Abstract 6894: Modeling the spectrum of vascular changes occurring in healthy and early malignant cancers on a chip
Authors: Franca Cristiane , Athirasala Avathamsa , Dimitriadis Emilios , Bays Jennifer , Yamada Kenneth , Chen Christopher , Bertassoni Luiz E. 
Published: March 2024

Abstract
The transition of a healthy tissue to a pre-malignant and subsequent malignant stage is typically characterized by a marked increase in extracellular fibrosis and collagen density. Such changes coincide with a significant increase in tissue stiffness as the tumor progresses. Despite the large body of work on endothelial cell changes in tumoral angiogenesis, little is known about the dynamic interactions of endothelial cells, perivascular cells, and the extracellular matrix in early-to-late cancers. Appreciating such interactions is crucial for understanding tumorigenesis and early tumor progression. To model the spectrum of vascular changes occurring on pre-tumoral and tumoral ecosystems, we developed an organ-on-a-chip model of biomimetic pericyte-supported capillaries with collagen having increasingly higher density, stiffness and discrete fibril microarchitectures. Briefly, 160-um channels were engineered using type I collagen that underwent fibrillogenesis at different temperatures (4, 16, 21, and 37oC). Thus, the microarchitecture and stiffness would vary from a soft reticular network (healthy/pre-cancerous vascular capillaries) to a stiff fibrillar mesh (fibrotic/tumoral vascular capillaries). We then seeded human umbilical vein endothelial cells (HUVECs) and mesenchymal stem cells (MSCs) in the collagen channels. After 48h, samples were fixed and stained for actin (cytoskeleton), NG2 (pericyte differentiation), and CD31 (endothelial cell junction), laminin, and cell anchorage system, imaged with a confocal microscope and analyzed with Imaris. In addition, we used a Nanostring panel with 770 genes related to the tumor microenvironment in healthy and fibrosis. Vascular capillaries engineered in contact with softer reticular collagen, consistent with a healthy ECM, showed more pericyte differentiation (p&lt;0.05), inter-endothelial cell junctions (p&lt;0.05), and effective barrier function. In contrast, stiffer fibrillar collagen, which is consistent with the characteristics of the fibrotic malignant extracellular microenvironment, was associated with cell migration outward the vessel, leakiness, and higher RNA expression of interleukin 8 (IL8), TP53, transforming growth factor beta, vimentin, and collagen III genes, thus suggesting a system that compatible with the spectrum of tumoral vasculature changes in cancer and pre-cancer lesions. When vessels were engineered without MSCs, those differences were drastically minimized, To further understand the mechanisms, HUVEC-perivascular cell adhesion was disrupted using silencing RNA for NOTCH3. Upon silencing NOTCH3, the morphology and function of vasculature were reestablished, pointing to a major role of perivascular cells in vascular changes in early tumors.
Funding: NIDCR 1K01DE030484-01A1 to CMF R01DE026170, 3R01DE026170-03S1 and 3R01DE026170-03S2 to LEB
Citation Format: Cristiane Franca, Avathamsa Athirasala, Emilios Dimitriadis, Jennifer Bays, Kenneth Yamada, Christopher Chen, Luiz E. Bertassoni. Modeling the spectrum of vascular changes occurring in healthy and early malignant cancers on a chip [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6894.