Szegezdi, E. | bioRxiv Science

bioRxiv2022

Natural killer cell-mimic nanoparticles can actively target and kill acute myeloid leukemia cells

Natural killer (NK) cells are effector lymphocytes of the innate immune system which play a crucial role in recognizing and killing emerging tumor cells. However, as the tumor evolves, it develops mechanisms to inactivate NK cells or hide from them. Here, we engineered a modular nanoplatform that acts as NK cells (NK cell-mimics), carrying the tumor-recognition and death ligand-mediated tumor-killing properties of an NK cell, yet without being subject to tumor-mediated inactivation. In particular, NK cell mimic nanoparticles (NK.NPs) incorporate two key features of activated NK cells: cytotoxic activity via the death ligand, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), and an adjustable tumor cell recognition feature based on functionalization with the NK cell Fc-binding receptor (CD16, FCGR3A) peptide, enabling the NK.NPs to bind antibodies targeting tumor antigens. NK.NPs showed potent in vitro cytotoxicity against a broad panel of cancer cell lines. Upon functionalizing the NK.NPs with daratumumab, a clinically used antibody specific for the CD38 protein expressed by AML cells, NK.NPs effectively targeted and eliminated patient-derived acute myeloid leukemia (AML) blasts and leukemia-initiating cells as well as CD38-positive AML cells in vivo, in a disseminated AML xenograft system. Specifically, NK.NPs lead to a significant reduction of AML burden in the bone marrow, spleen, and peripheral blood compared to non-targeted TRAIL-functionalized liposomes. Taken together, these findings demonstrate that NK.NPs are effective in mimicking NK cells antitumorigenic function and thereby underline their use as therapeutic tools.

cancer biology↗

bioRxiv2022

Single-cell characterisation of the hematopoietic bone marrow interactome in health and disease

1The bone marrow (BM) is a complex microenvironment and the primary site of hematopoiesis, coordinating the production of billions of blood cells every day. Despite the essential role of the hematopoietic niche in maintaining hemostasis and its relevance to hematopoietic diseases, many aspects of this environment remain poorly characterised due to experimental hurdles. Here we present a high-resolution characterisation of the niche in health and acute myeloid leukemia (AML) by establishing a comprehensive single-cell gene expression database of nearly 340,000 BM constituent cells encompassing all disease stages (healthy BM, AML at diagnosis, remission and relapse). We characterised the cell type composition of the BM and found that the proportions of both myeloid and lymphoid lineage cell types are significantly altered in AML. We also determined broadscale dysregulation of gene expression in almost all BM cell types upon establishment of AML, indicating that the entire niche is disrupted by the disease. Given the importance of interactions between hematopoietic cells and their microenvironment in regulating their function and properties, we determined all possible ligand-receptor interactions between hematopoietic stem and progenitor cells (HSPC) and every other BM constituent cell type. This analysis revealed a remarkable expansion of HSPC interactions in AML involving multiple BM constituent cells that can drive dysregulated HSPC-cell adhesion, immunosuppression and enhanced cytokine signalling. In particular, we found that interactions involving TGFB1 become widespread in AML and present evidence that these interactions can drive AML cell quiescence in vitro, thus highlighting TGFB1 signalling as a potential target for increasing drug sensitivity and preventing relapse. Our results shed light on potential mechanisms of enhanced competitiveness of AML HSPCs and an overall skewed microenvironment that fosters AML growth.

cancer biology↗