CAR cells in BMP-eBM are derived from in situ adipose tissue mesenchymal cells. (A-B) Parabiosis experiment. (A) Schematic overview. Cxcl12-GFP and C57BL6J mice were surgically unified. After 3 weeks, BMP-2/β-TCP was implanted subcutaneously into C57BL6J parabiont. Four weeks after implantation, BMP-eBM was harvested. (B) FCM analysis of CAR cells in BMP-eBM showing the absence of CAR cells (n = 4). (C-I) Cell transplantation experiment. (C) Schematic overview. Cells were isolated from LB-BM or inguinal white adipose tissue (iWAT) of Cxcl12-GFP mice and transplanted together with BMP-2/β-TCP into C57BL6J mice. Two weeks after transplantation, BMP-eBM was harvested. (D) Gating strategy for isolation of LB-BM–derived CD51⁺Cxcl12-GFP^– and CAR cells, iWAT-derived CD51⁺Cxcl12-GFP^– and CD51⁺Cxcl12-GFP^low cells. (E) FCM analysis of CAR cells in BMP-eBM after transplantation of cells isolated in panel D (n = 3). (F) Gating strategy for isolation of iWAT-derived CD51^lowCxcl12-GFP^– and CD51^highCxcl12-GFP^– cells. (G-H) FCM analysis of CAR cells in the BMP-eBM after transplantation of cells isolated as described in panel F (n = 3-4). (I) Fluorescence images of BMP-eBM transplanted with iWAT-derived CD51^highCxcl12-GFP^– cells. Left panel: green, Cxcl12-GFP; red, Emcn. Right panel: green, Cxcl12-GFP; red, LepR; blue, DAPI.