An overview of chronic myeloid leukemia and its animal models

"Hook&Loop" multivalent interactions based on disk-shaped nanoparticles strengthen active targeting

How to enhance active targeting efficiency remains a challenge. Multivalent interactions play a crucial role in improving the binding ability between ligands and receptors. It is hypothesized that nanoparticles bearing a flat conformation attain simultaneous formation of multiple ligand-receptor bindings, which could be vividly metaphorized by the "Hook&Loop" rationale. In this study, spherical, rod-shaped and disk-shaped folic acid-modified red blood cell membrane-coated biomimetic mesoporous silica nanoparticles (FRMSNs) were prepared to verify the shape-based multivalent interactions. The fundamental concepts of multivalent interactions have been proved by a series of both in vitro and in vivo evaluations. Physical characterization confirmed the morphology, shape and surface features of FRMSNs. Strengthened binding and internalization of disk-shaped FRMSNs by K562 cells stresses the merits of multivalent interactions. Whereas Bio-TEM visually demonstrates the proposed "plane" contact of disk-shaped particles with cells, quantification further confirmed strengthened "plane" binding affinity with folate binding proteins owing to multivalent interactions. In K562 xenograft mice, doxorubicin-loaded disk-shaped FRMSNs effectively slowed down chronic myeloid leukemia progression. It is concluded that disks favor multivalent interactions which leads to enhanced active targeting efficiency.

In Vitro and In Vivo Modeling of Normal and Leukemic Bone Marrow Niches: Cellular Senescence Contribution to Leukemia Induction and Progression

Cellular senescence is recognized as a dynamic process in which cells evolve and adapt in a context dependent manner; consequently, senescent cells can exert both beneficial and deleterious effects on their surroundings. Specifically, senescent mesenchymal stromal cells (MSC) in the bone marrow (BM) have been linked to the generation of a supporting microenvironment that enhances malignant cell survival. However, the study of MSC's senescence role in leukemia development has been straitened not only by the availability of suitable models that faithfully reflect the structural complexity and biological diversity of the events triggered in the BM, but also by the lack of a universal, standardized method to measure senescence. Despite these constraints, two- and three dimensional in vitro models have been continuously improved in terms of cell culture techniques, support materials and analysis methods; in addition, research on animal models tends to focus on the development of techniques that allow tracking leukemic and senescent cells in the living organism, as well as to modify the available mice strains to generate individuals that mimic human BM characteristics. Here, we present the main advances in leukemic niche modeling, discussing advantages and limitations of the different systems, focusing on the contribution of senescent MSC to leukemia progression.

Development of BCR-ABL1 Transgenic Zebrafish Model Reproducing Chronic Myeloid Leukemia (CML) Like-Disease and Providing a New Insight into CML Mechanisms

Zebrafish has proven to be a versatile and reliable experimental in vivo tool to study human hematopoiesis and model hematological malignancies. Transgenic technologies enable the generation of specific leukemia types by the expression of human oncogenes under specific promoters. Using this technology, a variety of myeloid and lymphoid malignancies zebrafish models have been described. Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasia characterized by the BCR-ABL1 fusion gene, derived from the t (9;22) translocation causing the Philadelphia Chromosome (Ph). The BCR-ABL1 protein is a constitutively activated tyrosine kinas inducing the leukemogenesis and resulting in an accumulation of immature leukemic cells into bone marrow and peripheral blood. To model Ph+ CML, a transgenic zebrafish line expressing the human BCR-ABL1 was generated by the Gal4/UAS system, and then crossed with the hsp70-Gal4 transgenic line. The new line named (BCR-ABL1pUAS:CFP/hsp70-Gal4), presented altered expression of hematopoietic markers during embryonic development compared to controls and transgenic larvae showed proliferating hematopoietic cells in the caudal hematopoietic tissue (CHT). The present transgenic zebrafish would be a robust CML model and a high-throughput drug screening tool.

