Fig. 4.
Retention of implanted BLK (lacZ)-AdCMV-BMP7-transduced cells during bone induction. BLK cells were stably transfected with pCMV-neo-lacZ plasmid encoding the bacterial β-galactosidase gene. Cells were transduced with empty adenovirus (control) or AdCMV-BMP7 (BMP7), implanted and harvested at the times indicated. Implants were stained for β-galactosidase activity before paraffin embedding and sectioning. Samples were stained with eosin only to allow visualization of blue β-galactosidase staining. Blue staining cells associated with osteoblast layers in 2- and 6-week samples are indicated by arrows. Only 2× magnifications of control implants are shown while 2× and 20× magnifications are shown for the AdCMV-BMP7 group. Bone formed by implanted, virally transduced cells was composed primarily of cells from the host.