Fig 2: Cell surface expression of melanoma antigens transiently expressed in COP5 cells.(A) FACS analysis was performed with immunostained living cells transfected with plasmids encoding for cancer melanoma antigens MART1, TRP1, MCAM, MAGEA4 and MAGEA10, and MLV Gag. The red line corresponds to cells expressing recombinant melanoma antigens, the blue line to cells without cancer antigen, and grey area shows the signal obtained with secondary Alexa488-labelled antibody. The percentage of gated cells is shown (blue for cells without cancer antigen and red for cells expressing recombinant melanoma antigens) on the image. The image of MLV Gag contains the data of five transfections obtained with electroporation with five different melanoma antigens. In all cases, one representative experiment out of the two performed is shown. MFI = Mean fluorescence intensity. (B) Western blot analysis of COP5 cells expressing melanoma antigens. Lane 1, mock control; lane 2, transfected cells.

Fig 3: Development of endothelial and mesenchymal like cells and maturation of hepatic endoderm.(a) CD34 and CD93 were detected in endothelial progenitor-like cells on day 7. CEBPa+marks the hepatic endoderm in the background (scale bars, 200 µm). (b) Development of endothelial-like cells (arrows indicate CD31). CD34 is present in the hepatocyte-like cell fraction (CEBPa+, CD146-) and in the endothelial-like cells (CEBPa-, CD146+). (c) CD51+, NES+, PDGFRa+ mesenchymal stem cell-like cells develop in conjunction with hepatoblasts. (d) AAT and CEBPa on day 8 and (e) 10 show maturation of hepatic endoderm. (f) Upregulation of AAT and fibrinogen (Fib) synthesis (ELISA). Data are mean±s.e.m., n=3 per group. Scale bars: 200 µm.

Fig 4: Development of fetal liver parenchymal and non-parenchymal cells.(a) CEBPa+ hepatocyte-like cells and CD31+ CD34+ vascular networks on day 14. (b) DES+ stellate-like cells (c) CK19+ AAT+ hepatocyte-like cells with CD146+ vascular-like structures. Scale bar, 200 µm. (d) Heatmap shows upregulation of hepatic genes between days 5 and 10. (UBC and EEF1A1 as used as control/housekeeping genes). (e) CK7+ bile duct-like channels develop within fetal hepatocyte-like cells; xz and yz slices on the left and bottom. Scale bar, 200 µm. (f) Further maturation of liver-like phenotype as evidenced by increasing albumin production (ELISA) and (g) albumin+ cells. Data are mean±s.e.m., n=3 per group. phAlb_mKate2 is a lentivirally integrated reporter where a short human albumin promoter drives expression of a red fluorescent protein (mKate2). Scale bar, 200 µm. (h) Confocal imaging and three-dimensional reconstruction of AAT+ hepatocyte-like cells (red) with an apical layer of CD34+ endothelial-like cells (green). Scale bar, 50 µm.

Fig 5: Single‐cell analysis reveals an MSC‐like expression pattern of Lepr. A) UMAP visualization of periodontium cells. Different cell populations were distinguished by color. B) UMAP plot representation of identified clusters in periodontium stromal cells. Cluster 0 represents fibroblasts expressing Periostin and Col1a1. Cluster 1 represents osteo‐lineage cells expressing Dmp1 and Sp7. Cluster 2 represents the progenitor population that expresses classic stromal stem cell markers such as Cxcl12, Cd90, and Cd146. C) Distribution of Lepr in periodontium stromal cells. D) The expression of PDLSC marker genes projected onto UMAP atlas. E) LEPR immunofluorescent staining of adult mouse PDL cryostat section. Scale bar: left: 100 µm; right: 25 µm.