Microfluidic models with enhanced tumor vascularization

Introduction:: Tumor vasculature plays a central role in tumor progression, as it provides transportation of nutrients and cells within the tumor microenvironment. Microfluidic platforms offer unique advantages for studying this process, as they can be used with human primary cells and patient-derived samples, instead of animal-based models, providing more clinically relevant results. Several microfluidic tumor models have been established, but the vascularization level inside the tumor is generally lower than the levels found in vivo.


Materials and Methods:: Here, we present two strategies for improving the extent of tumor vascularization in microfluidic platforms. The first strategy is to form tumor spheroids by sequentially adding fibroblasts to a pre-formed tumor spheroid (Sequential method). We demonstrated this method using tumor cell lines from kidney, lung, and ovary cancer. The second strategy is a new microfluidic device design that facilitates endothelial cell penetration into a tumor mass by appliying interstitial flow. We tested both tumor cell lines and patient-derived samples in our platform.

The vascular networks were formed with endothelial cells and stromal cells from healthy control or cancer patient in the microfluidic platforms. Confocal microscopy was used to detect the morphology of the tumor vasculature, vascularization of tumor spheroids/mass, and perfusability of the tumor-associated vessels. Chimeric antigen receptor (CAR) T cells targeting mesothelin were perfused into the vascularized tumor model, and a continuous flow was generated by microheart pump. CAR-T cell recruitment and killing were imaged by confocal microscopy. The cytokines secreted by the T cells were measured using traditional ELISA and Luminex multiplex ELISA assays.


Results, Conclusions, and Discussions:: Tumor spheroids formed by the sequential method have a higher FB density on the periphery, which enhances vascularization. The vessels close to the tumor spheroids made with this new strategy are more perfusable than the ones made with other methods. Using the second strategy, vessels were able to penetrate into the tumor mass and were perfusable, allowing dextran and bead perfusion. T cells that perfused into the tumor vasculature were able to interact, patrol in the tumor vessels, extravasate, and migrate to the tumor region. Compared to control T cells, CAR-T cells had a higher killing efficiency and secreted a higher concentration of inflammatory cytokines, such as IFNγ, IL-6, GM-CSF. Together, these microfluidic-based new strategies for establishing tumor models lead to increased vascularization in vitro, allowing for the examination of immune, endothelial, stromal, and tumor cell responses under static or flow conditions and could be useful for evaluate immunotherapies.


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References (Optional): : Zhengpeng Wan^#, Marie A Floryan^#, Mark F Coughlin, Shun Zhang, Amy X Zhong, Sarah E Shelton, Xun Wang, Chenguang Xu*, David A Barbie*, Roger D Kamm*. “New Strategy for Promoting Vascularization in Tumor Spheroids in a Microfluidic Assay.” Advanced Healthcare Materials, 2022, 2201784.