Deficient proliferation and expansion in vitro of two bone marrow cell populations from patients with acute myeloid leukemia in response to hematopoietic cytokines

Current challenges in the manufacture of clinical-grade autologous whole cell vaccines for hematological malignancies

Autologous whole cell vaccines use a patient's own tumor cells as a source of antigen to elicit an anti-tumor immune response in vivo. Recently, the authors conducted a systematic review of clinical trials employing these products in hematological cancers that showed a favorable safety profile and trend toward efficacy. However, it was noted that manufacturing challenges limit both the efficacy and clinical implementation of these vaccine products. In the current literature review, the authors sought to define the issues surrounding the manufacture of autologous whole cell products for hematological cancers. The authors describe key factors, including the acquisition, culture, cryopreservation and transduction of malignant cells, that require optimization for further advancement of the field. Furthermore, the authors provide a summary of pre-clinical work that informs how the identified challenges may be overcome. The authors also highlight areas in which future basic research would be of benefit to the field. The goal of this review is to provide a roadmap for investigators seeking to advance the field of autologous cell vaccines as it applies to hematological malignancies.

CD99 is a therapeutic target on disease stem cells in myeloid malignancies

Acute myeloid leukemia (AML) and the myelodysplastic syndromes (MDS) are initiated and sustained by self-renewing malignant stem cells; thus, eradication of AML and MDS stem cells is required for cure. We identified CD99 as a cell surface protein frequently overexpressed on AML and MDS stem cells. Expression of CD99 allows for prospective separation of leukemic stem cells (LSCs) from functionally normal hematopoietic stem cells in AML, and high CD99 expression on AML blasts enriches for functional LSCs as demonstrated by limiting dilution xenotransplant studies. Monoclonal antibodies (mAbs) targeting CD99 induce the death of AML and MDS cells in a SARC family kinase-dependent manner in the absence of immune effector cells or complement, and anti-CD99 mAbs exhibit antileukemic activity in AML xenografts. These data establish CD99 as a marker of AML and MDS stem cells, as well as a promising therapeutic target in these disorders.

Whole genome and transcriptome analysis of a novel AML cell line with a normal karyotype

Acute myeloid leukemia (AML) occurs when hematopoietic progenitor cells acquire genetic defects blocking the regulation of normal growth and differentiation. Although recurrent translocations have been identified in AML, almost half of adult AML patients present with a normal karyotype (NK-AML). While cell line models exist to study AML, they frequently have abnormal/unstable karyotypes, while primary cells from NK-AML patients are difficult to maintain in vitro. Here we provide a thorough molecular characterization of a recently established cell line, CG-SH, which has normal cytogenetics, representing a useful new model for NK-AML. Using high-throughput DNA sequencing, we first defined the genetic background of this cell line. In addition to identifying potentially deleterious SNVs in genes relevant to AML, we also found insertions in both GATA2 and EZH2, two genes previously linked to AML. We further characterized the growth of this model system in vitro with a cytokine mix that promotes faster cell growth. We assessed gene expression changes after the addition of cytokines to the culture media and found differential expression in genes implicated in proliferation, apoptosis and differentiation. Our results provide a detailed molecular characterization of genetic defects in this cell line derived from an NK-AML patient.

Serum cytokine and adhesion molecule profile differs in newly diagnosed acute myeloid and lymphoblastic leukemia

AIMS

To compare serum levels of 17 cytokines and 5 adhesion molecules in patients with newly diagnosed acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) using biochip array technology.

METHODS

A total of 15 AML and 15 ALL patients were studied. Serum samples were taken prior to anticancer therapy and were analyzed by biochip based immunoassays on the Evidence Investigator analyzer. This approach allows simultaneous detection of multiple analytes from a single sample. T-tests were used for statistical analysis.

RESULTS

Comparing cytokine and adhesion molecules levels in newly diagnosed AML and ALL patients, we found significant increase in AML in serum IL-4 (P < 0.0001), IL-2 (P < 0.01), IL-3 (P < 0.05), and significant decrease (P < 0.05) in serum VEGF and VCAM-1.

DISCUSSION

Our results indicate that serum profile of cytokines and adhesion molecules differs in newly diagnosed AML and ALL patients. Further studies are needed to establish if these alterations could be used as a clinically relevant biomarker for acute leukemias.

Expression of CD90, CD96, CD117, and CD123 on different hematopoietic cell populations from pediatric patients with acute myeloid leukemia

BACKGROUND AND AIMS

In trying to contribute to our knowledge on the biology of hematopoietic stem cells (HSC) and hematopoietic progenitor cells (HPC) from pediatric acute myeloid leukemia (AML), in the present study we analyzed the expression of four cell surface antigens relevant to human hematopoiesis-CD90, CD96, CD117, and CD123-in bone marrow from pediatric AML patients and normal control subjects.

METHODS

CD34(+) CD38(-) cells (enriched for HSC) and CD34(+) CD38(+) cells (enriched for HPC) were resolved on the basis of CD34 and CD38 expression. Concomitantly, expression of CD90 and CD96 or CD117 and CD123 was assessed by multicolor flow cytometry in each cell population.

