Ally to adversary: mesenchymal stem cells and their transformation in leukaemia

Specifics of Cryopreservation of Hydrogel Biopolymer Scaffolds with Encapsulated Mesenchymal Stem Cells

The demand for regenerative medicine products is growing rapidly in clinical practice. Unfortunately, their use has certain limitations. One of these, which significantly constrains the widespread distribution and commercialization of such materials, is their short life span. For products containing suspensions of cells, this issue can be solved by using cryopreservation. However, this approach is rarely used for multicomponent tissue-engineered products due to the complexity of selecting appropriate cryopreservation protocols and the lack of established criteria for assessing the quality of such products once defrosted. Our research is aimed at developing a cryopreservation protocol for an original hydrogel scaffold with encapsulated MSCs and developing a set of criteria for assessing the quality of their functional activity in vitro. The scaffolds were frozen using two alternative types of cryocontainers and stored at either -40 °C or -80 °C. After cryopreservation, the external state of the scaffolds was evaluated in addition to recording the cell viability, visible changes during subsequent cultivation, and any alterations in proliferative and secretory activity. These observations were compared to those of scaffolds cultivated without cryopreservation. It was shown that cryopreservation at -80 °C in an appropriate type of cryocontainer was optimal for the hydrogels/adipose-derived stem cells (ASCs) tested if it provided a smooth temperature decrease during freezing over a period of at least three hours until the target values of the cryopreservation temperature regimen were reached. It was shown that evaluating a set of indicators, including the viability, the morphology, and the proliferative and secretory activity of the cells, enables the characterization of the quality of a tissue-engineered construct after its withdrawal from cryopreservation, as well as indicating the effectiveness of the cryopreservation protocol.

The quest for the holy grail: overcoming challenges in expanding human hematopoietic stem cells for clinical use

Hematopoietic stem cell (HSC) transplantation has been the golden standard for many hematological disorders. However, the number of HSCs obtained from several sources, including umbilical cord blood (UCB), often is insufficient for transplantation. For decades, maintaining or even expanding HSCs for therapeutic purposes has been a "holy grail" in stem cell biology. Different methods have been proposed to improve the efficiency of cell expansion and enhance homing potential such as co-culture with stromal cells or treatment with specific agents. Recent progress has shown that this is starting to become feasible using serum-free and well-defined media. Some of these protocols to expand HSCs along with genetic modification have been successfully applied in clinical trials and some others are studied in preclinical and clinical studies. However, the main challenges regarding ex vivo expansion of HSCs such as limited growth potential and tendency to differentiate in culture still need improvements. Understanding the biology of blood stem cells, their niche and signaling pathways has provided possibilities to regulate cell fate decisions and manipulate cells to optimize expansion of HSCs in vitro. Here, we review the plethora of HSC expansion protocols that have been proposed and indicate the current state of the art for their clinical application.

FUBP3 regulates chronic myeloid leukaemia progression through PRC2 complex regulated PAK1-ERK signalling

The development of resistance and heterogeneity in differential response towards tyrosine kinase inhibitors (TKI) in chronic myeloid leukaemia (CML) treatment has led to the exploration of factors independent of the Philadelphia chromosome. Among these are the association of deletions of genes on derivative (der) 9 chromosome with adverse outcomes in CML patients. However, the functional role of genes near the breakpoint on der (9) in CML prognosis and progression remains largely unexplored. Copy number variation and mRNA expression were evaluated for five genes located near the breakpoint on der (9). Our data showed a significant association between microdeletions of the FUBP3 gene and its reduced expression with poor prognostic markers and adverse response outcomes in CML patients. Further investigation using K562 cells showed that the decrease in FUBP3 protein was associated with an increase in proliferation and survival due to activation of the MAPK-ERK pathway. We have established a novel direct interaction of FUBP3 protein and PRC2 complex in the regulation of ERK signalling via PAK1. Our findings demonstrate the role of the FUBP3 gene located on der (9) in poor response and progression in CML with the identification of additional druggable targets such as PAK1 in improving response outcomes in CML patients.

Hematopoietic Stem and Progenitor Cells (HSPCs) and Hematopoietic Microenvironment: Molecular and Bioinformatic Studies of the Zebrafish Models

Hematopoietic stem cells (HSCs) reside in a specialized microenvironment in a peculiar anatomic location which regulates the maintenance of stem cells and controls its functions. Recent scientific progress in experimental technologies have enabled the specific detection of epigenetic factors responsible for the maintenance and quiescence of the hematopoietic niche, which has improved our knowledge of regulatory mechanisms. The aberrant role of RNA-binding proteins and their impact on the disruption of stem cell biology have been reported by a number of recent studies. Despite recent modernization in hematopoietic microenvironment research avenues, our comprehension of the signaling mechanisms and interactive pathways responsible for integration of the hematopoietic niche is still limited. In the past few decades, zebrafish usage with regards to exploratory studies of the hematopoietic niche has expanded our knowledge for deeper understanding of novel cellular interactions. This review provides an update on the functional roles of different genetic and epigenetic factors and molecular signaling events at different sections of the hematopoietic microenvironment. The explorations of different molecular approaches and interventions of latest web-based tools being used are also outlined. This will help us to get more mechanistic insights and develop therapeutic options for the malignancies.

