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Biomedical subjects

Y Takaue

Publications and source records attributed to Y Takaue.

At least 91 records · Page 5Linked to original sources
PubMed1997

Evaluation of a cytokine combination including thrombopoietin for improved transduction of a retroviral gene into G-CSF-mobilized CD34+ human blood cells.

We examined cell culture conditions with various combinations of cytokines including thrombopoietin (TPO) to obtain the most efficient transduction of recombinant retrovirus vectors into G-CSF-mobilized blood CD34+ cells which were obtained from children and purified with an Isolex 50 system (Baxter; Deerfield, IL). Three different 4-day culture conditions for the stimulation of CD34+ cells were compared in terms of a cell-cycle analysis by fluorometry and gene transduction efficiency as determined by resistance to G418 and NeoR polymerase chain reaction (PCR) for individual colony-forming unit-granulocyte/macrophage (CFU-GM) grown in a methylcellulose culture system. The cytokines tested were: A) interleukin (IL)-6 + stem cell factor (SCF); B) IL-3 + IL-6 + SCF, and C) IL-3 + IL-6 + SCF + TPO. Without a cell culture, the percentage of CD34+ cells in the cell cycle (the percentage of cells in phases S and G2/M) was 4.6%. After a four-day culture (n = 5), this value increased with the addition of IL-3 (22%) or IL-3 + TPO (27%, p < 0.05) as compared to that with the baseline cocktail of IL-6 + SCF (15%). The cell number uniformly increased approximately 10-fold in each culture condition. The average efficiency of gene transfer into incubated CD34+ cells with the corresponding combinations of cytokines was, respectively, 57%, 47%, and 30% for G418-screened CFU-GM and 72%, 68%, and 51% for polymerase chain reaction-positive CFU-GM. A statistically significant difference (p < 0.01) was found for G418/CFU-GM with IL-3 + IL-6 + SCF (57%) versus IL-3 + IL-6 + SCF + TPO (30%). Hence, it is likely that the increased cell proliferation produced by the addition of TPO was not necessarily translated into an increased rate of retroviral-mediated gene transduction, possibly because TPO preferentially induced the differentiation of stem cells into mature progenitors in these culture systems.

Anti-Bacterial Agents↗
PubMed1997

Risk of cytomegalovirus infection after peripheral blood stem cell transplantation.

From 1992 to 1995, 105 patients received PBSCT in our hospitals and we observed no incidence of CMV-pneumonia. To clarify whether activation of CMV occurs in these patients shell vial cultures, CMV antigenemia and PCR (DNA-PCR and RT-PCR) were used as detection methods for CMV. Bronchoalveolar lavage (BAL) samples, MNC and PMN samples from peripheral blood leukocytes, and urine samples were taken from 17 patients on day 35 after PBSCT. CMV was detected in one urine specimen but not detected in any of the BAL, MNC or PMN specimens by shell vial culture. CMV antigenemia provided no positive data. Nine of the 74 samples taken from the 17 patients proved positive by DNA-PCR, but all CMV-mRNA results were negative by RT-PCR. We performed CMV antigenemia and PCR on MNC and PMN specimens from six patients every 1 to 2 weeks after transplantation to determine whether and when CMV was activated. Two patients tested positive transiently by DNA-PCR but negative throughout by both antigenemia and RT-PCR. These results suggest that the risk of CMV infection is low because the incidence of CMV activation in patients receiving PBSCT is low.

Adolescent↗
PubMed1997

Transduction of retrovirus-mediated NeoR gene into CD34+ cells purified from granulocyte colony-stimulating factor (G-CSF)-mobilized infant and cord blood.

