Functional analysis of myelodysplastic syndromes-derived mesenchymal stem cells.

Two different reports, including one from our own group, have recently demonstrated the presence of severe chromosomal abnormalities in mesenchymal stem cells (MSC) from patients with myelodysplastic syndromes (MDS). In the present study, we have assessed whether such cytogenetic abnormalities result in functional deficiencies in vitro. We found that both normal and MDS MSC showed similar expression patterns of cell adhesion molecules and extracellular matrix proteins. MDS MSC layers showed the capability to differentiate towards adipocytes, chondrocytes and osteoblasts, and supported the growth of early umbilical cord blood progenitors in a co-culture system. Unstimulated MDS MSC secreted more IL-1beta and after treatment with TNFalpha, they secreted more SCF, as compared to their normal counterparts. The present study demonstrates that, in spite of harboring severe chromosomal alterations, most of the functional properties of MDS-derived MSC remain normal, including their ability to support normal hematopoiesis in vitro.

Hematopoietic changes during progression from Fanconi anemia into acute myeloid leukemia: case report and brief review of the literature.

Fanconi anemia (FA) is a rare autosomal recessive disorder characterized by bone marrow (BM) failure and a wide array of physical abnormalities. Around 9% of FA patients develop acute myeloid leukemia (AML), which makes FA a good genetic model to study leukemogenesis. To date, however, no information exists on the functional integrity of the hematopoietic system of FA patients during the period in which they develop AML. Herein, we report on the characterization of hematopoietic progenitor cells from a pediatric FA patient that developed AML. Our results show that significant changes occurred in the hematopoietic system of the patient from the time he presented with FA to the time he developed AML. Such changes included marrow cellularity, frequency of CD34(+) cells and CFC, as well as proliferation potential of progenitor cells in liquid cultures supplemented with recombinant cytokines. Interestingly, no significant changes in the karyotype of marrow cells were observed, indicating that progression from FA into AML may proceed without major chromosomal alterations (i.e. translocations and/or deletions). This study represents one of the first steps towards the cellular characterization of the hematopoietic system in FA patients that develop AML.

Functional integrity in vitro of hematopoietic progenitor cells from patients with chronic myeloid leukemia that have achieved hematological remission after different therapeutic procedures.

In this study, we have assessed the in vitro growth of hematopoietic progenitor cells (HPC) from chronic myeloid leukemia (CML) patients that have recovered after different treatments. Bone marrow cells were obtained from 33 CML patients, including patients at diagnosis, before treatment (n=12), and patients that have achieved hematological remission (and in most cases a major cytogenetic response) after different therapeutic procedures (n=21), including patients treated with Interferon-alpha (IFN; n=5), imatinib mesylate (IMATINIB; n=8) and patients that received an allogeneic hematopoietic cell transplant (HCT; n=8). Marrow cells were enriched for CD34(+) cells and cultured in a serum- and stroma-free liquid culture system, supplemented with a combination of 8 recombinant cytokines. Normal samples were studied as controls. HPC from CML patients before therapy showed deficient proliferation and expansion potentials in culture (140-fold increase in nucleated cell number and 1.3-fold increase in colony-forming cell number) as compared to normal progenitors (1200-fold increase in nucleated cell number and 25-fold increase in colony-forming cell number). In contrast, HPC from patients treated with IMATINIB showed growth potentials similar to those of normal progenitors. Progenitors from patients after HCT also showed significant proliferation and expansion capacities. Interestingly, progenitors from IFN-treated patients showed proliferation and expansion kinetics similar to those of cells from untreated patients. These results indicate that, although treatment of CML patients with IFN, IMATINIB or HCT resulted in complete hematological remission (and a major cytogenetic response), only patients treated with IMATINIB and, to a lesser extent, with HCT showed a full hematopoietic recovery, as determined by the in vitro growth of HPC in our culture system.

Mesenchymal stem cells in myelodysplastic syndromes: phenotypic and cytogenetic characterization.