Bone Marrow Niches of Hematopoietic Stem and Progenitor Cells

The mammalian hematopoietic system is remarkably efficient in meeting an organism’s vital needs, yet is highly sensitive and exquisitely regulated. Much of the organismal control over hematopoiesis comes from the regulation of hematopoietic stem cells (HSCs) by specific microenvironments called niches in bone marrow (BM), where HSCs reside. The experimental studies of the last two decades using the most sophisticated and advanced techniques have provided important data on the identity of the niche cells controlling HSCs functions and some mechanisms underlying niche-HSC interactions. In this review we discuss various aspects of organization and functioning of the HSC cell niche in bone marrow. In particular, we review the anatomy of BM niches, various cell types composing the niche, niches for more differentiated cells, metabolism of HSCs in relation to the niche, niche aging, leukemic transformation of the niche, and the current state of HSC niche modeling in vitro.

The mechanisms of mutual relationship between malignant hematologic cells and mesenchymal stem cells: Does it contradict the nursing role of mesenchymal stem cells?

Mesenchymal stem/stromal cells (MSCs) are known as the issue in biology because of some unpredictable characteristics in the different microenvironments especially in their bone marrow niche. MSCs are used in the regenerative medicine because of their unique potentials for trans-differentiation, immunomodulation, and paracrine capacity. But, their pathogenic and pro-survival effects in tumors/cancers including hematologic malignancies are indisputable. MSCs and/or their derivatives might be involved in tumor growth, metastasis and drug resistance in the leukemias. One of important relationship is MSCs and hematologic malignancy-derived cells which affects markedly the outcome of disease. The communication between these two cells may be contact-dependent and/or contact-independent. In this review, we studied the crosstalk between MSCs and malignant hematologic cells which results the final feedback either the progression or suppression of blood cell malignancy. Video abstract.

Changes in Bone Marrow Stromal Progenitor Cells in Patients with Hematoblastosis at the Onset of the Disease

Multipotent mesenchymal stromal cells (MSC) are the key regulators of hematopoiesis. We studied changes in MSC characteristics in patients with myeloid leukemia and patients with lymphoproliferative diseases. MSC were obtained from the bone marrow of patients at the time of diagnostic puncture using a standard technique. Their proliferative potential and expression of genes associated with differentiation and regulation of hematopoiesis were studied. The total cell production of MSC in patients with leukemia at the onset of the disease did not differ from that in the group of healthy donors. The relative expression of the IL6, TGFb1 and TGFb2, PPARG genes was similar in all patients. The relative expression of the JAG1, LIF, IGF1, CSF1, IL1b, and IL1bR1 genes in MSC of patients with leukemia was enhanced and the relative expression of SDF1 was unchanged in comparison with MSC from donors. MSC from patients with leukemia were characterized by enhanced relative expression of PDGFRA and PDGFRB, and reduced expression of SOX9. Changes functions of the stromal microenvironment in patients with hemoblastoses attested to the role of stromal cells in the maintenance and spread of tumor cells.

Abnormal bone marrow microenvironment: the “harbor” of acute lymphoblastic leukemia cells

Bone marrow (BM) microenvironment regulates and supports the production of blood cells which are necessary to maintain homeostasis. In analogy to normal hematopoiesis, leukemogenesis is originated from leukemic stem cells (LSCs) which gives rise to more differentiated malignant cells. Leukemia cells occupy BM niches and reconstruct them to support leukemogenesis. The abnormal BM niches are the main sanctuary of LSCs where they can evade chemotherapy-induced death and acquire drug resistance. In this review, we focus on the protective effects of BM niche cells on acute lymphoblastic leukemia cells.

CXCL2 benefits acute myeloid leukemia cells in hypoxia

INTRODUCTION

Drug resistance and relapse of acute myeloid leukemia (AML) is still an important problem in the treatment of leukemia. Leukemia outbreak causes severe hypoxia in bone marrow (BM), remolding BM microenvironment (niche), and transforming hematopoietic stem cell (HSC) niche into leukemia stem cell (LSC) niche. AML cells and the microenvironment usually conduct "cross-talk" through cytokines to anchor resistant AML cells into LSC niche, thus supporting their survival. Therefore, this study was aimed to investigate the role of CXCL2 in the hypoxic AML niche.

METHODS

AML hypoxic niche was simulated by hypoxic culture of THP-1 and HL-60 cells in vitro, thus to study the effects of CXCL2 on the proliferation and migration of AML cells. The expression of hypoxia-inducible factor-1α (HIF-1α) and the activation of survival-related kinases such as PIM2 and mTOR under CoCl₂ -simulated hypoxic conditions were detected. The correlation between CXCL2 and the prognosis of AML with big data was verified.