To help establish an effective gene therapy protocol for patients with congenital metabolic diseases, we evaluated retrovirus-mediated transduction and long-term (LT) expression of the NeoR gene in cryopreserved and thawed CD34+ cells purified from granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood (PB) of infant and cord blood (CB). The results were compared with those in bone marrow (BM) CD34+ cells. The final purity of the CD34+-enriched fraction from PB, CB, and BM, based on FACS analysis, was 88 +/- 14%, 73 +/- 13%, and 68 +/- 19% (mean +/- SEM), respectively. Cells were then cultured for 96 hours with supernatant containing the vector in the presence of interleukin (IL)-3, IL-6, and stem cell factor (SCF). The average efficiency of gene transfer into mobilized PB (n = 5) or CB CD34+ cells (n = 6) was significantly higher than that into BM CD34+ cells, as measured by G418-resistant colony-forming units for granulocyte/macrophage (CFU-GM; 59% or 58% vs. 39%; p < 0.05) and PCR-positive CFU-GM (83% or 79% vs. 53%; p < 0.05). When the evaluation was made in an LT culture system with irradiated allogeneic marrow stroma, these efficiencies were, respectively, 74% or 61% vs. 34% (p < 0.005 or < 0.02) for G418-resistant CFU-GM at week 5 of long-term culture, and 88% or 83% vs. 63% (p < 0.05) for PCR-positive CFU-GM. Fluorometric examination was performed for cell-cycle analysis before and after culture, and the results showed that the fraction of cycling cells was largest in freshly prepared BM (18%), whereas only a small portion of PB (4.6%) and CB (2%) was cycling. However, this value was 17% in BM, 22% in PB, and 13% in CB after culture. These results suggest that mobilized PB from small children and CB cells are suitable and realistic targets for clinical gene therapy and that tandem transduction procedures can be achieved by combining CB and PB.

Antigens, CD34↗
PubMed1997

Peripheral blood stem cell transplantation; an update.

Patients with a number of different malignancies have been treated with high-dose chemotherapy and peripheral blood stem cell transplantation (PBSCT). PBSC already replaced bone marrow as the source of autologous hematopoietic progenitor support. This is due to ease of collection, rapid engraftment and less possibility of tumor cell contamination in the graft. Furthermore, allogeneic transplantation of granulocyte colony-stimulating factor (G-CSF) mobilized PBSC is now being increasingly performed. Recent advance of clinical PBSCT and new strategies are stressed in this review. New strategies include CD 34+cell purification, ex vivo expansion of PBSC and PBSC as a target cell for gene therapy. Major future advance may occur better understanding of the mechanism of mobilization and the biology of PBSC.

Hematopoietic Stem Cell Transplantation↗
PubMed1996

Effect of recombinant erythropoietin in interaction with stromal factors on cord blood hematopoiesis.

To investigate the effect of recombinant erythropoietin (Epo) on primitive human hematopoietic progenitor cells, we cultured cord blood mononuclear cells (CBMNC) and CB CD34+ cells in a Dexter-type long-term culture system (LTC), to which various concentrations of Epo were added at day 0 or 7, with or without direct contact with irradiated allogeneic human marrow stromal layers. In regular stroma-contact cultures, when CBMNC were inoculated, the addition of Epo at 1 to 10 U/mL induced a significant increase in LTC-initiating cells (LTC-IC), particularly in the myeloid component, compared with the control without Epo. Significantly more LTC-IC were generated by the delayed addition of Epo on day 7 than on day 0. On the other hand, when CD34+ cells were inoculated, physiologic concentrations of Epo (0.1 U/mL) induced a more than twofold increase in LTC-IC, which was attributed equally to both the myeloid and erythroid lineages, only when added on day 0. In stroma-noncontact cultures, which were created using a Transwell 0.4-micron microporous membrane filter, dose-dependent suppression of the myeloid component of LTC-IC was observed with a higher concentration of Epo (1 to 100 U/mL) when CBMNC was inoculated. On the other hand, without Epo, fourfold more LTC-IC was generated from CD34+ cells in stroma-noncontact than in stroma-contact cultures, which was then significantly augmented by the addition of Epo (0.1 or 10 U/mL) on day 0. This increase was due to both the myeloid and erythroid lineages. A higher concentration of Epo (100 U/mL) resulted in a decrease in LTC-IC, mainly in myeloid progeny, in all of the culture conditions. Hence, Epo may play an important physiologic role in the maintenance and proliferation of immature stem/progenitor cells, in close interaction with factors from marrow stromal cells.

