Ex vivo identification and characterization of a population of CD13high CD105+ CD45− mesenchymal stem cells in human bone marrow

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License.[Introduction]: Mesenchymal stem cells (MSCs) are multipotent cells capable of self-renewal and multilineage differentiation. Their multipotential capacity and immunomodulatory properties have led to an increasing interest in their biological properties and therapeutic applications. Currently, the definition of MSCs relies on a combination of phenotypic, morphological and functional characteristics which are typically evaluated upon in vitro expansion, a process that may ultimately lead to modulation of the immunophenotypic, functional and/or genetic features of these cells. Therefore, at present there is great interest in providing markers and phenotypes for direct in vivo and ex vivo identification and isolation of MSCs. [Methods]: Multiparameter flow cytometry immunophenotypic studies were performed on 65 bone marrow (BM) samples for characterization of CD13high CD105+ CD45– cells. Isolation and expansion of these cells was performed in a subset of samples in parallel to the expansion of MSCs from mononuclear cells following currently established procedures. The protein expression profile of these cells was further assessed on (paired) primary and in vitro expanded BM MSCs, and their adipogenic, chondrogenic and osteogenic differentiation potential was also determined. [Results]: Our results show that the CD13high CD105+ CD45− immunophenotype defines a minor subset of cells that are systematically present ex vivo in normal/reactive BM (n = 65) and that display immunophenotypic features, plastic adherence ability, and osteogenic, adipogenic and chondrogenic differentiation capacities fully compatible with those of MSCs. In addition, we also show that in vitro expansion of these cells modulates their immunophenotypic characteristics, including changes in the expression of markers currently used for the definition of MSCs, such as CD105, CD146 and HLA-DR. [Conclusions]: BM MSCs can be identified ex vivo in normal/reactive BM, based on a robust CD13high CD105+ and CD45− immunophenotypic profile. Furthermore, in vitro expansion of these cells is associated with significant changes in the immunophenotypic profile of MSCs.This work was supported by grants from the Instituto de Salud Carlos III, FEDER, Ministry of Economy and Competitivity, Madrid, Spain (grant PI11/02399; RETICEF RD12/0043/0021; RTICC RD12/0036/0048); Fundación Ramon Areces, Madrid, Spain (grant CIVP16A1806); Fundación Científica de la Asociación Española Contra el Cáncer (AECC); Consejería de Sanidad, Gerencia Regional de Salud de Castilla y León (SACYL) (grant BIO/SA24/13) and Fundación Samuel Solórzano Barruso (University of Salamanca, Spain); CT was supported by a grant co-financed by the European Social Fund and the Junta de Castilla y León (Spain).Peer Reviewe

Composite lymphoma of concurrent T zone lymphoma and large cell B cell lymphoma in a dog.

BackgroundEvolution of indolent to aggressive lymphoma has been described in dogs but is difficult to distinguish from the de novo development of a second, clonally distinct lymphoma. Differentiation of these scenarios can be aided by next generation sequencing (NGS)-based assessment of clonality of lymphocyte antigen receptor genes.Case presentationAn 8-year-old male intact Mastiff presented with generalized lymphadenomegaly was diagnosed with nodal T zone lymphoma (TZL) based on cytology, histopathology, immunohistochemistry and flow cytometry. Thirteen months later, the dog re-presented with progressive lymphadenomegaly, and based on cytology and flow cytometry, a large B cell lymphoma (LBCL) was diagnosed. Sequencing-based clonality testing confirmed the de novo development of a LBCL and the persistence of a TZL.ConclusionsThe occurrence of two distinct lymphoid neoplasms should be considered if patient features and tumor cytomorphology or immunophenotype differ among sequential samples. Sequencing-based clonality testing may provide conclusive evidence of two concurrent and distinct clonal lymphocyte populations, termed most appropriately "composite lymphoma"

Acute Myelomonocytic Leukemia With Tetrasomy 8: Histologic and Immunophenotypic Features Mimicking Acute Promyelocytic Leukemia

