(132g) Advancing Microphysiological Systems: Strategies for Perfusable Vascularized Tissues in Disease Modeling and Therapeutic Research

Microphysiological systems (MPS) have become indispensable tools for simulating the complex structures and functionalities of diverse tissues and organs, offering notable advantages over conventional 2D cell cultures and animal models in disease modeling, drug development, and therapeutic research. Critical to the success of MPS is the establishment of perfusable vasculature within engineered tissues, essential for replicating physiological conditions, including delivery of oxygen, nutrients, cells, and therapeutics. Despite the promise of MPS in generating vascularized tissues, existing strategies often struggle to achieve vascularization levels akin to those observed in vivo.

This research endeavors to overcome this challenge by developing innovative strategies and platforms for generating perfusable vascularized tissues, encompassing microvasculature (capillary), tumor, and liver organoids. To achieve physiologically relevant microvasculature formation in vitro, several pivotal methodologies have been devised, including the development of immortalized vascular cells (Wan et al., 2021), differentiation of endothelial cells (ECs) from induced pluripotent stem cells (iPSCs) via a doxycycline-inducible ETS Variant Transcription Factor 2 (ETV2) protocol (unpublished), a novel two-step seeding approach (Wan et al., 2022a), and the utilization of interstitial flow (IF) to enhance vasculogenesis (Zhang and Wan et al., 2022).

Furthermore, efforts have been directed towards enhancing tumor vascularization through innovative techniques such as a sequential method for forming tumor spheroids with increased fibroblast density (Wan et al., 2022b) and a novel microfluidic device design (unpublished) facilitating endothelial cell penetration into tumor masses. This model has been employed to evaluate chimeric antigen receptor T cell (CAR-T cell) responses and elucidate programmed death-ligand 1 (PD-L1) regulation by trans-endothelial flow within the tumor microenvironment (Advanced Science, in production).

Additionally, the establishment of perfusable vasculature in engineered liver tissues has been a focus (unpublished). By co-differentiating iPSCs using Gata6 and ETV2 transcription factors, highly vascularized liver organoids were generated and further refined through various strategies. These liver organoids were integrated into a perfusable vasculature within a microfluidic device, enabling comprehensive studies on liver regeneration, inflammation, infection, cancer, and injury.

In summary, these approaches present a reliable pathway for generating intricate, physiologically relevant vascular structures within engineered tissues, holding significant potential for applications in cancer studies, biomedical research, and preclinical testing.

References

Wan, Z., Zhang, S., Zhong, A.X., Shelton, S.E., Campisi, M., Sundararaman, S.K., Offeddu, G.S., Ko, E., Ibrahim, L., Coughlin, M.F., et al. (2021). A robust vasculogenic microfluidic model using human immortalized endothelial cells and Thy1 positive fibroblasts. Biomaterials 276, 121032.

Wan, Z., Zhong, A.X., Zhang, S., Pavlou, G., Coughlin, M.F., Shelton, S.E., Nguyen, H.T., Lorch, J.H., Barbie, D.A., and Kamm, R.D. (2022a). A Robust Method for Perfusable Microvascular Network Formation In Vitro. Small Methods 6, e2200143.

Zhang, S., Wan, Z. (co-1^st author), Pavlou, G., Zhong, A.X., Xu, L., and Kamm, R.D. (2022). Interstitial Flow Promotes the Formation of Functional Microvascular Networks In Vitro through Upregulation of Matrix Metalloproteinase‐2. Advanced Functional Materials, 2206767.

Wan, Z., Floryan, M.A., Coughlin, M.F., Zhang, S., Zhong, A.X., Shelton, S.E., Wang, X., Xu, C., Barbie, D.A., and Kamm, R.D. (2022b). New Strategy for Promoting Vascularization in Tumor Spheroids in a Microfluidic Assay. Adv Healthc Mater, e2201784.