Fig. 2: LPCs are a transitional cellular state between BECs and hepatocytes during transdifferentiation.

a, UMAP embedding of RNA velocity of EPCAM⁺ cells collected from Fah-LSL/LSL mice at day 25 after initial NTBC removal indicates the transition from BECs to LPCs. b, Schematic showing experimental strategy. c, Immunostaining for tdT, HNF4α, CK19, EPCAM, A6 or OPN on liver sections collected at days 25 and 33 after NTBC removal from CK19-CreER;Fah-LSL/LSL;R26-tdT mice. Yellow arrows indicate tdT⁺ LPCs and white arrows indicate tdT⁺ hepatocytes. Scale bars, 100 µm. d, Immunostaining for tdT, HNF4α, CK19 and FAH on liver sections collected at days 25 and 33 after NTBC removal. Scale bars, 50 µm. Yellow arrows indicate LPCs and white arrows indicate tdT⁺ hepatocytes. e, Immunostaining of tdT, HNF4α, CK19 and Ki67 on liver sections collected at days 25 and 33 after NTBC removal. Yellow arrows indicate LPCs and white arrows indicate tdT⁺ hepatocytes. Percentage of Ki67⁺ TLPCs and Ki67⁺tdT⁺ hepatocytes in tdT⁺ hepatocytes is shown on the right panel. Data represent mean ± s.d.; n = 5 mice. Scale bars, 100 µm. f, Immunostaining for tdT, HNF4α and CK19 on liver sections collected at different time points. Scale bars, 10 µm. g, Cell area quantification in TLPCs (CK19⁺HNF4α⁺ and CK19^lowHNF4α⁺) and hepatocytes (tdT⁺). Data represent mean ± s.d.; CK19⁺HNF4α⁺: n = 6 mice, CK19^lowHNF4α⁺ and Heps: n = 5 mice; CK19^lowHNF4α⁺ versus CK19⁺HNF4α⁺: *P = 0.02; Heps versus CK19^lowHNF4α⁺: *P < 0.0001. Statistical analysis was performed by ANOVA followed by Tukey’s method for multiple comparisons, and adjustments were made for multiple comparisons. h, Quantification of the number of TLPCs (CK19⁺HNF4α⁺ and CK19^lowHNF4α⁺) and hepatocytes (tdT⁺) per portal region ×60 field at different time points. Data represent mean ± s.d.; n = 5 mice. i, Schematic showing that TLPCs originate from BECs and differentiate into hepatocytes. Hep, hepatocyte; w/o, without.