Engineering a bioprinted vascularized 3D in vitro model to study tumor progression and liver metastasis (MetaLivMod)

• Applicants: Professor Dr.-Ing. Horst Fischer; Professor Dr. Fabian Kiessling
• Subject Area: Biomaterials
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 544947545

Animals are essential in medical research, but ethical concerns push the development of strategies to adhere to the '3R principle'. While in vitro models can partially replace animal experiments in preclinical cancer research, current 2D in vitro models and organ-on-a-chip devices are limited in their predictive capacity. They overlook critical features of solid diseases, such as their three-dimensionality, heterogeneity, tissue complexity and the delivery of nutrients and oxygen through functional vasculature. Advanced 3D in vitro models, creating a realistic microenvironment with space for cell migration, ensuring long-term stability and functional vessels, hold promise in modeling clinically-relevant dynamic biological events, including metastasis, angiogenesis, and immune response. Our research project builds on previous studies in which we established a 3D tumor model in a bioprinted environment with self-developing vascular structures to mimic the onset of metastasis in vitro. Our approach supported the growth of vascularized tumors to mesoscopic-size scales in perfusable bioreactors. During three weeks of dynamic cultivation, the capillary network formed functional connections with the bioprinted endothelium, allowing spontaneously migrating cancer cells to enter the circulating fluid. Moreover, patient-derived triple-negative breast cancer (TNBC) cells could be grown into artificial tumors with phenotypic heterogeneity and a tendency to metastasize that reflects their related human counterparts. Our research project aims to replicate TNBC hematogenous metastasis to the liver in vitro. This requires modeling the complex heterotypic cell interaction and the hemodynamics of the host environment. The connection of the components is realized by a functional vascular replicate, produced in a customized bioreactor using various 3D bioprinting processes. The primary tumor model consists of TNBC tumor spheroids embedded in a hydrogel blend containing stromal and endothelial cells. To mimic realistic metastatic formation, we will use human dermal microvascular endothelial cells in the hydrogel mix. During dynamic cultivation, motile cancer cells will infiltrate the extracellular matrix, intravasate the vessel, and extravasate in the hepatic tissue model. The crosstalk between the two tissue models will occur as a result of released chemical signaling molecules, hemodynamics, and interactions between cancer and hepatic cells. The complexity of the liver model will be tuned stepwise to systematically investigate how the various factors contribute to the metastatic cascade. Flow rate, vessel size, and pressure difference will be varied and immune cells will be added to the circulation to investigate their influence on metastasis formation. We expect the results of this research project to improve the understanding of the mechanisms of hematogenous metastasis and provide a partial alternative to animal experiments in the testing of new cancer drugs.

• DFG Programme: Research Grants