Keon Hee Yoo

Mesenchymal stem cells feeder layer from human umbilical cord blood for ex vivo expanded growth and proliferation of hematopoietic progenitor cells.

Ex vivo expansion of hematopoietic stem cells was suggested as the best way of overcoming problems caused by limited hematopoietic cell number for cord blood transplantation. In this study, we quantified and characterized an ex vivo expansion capacity of umbilical cord blood (UCB)-derived mesenchymal stem cells (MSCs) as a cell feeder layer for support of UCB-derived committed hematopoietic progenitor cells (HPCs) in the absence or presence of recombinant cytokines. The UCB-derived MSCs used in the study differentiated into osteoblast, chondrocytes, and adipocytes under proper conditions. Frequencies in colony forming unit-granulocyte, macrophage, colony forming unit-granulocyte, erythrocyte, macrophage, megakaryocyte, burst forming unit-erythrocyte, and colony forming unit-erythrocyte increased to 3.46-, 9.85-, 3.64-, and 2.03-folds, respectively, only in culture supplemented by UCB-derived MSCs as a cell feeder layer without recombinant cytokines (culture condition C). Identified expansion kinetics in all kinds of committed HPCs showed plateaus at 7 culture days, suggesting some consumable components were required for the expansion. Physiological importance and different roles for different committed HPCs of UCB-derived MSCs as a cell feeder layer were revealed by a distinguished expansion capacity for colony forming unit-megakaryocyte. The preferred maintenance of CD33−CD34+ in culture condition C was also identified. The presence of cobblestone-like areas as hematopoietic microenvironment and various cell feeder layer-originated hematopoietic cytokines including interleukin-1β and granulocyte, macrophage-colony stimulating factor were suggested as underlying mechanisms for the identified expansion capacity. The present numeric and biological information about intrinsic expansion capacity for UCB-derived committed HPCs will increase further biological and clinical applications of UCB-derived MSCs.

Stem and progenitor cells in human umbilical cord blood

Both stem cells and progenitor cells are present in umbilical cord blood (UCB) at a high frequency, making these cells a major target population for experimental and clinical studies. As the use of autologous or allogeneic hematopoietic stem cell transplantation in the treatment of various diseases has grown rapidly in recent years, the concept of UCB banking for future use has drawn increasing interest. Stem and progenitor cells derived from UCB offer multiple advantages over adult stem cells, such as their immaturity (which may play a significant role in reducing rejection after transplantation into a mismatched host) and ability to produce large quantities of homogeneous tissue or cells. These cells can also differentiate across tissue lineage boundaries into neural, cardiac, epithelial, hepatic, and dermal tissues. Human UCB provides an alternative cell source that is ethically acceptable and widely supported by the public. This paper summarizes the characteristics of human UCB-derived stem and progenitor cells and their potential therapeutic use for tissue and cell regeneration.

Clinical features and treatment outcomes of Langerhans cell histiocytosis: a nationwide survey from Korea histiocytosis working party.

A nationwide survey was conducted to clarify the clinical features and outcomes of Korean children with Langerhans cell histiocytosis (LCH). Korea Histiocytosis Working Party analyzed the data of 603 patients who were diagnosed with LCH between 1986 and 2010 from 28 institutions in Korea. Median age at diagnosis was 65 months (range, 0 to 276 mo). Bone was the most frequently affected organ (79.6%) followed by skin (19.2%). Initially, 419 patients (69.5%) had single-system involvement (SS), 85 (14.1%) with multisystem (MS) disease without risk organ involvement (MS-RO−), and 99 (16.4%) multisystem disease with risk organ involvement (MS-RO+). The 5-year overall survival (OS) rates in the SS, MS-RO−, and MS-RO+ groups were 99.8%, 98.4%, and 77.0%, respectively (P<0.001), and the 5-year reactivation rates were 17.9%, 33.5%, and 34.3%, respectively (P<0.001). The OS rate was lower in patients with RO involvement (P=0.025) and lack of response to initial treatment (P=0.001). MS involvement (P=0.036) was an independent risk factor for reactivation. Permanent consequences were documented in 99 patients (16.4%). Reactivation of disease, MS involvement, and age at diagnosis ⩽2 years were associated with higher incidence of permanent consequences. This study emphasized that further efforts are required to improve survival of MS-RO+ patients and reduce reactivation in younger patients with MS involvement.

