Publications

Leukaemias, driven by mutations in haematopoietic stem cells (HSCs), rely on interactions with the bone marrow (BM) niche and other cell populations such as mesenchymal stromal cells (MSCs) for growth and survival. While chimeric antigen receptor (CAR) T-cell therapy shows promise for other haematological malignancies, its application to acute myeloid leukaemia (AML) is hindered by tumour heterogeneity and off-target toxicity. Combining CRISPR-Cas9 gene editing with CAR T-cell therapy has potential for selectively targeting AML cells while sparing healthy tissue. However, validating the efficacy of these treatments prior to clinical trial is hampered by the differences between humans and animal models typically used for pre-clinical testing. Furthermore, traditional in vitro models fail to replicate the complexity of the BM niche and often overestimate treatments' efficacy. Here, we present a bioengineered human-cell containing endosteal BM niche model combining a fibronectin-presenting polymeric surface and a synthetic peptide hydrogel (PeptiGel) that mimics native BM tissue's mechanical properties. This platform supports niche phenotypes in MSCs and HSCs and enables the evaluation of combined CRISPR-CAR T-cell therapy, demonstrating potential as a preclinical human model for testing novel therapies.

JTD Keywords: Cd33, Extracellular-matrix, Hematopoietic stem-cells, Immunotherapy, Insights, Maintenance, Vivo

The bone marrow is a complex tissue with distinct cellular and mechanical heterogeneity, serving as the primary site for haematopoiesis. Under certain conditions, such as on the onset of mutations to healthy cells or alterations to the environment, the bone marrow can also become the origin of haematological malignancies, often characterized by uncontrolled self-renewal of hematopoietic stem cells, overproduction of immature progeny and remodelling of the tissue microenvironment. This remodelling alters the composition and mechanics of the extracellular matrix (ECM), facilitating the proliferation and metastasis of leukaemic cells. The elastic and dissipative properties of the ECM are hallmarks of both health and disease progression in different tissues. However, studying the mechanical properties of bone marrow is difficult owing to inaccessibility in situ. Advanced three-dimensional bioengineered models offer a way to recapitulate the mechanical properties of the bone marrow, but it remains challenging to incorporate the elastic and viscous components. Understanding the physiological and disease-specific mechanical ECM signatures is crucial for advancing bone marrow research and for developing therapeutics. In this Review, we explore the structure-function relationship of the bone marrow, emphasizing its complex mechanical behaviour, and discuss the bioengineered models that recapitulate the mechanical properties in the healthy and diseased bone marrow niche, stressing the importance of replicating ECM physiological and pathological mechanical signatures in the future.

JTD Keywords: Acute myeloid-leukemia, Extracellular-matrix stiffness, Fibrosis, Hematopoietic stem-cell, Lysyl-oxidase, Mesenchymal stromal cells, Microenvironment, N-cadherin, Progenitor cells, Suppor