Myelodysplastic syndromes (MDS) are a group of related disorders in which bone marrow stem cells malfunction, while the type is diagnosed based on the WHO classification revised in 2008. Although the diagnosis largely depends on the cytomorphology, it is difficult to diagnose MDS based on the morphology alone, particularly in patients with < 5% blasts in the bone marrow and a normal karyotype. In Japan, a grading system for the diagnostic accuracy of MDS was proposed in 2007, and evaluation of dysplasia (high, intermediate, low, minimal) is a characteristic part. Morphologic dysplastic changes are classified into highly specific category A (pseudo-Pelger-Huet anomaly, degranulation of neutrophils, micro-megakaryocytes, ringed sideroblasts) and less specific category B (dysplasia other than category A). With the use of this grading system, diagnostic problems should be reduced. Flow cytometry has also been proposed as a tool to improve the evaluation of marrow dysplasia, because immunophenotyping is an accurate method for quantitative and qualitative evaluations of hematopoietic cells, and MDS specimens have been found to exhibit abnormal expressions of several cellular antigens. In addition, the molecular classification of MDS has received marked attention in recent years. New molecular markers including RPS14, TET2, IDH1/2, SF3B1, ASXL1, RUNX1, TP53, EZH2, JAK2, and WT1 have been revealed to be important for the prognosis, as well as diagnosis and classification. In this report, we review MDS diagnostic approaches from the viewpoints of cytomorphology, immunophenotyping, and cytogenetics.

Multiple myeloma (MM) is a malignancy of plasma cells of the final maturation stage of B cells, characterized by atypical plasma cell proliferation in bone marrow and the production of monoclonal immunoglobulin. The history of chemotherapy for MM began in the early 1960s, when the efficacy of alkylating agents, particularly melphalan, was shown. High-dose therapy (HDT) has been the standard treatment for patients younger than 65 years since the superiority in terms of OS as well as PFS of HDT supported by autologous stem cell transplantation (ASCT) was reported. From the 2000s, the emergence of novel agents involving proteasome inhibitors such as bortezomib, and IMiDs such as thalidomide and lenalidomide, has been markedly changing MM treatment and improving the prognosis. As initial treatment, novel agents are frequently used since high response rates have been reported. For MM patients who are not candidates for HDT ASCT because of aging and/or organ dysfunction, combined therapies that consist of conventional chemotherapy and novel agents are usually recommended. The chromosomal aberrations frequently found in MM are 'hyperdiploid' or 'non-hyperdiploid' and immunoglobulin gene (Ig) translocation of chromosomes. It is known that the chromosomal aberration is associated with the treatment response and prognosis of MM patients, and this information is indispensable. Because chromosomal translocation is not readily detected by G banding, the FISH method is essential. In recent years, molecular mechanisms of MM have been revealed by microarrays (Gene Expression Profiles) and whole genome sequencing using next-generation sequencers. Furthermore, in-depth sequencing by such next-generation sequencers has revealed that MM is monoclonal, but shows intra-clonal heterogeneity at the onset of the disease from the viewpoint of genetic abnormality.

Acute myeloblastic leukemia (AML) is a disease which may be completely cured by intensive chemotherapy or stem cell transplantation. However, the prognoses are poor in elderly, refractory or recurrence cases. Molecular targeted drugs have been expected to improve the prognoses of patients with various cancers, but there are few kinds of molecular target drugs for AML. On the other hand, excellent drug exists such as tretinoin for acute promyelocytic leukemia. Molecular mechanisms have been elucidated in AML cells, and the molecules which can be the good target of the treatment have been identified. Novel molecular target drugs are also expected.

ATP binding membrane transporter such as multi drug resistant protein (MDR1) and breast cancer resistance protein (BCRP) are highly activated in side population (SP) of various normal organs. It has been demonstrated that various primary as well as cancer cell lines also possess SP. Since SP cells have been also known as the cancer initiating cell rich population in various cancers, the population might play a crucial role in the pathogenesis of multiple myeloma. Recent our works demonstrated that G2/M (e.g. CCNB1, CDC2), centrosome (e.g.AURKB, CENP), polycomb (e.g. EPC1, EZH2) and proteasome (e.g. UBE3C, PSMA5) related genes were upregulated in the SP of myeloma cell lines and CD138-positive primary samples. Although myeloma has been known as incurable disease, discovery of new agents such as immunomodulatory drugs (lenalidomide) and proteasome inhibitor (bortezomib) provide improvement of prognosis of the tumor entity. These drugs might be effective to downregulate aforementioned aberrantly upregulated gene products in myeloma SP. Here we show some evidences of use of these drugs for targeting myeloma-SP cells.