RESULTS

CD90 and CD117 were expressed in a low proportion of CD34(+) CD38(-) and CD34(+) CD38(+) cells and no significant differences were observed between normal marrow and AML at diagnosis. In contrast, CD96(+) cells and CD123(+) cells were found at significantly higher levels in both cell populations from AML at diagnosis, as compared to normal marrow. Levels of both cell surface markers after treatment remained higher than in normal marrow.

DISCUSSION

These results show an increased frequency of CD96(+) and CD123(+) cells within the CD34(+) cell population from pediatric AML; this is consistent with the findings reported previously for adult AML. Our study supports the notion that expression of such antigens should be explored for their use as markers for diagnosis and prognosis.

Lymphoid progenitor cells from childhood acute lymphoblastic leukemia are functionally deficient and express high levels of the transcriptional repressor Gfi-1

Acute lymphoblastic leukemia (ALL) is the most frequent malignancy of childhood. Substantial progress on understanding the cell hierarchy within ALL bone marrow (BM) has been recorded in the last few years, suggesting that both primitive cell fractions and committed lymphoid blasts with immature stem cell-like properties contain leukemia-initiating cells. Nevertheless, the biology of the early progenitors that initiate the lymphoid program remains elusive. The aim of the present study was to investigate the ability of lymphoid progenitors from B-cell precursor ALL BM to proliferate and undergo multilineage differentiation. By phenotype analyses, in vitro proliferation assays, and controlled culture systems, the lymphoid differentiation potentials were evaluated in BM primitive populations from B-cell precursor ALL pediatric patients. When compared to their normal counterparts, functional stem and progenitor cell contents were substantially reduced in ALL BM. Moreover, neither B nor NK or dendritic lymphoid-cell populations developed recurrently from highly purified ALL-lymphoid progenitors, and their proliferation and cell cycle status revealed limited proliferative capacity. Interestingly, a number of quiescence-associated transcription factors were elevated, including the transcriptional repressor Gfi-1, which was highly expressed in primitive CD34⁺ cells. Together, our findings reveal major functional defects in the primitive hematopoietic component of ALL BM. A possible contribution of high levels of Gfi-1 expression in the regulation of the stem/progenitor cell biology is suggested.

Involvement of oxidative stress in the relapse of acute myeloid leukemia

The aims of the present study were to determine the level of oxidative stress and the salient factors leading to the relapse of acute myeloid leukemia (AML). Oxidative stress-related parameters and the expressions of specific genes were monitored in 102 cases of AML during a pretreatment period from a primary status to a relapse status. In addition, age-matched healthy subjects were classified as controls. The activities of adenosine deaminase and xanthine oxidase were higher in the relapse condition, whereas those of glutathione peroxidase, monoamine oxidase, and superoxide dismutase, and the total antioxidant capacity (T-AOC) were lower in the primary condition and in controls. Of particular note, levels of advanced oxidation protein products, malondialdehyde, and 8-hydroxydeoxyguanosine were also significantly higher in relapse patients. Furthermore, real-time PCR with SYBR Green revealed that the expression levels of human thioredoxin (TRX) and indoleamine 2,3-dioxygenase were increased in relapse patients. Pearson correlation analysis revealed that the T-AOC was positively correlated with GSH but negatively correlated with 8-OHdG, TRX, and indoleamine 2,3-dioxygenase. Linear regression showed that a low T-AOC and up-regulated TRX expression were the independent factors correlated with relapse. A strong association between oxidative stress and the incidence of disease relapse was observed, which has potential prognosis implications. These results indicate that oxidative stress is a crucial feature of AML and probably affects the development and relapse of AML.

Defective in vitro growth of primitive hematopoietic cells from pediatric patients with acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a neoplastic hematologic disorder that arises at the level of a primitive stem/progenitor cell. Most studies on the biology of the hematopoietic system in AML have focused on cells from adult patients; much less is known about hematopoietic cells from childhood AML.

PROCEDURE

By using a negative immunoselection system, we have obtained a primitive cell population (enriched for CD34(+) Lin(-) cells) from the bone marrow (BM) of 17 pediatric AML patients and characterized its proliferation, expansion, and differentiation potentials in liquid cultures supplemented with a mixture of 8 different recombinant stimulatory cytokines.

RESULTS

The proportion of CD34(+) cells in AML patients was extremely heterogeneous, ranging from 0% to 74%. Regardless of their CD34(+) cell content, and in contrast to normal cells, AML cells showed a deficient capacity to proliferate even in the presence of the stimulatory cytokines. AML progenitors were unable to generate new progenitor cells, indicating their inability to expand. Interestingly, AML cells were able to differentiate in culture, giving rise to morphologically recognizable precursors. A major difference, however, as compared to hematopoietic progenitors from normal subjects, was the fact that whereas in cultures of normal cells both myeloid and erythroid precursors were produced, in AML cultures the vast majority of the cells generated corresponded to myeloid cells, mostly mature macrophages.

CONCLUSION

As compared to their normal counterparts, primitive hematopoietic cells from pediatric patients with AML possess impaired proliferation, expansion, and differentiation potentials in vitro.