Antigens, CD34↗
PubMed1996

Stem-cell factor regulates the expression of cyclin A and retinoblastoma gene product in the growth and differentiation pathway of human megakaryocytic cells.

The biological effects of c-kit ligand (stem-cell factor: SCF) on an immortalized human megakaryocytic cell line (CMK) was evaluated using methods including the 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, surface marker analysis, DNA cell-cycle analysis and immunoblotting. SCF stimulated the growth of CMK cells. Incubation with SCF resulted in increased expression of IIb/IIIa platelet-related glycoprotein (gpIIb, IIIa), indicating enhanced differentiation of CMK cells. Treatment of CMK cells with SCF resulted in a decrease in the subpopulation in the G1 phase, with a reciprocal increase in those in the S phase and the G2 + M phase. Moreover, SCF significantly increased cellular expression of cyclin A, a regulatory subunit of cyclin-dependent protein kinase (CDK), and the ratio of phosphorylated/dephosphorylated retinoblastoma gene product (RB protein). These results suggest that SCF stimulates the growth and differentiation of megakaryocytic cells possibly through mechanisms related to the activation of cell-cycle-dependent serine/threonine kinase and inactivation of the nuclear tumor-suppressor gene product.

Cell Differentiation↗
PubMed1996

Alterations of CDKN2 gene structure in childhood acute lymphoblastic leukemia: mutations of CDKN2 are observed preferentially in T lineage.

We analyzed homozygous deletions and mutations of the CDKN2(p16(INK4A)/MTS1) gene, using polymerase chain reaction and Southern blot analysis, in 120 children with acute lymphoblastic leukemia (ALL). Homozygous deletion was found in 17 of 89 (19%) precursor B-ALL patients, in 11 of 24 (46%) T-ALL patients, and in 0 of 7 other phenotype ALL patients. After excluding 28 (23%) patients who showed a homozygous deletion of CDKN2, we found that three patients (3%) had mutation at exon 2 of CDKN2 using PCR-SSCP and sequencing strategy. One had a CGA to TGA nonsense mutation (Arg to stop) at codon 72, one had a 1-bp deletion at codon 117, and the third had a 2-bp deletion at codon 70, resulting in frameshifts in the two latter patients. All three of these patients were T phenotype ALL, and the incidence of mutation in the 24 T-ALL patients examined was 13%. In contrast, no mutation was detected in the remaining patients with precursor-B or other type ALL (0/96). Our results suggest that mutational inactivation of the CDKN2 gene may contribute to the leukemogenic growth, especially in some patients with T-ALL.

Adolescent↗
PubMed1996

Detection and quantification of TEL/AML1 fusion transcripts by polymerase chain reaction in childhood acute lymphoblastic leukemia.

We investigated TEL/AML1 fusion mRNA in 108 children with acute lymphoblastic leukemia (ALL) (86 B-lineage ALL, 15 T-ALL, two mixed lineage ALL, and five other phenotypes) using reverse transcriptase-polymerase chain reaction (RT-PCR). TEL/AML1 transcripts were found in 14 patients (13%) including three relapsed patients, and were unexceptionally limited to B-lineage ALL patients. The incidence of TEL/AML1 transcripts among B-lineage ALL was 16% (14/86). The reciprocal AML1/TEL transcripts were detected in 12 (86%) of the 14 cases expressing a TEL/AML1 transcript. In three cases, the TEL gene was fused to exon 3 of the AML1 gene, and to exon 2 in the remaining cases. To evaluate the amount of TEL/AML1 molecules for the quantification of a minimal residual disease (MRD), a plasmid vector which contained either a long TEL/AML1 PCR product (464 bp) or a short one (425 bp) was used as a competitor. We amplified RNAs obtained from bone marrow (BM) at complete remission or from peripheral blood stem cell (PBSC) harvests in two representative cases. For one PBSC harvest showing a positive result, a competitive PCR was carried out to quantify the amount of MRD. A 1:4 dilution series of competitor vectors was constructed, and each vector was added to a PCR reaction which contain a constant amount of cDNA obtained from the PBSC harvest. An equivalent point was compared to that of corresponding samples at diagnosis. Using this method, MRD in the PBSC harvest was 3.9:10(3). Our results elucidated the incidence, lineage-specificity, and variant forms of TEL/AML1 fusion transcripts in childhood ALL. Since the percentage of other chromosomal translocations in childhood ALL is not more than 5%, TEL/AML1 transcript would be the most feasible clone-specific marker for these patients. In addition, our method could be a powerful tool for quantification of the TEL/AML1 transcript and for the detection of MRD.