Human acute myeloid leukemia is organized as a hierarchy initiated and maintained by "leukemia stem cells(LSC)" which possesses self-renewal capacity. LSCs are therapeutic targets and must be eliminated to cure the patients. Recent advances in LSC research provided insights into the cell surface antigens preferentially expressed on AML-LSCs compared with normal hematopoietic stem cells and the signaling pathways defining the LSC characteristics. These molecules are potential targets to eradicate LSCs. Especially, monoclonal antibodies targeting surface antigens expressed on LSCs, including CD123, CD44, TIM-3 and CD47 have been shown its efficacy against AML-LSCs in xenotransplant models.

Primary amyloid light chain (AL) amyloidosis is the most common and most aggressive form of systemic amyloidosis. In AL amyloidosis, the products of free light chains (FLCs) of monoclonal amyloidogenic plasma cells deposit in the heart, kidneys, liver, gastrointestinal tract, autonomic nerve systems, and soft tissues, consequently leading to progressive disability and organ failure. Tissue biopsy (mainly bone marrow and subcutaneous fat aspirate) staining with Congo red to demonstrate amyloid deposits is required for diagnosis. Autologous stem cell transplant is the preferred treatment method; however, only 25% of patients are eligible. Non-transplant candidates can be offered melphalan-dexamethasone or clinical trials of new agents (thalidomide, lenalidomide, and bortezomib), which have been shown to improve survival. N-terminal pro-brain natriuretic peptide (>1800 ng/l), cardiac troponin T (>0.025 ng/ml), and dFLC (>180 mg/l) are known poor prognostic factors. Late diagnosis remains a major obstacle for initiating effective therapy while organ dysfunction is still recoverable.

Metals are effectively used in biological systems under the strict regulation for exploiting their specific and broad reactivities. For example, manganese (Mn) can induce catecholamines-mediated oxidative biological damage in cooperation with iron (Fe) and/or copper (Cu). In children, the damage could induce developmental disorders such as attention deficit hyperactivity disorder (ADHD). We hypothesize that infant neurons are more labile to metals than adult ones due to the prematured protection systems and sensitive differentiating cells. An experimental system reconstituting neural differentiation is expected to assess the influences of endogenous/exogenous factors including metals. In this study, we investigated an impact of Mn together with Fe and dopamine (DA) on neural differentiation of mouse embryonic stem cells (mESCs). The differentiation of mESCs was initiated by embryoid bodies (EBs) formation in the presence of all-trans retinoic acid, and then EBs were treated with Mn, Fe and/or DA. Then, the mRNA levels of neural differentiation marker genes (Nestin, Emx2, Mtap2, Th, Olig2 and Gfap) were examined using realtime RT-PCR analysis. Mn or DA alone reduced Mtap2, Th and Olig2 expression levels and increased Nestin. Moreover, combined treatment of Mn and DA also increased Nestin expression level. On the other hand, Fe alone reduced Mtap2, Th and Olig2 expression levels, and increased Emx2. Combined treatments of Fe with Mn or DA also tended to increase Emx2 expression level. These effects emerged at about 100 times less concentration than that inducing cytotoxicity in human neuroblastoma. The present study showed that Mn inhibits neural development, and that our mESCs system can be a useful tool to elucidate the toxicity mechanism as well as to evaluate the effects of metals and chemicals on differentiating cells.

The hematopoiesis takes place in the bone marrow. Because bone marrow is the "marrow" of the bone, bone marrow does not exist without bone. The specialized microenvironment for hematopoietic stem cells (HSCs) to be appropriately functional is called "niche" . In the recent ten years since the bone-forming osteoblast was identified as a HSC niche, the entire mesenchymal lineage cells from mesenchymal stem cells to end-terminal osteocytes have been recognized as niche cells or niche-modulators. Among these, mesenchymal stem/progenitor cells are located at perivascular area. The very recent study showed the difference between arteriolar and sinusoidal niches. It is likely that the vascular network and the bone tissue are connected by the mesenchymal lineage cells as a complex of bone forming system, and HSCs utilize this complex as a series of niche.

