FIG. 2. Methods to determine cell fusion or transdifferentiation from BM cells.

(A) Bone marrow (BM) cells are isolated from mice with constitutive Cre recombinase (Cre) and green fluorescent protein (GFP) protein expression and transplanted into lethally irradiated mice in which a stop cassette is floxed before the β-galactosidase (LacZ) reporter gene. Fused cells express LacZ via Cre-mediated recombination of floxed stop cassette and also express GFP, whereas transdifferentiated cells express only GFP. Donor cells express only GFP, whereas recipient cells express neither GFP nor LacZ. (B) BM cells are isolated from mice with constitutive GFP expression and transplanted into lethally irradiated mice with constitutive LacZ expression. Fused cells express both GFP and LacZ, and true transdifferentiation cells express only GFP. Donor cells express only GFP, and recipient cells express only LacZ. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article at www.liebertonline.com/ars).