RESULTS

(a) CXCL2 promoted the proliferation and migration of AML cells. (b) CXCL2 up-regulated the expression of PIM2 by enhancing the transcriptional activity of HIF-1α. (c) CXCL2 activated mTOR in AML cells. (d) CXCL2 was associated with poor prognosis in AML.

CONCLUSION

CXCL2 promotes survival, migration, and drug resistance pathway of AML cells in hypoxia and is associated with poor prognosis in AML. Therefore, CXCL2 can be considered as an important factor in promoting the development of AML cells in hypoxia.

Biopolymer Hydrogel Scaffold as an Artificial Cell Niche for Mesenchymal Stem Cells

The activity of stem cell processes is regulated by internal and external signals of the cell "niche". In general, the niche of stem cells can be represented as the microenvironment of the cells, providing a signal complex, determining the properties of the cells. At the same time, the "niche" concept implies feedback. Cells can modify their microenvironment, supporting homeostasis or remodeling the composition and structure of the extracellular matrix. To ensure the regenerative potential of tissue engineering products the "niche" concept should be taken into account. To investigate interactions in an experimental niche, an original hydrogel biopolymer scaffold with encapsulated mesenchymal adipose-derived stem cells (ASCs) was used in this study. The scaffold provides for cell adhesion, active cell growth, and proliferative activity. Cells cultured within a scaffold are distinguished by the presence of a developed cytoskeleton and they form a cellular network. ASCs cultured within a scaffold change their microenvironment by secreting VEGF-A and remodeling the scaffold structure. Scaffold biodegradation processes were evaluated after previous culturing of the ASCs in the scaffolds for periods of either 24 h or six days. The revealed differences confirmed that changes had occurred in the properties of scaffolds remodeled by cells during cultivation. The mechanisms of the identified changes and the possibility of considering the presented scaffold as an appropriate artificial niche for ASCs are discussed.

Analysis of Bone Tissue Condition in Patients with Diffuse Large B-Cell Lymphoma without Bone Marrow Involvement

We studied changes in the bone tissue in patients with diffuse large B-cell lymphoma at the onset of the disease (N=41; before chemotherapy) and 5-16 years after the end of treatment (N=47). Osteodensitometry, biochemical markers of osteoporosis in the blood and urine, and gene expression in multipotent mesenchymal stromal cells were analyzed. In multipotent mesenchymal stromal cells of all patients, the expression of genes associated with bone and cartilage differentiation (FGF2, FGFR1, FGFR2, BGLAP, SPP1, TGFB1, and SOX9) was changed. In primary patients, the ratio of deoxypyridinoline/creatinine in the urine and blood level of β-cross-laps were increased, while plasma concentration of vitamin D was reduced, which indicates activation of bone resorption. No differences between the groups were revealed by osteodensitometry. No direct relationship between changes in gene expression in multipotent mesenchymal stromal cells and osteoporosis markers was found. The presence of a tumor in the body affects the bone marrow stroma, but achievement of remission and compensatory mechanisms provide age-appropriate condition of the bone tissue.

Targeting BMP signaling in the bone marrow microenvironment of myeloid leukemia

The bone morphogenetic protein (BMP) pathway regulates the fate and proliferation of normal hematopoietic stem cells (HSC) as well as interactions with their niche. While BMP2 and BMP4 promote HSC differentiation, only BMP4 maintains HSC pool and favors interactions with their niche. In myeloid leukemia, we have identified intrinsic and extrinsic dysregulations of the BMP pathway in Chronic Myeloid Leukemia (CML) and Acute Myeloid leukemia (AML) responsible for leukemic stem cells (LSC) survival. In AML, BMP pathway alterations sustain and promote resistant immature-like leukemic cells by activating a new signaling cascade. Binding of BMP4 to BMPR1A leads to ΔNp73 expression, which in turn induces NANOG, altogether associated with a poor patient's prognosis. Despite efficient targeted therapies, like Tyrosine Kinase Inhibitors (TKI) in CML, many patients retain LSCs. Our laboratory demonstrated that the BMP pathway sustains a permanent pool of LSCs expressing high levels of BMPR1B receptor, that evolve upon treatment to progressively implement a BMP4 autocrine loop, leading to TKI-resistant cells. Single cell RNA-Seq analysis of TKI-persisting LSCs showed a co-enrichment of BMP with Jak2-signaling, quiescence and stem cell (SC) signatures. Using a new model of persisting LSCs, we recently demonstrated that BMPR1B+ cells display co-activated Smad1/5/8 and Stat3 pathways and could be targeted by blocking BMPR1B/Jak2 signal. Lastly, a specific BMPR1B inhibitor impaired BMP4-mediated LSC protection against TKIs. Altogether, data based on various studies including ours, indicate that BMP targeting could eliminate leukemic cells within a protective bone marrow microenvironment to efficiently impact residual resistance or persistence of LSCs in myeloid leukemia.