Rare cases of acute myeloid leukemia (AML) with tetrasomy 8 have been reported. Tetrasomy 8, a poor prognostic factor, has been predominantly associated with AML with monocytic differentiation. We report an unusual case of acute myelomonocytic leukemia (AMML) with tetrasomy 8 showing histologic and immunophenotypic features mimicking acute promyelocytic leukemia (APL). The patient is a 63-year-old African American man with molar pain, gum swelling and bleeding, generalized fatigue, leukocytosis, anemia, and thrombocytopenia. A peripheral blood smear showed increased white cells with many immature granulocytic forms. Approximately 40% of the cells exhibited classical blast morphology, 40% were slightly enlarged and exhibited a small to moderate amount of cytoplasm with a variable number of cytoplasmic granules resembling atypical promyelocytes, and 10% exhibited morphology typical of promyelocytes. The presence of promyelocytes and atypical promyelocytes was highly suggestive of APL. Flow cytometry performed on the peripheral blood showed the leukemic cells to express CD11b (subset), CD33, CD56, and CD64 (subset), with no expression of HLA-DR or CD34, suggestive of APL; however, the blasts were negative for CD117. Subsequent bone marrow aspirate/biopsy evaluation was consistent with AMML. FISH analysis showed tetrasomy 8 and absence of PML/RARA gene rearrangement. In this case, AMML with tetrasomy 8 morphologically and immunophenotypically mimicked APL. The treatment and prognosis of these subtypes of AML are significantly different. This case illustrates the importance of cytogenetic analysis and thorough bone marrow evaluation in determining accurate diagnosis of AML

B-Cell Precursors: Immunophenotypic Features in the Detection of Minimal Residual Disease in Acute Leukemia

Minimal residual disease (MRD) as a tool to monitor response to therapy is both a criterion for detailed risk stratification and an independent prognostic factor in childhood acute lymphoblastic leukemia (ALL). Immunological assays particularly flow cytometry (FC) are priority methods in MRD monitoring. Multicolor flow cytometry makes it possible to most fully characterize the immunophenotype of tumor B lymphoblasts and reveal leukemia-associated immunophenotypes not only according to the CD58 and CD38 antigens but also as an additional criterion of aberrancy. This allows you to identify and select individual criteria for further monitoring of minimal residual disease for each patient with ALL. The aim of this chapter is to compare immunophenotyping features of normal B-cell precursors and B-lymphoblasts in acute leukemia and to show possibilities of use of a leukemia-associated immunophenotype in monitoring of the MRD

Immunophenotypic features of immaturity of neural elements in ovarian teratoma.

学位記番号：医博甲161

B-cell Prolymphocytic Leukemia in a Young Male

B-cell prolymphocytic leukemia [B-PLL] is a neoplasm of B prolymphocytes affecting the peripheral blood, bone marrow and spleen. The principal disease characteristics are massive splenomegaly with absent or minimal peripheral lymphadenopathy and a rapidly rising lymphocyte count. Here, we report a case of B-PLL in a 42 year old male who had come for routine health check up

A case of eosinophilic fasciitis and generalized morphea overlap

A 60-year old man developed skin hardening and edema on his extremities. Although he had been treated with oral prednisolone at another hospital, skin stiffness relapsed during tapering of prednisolone. At the initial visit to our department, physical examination showed skin hardening of the extremities and also symmetric erythematous macules on the back. Histological examination revealed fasciitis on the forearm and morphea on the back. Eosinophilic fasciitis is occasionally associated with morphea. However, cases of concurrent eosinophilic fasciitis and generalized morphea are rare. In the present case, CD34 was differentially expressed in both lesions, suggesting eosinophilic fasciitis and morphea are separate diseases with different origin of mesenchymal cells

Study of morphocytochemical and immunophenotypic features of acute leukemia stem cells