Adolescent↗
PubMed1995

Collection and transplantation of peripheral blood stem cells in very small children weighting 20 kg or less.

The safety and efficacy of harvesting peripheral blood hematopoietic stem cells (PBSC) were evaluated in 38 children weighing 20 kg or less, with the smallest patient weighing 7 kg. The patients had a median age of 42 months and included 26 children with acute leukemias or lymphoma and 12 with various solid tumors. A total of 81 aphereses were performed, mostly in the recovery phase of chemotherapy, with or without granulocyte colony-stimulating factor, using a CS-3000 cell separator and regular procedure no. 3. Blood was withdrawn at a mean rate of 30 mL/min (range, 17 to 46 mL/min) through a temporary radial arterial catheter (20 to 24 guage) and returned through a larger catheter in a peripheral vein. Morbidity related to PBSC harvest was low and all aphereses were completed within 3 hours. The volume of blood per kilogram processed for each apheresis ranged from 85 to 615 mL (median, 270 mL). The median number of colony-forming units--granulocyte-macrophage (CFU-GM) and CD34+ cells collected were, respectively, 34 x 10(4)/kg and 15 x 10(6)/kg per apheresis and 126 x 10(4)/kg and 31 x 10(6)/kg per patient. Thirty-three patients (87%) required only a single apheresis to collect the minimum requirement of 10 x 10(4) CFU-GM/kg, including 28 patients (74%) from whom 30 x 10(4) CFU-GM/kg was obtained in a single apheresis. Twenty-three of the patients subsequently underwent autografts with PBSC. The median number of days required to achieve an absolute granulocyte count of 0.5 x 10(9)/L and a platelet count of 50 x 10(9)/L were, respectively, 10 (range, 6 to 15) and 14 (range, 9 to 46). The patients remained dependent on platelet transfusion support for a median of 10 days (range, 5 to 35). Thus, harvesting PBSC in very small children with active cancers is effective and safe and does not involve the risk of anesthesia or multiple invasive marrow aspirations.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Optimal growth of human blood hematopoietic progenitor cells collected by apheresis for autografts.

For safe autografts with peripheral blood hematopoietic cells (PBSCT), better methods for determining the kinetics of stem cell populations and predicting engraftment speed after PBSCT need to be established. Current methods include culture in semi-solid medium and measurement of CD34 cell surface antigen. In this study with only partially purified blood cells obtained from children with cancer in remission, we compared the effects of phytohemagglutinin-stimulated lymphocyte-conditioned medium (PHA-LCM) and recombinant human cytokines on the growth of progenitor cells in a methylcellulose culture system. Interleukin-3 (IL-3) alone supported more progenitor growth than standard PHA-LCM by a factor of 1.54 for colony-forming unit granulocyte/macrophages (CFU-GM) and by a factor of 1.84 for burst-forming unit/erythroids (BFU-E). No significant change, in terms of the number of growing colonies, was observed by adding granulocyte/macrophage colony-stimulating factor (GM-CSF), granulocyte-CSF (G-CSF), or IL-1 to IL-3. However, the addition of G-CSF resulted in increased colony size. A further increase in CFU-GM growth was observed by the addition of IFN-gamma to the combination of cytokines. No significant effect was observed when stem cell factor (SCF) was added to the combination of cytokines containing IL-3, G-CSF, and IFN-gamma. This analysis suggests that the combination of IL-3, G-CSF, and IFN-gamma may provide sufficient stimulation for the growth of human blood cells. The effects of different oxygen tensions on progenitor growth in the presence of IL-3, G-CSF, and IFN-gamma were also evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Synergism of interleukin 12, interleukin 3 and serum factor on primitive human hematopoietic progenitor cells.