Zebrafish disease models in hematology: Highlights on biological and translational impact

Zebrafish (Danio rerio) has proven to be a versatile and reliable in vivo experimental model to study human hematopoiesis and hematological malignancies. As vertebrates, zebrafish has significant anatomical and biological similarities to humans, including the hematopoietic system. The powerful genome editing and genome-wide forward genetic screening tools have generated models that recapitulate human malignant hematopoietic pathologies in zebrafish and unravel cellular mechanisms involved in these diseases. Moreover, the use of zebrafish models in large-scale chemical screens has allowed the identification of new molecular targets and the design of alternative therapies. In this review we summarize the recent achievements in hematological research that highlight the power of the zebrafish model for discovery of new therapeutic molecules. We believe that the model is ready to give an immediate translational impact into the clinic.

Re-balance of memory T cell subsets in peripheral blood from patients with CML after TKI treatment

T cell immune surveillance is considered an important host protection process for inhibiting carcinogenesis. The full capacity of T cell immune surveillance is dependent on T cell homeostasis, particularly for central memory T (T_CM) cells and stem cell memory T (T_SCM) cells. In this study, distribution of T cell subsets in peripheral blood from 12 patients with chronic myeloid leukemia (CML) and 12 cases with CML in complete remission (CR) was analyzed using a multicolor flow cytometer, and 16 samples from healthy individuals (HIs) served as control. The proportion of CD8⁺ T_SCM and CD4⁺ and CD8⁺ T_CM cells were lower, while CD4⁺ effector memory T (T_EM) cells and CD4⁺ and CD8⁺ terminal effector T (T_EF) cells were higher in CML patients compared with HIs. Moreover, the proportion of CD8⁺CD28^- T cells, which were found to have the immune suppressive function, increased in the naive T (T_N) cell and T_CM subsets in CML patients compared with HIs. Our study reveals that elimination of leukemia cells by treating with tyrosine kinase inhibitors (TKIs) restores the memory T cell distribution from a skewed pattern in CML patients who are under leukemia burden, indicating that leukemia-specific immune responses mediated by T cells might be induced and maintained in CML patients, however, these responsive T cells might gradually become exhausted due to the continued existence of leukemia cells and their environment; therefore, T cell activation using a different approach remains a key point for enhancing global T cell immunity in CML patients, even for those with CR status.

Combination of White Blood Cell Count at Presentation With Molecular Response at 3 Months Better Predicts Deep Molecular Responses to Imatinib in Newly Diagnosed Chronic-Phase Chronic Myeloid Leukemia Patients

The aim of this study was to evaluate the impact of white blood cell (WBC) counts at presentation on the achievement of deep molecular response.A total of 362 newly diagnosed chronic-phase chronic myeloid leukemia patients (CML-CP) receiving 400 mg/day imatinib were serially monitored for a median of 36 months (range 6-115).Patients showing an optimal response at 3, 6, and 12 months as defined by the 2013 European LeukemiaNet recommendations had significantly lower WBC counts at presentation than those showing nonoptimal responses (all P < 0.0001). Among the cutoff values with a similar Youden index, 150 × 10E9/L (abbreviated WBC > 150) was selected to identify the greatest amount of patients with the potential to achieve a sustained molecular response of 4.5 (MR4.5). Regardless of whether the Sokal risk score was included, the BCR-ABL value at 3 months, WBC counts at presentation, hemoglobin levels, and sex were the common independent predictors for an MR4.5, with the former 2 presenting the highest hazard risk. Low Sokal risk scores did not independently predict the achievement of an MR4.5. Patients with concurrent WBC > 150 and BCR-ABL(IS) ≤ 10% had a similar incidence of 4-year MR4.5 compared with patients with concurrent WBC ≤ 150 and BCR-ABL(IS) > 10% and concurrent WBC > 150 and BCR-ABL(IS) > 10% (13.5% vs 13.2% vs 8.8%, P = 0.47), and all of these values were significantly lower than the values for patients with concurrent WBC ≤ 150 and BCR-ABL(IS) ≤ 10% (55.0%, all P < 0.0001). Patients with concurrent WBC ≤ 150 and BCR-ABL(IS) ≤ 10% had better 4-year event-free survival rates, progression-free survival rates, and overall survival rates compared with patients with WBC > 150 or BCR-ABL(IS) > 10%. The combination of WBC count at presentation and BCR-ABL(IS) at 3 months provides improved predictions of deep molecular response in imatinib-treated CML-CP patients. Therefore, the WBC count at presentation might be used to differentiate patients at the beginning of imatinib treatment.