Bone marrow-derived mesenchymal stem cells (MSC) have been defined as primitive, undifferentiated cells, capable of self-renewal and with the ability to give rise to different cell lineages, including adipocytes, osteocytes, fibroblasts, chondrocytes, and myoblasts. MSC are key components of the hematopoietic microenvironment. Several studies, including some from our own group, suggest that important quantitative and functional alterations are present in the stroma of patients with myelodysplasia (MDS). However, in most of such studies the stroma has been analyzed as a complex network of different cell types and molecules, thus it has been difficult to identify and characterize the cell(s) type(s) that is (are) altered in MDS. In the present study, we have focused on the biological characterization of MSC from MDS. As a first approach, we have quantified their numbers in bone marrow, and have worked on their phenotypic (morphology and immunophenotype) and cytogenetic properties. MSC were obtained by a negative selection procedure and cultured in a MSC liquid culture medium. In terms of morphology, as well as the expression of certain cell markers, no differences were observed between MSC from MDS patients and those derived from normal marrow. In both cases, MSC expressed CD29, CD90, CD105 and Prolyl-4-hydroxylase; in contrast, they did not express CD14, CD34, CD68, or alkaline phosphatase. Interestingly, in five out of nine MDS patients, MSC developed in culture showed cytogenetic abnormalities, usually involving the loss of chromosomal material. All those five cases also showed cytogenetic abnormalities in their hematopoietic cells. Interestingly, in some cases there was a complete lack of overlap between the karyotypes of hematopoietic cells and MSC. To the best of our knowledge, the present study is the first in which a pure population of MSC from MDS patients is analyzed in terms of their whole karyotype and demonstrates that in a significant proportion of patients, MSC are cytogenetically abnormal. Although the reason of this is still unclear, such alterations may have an impact on the physiology of these cells. Further studies are needed to assess the functional integrity of MDS-derived MSC.

In vitro characterization of hematopoietic microenvironment cells from patients with myelodysplastic syndrome.

In vitro studies on the functional integrity of the hematopoietic microenvironment in myelodysplasia have been controversial. Although some of them suggest that such a microenvironment is functionally normal, there is increasing evidence indicating that there are alterations in the function of microenvironment (adherent) cell layers from myelodysplastic syndromes (MDS) marrow. Adherent cell layers developed in vitro, however, consist of a mixture of different cell types-mostly fibroblasts and macrophages-thus, it is not clear which cell type(s) is(are) functionally abnormal in this disorder. In order to address this issue, in the present study, we first assessed some functional properties of MDS-derived adherent cell layers, as a whole, and then we analyzed those same functional properties after separating these cells into two different populations: a fibroblast-enriched cell layer and a macrophage-enriched cell layer. When whole adherent layers from MDS patients were analyzed, no significant differences were observed, as compared to their normal counterparts, in terms of morphology and total cell number. A major difference, however, was observed when analyzing the production of the cytokines interleukin-6 (IL-6) and tumor necrosis factor (TNF-alpha). Indeed, adherent layers from MDS patients produced higher levels of these cytokines (2- and 22-fold, respectively), as compared to normal layers. When fibroblast- and macrophage-enriched cell layers were analyzed, a higher apoptotic index was observed in those derived from MDS marrow (4% of TUNEL-positive cells in normal fibroblast layers versus 27% in MDS-derived fibroblast layers; 7% of TUNEL-positive cells in normal macrophage layers versus 24% in MDS macrophage layers). Macrophages from MDS marrow produced significantly higher levels of TNF-alpha (nine-fold) than their normal counterparts. MDS-derived fibroblasts, on the other hand, produced higher levels of IL-6 (nine-fold), as compared to normal fibroblasts. Surprisingly, whereas normal fibroblasts showed a discrete production of TNF-alpha, we found a very high production of this cytokine in cultures of fibroblasts from MDS patients. In summary, in the present study we have demonstrated that, at least in vitro, both fibroblasts and macrophages from MDS bone marrow (BM) are functionally abnormal. Such abnormalities include an increased apoptotic index, as well as a high production of both IL-6 and TNF-alpha.

Estudio citogenético en pacientes con leucemia mieloblástica aguda: Caracterización de grupos de riesgo por estudios cromosómicos / Cytogenetic study in patients with acute myeloblastic leukemia: Characterization of high risk groups by cytogenetic studies

Presentamos el estudio citogenético en 30 pacientes adultos en los que se diagnosticó leucemia mieloblástica aguda de novo, para caracterizar grupos de mayor riesgo en nuestra población. Los pacientes fueron tratados con esquemas conocidos "7 + 3" de daunorrubicina y arabinósido de citosina; así como ácido retinoico en los casos de M3. El cariotipo se realizó al momento del diagnóstico y en el seguimiento cada seis a ocho meses. Se observaron alteraciones cromosómicas en 90 por ciento de los casos, una incidencia mayor a la registrada en la literatura. Una respuesta clínica efectiva con periodos más largos de remisión y supervivencia se observó en los pacientes que tenían M2 con t(8;21), M4 con rearreglos de (16g) o cariotipo normal. En cambio, los pacientes con M3 y t(15;17) o los que presentan t(9;22), +8, o -7 tuvieron las peores respuestas, con menor tiempo de remisión y los más altos índices de mortalidad, por lo que deben considerarse de alto riesgo en nuestra población

