An Approach for Formation of Vascularized Liver Tissue by Endothelial Cell–Covered Hepatocyte Spheroid Integration

Abstract

Tissue vascularization in vitro is necessary for cell transplantation and is a major challenge in tissue engineering. To construct large and regularly vascularized tissue, we focused on the integration of endothelial cell-covered spheroids. Primary rat hepatocytes were cultured on a rotary shaker, and 100-150 mum spheroids were obtained by filtration. The hepatocyte spheroids were coated with collagen by conjugation with a type 1 collagen solution. Collagen-coated hepatocyte spheroids were cocultured with human umbilical vein endothelial cells (HUVECs), and monolayered HUVEC-covered hepatocyte spheroids were constructed. Without a collagen coat, many HUVECs invaded hepatocyte spheroids but did not cover the spheroid surface. To construct regularly vascularized tissue, we packed HUVEC-covered hepatocyte spheroids in hollow fibers used for plasma separation. Packed spheroids attached to each other forming a large cellular tissue with regular distribution of HUVECs. At day 9 after packing, HUVECs invaded the hepatocyte spheroids and a dense vascular network was constructed. Collagen coating of spheroids is useful for the formation of endothelial cell-covered spheroids and subsequent regular vascularized tissue construction.

Physiologically Low Oxygen Enhances Biomolecule Production and Stemness of Mesenchymal Stem Cell Spheroids

“…32,33 Increased fibronectin, laminin, and collagen I were associated with a larger number of attached and integrated spheroids as well. [34][35][36] The presence of fibronectin, laminin, collagen, and GAGs was also desirable to mimic the cell conditions in vivo and therefore served as a better model environment for highthroughput assay. 37 All of these ECM components were found in detectable levels in the hMSC spheroids, with levels increasing under low oxygen at later time points.…”

Inventions and Innovations in Preclinical Platforms for Cancer Research

“…Collagen gel was also used for covering hepatocyte spheroids with endothelial cells by coating the hepatocyte spheroids initially with the collagen gel [62]. As cell-cell adhesions and attachments between non-identical cells develop slower and weaker [59], collagen gel acts as an anchorage for endothelial cells to stick to the hepatocyte spheroid preference.…”

State-of-the-art of 3D cultures (organs-on-a-chip) in safety testing and pathophysiology

“…It is known that the non-parenchymal cells (NPCs) also play a role in hepatotoxicity. Various 3D cocultures of hepatocytes with NPCs have been reported, e.g., models for vascularized liver (Inamori et al, 2009) with co-cultured spheroids or in-chip based systems (Messner et al, 2013;Powers et al, 2002). However, this area needs further development for toxicological purposes, e.g., in case of immunity mediated toxicity and other pathophysiology such as fibrosis.…”