Atypical basal ganglia germinoma presenting as cerebral hemiatrophy: diagnosis and follow-up with 11C-methionine positron emission tomography

ObjectsSome basal ganglia germinomas are difficult to diagnose in early stage of disease due to vague initial presentation without discernable mass lesion on brain imaging. We performed this study to determine the usefulness of 11C-methionine positron emission tomography (MET PET) for the diagnosis and monitoring of disease activity.Materials and methodsMET PET was performed in three consecutive patients; they presented with cerebral hemiatrophy without definite mass lesions on brain image. The maximum standard tracer uptake values (max SUVs) were calculated and used for the quantitative evaluation of the abnormal MET uptake. A pathological diagnosis was made after stereotactic biopsy using MET PET/computed tomography. The max SUVs significantly decreased after treatment.ConclusionBasal ganglia germinoma should be considered in the differential diagnosis of patients with progressive hemiparesis and hemiatrophy on magnetic resonance imaging. The MET PET was useful for diagnosis, and it can be valuable in evaluation of treatment effects and monitoring for tumor recurrence.

Expression of MET in alveolar soft part sarcoma

Alveolar soft part sarcoma (ASPS) is a rare soft tissue sarcoma which is characterized by the presence of a specific chromosomal translocation encoding the chimeric transcription factor (ASPL-TFE3) that activates expression of MET. We reviewed the clinical features and treatment outcome of 12 ASPS patients. The presence of ASPL-TFE3 fusion transcripts was assessed by reverse transcriptase polymerase chain reaction. In addition, we performed immunohistochemical studies for MET, TFE3, Ki-67, and EGFR expression. Lower extremity was the most commonly affected primary site (2 thigh, 3 lower leg, and 1 foot). Of four patients who received primary cytotoxic chemotherapy, no patient demonstrated treatment response. With follow-up duration of 94.4xa0months, median overall survival was 53.2 (95% C.I. 40.9–65.5) months. The immunohistochemical staining demonstrated 100% TFE3 positivity (8 of 8), 75% MET positivity (6 of 8) with a strong association between TFE3 expression and MET positivity with correlation coefficient of 0.808 (Pxa0=xa00.02). The high expression of MET in ASPL-TFE3 (+) ASPS may further support the potential role of targeted agents against MET in this rare, chemoresistant tumor.

Toxicity of tandem high-dose chemotherapy and autologous stem cell transplantation using carboplatin-thiotepa-etoposide and cyclophosphamide-melphalan regimens for malignant brain tumors in children and young adults

The number of studies examining the use of tandem high-dose chemotherapy and autologous stem cell transplantation (HDCT/auto-SCT) to treat high-risk or recurrent brain tumors is increasing. However, studies addressing the toxicity associated with tandem HDCT/auto-SCT, particularly during the second HDCT/auto-SCT, are very limited. For this reason, we retrospectively evaluated the toxicity of tandem HDCT/auto-SCT with carboplatin-thiotepa-etoposide (CTE) and cyclophosphamide-melphalan (CM) regimens when used to treat high-risk or recurrent brain tumors. A total of 109 patients who received a first HDCT/auto-SCT and 100 who proceeded to a second HDCT/auto-SCT between May 2005 and December 2013 were included. Hematologic recovery was rapid during both the first and second HDCT/auto-SCT. In the first HDCT/auto-SCT, mucositis-related gastrointestinal toxicity was frequent, and two (1.8xa0%) patients died from toxicity [one hepatic veno-occlusive disease (VOD) and one sepsis]. In the second HDCT/auto-SCT, mucositis-related toxicity was milder than in the first round. However, hepatic VOD frequency was high (20.0xa0%), and six (6.0xa0%) patients died from toxicity (four hepatic VODs, one asphyxia, and one sepsis). Multivariate analysis indicated that age younger than 8xa0years was the only significant predictor for hepatic VOD. All six patients who died from toxicity during the second HDCT/auto-SCT were younger than 9xa0years of age. This study demonstrates that tandem HDCT/auto-SCT using CTE/CM regimens was generally feasible. However, dose reduction during the second HDCT/auto-SCT in young children might be needed to decrease the death rate from toxicity.

Strategies to improve the immunosuppressive properties of human mesenchymal stem cells

Mesenchymal stem cells (MSCs) are of particular interest for the treatment of immune-related diseases because of their immunosuppressive capacities. However, few clinical trials of MSCs have yielded satisfactory results. A number of clinical trials using MSCs are currently in progress worldwide. Unfortunately, protocols and methods, including optimized culture conditions for the harvest of MSCs, have not been standardized. In this regard, complications in the ex vivo expansion of MSCs and MSC heterogeneity have been implicated in the failure of clinical trials. In this review, potential strategies to obtain MSCs with improved immunosuppressive properties and the potential roles of specific immunomodulatory genes, which are differentially upregulated in certain culture conditions, will be discussed.

