PCK1 and fibrosis: In particular, the expression levels of most important liver functioning protein, Alb, and Pck1, the marker of hepatic progenitor cells which are essential for liver regeneration in serious liver injury, were significantly increased in 3D-Exo treatment group (Figs. 3b, 4f, Additional file 1: Fig. S10), indicating the reconstitution of the liver and the recovery of liver function in treated fibrosis mice (Fig. 3b–e).