A 3D lymph node model for chronic lymphocytic leukaemia recapitulates microenvironmental features and drug response <i>in vitro</i>

Chronic lymphocytic leukaemia (CLL) cells circulate between the blood, bone marrow (BM) and lymphoid organs, where interactions with the lymph node (LN) microenvironment enhance their survival, proliferation and drug resistance. Most in vitro models fail to reproduce the spatial and cellular complexity of the LN niche, limiting studies of tissue-specific drug responses. To address this, we developed a 3D LN model using a gelatine scaffold and a clinorotator bioreactor previously validated for a BM system. The scaffold was seeded with human lymphatic fibroblasts and endothelial cells, which deposited extracellular matrix and supported patient-derived CLL cell viability and proliferation. Consistent with in vivo observations, CLL cells within the scaffold downregulated the chemokine receptor CXCR4, further reduced upon proliferative stimulation. Final validation involved treatment with targeted therapies: the BCL-2 antagonist venetoclax and the BTK inhibitor ibrutinib. Venetoclax treatment revealed greater CLL protection within the LN environment than in BM, whereas the mobilizing effect of ibrutinib was comparable between these two niches. This 3D LN model offers an effective ex vivo platform for studying microenvironment-tumour interactions and tissue-specific drug responses.