A Tissue-Engineered 3D Microvessel Model Reveals the Dynamics of Mosaic Vessel Formation in Breast Cancer

Abstract

In solid tumors, vascular structure and function varies from the core to the periphery. This structural heterogeneity has been proposed to influence the mechanisms by which tumor cells enter the circulation. Blood vessels exhibit regional defects in endothelial coverage, which can result in cancer cells directly exposed to flow and potentially promoting intravasation. Consistent with prior reports, we observed in human breast tumors and in a mouse model of breast cancer that approximately 6% of vessels consisted of both endothelial cells and tumor cells, so-called mosaic vessels. Due, in part, to the challenges associated with observing tumor-vessel interactions deep within tumors in real-time, the mechanisms by which mosaic vessels form remain incompletely understood. We developed a tissue-engineered model containing a physiologically realistic microvessel in coculture with mammary tumor organoids. This approach allows real-time and quantitative assessment of tumor-vessel interactions under conditions that recapitulate many in vivo features. Imaging revealed that tumor organoids integrate into the endothelial cell lining, resulting in mosaic vessels with gaps in the basement membrane. While mosaic vessel formation was the most frequently observed interaction, tumor organoids also actively constricted and displaced vessels. Furthermore, intravasation of cancer cell clusters was observed following the formation of a mosaic vessel. Taken together, our data reveal that cancer cells can rapidly reshape, destroy, or integrate into existing blood vessels, thereby affecting oxygenation, perfusion, and systemic dissemination. Our novel assay also enables future studies to identify targetable mechanisms of vascular recruitment and intravasation.Significance: A tissue-engineered microdevice that recapitulates the tumor-vascular microenvironment enables real-time imaging of the cellular mechanisms of mosaic vessel formation and vascular defect generation.

Microfluidic and Organ-on-a-Chip Approaches to Investigate Cellular and Microenvironmental Contributions to Cardiovascular Function and Pathology

“…The model is designed to be compatible with live cell imaging and allow for real time visualization of tumor-vessel interaction within a physiological relevant ECM microenvironment. Using this platform, they identified multiple cellular mechanisms where tumor cells could interact, displace, and disrupt vascular function (Silvestri et al, 2020 ). Importantly, these results highlight the utility of the advanced imaging methods that come with using microfluidic platforms for studying cellular processes that are difficult to capture in animal disease models.…”

The Normal and Brain Tumor Vasculature: Morphological and Functional Characteristics and Therapeutic Targeting

“…A number of these works were done in tumor types other than glioblastoma. For example, Silvestri et al (2020) developed a tissue-engineered model of a 3D co-culture of microvessels and mammary tumor organoids. They first fabricated a collagen gel scaffold with cylindrical channels filled with endothelial cells as a microvessel device.…”

Organoids in cancer research: a review for pathologist‐scientists

“…In addition to modeling the impact of immune and stromal cells on tumor cell invasion into ECM, organoids can also be used to model invasion into other structures in the microenvironment. Silvestri et al [36] recently described an organoid model of vascular invasion. By co‐culturing breast cancer organoids with engineered endothelium‐lined microvessels, this model allowed direct quantitative assessment of tumor–vessel interactions, demonstrating vascular invasion and mosaic vessel formation, which closely recapitulates vascular invasion in multiple human tumor types [36–38].…”