We report herein a 21-year-old hepatitis B virus (HBV) female carrier who developed persistent fever, lymphadenopathy and pancytopenia in September of 2000. Hemophagocytes were found in the bone marrow smears. Epstein-Barr virus (EBV) serology showed positive for VCA-IgG, IgM and EB-ER and negative for EBNA. The EBV genome was detected in the peripheral blood. The patient was diagnosed as having EBV-associated hemophagocytic syndrome (EBV-AHS) and received chemotherapy. Although she was treated with lamivudine three months after the initiation of chemotherapy, she developed severe hepatitis. She recovered from the hepatitis through a combination of plasma exchange, immunosuppressive and antiviral therapies. Because of the refractoriness of her EBV-AHS to chemotherapy, she received allogeneic peripheral blood stem cell transplantation (PBSCT) from her HLA-identical brother. Hepatitis B did not recur after the PBSCT under administration of lamivudine. The EBV genome in the peripheral blood disappeared soon after the PBSCT but it was revealed again after the initiation of prednisolone for the treatment of acute GVHD. A donor lymphocyte infusion (DLI) was given on day 169 and the EBV genome copy number in the peripheral blood gradually decreased and disappeared. Although the origin of the EBV-infected cells could not be determined as being from the host or donor, DLI was a useful treatment for the recurrence of EBV infection after allogeneic stem cell transplantation for EBV-AHS.

It has been reported that the adult mammalian harbors stem cells or progenitors that retain the potential for both neural production and differentiation. Recently, several progenitors derived from non-neural samples as well as the neural tissues in humans are thought to be a good candidate for the regenerative medicine. Multipotent embryonic stem cells prepared from the fertilized egg or neural stem cells from fetus may be used as allotransplants. Progenitors derived from adult brain, bone marrow, code blood, or lipid can be used as autotransplants. Bone marrow in adult mammals contains several types of precursor and stem cells such as hematopoietic stem cells, non-hematopoietic stem cells, and other unknown precursor cells. The distinct population of progenitor cells in the bone marrow are thought to retain the potential for both neural production and differentiation, and may contribute to a therapeutic strategy for stroke. In the present report, the possible therapeutic strategy of the stem cell transplantation for the stroke is discussed.

The mortality of stroke is still the those of single organs. Even if patients survive the brain attack they often suffer from not only motor functional disability but also psychiatric problems such as post-stroke depression and decrease in spontaneity. The stoke is the number one cause of the bed-ridden state "Netakiri". Presently only anti-thrombotic and anti-oxidative stress therapies are available and the ischemic core destroyed immediately after the stroke could never be rescued. We have started to study the basic aspect of transplantation therapy of cerebral infarction using neural stem cells. Using a focal ischemic model of the gerbil by repeated occlusion of the unilateral carotid artery, we grafted human neural stem cells which were cultured and proliferated for a long period. Grafted animals showed significant and marked improvement in all three functions including motor, sensory and cognitive functions associated with a significant reduction of infarction volume. Synaptic contacts between neurons from grafted human neural stem cells and host neurons were confirmed by immuno-electron microscopy. This is a very encouraging report although it is necessary to elucidate the precise mechanism of the functional recovery or the effect of neural stem cell transplantation.

Multipotent adult progenitor cells, which can differentiate into mesenchymal cells as well as cells with visceral mesoderm, neuroectoderm and endoderm characteristics, have been identified in the bone marrow. We examined whether bone marrow-derived cells can differentiate into the major cell types in the brain, including neuron, astrocyte, microglia and endothelium, in response to cerebral focal ischemia under treatment with cytokines. Bone marrow cells, which were sampled from green fluorescent protein (GFP)-expressing transgenic mice, were transplanted into irradiated female C57 Black/6 mice. Two months later, the recipient mice received permanent occlusion of the middle cerebral artery, then were treated with cytokines. One month after the occlusion, GFP-expressing cells, considered to be bone marrow-derived, were identified as neurons, endothelial cells, microglias and macrophages by means of NeuN, CD31, major histocompatibility complex class I antigen, and CD45 labeling, respectively, observed with confocal microscopy. These results indicate that the bone marrow-derived cells are, at least in part, a source of neurons as well as endothelial cells generated in response to cerebral infarction, in the presence of cytokines. This finding may suggest a new therapeutic strategy to enhance neuronal and vascular regeneration after stroke in the clinical field.

