Fig. 1. EC-produced HGF promotes reconstitution of transplanted parenchymal cells in the injured lung and liver in mice.

(A) Schema illustrating the strategy to test incorporation of transplanted alveolar epithelial progenitor in normal and injured lungs. TdTomato-expressing AEC2s (red) were instilled into recipient lungs via trachea. To induce lung repair, mice were subjected to multiple intratracheal injections of Acid or Bleo.

(B) Immunostaining of SFTPC performed to visualize endogenous (TdTomato⁻SFTPC⁺, indicated by arrow head in inset) and grafted (TdTomato⁺SFTPC⁺, labeled with arrow in inset) AEC2s in mice after three Bleo or Acid injections. Result of AEC2 transplantation in normal mouse lungs is shown in fig. S1A.

(C) Approach to examine the incorporation of hepatocytes in normal and injured mouse livers. Hepatocytes were transplanted to recipient mice via intrasplenic injection of TdTomato⁺ hepatocytes, and sections were co-stained with hepatocyte marker hepatic nuclear factor 4α (HNF4).

(D) Immunostaining showing incorporation of transplanted HNF4⁺TdTomato⁺ hepatocytes in the liver after three injections of CCl₄. Incorporation of hepatocytes transplanted after 8th CCl₄ and data showing hepatocytes transplanted into normal mice are presented in fig. S1B, C.

(E) Schema illustrating the approach to test organ regeneration, fibrosis, and incorporation of parenchymal cells in mice with EC-specific deletion of Hgf (Hgf^iΔEC/iΔEC). Hgf^iΔEC/iΔEC and control Hgf^iΔEC/+ mice were subjected to lung and liver injury and transplanted with TdTomato⁺ AEC2s or hepatocytes. Regeneration, fibrosis, and incorporation of injected parenchymal cells (engraftment) were compared between Hgf^iΔEC/iΔEC and control mice.

(F) Survival rate of Hgf^iΔEC/iΔEC and Hgf^iΔEC/+ mice after Bleo injection every 12 days.

(G) Sirius red staining of lung tissue from mice in (F).

(H) Survival rate of Hgf^iΔEC/iΔEC and Hgf^iΔEC/+ mice after CCl₄ injection every 3 days.

(I) Sirius red staining of liver tissue from mice in (H).

(J) Sirius red staining depicting collagen deposition, and immunostaining illustrating transplanted AEC2s (red) in the injured mouse lungs.

(K) Sirius red staining and immunostaining showing transplanted hepatocytes (red) in the injured mouse livers. Five mice per group were analyzed for qualitative staining experiments. Scale bars, 50 μm.