Interleukin 12 (IL-12), or natural killer cell stimulatory factor (NKSF), has multiple biologic effects on T lymphocytes and natural killer cells. In this study, we evaluated the effect of IL-12 on human hematopoiesis by analyzing the growth of CD34+33- cells in methylcellulose culture with or without serum. Blood cells were collected by apheresis from an expanded stem cell pool during the rebound phase of hematopoiesis after chemotherapy and purified by combined purification procedures to yield target CD34+33- cells. IL-12, by itself or in combination with IL-3 and erythropoietin (Epo), had no effect on the formation of colonies from the unfractionated blood mononuclear cells. In the presence of fetal bovine serum (FBS), IL-12 increased the number of colony forming units for granulocyte-macrophage (CFU-GM) from CD34+33- cells which responded to IL-3, but not the number of CFU-GM from those which responded to stem cell factor (SCF) or granulocyte colony stimulating factor (G-CSF). This effect was not abolished by the addition of monoclonal antibodies against tumor necrosis factor alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-1 alpha, IL-6, G-CSF, or granulocyte/macrophage CSF (GM-CSF). However, the stimulatory effect of IL-12 was abolished in secondary plating in serum-containing methylcellulose culture after short-term (48 h) liquid incubation with IL-3.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, CD↗
PubMed1995

Quantitative and qualitative comparative analysis of gradient-separated hematopoietic cells from cord blood and chemotherapy-mobilized peripheral blood.

Some of the uncertainty regarding the use of cord blood (CB) in transplant settings includes the suspected relative rarity of hematopoietic stem cells (SC) in CB and the feasibility of incorporating a cell separation protocol to remove red blood cells, which may result in an unacceptable loss of SC. To address this uncertainty, we isolated a SC fraction by Percoll or Ficoll gradients from CB and peripheral blood (PB), which had been mobilized by chemotherapy. The frequencies of mononuclear cells (MNC), CD34+ cells, colony-forming units granulocyte-macrophage (CFU-GM), and the output of colony-forming cells (CFC) after five weeks in long-term culture (LTC) assay were then evaluated. The mean numbers of these cells per ml of CB sample before gradient separation were, respectively, 4.9 x 10(6), 13.8 x 10(4), 3.0 x 10(3) and 681 (n = 37). In the recovery phase of PB, these numbers were, respectively, 2.0 x 10(6), 14.9 x 10(4), 3.5 x 10(3) and 270 per ml of processed blood at apheresis (n = 35). After Percoll separation, the recovery rates of these cells were, respectively, 29%, 92%, 97% and 95% in CB, and 65%, 87%, 123% and 102% in PB. After Ficoll separation of CB, the rates were, respectively, 55%, 107%, 92% and 105%. These results suggest that CB contains an adequate number of more immature progenitors which can be retained after cell separation with Percoll or Ficoll, thereby making it feasible to incorporate a cell processing procedure into a CB transplant protocol. Percoll separation provided a greater enrichment of cells than Ficoll.

Adolescent↗
PubMed1995

Improved treatment results of non-Hodgkin's lymphoma in children: a report from the Children's Cancer and Leukemia Study Group of Japan.