Cytogenetic findings in 303 mexican patients with de novo acute myeloblastic leukemia

In this report we show the chromosomal changes seen in a group of 303 Mexican patients with de novo Acute myeloblastic Leukemia (AML). Two hundred forty-two patients were diagnosed and treated at two hospitals affiliated with the Instituto Mexicano del Seguro Social (IMSS). These are the Centro Medico Nacional Siglo XXI and Centro Medico La Raza Hospitals; the remaining 61 patients were diagnosed and treated at the Hospital General de Mexico (HGM). Clonal abnormalities were detected in 75.6 percent of the patients; this result agrees with what has been reported in other large series of AML studies. The incidence of changes per hospital was similar in patients from the IMSS hospitals (72-75 percent), while an increase was seen in patients from the HGM (85.2 percent). The cromosomal changes seen in this study in order of frequency were: t(15;17)[18.8 percent], t(9;22)[9.2 percent], miscellaneous chromosomal changes (mainly rearrangementa of chromosomes 1,2,3,12 y 17) [8.2 percent], abnormalities of 16q22 [7.3 percent], t(8;21)[6.3 percent], -7/del(7q)[5.6 percent], t(6;9)[5.3 percent), and abnormalities of 11q23 [4.6 percent]. We reported an increase in the indicidence of certain types of chromosomal changes seen in cases of AML, in comparison with reports from other countries. These differences must not be disregarded. We support this finding when comparing distribution of changes in the population of patients seen in the IMSS hospitals with those from the HGM; the main difference lies in the socioeconomic level

El interferón en la erradicación del cromosoma Filadelfia de la leucemia mieloide crónica / Interferon in the suprpression of Philadelphia chromosome of chronic myeloid leukemia

Objetivo. Evaluar si el interferón-alfa humano recombinante (IFN), combinado con quimioterapia, suprime la clona portadora del cromosoma Filadelfia en pacientes con leucemia mieloide crónica (LMC). Material y métodos. Se estudiaron 53 pacientes con LMC en fase crónica de novo. Los pacientes recibieron uno de tres esquemas de tratamiento: a) inducción a la remisión con daunorrubicina, vincristina, arabinósido de citosina y prednisona (DOAP) y mantenimiento con IFN (n = 12); b) inducción con busulfán (BUS) o hidroxiurea (HIDX) siguiendo el mantenimiento con IFN (n = 26); c) inducción con DOAP y mantenimiento con BUS (n = 15). Resultados. La remisión hematológica se observó dos a seis meses después del inicio de tratamiento: 10 tuvieron remisión completa, seis parcial, 14 menor y 23 nula. Los 16 con respuesta completa o parcial recibieron IFN. Ninguno de los 15 casos mantenidos con BUS tuvo respuesta parcial o completa. La proporción de casos con respuesta citogenética completa (3/12) fue ligeramante menor en los tratados con quimioterapia intensiva (DOAP/IFN) que en aquéllos (7/26) de quimioterapia convencional (BUS/HIDX/IFN). Conclusiones. Nuestros resultados muestran que: a) el IFN en combinación con quimioterapia contribuyó a lograr respuesta citogenética parcial o completa en 30 por ciento de los casos; y b) la quimioterapia (DOAP) combinada con IFN no fue superior, en términos de respuesta citogenética, al tratamiento combinado de monodrogas (Bus/Hidx) con IFN

Estudio citogenético en 22 adultos y tres niños con leucemia linfoblástica aguda / Cytogenetic study in 22 adults and therr children with acute lymphoblastic leukemia

Se presentan los resultados del estudio citogenético realizado en sangre periférica y/o médula ósea de 25 pacientes (22 adultos y 3 niños) con LLA estudiados entre 1987 a 1990. Todos los casos presentaron alteraciones cromosómicas (25/25), aunque en 23 pacientes (23/25) estaba presente una línea celular normal. Entre las aberriguaciones estructurales encontradas están t(17;19) (q11;p13), t(2;9;22)(q34;q34;q11), t(1;7)(p13;q33), t(6;11)(q26;p16), t(3;4)(q24-25;q26), t(1;12)(q23;q34), t(2;18)(q15;p12), t(2;4;)(q23;35) y t(4;11)(q21ñq23). Estos rearreglos fueron indicadores de riesgo y se correlacionaron con la respuesta al tratamiento y la supervivencia de los pacientes. Algunas de estas anomalías no habían sido previamente descritas en LLA; sin embargo, los puntos de ruptura coinciden con los observados en otras neoplasias hematológicas, lo cual suguiere que esas regiones son críticas en la patogénesis de estos desórdenes.