Generation of bioengineered liver grafts densely recellularized using human liver organoids.

Bioengineered livers using decellularized extracellular matrix (ECM) scaffolds hold promise for transplantation therapies. However, conventional recellularization methods involving cell injection via blood vessels encounter challenges in recapitulating the complexity of hepatic tissues, including high cellularity, differentiation hierarchy, and cellular heterogeneity. Here, we developed a methodology termed "combined single-cell and organoid (CSO) injection." We injected human liver organoids (HLOs) and dispersed organoid cells via direct puncture and vascular injection into a decellularized porcine ECM scaffold, respectively. This process facilitated the construction of densely populated and self-organized liver-like tissues (CSO Livers) that formed cell-cell/cell-ECM interactions. The tissues displayed hepatic characteristics, including ALBUMIN secretion, robust expression of liver-associated genes, and cellular heterogeneity comprising hepatocytes, cholangiocytes, as well as stellate-like and endothelial cells. Furthermore, we demonstrated that CSO-Livers functioned as grafts in immunodeficient mice and in a microminipig model of liver fibrosis through transplantation via vascular anastomosis. These findings indicate the applicability of the combined single-cell and organoid (CSO) injection method for generating bioengineered liver grafts using HLOs.