From 1985 to 1989, 69 patients with non-Hodgkin's lymphoma (NHL) were treated by members of the Children's Cancer and Leukemia Study Group of Japan with a protocol consisting of vincristine, prednisolone, cyclophosphamide, doxorubicin, high-dose methotrexate (HD-MTX), mercaptopurine and cytarabine; central nervous system (CNS) prophylaxis with intrathecal MTX and hydrocortisone (NHL855). The 4-year event-free survival (EFS) was 78% (S.E., 10%) for patients with localized disease (n = 18) and 38% (S.E., 7%) for those with advanced disease (n = 51). Among the patients with advanced disease, those with non-lymphoblastic lymphoma tended to have a better 4-year EFS than those with lymphoblastic lymphoma (52% vs. 25%). Based on these findings, we initiated a new protocol NHL890 in which patients were assigned to two different chemotherapies according to the histology. Non-lymphoblastic subtype was treated almost identically to NHL855 while asparaginase and VP-16 were newly added in the consolidation-maintenance phase in advanced-stage lymphoblastic lymphoma. Sixty-seven patients with advanced disease were assessable. The overall 4-year EFS for advanced disease improved to 69% (S.E., 6%). A significant improvement was gained in the lymphoblastic lymphoma with a 4-year EFS of 56% (S.E., 11%) as compared with 25% (S.E., 9%) in the preceding study (P < 0.05). These findings suggest the importance of histology in the treatment of advanced-stage non-Hodgkin's lymphoma in childhood.

Adolescent↗
PubMed1995

Effects of monocyte-macrophage colony-stimulating factor (M-CSF) on in vitro erythropoiesis of marrow progenitor cells from patients with renal anemia.

We examined the influence of monocyte-macrophage colony-stimulating factor (M-CSF) on erythropoiesis both in vitro and in vivo in 98 patients with chronic renal failure who were undergoing hemodialysis. Serum levels of M-CSF and the clinical response to therapy with human recombinant erythropoietin (Epo) were analyzed. The following results were obtained: 1) The serum level of M-CSF was 6.90 +/- 2.41 ng/ml in the patient population (n = 98), but only 2.0 +/- 0.3 ng/ml in 10 healthy donors. 2) 41 of the 98 anemic patients were treated with various doses of Epo for 3 months, and the average increase in the blood hemoglobin level during this period was 26.1 +/- 12.5 mg/dl/unit of Epo/kg patient's b.w./week. Lower levels of M-CSF before treatment significantly predicted a better response to subsequent Epo therapy (r = -0.496, p < 0.001). 3) When cultured with a maximally stimulatory amount of Epo (10 IU/ml), the number of marrow early erythroid progenitor cells (burst-forming unit for erythroid, BFU-E) in patients was identical to that in normal donors, while the number of late progenitors (colony-forming unit for erythroid, CFU-E) was relatively lower in patients. 4) The addition of recombinant M-CSF to the culture resulted in suppression of erythroid progenitor cell growth in the patient population, but induced enhancement in normal donors. The inhibitory effect of M-CSF on the patients' cells was not eliminated by the addition of antibodies against interleukin-1 alpha/beta, tumor necrosis factor-alpha, or interferon-alpha/beta/gamma. Supernatants from marrow mononuclear cells cultured in the presence of M-CSF carried this inhibitory effect on marrow CD34+ cells obtained from patients. Together, these results suggest that M-CSF aggravates a previously existing decreased sensitivity of erythroid progenitor cells to Epo in some patients with renal anemia.

Adolescent↗
PubMed1995

Patient with extensive small cell lung cancer given moderately dose-intensified chemotherapy and peripheral blood stem cell support.

Although recent progress in multi-drug chemotherapy has increased the median survival of patients with extensive Small cell lung cancer (SCLC) to 7 months, 2-year survivors are still exceptional. We describe a 40-year-old man with extensive SCLC involving the lungs and systemic nodes who was initially treated with 6 cycles of an alternating combination regimen consisting of cyclophosphamide, doxorubicin, vincristine, cisplatin and etoposide. After the second cycle of the regimen, Peripheral blood stem cells (PBSC) were harvested and frozen. The patient then received a moderately dose-intensified regimen consisting of cisplatin (80 mg/m2) and etoposide (500 mg/m2 X 3), followed by infusion of the thawed PBSC. Hematopoietic recovery was rapid, and the patient remained tumor free for 12 months until multiple tumor recurrence.

