VesselBox enables controlled perfusion of a vascularized 3D microenvironment to model leukemia cell trafficking <i>ex vivo</i>

Chronic lymphocytic leukemia (CLL) is a common form of adult leukemia characterized by the accumulation of CD5+ B cells in the blood and lymphoid tissues. Interactions between malignant cells and endothelial cells of the vasculature influence CLL progression, though the underlying mechanisms are poorly understood. To investigate how the vasculature contributes to CLL cell dissemination, we developed a modular bioreactor called “VesselBox” by three-dimensional (3D) printing. This system enables selective perfusion of a milliscale vessel-like structure embedded within a lymphoid microenvironment designed to recapitulate selected structural features of CLL tissue niches created using 3D bioprinting and casting. We first performed numerical simulations to optimize perfusion parameters to support cell homeostasis. Upon vessel maturation, confirmed by endothelial marker expression, we demonstrated that VesselBox supports sustained perfusion for up to 7 days. By recirculating CLL cells through the system, we demonstrate its feasibility as a platform to assess CLL cell localization and immunophenotypic changes under dynamic conditions. This platform provides a framework for ex vivo analysis of CLL trafficking and offers the potential to uncover therapeutic targets by characterizing circulating and extravasated cells in the presence or absence of drug treatments.