Rheumatoid arthritis (RA) is an autoimmune disease represented by chronic inflammation and following structural damage at the articular joints. Progression of the disease causes disability and subsequent early retirement or a care-requiring condition. Although new agents have the potential of complete inhibition of joint damage, there is still a considerable number of patients with progressed joint damage who couldn't receive the benefits of these agents because of the long duration of their disease or uncontrollable disease activity. Thus, a new treatment tool for RA aiming at joint repair is necessary. Mesenchymal stem cells (MSCs) are known to build bone and cartilage, and also have immunosuppressive ability. We have considered MSCs as a new treatment tool of RA, and have reported that MSCs suppress osteoclastogenesis. More recently, we also reported that inflammation induces osteogenesis and suppresses the chondrogenesis of MSCs. An investigation of a new delivery system of MSCs to the target lesion is now ongoing. The data from this investigation suggest that MSCs can be a new application in the treatment of RA.

Recently, studies on regenerative stem cell therapy are being encouraged, and efforts to generate dendritic cells, which play important roles in cancer immunotherapy, from stem cells are being made in the field of tumor immunology. Therapeutic acquisition of stem cells has important clinical applications. Studies on induced pluripotent stem(iPS)cells generated from somatic cells with pluripotent genes have advanced in recent years. Stem cells are reported to be found in adipose tissue (adipose-derived stem cells, ADSC). Our goal is to develop a new cancer vaccine by using dendritic cells generated from ADSC. In a preliminary study, we examined whether iPS cells can be generated from ADSC to serve as a source of dendritic cells.We introduced a plasmid with pluripotent genes(OCT3/4, KLF4, SOX2, L-MYC, LIN28, p53-shRNA)into an ADSC strain derived from adipose tissue by electroporation and subsequently cultured the cells for further examination. A colony sugges- tive of iPS cells from ADSC was observed. OCT3/4, KLF4, SOX2, L-MYC, and LIN28 mRNAs were expressed in the cultured cells, as confirmed by reverse transcriptase-polymerase chain reaction(RT-PCR). On the basis of these results, we confirmed that iPS cells were generated from ADSC. The method of inducing dendritic cells from iPS cells has already been reported, and the results of this study suggest that ADSC is a potential source of dendritic cells.

Stem cells are characterized by their ability to self-renew and differentiate into cells in the tissues, and have an important role in the maintenance of tissues and/or organs. Even in cancers in which accumulated gene mutations drive the abnormalities in cell proliferation and differentiation, the presence of stem cells, called cancer stem cells, has been proposed. Current observations suggest that cancer stem cells have properties reminiscent of normal stem cells and have pivotal roles in tumor development, recurrence, and metastasis. Because cells in a multicellular organism contain basically the same genetic information, the mechanisms that regulate gene expression, such as microRNAs and epigenetics, are critical for the proper differentiation of stem cells. Indeed, studies have shown that cooperative interactions between microRNAs and epigenetics regulate stem cell properties. We have previously reported that the microRNAs in the miR-200 clusters are coordinately downregulated in human breast cancer stem cells and normal breast stem cells. Among them, miR-200c targets the Polycomb group protein BMI1, a critical regulator of stem cell functions. The expression of the miR-200 precursor is regulated by histone modifications and Polycomb group proteins. Moreover, miR-22 targets a DNA demethylase and suppresses the expression of the miR-200 precursor, thereby enhances the expression of BMI1. Considering the recent development of therapies that target cancer stem cells and/or epigenetics, understanding the molecular mechanisms for stem cell regulation is becoming increasingly important.

Intestinal mucosa is renewed throughout life in a repeating cycle of proliferation, differentiation, and cell death. Intestinal stem cells play a very important role in the maintenance of the intestinal environment, which is frequently exposed to various factors such as food, infections, microbiota elements, drugs, and metabolic products. Therefore, identification of intestinal epithelial stem cells might help in understanding intestinal regulation. On the other hand, dividing intestinal stem cells may, by an unknown mechanism, give rise to cancer stem cells that cause the various malignant types of colon cancer. In this paper, current developments in the study of the regulation of both intestinal stem cells and cancer stem cells are reviewed.