Adult↗
PubMed1995

Prospective monitoring of minimal residual disease during the course of chemotherapy in patients with acute lymphoblastic leukemia, and detection of contaminating tumor cells in peripheral blood stem cells for autotransplantation.

A prospective study for detecting minimal residual disease (MRD) was conducted on children with acute lymphoblastic leukemia (ALL). Thirty-nine patients (38 B-lineage ALL, one T-ALL) with TCR delta rearrangements could be followed for 21 to 44 months (mean 30.9 months) excluding four patients who died. One hundred and ninety four bone marrow (BM) samples and 13 peripheral blood stem cell (PBSC) grafts were available for detection of MRD. Initially 34 cases were treated prospectively according to the CCLSG risk-stratified protocols for ALL (ALL874 or ALL911), and five cases according to the other protocols. Conventional chemotherapy was replaced by autologous PBSC transplantation (PBSCT) in five patients, by allogenic BM transplantation (BMT) in one patient, or suspended in another patient. Twenty-nine of 32 children in whom conventional chemotherapy could be continued without interruption remain in complete remission (CR). In 24 of the 29 patients MRD became undetectable within 12 months of their diagnosis. In five cases, BM samples obtained during maintenance therapy exhibited residual leukemia cells, and yet none of them relapsed (mean follow-up period 28.6 months). Our results thus indicate that intensive maintenance therapy for patients with PCR-positive results during consolidation therapy may prevent subsequent relapse. Nine events of relapse were diagnosed in eight patients (five BM, two isolated central nervous system (CNS), one combined BM and CNS, one isolated skin relapse). An increase or a re-emergence of MRD was detected in BM samples obtained from patients prior to BM relapse, but one patient remained in CR despite reappearance of leukemic cells following a PCR-negative status. Monitoring of MRD failed to predict isolated CNS or skin relapse. PBSCT allows high-dose cytoreduction therapy for patients with refractory neoplasia. In our study, leukemic cells were identified in eight of 13 PBSC grafts harvested from five patients. Three of four children who received PBSC grafts containing leukemic cells relapsed within 6 months after PBSCT. Monitoring of MRD as part of quality control of PBSC grafts may ultimately contribute to improvements in PBSCT procedures.

Child↗
PubMed1995

[Intensive and high-dose chemotherapy with peripheral blood stem cell transfusion for pediatric malignant brain tumor].

In this study, the newly developed marrow-rescue therapy during myelosuppression is utilized. In this therapy, peripheral blood stem cell transfusion (PBSCT) is administered following high-dose chemotherapy. Harvest of peripheral blood stem cells (PBSC) during myelosuppression following marrow-ablative chemotherapy is a safe, reliable procedure in children with leukemia. And administration of these cryopreserved PBSC is useful in reducing myelosuppression following intensive/ultra high-dose chemotherapy. In this study, several courses of intensive chemotherapy (1 course: VP-16 300mg/m2 x 5 days + carboplatin 400-500mg/m2 x 3 days) and one course of ultra-high dose chemotherapy (1 course: VP-16 400mg/m2 x 8 days + carboplatin 800mg/m2 x 5 days + MCNU 250, 200mg/m2 x each day) with PBSC transfusion were applied in four cases of pediatric malignant brain tumors (2 cases of medulloblastoma, one case of pineoblastoma and anaplastic ependymoma) after surgical reduction. With PBSC transfusion, myelosuppression following high-dose chemotherapy could be overcome without serious complication in all cases. Three cases showed complete remission and one showed partial remission after the operation and intensive chemotherapy. However, CSF dissemination appeared in two cases and they died 20 and 28 months after the onset respectively. Intensive/ultra high-dose chemotherapy with PBSC transfusion is a safe procedure in children with malignant brain tumors. This procedure may enable the postponement of radiation for pediatric malignant brain tumor cases under three years of age.

Age of Onset↗