Yoji Ogasawara

Prognostic factors of hemophagocytic syndrome in adults: analysis of 34 cases

Abstract: Hemophagocytic syndrome (HPS) presents with fever, pancytopenia, liver dysfunction and increase in hemophagocytic histiocytes in various organs. Although there are two major classifications of HPS in adults, malignant and reactive histiocytosis, it is often very difficult to distinguish between these disorders. We analyzed the laboratory data of patients with HPS to evaluate prognostic factors. Of 34 patients, 14 survived, and 20 died. The median age of survivors was 29.6 ± 11.5 yr significantly younger than those who died (54.7 ± 17.8 yr). Twenty patients had no obvious underlying disease, the other 13 had hematological malignancies or viral infections. Comparison of laboratory data revealed that nonsurvivors had significantly lower Hb and platelet values on admission. During treatment, worsening of anemia and thrombocytopenia, increase of transaminase and biliary enzymes were similarly more prominent. Risk factors associated with death were: age over 30 yr, presence of disseminated intravascular coagulation, increased ferritin and β2‐microglobulin, anemia accompanied by thrombocytopenia and jaundice. Our data suggests that patients with HPS and any of these risk factors should be treated aggressively with sufficient chemotherapy and supportive care.

Long‐term administration of G‐CSF for aplastic anaemia is closely related to the early evolution of monosomy 7 MDS in adults

There is an increasing incidence of the evolution of myelodysplastic syndrome (MDS) from aplastic anaemia (AA) with immunosuppressive treatment. In paediatric patients G‐CSF is also reported to increase MDS evolution, but this process is not precisely understood in children or in adults. Therefore risk factors of MDS evolution in adults are evaluated here. Of 72 patients, five developed MDS. In 47 patients without cyclosporine (CyA) or antithymocyte globulin (ATG) therapy, only one developed MDS with trisomy 8, 242 months after diagnosis. But of 25 patients treated with either CyA or ATG, four developed monosomy 7 MDS within 3 years. Of these 25 patients, 18 were treated with G‐CSF and the four patients (22.2%) who developed MDS were found in this group. The cumulative dose and the duration of G‐CSF administration were significantly elevated in patients who developed MDS when compared with those who did not, 822.3 ± 185.0 v 205.4 ± 25.5 μg/kg (P < 0.05) and 187.5 ± 52.5 v 72.0 ± 24.6 d (P < 0.002), respectively. However these two values for CyA did not differ significantly. Statistically, treatment with CyA, G‐CSF and combined G‐CSF and CyA were significantly related to MDS evolution. The administration of G‐CSF for more than a year was the most important factor (P = 0.00). These results suggested that a close relationship exists between G‐CSF and subsequent monosomy 7 MDS from AA in adults who receive immunosuppressive therapy. Long‐term administration of G‐CSF should be prohibited in order to prevent MDS evolution.

Gene transfer into vascular cells using adeno-associated virus (AAV) vectors.

OBJECTIVES Recombinant viral vectors based on the nonpathogenic parvovirus, adeno-associated virus (AAV), have a number of attractive features for gene therapy, including the ability to transduce non-dividing cells and its long-term transgene expression. In this study, an AAV vector containing bacterial beta-galactosidase gene (lacZ) was used to transduce cultured rat vascular smooth muscle cells (VSMC) in vitro and rat thoracic aortas ex vivo. METHODS VSMC were transduced with AAV-lacZ at multiplicities of infection (MOI) ranging from 5.0 x 10(5) to 1.0 x 10(7). Expression of beta-galactosidase (beta-gal) in VSMC was evaluated by X-gal staining and a beta-gal ELISA method. Excised rat aortas were incubated with medium containing AAV-lacZ. Expression of beta-gal in the aortic segments was evaluated by X-gal staining. RESULTS With increasing MOI, up to 50% of cultured VSMC were positive by X-gal staining and the beta-gal expression increased up to 15 ng/mg protein. The expression gradually decreased during the culture but was detectable for at least 1 month. In the ex vivo study, AAV vectors transduced endothelial and adventitial cells in rat aortic segments, while no expression was seen in medial VSMC. CONCLUSIONS AAV vectors can efficiently transduce rat VSMC in vitro. AAV-mediated ex vivo gene transfer into the normal aorta resulted in efficient gene transfer into endothelial and adventitial cells but not into medial VSMC. These findings suggest that AAV-based vectors are promising for use in cardiovascular gene therapy.

