Bone marrow derived mesenchymal stem cells from chronic myeloid leukemia t(9;22) patients are devoid of Philadelphia chromosome and support cord blood stem cell expansion.

Chronic myeloid leukemia (CML) is a clonal myeloproliferative disorder of hematopoietic stem cells. It is characterized at cytogenetic level by the Philadelphia (Ph) chromosome and at the molecular level by the BCR/ABL gene rearrangement. Bone marrow derived mesenchymal stem cells (MSCs) are also pluripotent stem cells that can differentiate into several mesenchymal tissues. To date, no study has been performed to characterize whether MSCs from CML harbor the abnormal Ph chromosome similar to CML bone marrow cells. We isolated and characterized MSCs from diagnostic marrow samples (n=11) and showed that MSCs can be readily isolated from CML marrow and exhibit major expansion potential as well as intact osteogenic differentiation ability. Moreover, they do not harbor the Ph chromosome confirmed by fluorescence in situ hybridization (FISH) and reverse transcriptase polymerase chain reaction (RT-PCR). Thus, we demonstrated that CML marrow is an abundant source of MSCs appearing through both FISH and RT-PCR not to be involved by the malignant process of CML. Furthermore, these MSCs from a CML patient could support in vitro cord blood expansion as those MSCs from a normal donor. Since MSCs are able to support engraftment of hematopoietic stem cells in stem cell transplantation (SCT) as well as suppress alloreactive T cells causing graft-versus-host disease, this current report thus provides evidence that in a SCT setting of CML patients, autologous MSCs could be a source of stem cell support in future cell therapy applications.

Secondary Burkitt lymphoma in a retinoblastoma patient with 13q deletion syndrome.

We report a boy with constitutional deletion 13q chromosome associated with dysmorphic features and bilateral retinoblastoma. The patient developed secondary Burkitt lymphoma 5 years after the diagnosis of retinoblastoma at the age of 8 months. He has completed treatment for both malignancies. At present, he is 7 years old and still in remission.

Generation of CD3+ CD56+ cytokine-induced killer cells and their in vitro cytotoxicity against pediatric cancer cells.

A certain number of pediatric cancer patients still succumb to relapse following conventional treatment of their malignancies. One of the mechanisms of relapse is escape from immunity. Adoptive cellular immunotherapy with effector cells has the potential to overcome this escape. In adults, the CD3+ CD56+ cell, a cytokine-induced killer (CIK) cell, appears to be a promising effector cell type with the greatest cytotoxicity. This effector cell type may work in children as well. No similar studies with children have been published. We speculated that expanded CD3+ CD56+ cells obtained from pediatric cancer patients during remission would act similarly against various pediatric tumor cell lines; therefore, we undertook the present study to find support for our speculation. This study was undertaken to generate and expand CD3+ CD56+ CIK cells from normal peripheral blood mononuclear cells (PBL) obtained from 6 children with cancer (2 with acute lymphoblastic leukemia, 2 with large cell lymphoma, and 2 with osteosarcoma) in remission after intensive chemotherapy and to study the cytotoxic activities of these cells against chronic myeloid leukemia cell line K562 t(9;22), 4 pediatric tumor cell lines [infant acute lymphoblastic leukemia RS4 t(4;11), TEL/AML acute lymphoblastic leukemia REH t(12;21), alveolar rhabdomyosarcoma Rh-Cr t(2;13), and Ewing sarcoma EW-Le t(11;22)], and 2 pediatric glioblastoma multiforme cultured cell lines (G74 and G77). CIK cells were generated and expanded in culture medium to which interferon gamma, monoclonal antibody against CD3, and interleukin 2 were added at appropriate times. Cells were counted by flow cytometry. Net lactate dehydrogenase release from target cells incubated with CIK cells was used as an index of CIK cell cytotoxicity against various pediatric tumor cell lines. The results show that after 21 days in culture CD3+ CD56+ CIK cells derived from the 6 pediatric patients accounted for a median of 28.3% of the entire culture (range, 10.7%-36.4%). Before expansion no such cells were found in any of the 6 children. Median lytic activity rates of CIK cells were 45.5% to 64.5%, rates that contrasted drastically to the lytic activity rates of PBL, which were only 8% to 12%. The findings of the present study are encouraging. They provide information for developing adoptive immunotherapy for future clinical trials with pediatric cancer patients, particularly those patients with minimal residual disease after intensive chemotherapy or stem cell transplantation (especially nonmyeloablative transplantation procedures).