Telomeres are structural elements that seal and protect the ends of linear chromosomes from illegitimate recombination, end-to-end fusion, or being recognized as damaged DNA. These repeats are gradually lost with cellular replication and aging. Telomere attrition eventually leads to critically short telomeres, inducing cellular proliferative senescence and/or apoptosis possibly due to genomic instability. It is thought that telomeres are shortened as a result of pathogenic mutations in telomerase gene components which are DKC1, telomerase RNA component (TERC), and telomerase reverse transcriptase (TERT), and in SBDS gene that lead to an impairment in the proliferative capacity of hematopoietic stem cells in patients with inherited and acquired bone marrow failures.

Among different immune pathophysiologies of anemia, those of bone marrow failure syndromes such as aplastic anemia and myelodysplastic syndrome are most difficult to understand. An increase in the proportion of glycosylphosphatidyl-inositol anchored protein-deficient cells has been identified as the best marker for the presence of immune pathophysiology in this elusive syndrome. The significance of detecting small populations of such paroxysmal nocturnal hemoglobinuria (PNH)-type cells was substantiated by a recent observation that PNH-type cells arose from a donor-derived hematopoietic stem cell with a PIG-A mutation in an aplastic anemia patient with late graft failure which responded well to immunosuppressive therapy. Identification of auto-antigens capable of inducing cytotoxic T cells against hematopoietic stem cells is necessary to prove the escape of PIG-A mutant clone from the immune system attack using animal models.

Erythroid development is influenced by cytokines: erythropoietin (Epo) and stem cell factor (SCF), which works synergistically. Epo is the major regulator of erythropoiesis, which is produced by kidneys with an inverse relation to oxygen availability. The Epo gene expression is controlled by HIF-1alpha. After binding the Epo-receptor, it activates the JAK2-STAT5 pathway, PI3K-AKT pathway and so on. Finally, these signals enhance erythropoiesis. All hematopoietic cells are derived from the hematopoietic stem cells (HSCs). HSCs are localizing in a two different bone-marrow microenvironment: the osteoblastic niche and the vascular niche. The erythroid progenitors are induced from HSCs mainly by the membrane bound SCF derived from the bone-marrow stromal cells and then entrapped in the extracellular matrix.

Hematopoietic stem cells (HSCs) maintain themselves over cell divisions (self-renewal) and produce all kinds of blood cells (multi-potency). Depletion of these cells eventually causes hematopoietic failure, while deregulated HSC division causes development of myeloproliferative disorders and leukemias. HSCs can be prospectively purified to nearly homogeneity in mice, but such a high-level purification has not been achieved in humans. HSCs are localized to an anatomical place called 'niche'. Specialized osteoblasts arrayed on the endosteum of cavernous bone and sinusoidal endothelial cells located at the distant position from the endosteum are the two representative candidates of such an HSC niche. A number of adhesion molecules and signaling molecules are thought to comprise the niche-HSC synapse. HSCs divide only once in 1-2 months. Both environmental signaling from the niche and HSC-autonomous molecular programs contribute to the quiescent state of HSCs, which is essential for the maintenance of HSC self-renewal capacity and homeostasis of blood production.

Bioactive compounds that may control the specific differentiation from mouse embryonic stem (ES) cells into cardiac-like cells have been screened from herbal medicines. Among seven preparations, Panax ginseng was found to promote the differentiation into beating cells and to sustain their beating for longer than the control. Active compounds were found in its water-soluble fraction. Although they were not isolated, their candidates were surveyed in 42 compounds selected from the database of P. ginseng. Finally we found that vitamin B12 (VB12) and methionine were active. VB12 accelerated the differentiation into beating cells and made the beating rate constantly 100%. Moreover, VB12 was effective in the recovery of beating that was inhibited by spermine action. The mechanism of action of VB12 is discussed in termo of the relevance of intercellular electrical signal transduction.

During 1996 and 2006, we examined clinically 37 patients and neuropathologically 13 autopsy cases with amyotrophic lateral sclerosis/parkinsonism-dementia complex of the Kii peninsula (Kii ALS/PDC). The ages of onset were between 52 years and 74 years (mean age: 65.3 years). The male to female ratio was 1:1.85. The ratio of positive family history where ALS or PDC occurred within the fourth degree of the relatives was 78.4% in the patients with Kii ALS/PDC. The average duration of the illness was 6.47 years. Kii ALS/PDC was divided into five clinical subtypes, pure ALS form, ALS with dementia form, PDC with parkinsonism predominant form, PDC with dementia predominant form (that is called late-life dementia in Guam) and PDC with ALS features form. Unique pigmentary retinopathy was found in 33.3% of the patients with Kii ALS/PDC. CT/MRI images showed atrophy of the frontal and temporal lobes and SPECT images showed a decrease in the blood flow of the frontal and temporal lobes. The cardiac 123I-MIBG uptake was decreased in 4 out of 8 patients with ALS/PDC and the decrease in uptake correlated with the modified Hoehn-Yahr staging. The cardinal neuropathological features of Kii ALS/PDC were abundant neurofibrillary tangles (NFTs) associated with loss of nerve cells in the cerebral cortex and the brain stem, and findings of ALS neuropathology. Ultrastructurally, NFTs consisted of paired helical filaments. Tau protein, a main component of NFTs, was consisted of 3R and 4R tau isoforms, and phosphoryrated at 18 sites of tau phosphoryrated sites. The neurons of dentate gyrus of hippocampus and anterior horn cells were stained with anti-TDP-43 antibody. The clinical and neuropathological aspects of Kii ALS/PDC are regarded as being identical with those of Guam ALS/PDC.

A 55-year-old man with acute promyelocytic leukemia in the first relapse was treated with arsenic trioxide as salvage therapy. After obtaining molecular remission, he underwent autologous peripheral blood stem cell transplantation (PBSCT) with busulfan and melphalan conditioning. The transplant dose of CD 34-positive cells was sufficient, and engraftment was prompt. Platelet count increased to 320 x 10(9)/1 on day 21; however, it rapidly decreased to 27 x 10(9)/l on day 37. Despite treatment with corticosteroid, the platelet count decreased to 6 x 10(9)/l on day 55. About one month after cyclosporine administration, thrombocytopenia gradually improved. This clinical course suggests immune-mediated thrombocytopenia following autologous PBSCT.

We retrospectively investigated the hematopoietic cell transplantation-specific comorbidity index(HCT-CI)to predict non relapse mortality. Of 127 patients who underwent transplantation between January 2000 and December 2003 with conditioning consisting of total body irradiation, cyclophosphamide and thiotepa, HCT-CI scores were obtained for 83 patients. Median age was 42 years. The sources of stem cells included HLA-identical bone marrow or peripheral blood from sibling(30), HLA-matched bone marrow from unrelated donors(45), and HLA-mismatched bone marrow or peripheral blood from family donors(8). Hematological disease was divided into two groups, standard risk(47)and high risk(36). Standard risk indicates acute leukemia in first or second remission and chronic myelocytic leukemia in first chronic phase, while high risk indicates all other diagnoses. There were 45 patients with moderate or severe pulmonary comorbidities. 55 patients with HCT-CI scores of 2 or less had higher 2-year overall survival than 28 patients with HCT-CI scores of 3 or more(65% vs. 36%, p=0.0009). Although the non relapse mortality rate was not different, HCT-CI scores were a more useful indicator to predict survival in high risk patients than in standard risk patients. Prospective evaluation is warranted to clarify the usefulness of HCT-CI.