Comparison Study of the Eosin-5′-Maleimide Binding Test, Flow Cytometric Osmotic Fragility Test, and Cryohemolysis Test in the Diagnosis of Hereditary Spherocytosis

OBJECTIVESnCurrent guidelines recommend the eosin-5-maleimide (EMA) binding test and cryohemolysis test for screening for hereditary spherocytosis (HS), and the flow cytometric osmotic fragility (FC OF) test was recently developed to replace the classic OF test. We evaluatedthe performance of the EMA binding test, FC OF test, cryohemolysis test, and the hemoglobin (Hb)/mean corpuscular hemoglobin concentration (MCHC) ratio in the diagnosis of HS and assessed whether these tests reflect the clinical severity of HS.nnnMETHODSnA total of 153 patients with anemia (33 with HS, 40 with autoimmune hemolytic anemia, 40 with anemia of chronic disease, and 40 with iron deficiency anemia [IDA]) and 140 healthy controls were enrolled, and the performance of the three tests was evaluated.nnnRESULTSnBoth the EMA binding test (area under the curve [AUC], 0.996) and the FC OF test (AUC, 0.992) performed satisfactorily, but the cryohemolysis test (AUC, 0.723) performed significantly worse because of false positivity in patients with IDA. The Hb/MCHC ratio (P < .001) was able to reflect the clinical severity of HS.nnnCONCLUSIONSnOur results demonstrate that both the EMA binding and FC OF tests are useful as screening tests for the diagnosis of HS, but the cryohemolysis test has limited use due to its false positivity in IDA, with the Hb/MCHC ratio the most useful parameter for assessing the clinical severity of HS.

Tandem high-dose chemotherapy and autologous stem cell transplantation for anaplastic ependymoma in children younger than 3 years of age

The present study evaluates the feasibility and effectiveness of tandem high-dose chemotherapy and autologous stem cell transplantation (HDCT/autoSCT) in very young children with anaplastic ependymoma. We aimed both to improve survival and to avoid unacceptable late adverse effects of radiation therapy (RT) by avoiding or deferring RT until 3xa0years of age. Five consecutive patients younger than 3xa0years of age with anaplastic ependymoma were enrolled from April 2006 to November 2008. Tandem HDCT/autoSCT was given following six cycles of induction chemotherapy. RT was either not given or deferred until 3xa0years of age if the patient was in complete response after tandem HDCT/autoSCT. Median age at diagnosis was 16 (range 12–28) months. Four patients had significant residual tumor (>1.5xa0cm2) after initial surgery, and three had leptomeningeal seeding. Toxicities during induction chemotherapy and tandem HDCT/autoSCT were manageable. No tumor progressed during induction chemotherapy and tandem HDCT/autoSCT, and RT was thus avoided or deferred until 3xa0years of age in all patients. All patients are alive at median follow-up of 45 (range 31–62) months from diagnosis, although tumor progressed in one patient. No significant endocrine dysfunction occurred except for hypothyroidism in one patient. Cognitive function was also acceptable in all patients but one who had significant neurologic injury during surgery. Our results indicate that treatment with tandem HDCT/autoSCT is feasible in very young children with anaplastic ependymoma and may improve the survival of patients with acceptable long-term toxicity.

Gene mutations in the Ras pathway and the prognostic implication in Korean patients with juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a rare hematologic malignancy in children. Hyperactivation of the Ras pathway from gene mutations is known to be the key culprit in the development of JMML. In this study, we investigated Ras pathway mutations and prognostic implication in Korean patients with JMML. A total of 22 Korean patients with JMML were recruited from two institutions (19 boys and three girls; median age, 17xa0months; range, 1–74xa0months). Hematologic and cytogenetic findings were reviewed. Mutation analyses involved PTPN11, KRAS, NRAS, and CBL genes by direct sequencing analyses (selected exons except in CBL). Survival analysis was performed by the Kaplan–Meier method. Cytogenetic and/or gene mutations were detected in 18 patients out of 22 (82%). Four patients (18%) had chromosomal abnormalities, with monosomy 7 being the most common. Seventeen (77%) had gene mutations. PTPN11 mutations were detected in 13 patients (59%). The patient heterozygous for c.854T>C had Noonan syndrome. NRAS and KRAS mutations were detected in two patients (9%) and one patient (5%), respectively. A homozygous CBL mutation was detected in one patient (5%; c.1228-2A>G). All mutations detected were previously reported mutations. Survival analyses suggested an unfavorable prognostic implication of PTPN11 mutation, albeit without a statistical significance. Collectively, the results from molecular genetics study and survival analyses suggested a relatively higher frequency and unfavorable prognostic implication of PTPN11 mutations in Korean patients with JMML.