Acute myeloid leukemia (AML) has been treated with combination chemotherapy, hematopoietic stem cell transplantation (HSCT) and differentiation induction therapy. Intensive induction and consolidation therapy including high dose cytarabine (HDAC) is a widely used combination in chemotherapy in the USA and European countries. In Japan, the efficacy of HDAC needs to be evaluated under a good clinical trial. Stem cell source for HSCT has been expanded, and the number of peripheral blood stem cell transplantations is greater than that of bone marrow transplantation, especially for auto-transplantation. Despite some randomized clinical trials, we still do not know whether HSCT provides longer survival than chemotherapy for patients with AML when performed during their first remission. Differentiation therapy for acute promyelocytic leukemia (APL) using ATRA showed clear success in the treatment for AML. APL is stratified with its specific karyotype and morphology, and this stratification leads to the improvement of overall survival of patients with APL. Several clinical study groups in the world have studied prognostic factors and it has been shown that the chromosomal abnormality of AML cells is closely related to the response to the chemotherapy. The stratification of AML using these prognostic factors is incorporated in some clinical trials to determine whether this approach actually leads to better survival for patients with AML.

Embryonic stem (ES) cells are pluripotential cells, and enable us to study mechanisms of cell differentiation. Gene disruption of ES cells by homologous recombination is to be clear the function of targeted genes. Recently, it has been reported that bone marrow hematopoietic stem cells have a potential to differentiate into neuronal cell, muscle cell, liver cell, epidermal cell, and also epithelial cell lineages. Moreover, cloned animals from somatic cell nuclei were produced. Here, we show osteoclastogenesis, and endothelial cell-genesis from single ES cell, and discuss the possibility for organogenesis in vitro. Furthermore, we would like to summon to understand usefulness and dangerousness of the regenerative medicine.

A 41-year-old man visited his doctor in May 2000 because of a sore throat and high fever. His symptoms did not improve, despite administration of antibiotics and nonsteroidal anti-inflammatory drugs. Since a chest X-ray examination revealed an anterior mediastinal bulky tumor, he was referred and admitted to our hospital on June 21, 2000. The peripheral white blood cell count was 44,540/microliter with 74% myeloblasts. Bone marrow aspiration revealed a hypercellular marrow with 82% myeloblasts, which were negative for peroxidase and alpha-naphthyl butylate esterase staining. Blast cells were positive for CD7, CD13, CD33, CD34, and HLA-DR, and negative for CD56. A needle biopsy specimen of the mediastinal tumor consisted of myeloblasts. We diagnosed the patient as having CD7 (+) acute myeloid leukemia (AML) (M0) with a bulky mediastinal mass based on the surface marker analysis, although the clinical features resembled myeloid/NK precursor acute leukemia. The patient achieved a complete remission after two courses of induction therapy. We are planning an allogeneic stem cell transplantation during his first remission because of the high risk of relapse.

The in vitro effect of various glycosaminoglycans (GAGs) on the clonal growth of CD34+ megakaryocytic progenitor cells (CFU-Megs) isolated from human placental/umbilical cord blood (CB) was evaluated in human plasma containing semisolid culture stimulated by recombinant human thrombopoietin (TPO). The GAGs, including hyaluronic acid from human umbilical cords (HA-h), pig skins (HA-p) and rooster combs (HA-r), or keratan sulfate (KS), various chondroitin sulfates (CS-A, B, C, D, E), and heparan sulfate (HS), were tested. Each GAG alone did not affect the clonal growth of CFU-Meg. In the presence of TPO, adding of HA-p or HS (100 micrograms/ml) resulted in an approximately 1.3-fold increase, in the total number of colonies, due to an increase in large megakaryocyte colonies. In contrast, CS-E led to a marked decrease in CFU-Meg growth. At the end of the culture, the total number of cells increased 3.0-fold of the initial value of the control, but adding HA-p or HS showed an approximately 9.1-fold or 18.3-fold increase. Similarly, the total number of CFU-Meg detected in the harvested cells increased to 4.8-fold of the initial value, while, an approximately 18.3-fold or 38.8-fold increase was observed in the culture containing HA-p or HS, respectively. Flow cytometric analysis of the harvested cells showed no significant difference in the expression of surface antigens and DNA ploidy distribution of megakaryocytes between the control and GAG treatments. These results suggest that HA-p and HS promote the proliferation of immature CB CD34+ CFU-Meg in the presence of TPO.