Neural stem cells are considered the ultimate lineage precursors to all neurons and glia. Despite the significance of neural stem cells in the mammalian brain development, their ontogenesis remains unclear. We have established a colony-forming embryonic stem (ES) sphere assay, where ES cells were cultured in serum-free media in the presence of leukemia inhibitory factor (LIF) to form floating spheres. LIF-dependent ES cell-derived sphere cells showed self-renewal and neural multipotentiality, cardinal features of the neural stem cell, but retained some non-neural properties and broader potential. We dabbed the cells in the ES cell-derived sphere of primitive neural stem cells. LIF-dependent sphere-forming cells were also present in the epiblast of embryonic day 5.5-7.5 mouse embryos. The generation of the in vivo primitive neural stem cell was independent of Notch signaling but the activation of Notch pathway was necessary for the transition from the primitive neural stem cell to the neural stem cell. We propose that the neural stem cell originates from the pluripotent inner cell mass/epiblast cell via the primitive neural stem cell stage under the control of Notch signaling.

It had been long believed that our adult mammalian central nervous system (CNS) does not regenerate after damage due to injuries or degenerative diseases, as Santiago Ramóny Cajal had indicated long time ago. Today, however, CNS came to be recognized as an important target of so called "regenerative medicine". We have been proposing that regeneration of CNS does include the following three concepts: i) re-growth of the damaged neuronal axons, ii) replenishment of lost neural (or neuronal) cells and iii) recovery of lost neural functions. Here, we would like to emphasize that to recapitulate normal neural development is an essential strategy for CNS-regeneration. In this review, we would like to take Parkinson's disease and spinal cord injury as examples to discuss actual strategy aiming for CNS-regeneration.

The aims of neurology in Japan in the 21st Century should include establishment of therapeutic measures for neurological diseases, training clinical neurologists to cover both static and dynamic aspects of neurology, and application of gene therapy and neurogenesis to clinical neurology. It is also important to note that once any neurological disease develops, remaining sequelae are usually not curable, so the problem of how to prevent the onset of neurological diseases, that is preventive neurology, will become increasingly important. The key target for prevention in neurology is cerebro-vascular disease, since it is very common. Many risk factors are known for ischemic CVD. However, even for the management of hypertension, the so-called number needed to treat (NNT) is 29-118/5 years for primary prevention and 14-23/5 years for secondary prevention. It is also important to consider genetic factors that influence CVD, including abnormal plasminogen, Lp (a), ACT Isehara 1 gene, apolipoprotein E and so on, since these congenital factors reinforce known acquired risk factors, such as hypertension. In addition, the presence of asymptomatic cerebral infarction, as well as PVH and DSWMH, in MRI T2-weighted images is an important predictor of future symptomatic CVD. Finally, storage of one's own bone marrow cells might be useful, since in the event of onset of CVD, dementia or other neurological diseases, autotransplantation with cytokine might become available for neurogenesis. The results of our recent experiments indicate that this idea may be feasible.

Embryonic stem (ES) cell lines are pluripotent stem cell lines that can be propagated indefinitely in culture, retaining their potency to differentiate into every type of cell and tissue in the body. ES cell lines were first established from mouse blastocysts, and have been used for research in developmental biology. ES cells have been proven to be very valuable in the genetic modification of the mouse, especially in producing knockout mice. Since establishment of human ES cell lines was reported, their use in cell replacement therapies has been enthusiastically expected. There have been reports of the differentiation of several useful cell types from human ES cell lines, and clinical use of functional tissues and cells from human ES cells is anticipated. In Japan, there have also been many demands for the use of human ES cells in basic and pre-clinical research. We obtained governmental permission to establish human ES cell lines in April 2002 and started research using donated frozen embryos in January 2003. We successfully established three ES cell line from three blastocysts. These cell lines will be distributed at cost to researchers who have governmental permission to use human ES cells.

The aim of this study was to define transcriptional changes that occur during dexamethasone-induced in vitro osteoblastic differentiation using human mesenchymal stem cells (hMSCs). Bone marrow derived hMSCs from three individual donors were grown in DMEM containing 10% fetal bovine serum and antibiotics (basal media, BM). At confluence (Day 0), cells were grown in BM or BM plus ascorbic acid, beta-glycerophosphate and dexamethasone (OS). At 0, 3, 7 and 14 days, total RNA was isolated from hMSCs, and 32ρ-labelled probes were synthesized. Atlas 1.2 gene arrays (Clontech) were hybridized with donor-specific cDNA probes. Acquired data were analyzed using GeneSpring Software (Silicon Genetics) enabling normalization and averaging of donor-specific data sets at each time point. Only 8, 31, and 27 genes were upregulated more than 3-fold at 3, 7 and 14 days, respectively. Over 50 genes were downregulated at each time point. Interestingly, the results of this study did not reflect commonly identified genes that are frequently considered in cellular differentiation along the osteoblastic lineage. Instead, some interesting genes were upregulated. Seven days exposure to OS media resulted in the relatively high induction of several genes, including growth factors and receptors which affect adipocyte, chondrocyte and osteoblast differentiation. IGF II and FGFR 3, FGFR 2 were upregulated in the middle of 14 days' induction. Examination of gene expression at day 14 also revealed a number of receptors (LEPR) and transcription factors (ROR alpha) were upregulated during 14 days. These could be of importance to the process of early stage differentiation.