Vascularised and functional human liver from an iPSC-derived organ bud transplant

Critical shortage of donor organs for treating end-stage organ failure highlights the urgent need for generating organs from induced pluripotent stem cells (hiPSCs). Despite many reports describing functional cell differentiation, no studies have succeeded in generating a three-dimensional vascularised organ such as liver. Here, we show the generation of vascularised and functional human liver from hiPSCs by transplantation of liver buds created in vitro (hiPSC-LBs). Specified hepatic cells self-organised into three-dimensional hiPSC-LBs by recapitulating organogenetic interactions between endothelial and mesenchymal cells. Immunostaining and gene expression analyses revealed resemblance between in vitro grown hiPSC-LBs and in vivo liver buds. Human vasculatures in hiPSC-LB transplants became functional by connecting to the host vessels within 48 hours. The formation of functional vasculatures stimulated the maturation of hiPSC-LBs into tissue resembling the adult liver. Highly metabolic hiPSC-derived tissue performed liver-specific functions such as protein production and human-specific drug metabolism without recipient liver replacement.