Abstract: A method of culturing animal cells, preferably primary hepatocytes, including a first step of culturing the animal cells in non-adherent culture vessel, preferably a low or ultra-low attachment culture vessel, a second step of embedding the animal cells in a collagen matrix or in a gelatin matrix, and a third step of culturing the animal cells embedded in the collagen matrix or in the gelatin matrix, thereby obtaining 3D animal cell structures including proliferative animal cells, preferably spheroids including proliferative primary hepatocytes. Also, a spheroid including proliferative primary hepatocytes and the uses thereof for engineering an artificial liver model or an artificial liver organ, and for assessing in vitro the liver toxicity, genotoxicity and/or the effects of a drug or a compound.