A selective amplifier gene for tamoxifen‐inducible expansion of hematopoietic cells

We have developed a novel system for expansion of gene‐modified hematopoietic stem/progenitor cells to overcome the low efficiency of current gene transfer methodology. This system involves ‘selective amplifier genes’, that encode fusion proteins between the granulocyte colony‐stimulating factor receptor (GCR) and the hormone‐binding domain of estrogen receptor (ER). Hematopoietic progenitors expressing the chimeras showed estrogen‐responsive growth in a controllable manner. However, endogenous estrogen may activate the fusion proteins in vivo, depending on the hormonal status of the subjects.

The Use of Heterologous Promoters for Adeno- Associated Virus (AAV) Protein Expression in AAV Vector Production

Although adeno‐associated virus (AAV) vectors are potentially useful gene transfer vehicles for gene therapy, the vector production system is currently at the developmental stage. We constructed AAV helper plasmids (Rep and Cap expression plasmids) by replacing a native AAV promoter, p5, with various heterologous promoters to examine whether the efficiency of AAV vector production was influenced by modulating the AAV protein expression pattern. The helper plasmids containing heterologous promoters (EF, CMV, SV40, B19p6, and CAG promoters, respectively) expressed Rep78/68 more efficiently than a conventional helper plasmid (pIM45), but the expression of Rep52/40 and Cap decreased, resulting in a significant reduction in AAV vector production. Furthermore, the efficiency of vector production never fully recovered even if the Cap proteins were supplied by an additional expression plasmid. A large amount of Rep78/68 and/or a reduced level of Rep52/40 may have deleterious effects on AAV vector production. The present findings will aid in the development of a more efficient AAV vector production system.

Fas and Mutant Estrogen Receptor Chimeric Gene: A Novel Suicide Vector for Tamoxifen-inducible Apoptosis

Several cancer gene therapy strategies involve suicide genes to kill the neoplasm, or to regulate effector cells such as lymphocytes. We have developed an inducible apoptosis system with a Fasestrogen receptor fusion protein (MfasER) for rapid elimination of transduced cells. In the present study, we further improved this molecular switch for estrogen‐inducible apoptosis to overcome concerns with the wild‐type estrogen receptor and its natural ligand, 17β‐estradiol (E2). The ligand‐binding domain of MfasER was replaced with that of a mutant estrogen receptor which is unable to bind estrogen yet retains affinity for a synthetic ligand, 4‐hydroxytamoxifen (Tm). The resultant fusion protein (MfasTmR) and MfasER were expressed in L929 cells for examination of their ligand specificities. Tm induced apoptosis in MfasTmR‐expressing cells (L929MfasTmR) at 10‐8M or higher concentrations, but induced no apoptosis in MfasER‐expressing cells (L929MfasER) at up to 10‐6M. On the other hand, E2 induced apoptosis in L929MfasER at concentrations as low as 10‐10–10‐9M, while it did so partially in L929MfasTmR at concentrations greater than 10‐7M. Thus, L929MfasTmR cells were highly susceptible to Tm, but refractory to E2, with 100–1,000 times more tolerance than L929MfasER. These results suggest that the MfasTmR/Tm system would induce apoptosis in the target cells more safely in vivo, working independently of endogenous estrogen.

Highly regulated expression of adeno-associated virus large Rep proteins in stable 293 cell lines using the Cre/loxP switching system

Since the Rep proteins of adeno-associated virus (AAV) are harmful to cells, it is difficult to obtain stable cell lines that express them constitutively. In this study, stable 293 cell lines were obtained in which large Rep expression was inducible by using the Cre/loxP switching system. To determine the function of the induced Rep proteins, the packaging capacity was examined after supplementation with a plasmid expressing small Rep and Cap proteins. A significant amount of recombinant AAV (5.5 x 10(8) vector particles per 10 cm dish) was produced by transfection with a vector plasmid and infection with Cre-expressing recombinant adenovirus, indicating that the large Rep proteins retained the function required for packaging. These findings indicate that large Rep protein expression can be strictly regulated by the Cre/loxP system and will also serve as a basis for the development of an efficient AAV-packaging cell line.