Peripheral blood stem cell harvest with lenograstim (glycosylated rhG-CSF) was performed 12 times from 10 normal donors. Five micrograms/kg of lenograstim was administered subcutaneously twice a day (10 micrograms/kg/day) for 4 to 6 days, and apheresis was performed on day 5 to 7 depending on the collected CD 34+ cell counts. We collected a sufficient number of CD 34+ cells in 9 mobilizations from 7 donors less than 50 years of age, with a total number of collected CD 34+ cells in each mobilization of 22.1 +/- 6.5 x 10(7). In contrast, we could not obtain a sufficient number of CD 34+ cells in 2 mobilizations from 3 donors above 50 years of age, with a total number of collected CD 34+ cells of 9.8 +/- 3.3 x 10(7). Although all donors had adverse events in response to lenograstim administration, all of them were grade 2 or less toxicity. These results indicate that peripheral blood stem cell mobilization and apheresis by lenograstim is safe and well tolerated, but the risk of poor mobilization may become higher in donors more than 50 years of age.

Stem cells are defined as cells with the ability for self-renewal and differentiation. Hematopoietic stem cells are well known, and their application is useful for the treatment of various kinds of diseases. Recently, neural stem cells have been identified even in the adult brain, which has up to now been considered to be a tissue with no regenerative capacity. In addition, it has emerged that tissue stem cells can differentiate into various kinds of cells beyond their original characteristics. Here, we discuss the self-renewal mechanisms of embryonic stem (ES) cells, hematopoietic stem cells and neural stem cells.

Hematopoietic stem cell transplantation(HSCT) increase the chances of cure of many hematological malignancy. The clinical laboratory plays a major role in support of HSCT. Both transplantation-specific laboratory test(tissue typing, assessment of graft viability/rejection, evaluation of minimal residual disease, and measurement of immunosuppressive drugs) and routine clinical laboratory tests(biochemical, hematological, serological, urinary, bacteriological, and physiological examinations) are significant. Hematopoietic stem cells(HSC) are usually assessed as CD34+ cells, while immature cells determined by automated hematology analyzers can simply evaluate HCS. These automated immature cell counts are earlier markers of engraftment following transplantation than the traditional indicators(neutrophils and platelets). After transplantation, infections, regimen-related toxicities, graft-versus host disease, veno-occlusive disease, and thrombotic microangiopathy are the serious complications, which are causes of expected mortality and morbidity in HSCT. Clinical laboratory monitoring may contribute early diagnosis and treatment of the complications, resulting in prevention of the adverse events.

From January 1996 to December 1999, fifteen patients with germ cell tumors underwent peripheral blood stem cell harvest during 15 courses of bleomycin, etoposide, cisplatin (BEP), 4 courses of etoposide, ifosfamide, cisplatin (VIP) and 3 courses of high-dose etoposide mobilization at Nagoya University Hospital. We performed 29 aphereses during BEP, eight during VIP, and six during high-dose etoposide. Although we were able to harvest 4.4 x 10(6)/kg of median CD34 positive cells per apheresis during BEP, the number of stem cells (more than 4 x 10(6)/kg of CD34 positive cells), which are needed for tandem high-dose chemotherapy, could not be obtained during four courses of BEP. For three patients in whom white blood cell counts at nadir were 2,000/microL or more, however, the required number of CD34 positive cells were harvested. VIP provided only 1.7 x 10(6)/kg of median CD34 positive cells per apheresis, while, 7.3 x 10(6)/kg of CD34 positive cells were harvested during high-dose etoposide mobilization. The dose of G-CSF was a significant factor for the number of CD34 positive cells harvested during BEP (p = 0.02); however, there might be some relationship between the harvest and the number of the peripheral white blood cells on the day of apheresis (p = 0.08), the day to start G-CSF (p = 0.13), or the day to initiate apheresis (p = 0.27). Based on our experience, it is recommended that 5 micrograms/kg of G-CSF should be started from the 14th or 15th day of BEP until the last apheresis and that aphereses should be performed between the 19th and 21st day, especially at the days when the peripheral white blood cell count increases beyond 10,000/microL.

