（ニューロン）の機能維持を目的とするが，脳血管障害のように機能障害の原因が細胞の死滅に基づくことは多い．一方，脳腫瘍の治療においては薬物療法や放射線療法といった腫瘍細胞の死滅を目標とするものが大きな位置を占める．いずれの場合にも，細胞死の機序を理解することは各種病態や治療法の理解のうえで重要である．現在のところ最も研究の進んでいる細胞死の型はアポトーシスである．そのなかで重要な位置を占めるミトコンドリアにおける反応および抗アポトーシス因子について概要を紹介する．

Neuroscience 細胞死：最近の知見

Degeneration and regeneration of the nervous system

A stereotaxic atlas of the rat brain

In spite of the advances in the knowledge of adult stem cells (ASCs) during the past few years, their natural activities in vivo are still poorly understood. Mesenchymal stem cells (MSCs), one of the most promising types of ASCs for cell-based therapies, are defined mainly by functional assays using cultured cells. Defining MSCs in vitro adds complexity to their study because the artificial conditions may introduce experimental artifacts. Inserting these results in the context of the organism is difficult because the exact location and functions of MSCs in vivo remain elusive; the identification of the MSC niche is necessary to validate results obtained in vitro and to further the knowledge of the physiological functions of this ASC. Here we show an analysis of the evidence suggesting a perivascular location for MSCs, correlating these cells with pericytes, and present a model in which the perivascular zone is the MSC niche in vivo, where local cues coordinate the transition to progenitor and mature cell phenotypes. This model proposes that MSCs stabilize blood vessels and contribute to tissue and immune system homeostasis under physiological conditions and assume a more active role in the repair of focal tissue injury. The establishment of the perivascular compartment as the MSC niche provides a basis for the rational design of additional in vivo therapeutic approaches. This view connects the MSC to the immune and vascular systems, emphasizing its role as a physiological integrator and its importance in tissue repair/regeneration.

https://stemcellsjournals.onlinelibrary.wiley.com/doi/pdf/10.1634/stemcells.2007-1122

In search of the in vivo identity of mesenchymal stem cells

Induced pluripotent stem (iPS) cells can be derived from a wide range of somatic cells via overexpression of a set of specific genes. With respect to their properties, iPS cells closely resemble embryonic stem cells. Because of their main property, pluripotency, iPS cells have excellent prospects for use in substitutive cell therapy; however, the methods of directed differentiation of iPS cells have not been yet sufficiently elaborated. In this work, we derived human iPS cells from fetal neural stem (FNS) cells by transfection with a polycistronic plasmid vector carrying the mouse Oct4, Sox2, Klf4, and c-Myc genes or a plasmid expressing the human OCT4 gene. We have shown that human FNS cells can be effectively reprogrammed despite a low transfection level (10%-15%) and that the use of 2-propylvaleric (valproic) acid and BIX-01294 increases the yield of iPS cell clones to ∼7-fold. Further, transient expression of OCT4 alone is sufficient for reprogramming. The iPS cells obtained express all the major markers of embryonic stem cells and are able to differentiate in vitro into ectodermal, mesodermal, and endodermal derivatives. In addition, we have found that the human iPS cells derived from FNS cells can be successfully subjected to in vitro directed chondrogenic differentiation to form functional cartilaginous tissue.

Human Induced Pluripotent Stem Cells Derived from Fetal Neural Stem Cells Successfully Undergo Directed Differentiation into Cartilage

The retinal pigment epithelium (RPE) plays a key role in the development of many eye diseases leading to visual impairment and even blindness. Cell culture models of pathological changes in the RPE make it possible to study factors responsible for these changes and signaling pathways coordinating cellular and molecular mechanisms of cell interactions under pathological conditions. Moreover, they give an opportunity to reveal target cells and develop effective specific treatment for degenerative and dystrophic diseases of the retina. In this review, data are presented on RPE cell sources for culture models, approaches to RPE cell culturing, phenotypic changes of RPE cells in vitro, the role of signal pathways, and possibilities for their regulation in pathological processes.

/pdf/cell-models-to-study-regulation-of-cell-transformation-in-1neb6ba01p.pdf

Cell Models to Study Regulation of Cell Transformation in Pathologies of Retinal Pigment Epithelium

Behavior of human neural progenitor cells transplanted to rat brain.

Human neural stem cells (HNSCs) are used in studies of neural development and differentiation, and are regarded as an alternative source of tissue for neural transplantation in degenerative diseases. Selection and standardization of HNSC samples is an important task in research and clinical approaches. We evaluated embryonal brain matter obtained from human 8-12-week-old fetuses by means of flow cytometry on a panel including: nestin; vimentin; NeuN; GFAP; b-tubulin III; CD56; N-Cad; OB-Cad; HLA-ABC; HLA-DR; CD34, and annexin. Samples from embryos of even the same gestation differ dramatically regarding neural cell development, their phenotype and viability. The samples containing the highest proportion of stem cells and multipotent progenitors of neural types, and the least of definitive cells and antigens of histocompatibility, were selected for further expansion in serum-free medium. Secondary phenotyping 14 days later revealed again a marked heterogeneity of the cultures. For the final culturing for 24 h in a serum-containing medium we selected only samples having following phenotype: nestin1, and vimentin1 no less than 25%; HLA-DR1 and CD341 no more than 5%; GFAP1 no more than 10%; b-tubulin1 no more than 20%; CD561, N-Cad1, OB-Cad1, HLA-A,B,C1, and annexin1 no more than 15%; cell viability no less than 60%. Immunocytochemical study of selected samples proved that numerous neural stem cells, and neuro- and glioblasts necessary for transplantation were present. Our results demonstrate that the flow cytometry phenotyping allows the screening and standardization of HNSC samples for further expansion and transplantation. © 2002 Elsevier Science B.V. All rights reserved. Theme: Development and regeneration Topic: Genesis of neurons and glia

M. A. Aleksandrova

Papers

Human Induced Pluripotent Stem Cells Derived from Fetal Neural Stem Cells Successfully Undergo Directed Differentiation into Cartilage

Cell Models to Study Regulation of Cell Transformation in Pathologies of Retinal Pigment Epithelium

Behavior of human neural progenitor cells transplanted to rat brain.

Interactive report Evaluation of progenitor cell cultures from human embryos for neurotransplantation

Evaluation of progenitor cell cultures from human embryos for neurotransplantation.