Pseudo-Gaucher Cell Proliferation Associated with Myelodysplastic Syndrome

We report an extremely rare case of pseudo-Gaucher cell proliferation with myelodysplastic syndrome (MDS). A 77-year-old Japanese man was referred to our hospital with splenomegaly and thrombocytopenia, and subsequent bone marrow aspiration revealed infiltrates of foamy vacuolated macrophages without any evidence of other morphologic abnormalities. A karyotype analysis showed the presence of 46,XY,del(20)(q11) in 20 of 20 examined bone marrow cells. We performed a splenectomy, and the resulting pathologic findings revealed massive infiltration of foamy vacuolated macrophages, which were morphologically compatible with Gaucher cells. The activities of β-glucosidase and acid sphingomyelinase were within normal ranges; therefore, the foamy vacuolated macrophages were considered pseudo-Gaucher cells. A diagnosis of MDS, subclassified as refractory anemia, was then made according to World Health Organization classification guidelines. Pseudo-Gaucher cell proliferation and infiltration might therefore be observed in other patients presenting with MDS.

Efficient Production of Adeno‐associated Virus Vectors Using Split‐type Helper Plasmids

Adeno‐associated virus (AAV) vectors are potentially useful vehicles for the delivery of therapeutic genes into human cells. To determine the optimal expression pattern of AAV proteins (Rep78, Rep68, Rep52, Rep40, and Cap proteins) for packaging the recombinant AAV genome, helper plasmids were split into two portions. In this study, two sets of split‐type helper plasmids were prepared; i.e., 1) a Rep expression plasmid (pRep) and Cap expression plasmid (pCap), and 2) a large Rep expression plasmid (pR78/68) and small Rep plus Cap expression plasmid (pR52/40Cap). When AAV vectors were produced using these sets of split‐type helper plasmids at various ratios, the optimal ratio of (large) Rep expression plasmid and Cap expression plasmid was 1 to 9 for both sets. More importantly, the titers were comparable to or even higher than that of a conventional helper plasmid (pIM45) (4.9±2.1×1011 vector particles/10 cm dish for pRep and pCap; 2.9±1.6×1011 vector particles/10 cm dish for pR78/68 and pR52/40Cap; and 1.8±0.16×1011 particles/10 cm dish for pIM45). Western analysis of AAV proteins suggests that the expression of a relatively small amount of large Rep and a large amount of Cap is important for optimal vector production. The present study shows that the AAV helper plasmid can be split without losing the ability to package the recombinant AAV genome, and provides us with valuable basic information for the development of efficient AAV packaging cell lines.

Intensified Daunorubicin in Induction Therapy and Autologous Peripheral Blood Stem Cell Transplantation in Postremission Therapy (Double-7 Protocol) for Adult Acute Myeloid Leukemia

To investigate whether an intensified dose of daunorubicin (DNR) in induction therapy and autologous peripheral blood stem cell transplantation (PBSCT) in the postremission period are effective treatments, we used a Double-7 protocol to treat adult patients with de novo acute myeloid leukemia (excluding M0 and M3). Induction therapy consisted of 40 mg/m2 of DNR intravenous drip infusion for 7 days and 200 mg/m2 of ara-C by continuous infusion for 7 days (7 + 7 DC regimen). Patients who achieved complete remission (CR) were given high-dose chemotherapy with autologous PBSCT in postremission therapy. Of the 22 assessable patients, 16 attained CR (73%). Disease-free survival (DFS) and overall survival (OS) at 3 years were 61.2% and 48.1%, respectively. Nine of the CR patients underwent PBSCT without therapy-related mortality. Patients in a favorable cytogenetic group (n = 7) attained 100% CR and long-term survival (71.4% DFS and 85.7% OS at 3 years). Thus, intensified DNR administration of 280 mg/m2 (40 mg/m2 per day for 7 days) in induction therapy for adult patients younger than 60 years of age might be optimal or at least comparable with the new anthracyclines such as idarubicin. In addition, autologous PBSCT in postremission therapy might improve DFS and OS, at least for patients in a favorable cytogenetic group, such as those with a t(8;21) abnormality.Int J Hematol. 2002; 76: 436-445.