Reconstructing the human hematopoietic niche in immunodeficient mice: opportunities for studying primary multiple myeloma

Abstract

Interactions within the hematopoietic niche in the BM microenvironment are essential for maintenance of the stem cell pool. In addition, this niche is thought to serve as a sanctuary site for malignant progenitors during chemotherapy. Therapy resistance induced by interactions with the BM microenvironment is a major drawback in the treatment of hematologic malignancies and bone-metastasizing solid tumors. To date, studying these interactions was hampered by the lack of adequate in vivo models that simulate the human situation. In the present study, we describe a unique human-mouse hybrid model that allows engraftment and outgrowth of normal and malignant hematopoietic progenitors by implementing a technology for generating a human bone environment. Using luciferase gene marking of patient-derived multiple myeloma cells and bioluminescent imaging, we were able to follow pMM cells outgrowth and to visualize the effect of treatment. Therapeutic interventions in this model IntroductionIn the BM, specialized microenvironments such as hematopoietic niches regulate hematopoiesis. Within these niches, hematopoietic stem cells (HSCs) are present in a complex network consisting of mesenchymal stromal cells (MSCs), osteoblasts, osteoclasts, endothelial cells, and adipocytes embedded in an extracellular matrix. The bidirectional interactions with the hematopoietic niche are essential for HSC maintenance and function. [1][2][3][4] The BM niche is also thought to serve as a sanctuary site for leukemic stem cells (LSCs), which, in addition to their immortalizing genetic events, highly depend on interaction with the microenvironment to survive and proliferate. 5,6 Although the majority of leukemias initially respond to therapeutic intervention, relapse rates are high. [7][8][9] There is increasing evidence that the tumor niche plays a crucial role in the survival and drug resistance of LSCs. Interactions with the niche provide signals protecting the LSCs from apoptosis and eventually leading to the selection and outgrowth of a resistant cell. 10-13 Therefore, it is apparent that the hematopoietic niche plays an important role in hematopoietic development and in chemotherapy resistance of BM-localized leukemic and solid tumors.Although our understanding of how the BM niche regulates HSC self-renewal and confers therapy resistance has advanced greatly over the past years, most of this knowledge is based on genetic loss-of-function or gain-of-function murine models. 1,2,10,11,14 However, these murine models do not simulate human physiology and much of the constituents of the human hematopoietic niche remain largely unclear. [14][15][16] This emphasizes the need for more suitable models that recapitulate the human BM microenvironment and, very importantly, facilitate the engraftment and outgrowth of normal HSCs and patient-derived tumor cells within these protected sites.In the present study, we describe a unique humanized model that implements a novel scaffold-based technology for generating a human bone environment in RAG 2 Ϫ/Ϫ ...

Sepantronium bromide (YM155) improves daratumumab-mediated cellular lysis of multiple myeloma cells by abrogation of bone marrow stromal cell-induced resistance

“…Therefore, we tested the susceptibility of MM cells toward daratumumab-dependent ADCC not only in the absence versus presence of BMSCs but also in the absence versus presence of the small molecule YM155 that effectively suppresses survivin expression in tumor cells, but also modulates other anti-apoptotic molecules like MCL. 1,8,9 Prior to these assays, we confirmed that survivin is up-regulated in MM cells upon interaction with stromal cells (Figure 2A), and, importantly, we carefully determined the dose range of YM155 that induced a sub-maximal level of MM cell lysis ( Figure 2B), but was completely non-toxic for NK cells ( Figure 2C). At these dose ranges, YM155 was also non-toxic to BMSCs, as we have documented previously.…”

Pre-clinical evaluation of CD38 chimeric antigen receptor engineered T cells for the treatment of multiple myeloma

“…The MM microenvironment is known to provide essential signals for survival, growth and, more importantly, immune resistance of MM cells. 11,12,27,28 Since our model includes some of the microenvironment-related aspects, our results suggest that the efficacy of CART-cell treatment could be improved if the therapy were to be combined with immune checkpoint inhibitors and/or with survivin and/or MCL-1 inhibitors which are effective modifiers of cell adhesion-mediated immune resistance induced by the tumor microenvironment. 11 Unlike a number of earlier reports, which mainly focused on the anti-tumor efficacy of CD38-CART cells, [29][30][31] we devoted a considerable part of our investigation to identifying the potential drawbacks and risks of CD38-CART-cell therapy.…”

“…-/-mice, in which a humanized bone marrow-like niche for MM cells is generated by subcutaneous implantation of ceramic scaffolds coated with human bone marrow stromal cells 11,12 ( Figure 4). Thus, we implanted such scaffolds seeded with luciferase-transduced UM9 MM cells in the back of the mice (6 scaffolds per mouse).…”

“…After a week of in vitro culture, humanized scaffolds were seeded with CD38 + UM9 cells and implanted subcutaneously into the mice, as described previously, 11,12 and in the Online Supplementary Methods.…”

Humanized hemato-lymphoid system mice

“…Moreover, Groen et al demonstrated the engraftment of primary human multiple myeloma cells into a scaffold-based ectopic BM niche. 64 By using luciferase gene marking of multiple myeloma cells they were able to visualize myeloma growth and therapeutic response. From these interesting observations it can be inferred that stromal cells, through their interaction with diseased hematopoietic cells, contribute actively to disease development and that a functional human BM niche may be necessary to fully recapitulate human disease in vivo.…”