Fig. 7. EphA2-deficiency impairs vascular assembly in vivo. (A) Lung microvascular endothelial cells (MPMEC) isolated from heterozygous (+/–) or EphA2-deficient (–/–) mice were transduced with adenoviruses encoding nuclear ß-galactosidase, suspended in growth-factor-reduced Matrigel, and transplanted into nude mice to examine vascular assembly in vivo. (A) After 4 and 10 days, Matrigel plugs were collected and cryosections were X-gal stained to detect exogenous endothelial cells. Scale bar, 10 µm. Arrowheads indicate LacZ-positive exogenous MPMEC. (B) Assembled vascular structures were detected in EphA2^+/– plugs, but not in EphA2^-/– plugs, after 7 days. Scale bar in upper panels, 10 µm; lower panels, 5 µm. Arrowheads indicate LacZ-positive exogenous MPMEC. No LacZ-positive cells were detected in plugs containing Matrigel only. (C) Cryosections from MPMEC plugs were co-stained for LacZ expression and CD31. Both heterozygous and EphA2-deficient MPMEC were positive for CD31 staining (arrows), though EphA2-deficient MPMEC lacked the elongated, endothelial morphology observed in heterozygous MPMEC. LacZ-positive, exogenous MPMEC from heterozygous mice associated with host endothelium (asterisk), while EphA2-deficient MPMEC did not. Scale bar, 2 µm. Data are representative of six independent plugs per genotype derived from three independent donor mice from each genotype.