Molecular genetic and cytoimmunological markers have been applied for the detection of minimal residual disease (MRD) in hematological malignancies. These markers include surface markers or rearranged T-cell receptor and immunoglobulin genes in the lymphoid malignancies and fused genes associated with chromosomal translocations such as BCR-ABL in t(9;22) or PML-RAR alpha in t(15;17) in myeloid malignancies. The expression of the WT1 gene is recognized as the universal tumor marker for a wide variety of hematological malignancies. Using these sensitive markers, a tumor cell in 10,000 to 1,000,000 normal cells can be detected. By examining a large number of patients, it has been shown that the MRD in the early phase of chemotherapy has a correlation with the prognosis of childhood ALL. Based on these observations, a new strategy of chemotherapy in which the post-remission therapy is modified based on the MRD results has begun. The amount of tumor cells contaminated in the autologous stem cell grafts in ALL patients might be related to the prognosis. The diagnosis of MRD will be used as an important routine examination in chemotherapy for leukemia/lymphoma patients.

We determined the distribution of mast cells in nasal mucosa and studied their proliferation. Inferior turbinate mucosa was sampled in 13 patients with allergic rhinitis (allergic group) and 5 without (non allergic group) and stained immunohistochemically using anti mast cell tryptase antibody, anti-c-kit antibody, anti-PCNA antibody, and anti mast cell chymase antibody. Tissue sections stained with anti tryptase antibody revealed a higher degree of infiltration of tryptase-positive cells, i.e., mast cells, in the allergic group than in non allergic group. In the allergic group, the number of tryptase-positive cells, c-kit-positive cells, and PCNA-positive cells was significantly greater in the epithelium and shallow lamina propria than that in the deep lamina propria. Tryptase-positive, c-kit-positive cells, i.e., c-kit-positive mast cells, and tryptase-positive, PCNA-positive cells, i.e., PCNA-positive mast cells, were also abundunt in the epithelium and shallow lamina propria. The stem cell factor and c-kit receptor are reported to play a primary role in mast cell differentiation and proliferation. PCNA-positive cells represent actively proliferating cells. Based on the above, we concluded that mast cells in the epithelium and shallow lamina propria in the allergic group differentiated and proliferated more actively than those in the deep lamina propria.

High-dose therapy with peripheral blood stem cell transplantation (HDT/PBSCT) was performed as one aspect of front-line therapy in patients with poor-risk aggressive non-Hodgkin's lymphoma (high-intermediate/high risk) according to the age-adjusted international prognostic index (aaIPI). Twenty-nine patients were enrolled in this study between November 1994 and March 1999. CHOP + etoposide (CHOP-E) was used as an initial chemotherapy and as a chemotherapy agent for the purpose of cell harvesting. Peripheral blood stem cells were harvested from 17 patients, and HDT with CEC (carboplatin, etoposide, cyclophosphamide)/PBSCT was performed in 11 patients. Eighteen patients dropped out, including five for whom CHOP-E therapy was ineffective and 5 who did not give consent for cell harvesting or HDT/PBSCT. CHOP-E therapy produced complete remission (CR) in 15 out of 26 patients (58%) after discounting the 3 who were ineligible among the 29 who were initially enrolled. The median observation period after PBSCT in the 11 patients who underwent HDT/PBSCT was 25 months (3 to 50 months), and the 3-year disease-free survival rate was 73%. No serious complications associated with the transplantation were observed. We were able to confirm the feasibility and safety of HDT/PBSCT as one form of front-line therapy for aggressive non-Hodgkin's lymphoma in patients under 60 years of age.

A 53-year-old woman was admitted to the hospital because of headache and disturbance of consciousness. She was afebrile. No inflammatory reaction was identified on serologic examination. Radiological findings showed acute-subacute, massive intracerebral hemorrhage in the right temporal lobe, compressing the brain stem contra-laterally. On the day of admission, she underwent a right temporal craniotomy for the removal of the mass lesion. The resected brain tissue demonstrated a small hemorrhage and edema accompanied by the infiltration of lymphoid cells into the subarachnoid space. Several days after surgery, the patient became lethargic and showed urinary incontinence. Late onset of fever and CSF findings suggested she was suffering from viral encephalitis. Serological findings, however, disclosed no antibody production against HSV, HZV, or CMV. For the diagnosis, a biopsy of the brain was carried out and herpes encephalitis was subsequently proved. Unfortunately, her condition deteriorated quickly and she died without anti-viral treatment.