The immunophenotypic profile of hematopoietic stem cells (HSC) and hematopoietic precursor cells as well as leukemic stem cells (LSC) has been extensively studied in several laboratories worldwide. The results of our studies suggest that the standard panel for classification of acute leukemias should be supplemented with several new markers allowing us to identify more precisely the different forms of the leukemias being of the closely related origin, for example AML M6b and AML M7. The common bipotent LSC in AML M7 of low grade and AML M6b may exist analogous to precursor cell common for megakaryocytopoiesis and erythropoiesis. We have also found the similarity between blast cells in pro-B-ALL [t (4;11), 11q23] and AML M5a [t (9;11), 11q23]. Such similarity of immunophenotype and cytogenetic abnormalities in blast cells in pro-B-ALL and AML M5a may be considered as hint explaining the cases of AML M5a as a recurrence of leukemia in children with originally diagnosed pro-B-ALL.Иммунофенотипический профиль стволовых лейкемических клеток (СЛК) интенсивно изучают в ряде лабораторий мира. Результаты данного исследования подтверждают, что стандартная панель для классификации острых лейкозов (ОЛ) должна быть дополнена рядом новых маркеров. Это позволяет более точно идентифицировать близкие по происхождению формы ОЛ, например ОМЛ М6b и ОМЛ М7. Предполагается существование общей низкодифференцированной бипотентной ЛСК при ОМЛ М7 и ОМЛ М6b, подобной нормальной общей клетке-предшественнице мегакариоцитопоэза и эритропоэза. Установлено также сходство бластных клеток при про-В-ОЛЛ с перестройкой хромосомного участка 11q23 и транслокацией (4;11) и бластных клеток при ОМЛ М5а c перестройкой того же хромосомного участка 11q23 и транслокацией (9;11). Подобное сходство иммунофенотипа и цитогенетических аномалий при указанных 2 формах ОЛ объясняет появление бластов с фенотипом ОМЛ М5а при рецидиве заболевания у детей, у которых ранее был диагностирован про-В-ОЛЛ

The use of targeted sequencing and flow cytometry to identify patients with a clinically significant monocytosis

The diagnosis of chronic myelomonocytic leukaemia (CMML) remains centred on morphology, meaning the distinction from a reactive monocytosis is challenging. Mutational analysis and immunophenotyping have been proposed as potential tools for diagnosis however have not been formally assessed in combination. We aimed to investigate the clinical utility of these technologies by performing targeted sequencing, in parallel to current gold standard techniques, on consecutive samples referred for investigation of monocytosis over a 2-year period (n=283). Results were correlated with the morphological diagnosis and objective outcome measures including overall survival (OS) and longitudinal blood counts. Somatic mutations were detected in 79% of patients, being invariably identified in those with a confirmed diagnosis (99%) though also in 57% of patients with non-diagnostic BM features. The OS in non-diagnostic mutated patients was indistinguishable from those with CMML (p=0.118) and significantly worse than unmutated patients (p=0.0002). On multivariate analysis age, ASXL1, CBL, DNMT3A, NRAS & RUNX1 mutations retained significance. Furthermore, the presence of a mutation was associated with a progressive fall in haemoglobin/platelet levels and increasing monocyte counts compared with mutation negative patients. Of note, the immunophenotypic features of non-diagnostic mutated patients were comparable to CMML patients and the presence of aberrant CD56 was highly specific for detecting a mutation. Overall, somatic mutations are detected at high frequency in patients referred with a monocytosis irrespective of diagnosis. In those without a WHO defined diagnosis, the mutation spectrum, immunophenotypic features and OS are indistinguishable from CMML patients and these patients should be managed as such

Unlocking the potential of anti-CD33 therapy in adult and childhood acute myeloid leukaemia

Acute Myeloid Leukaemia (AML) develops when there is a block in differentiation and uncontrolled proliferation of myeloid precursors, resulting in bone marrow failure. AML is a heterogeneous disease clinically, morphologically, and genetically, and biological differences between adult and childhood AML have been identified. AML comprises 15-20% of all children less than fifteen years diagnosed with acute leukaemia. Relapse occurs in up to 40% of children with AML and is the commonest cause of death.1,2 Relapse arises from leukaemic stem cells (LSCs) that persist after conventional chemotherapy. The treatment of AML is challenging and new strategies to target LSCs are required. The cell surface marker CD33 has been identified as a therapeutic target, and novel anti-CD33 immunotherapies are promising new agents in the treatment of AML. This review will summarise recent developments emphasising the genetic differences in adult and childhood AML, while highlighting the rationale for CD33 as a target for therapy, in all age groups