FIG. 4.

hASCs stimulate mouse osteoblast (mOB) activity in a calvarial defect. (A) Histological analysis of the defect edge of defects left empty, treated with scaffold only, or treated with scaffold/hASCs at 2 weeks postoperatively. In the upper right corner, a low magnification image (2×) of the defect site in the right parietal bone (pb) and surrounding calvaria is shown for orientation purposes. The black dotted line depicts the edge of the defect site in the top panel of (A–D). The red dotted line outlines the defect site. Higher magnification images of the defect site, area outlined in white dotted lines in top panel of (A), can be seen in the bottom panel of (A–D). (A) Safranin-O staining, in which osteoid appears light blue. An absence of cartilage was noted in all sections, which would appear pink. (B) ALP staining, nonspecific for mouse versus human activity. (C) Runt-related transcription factor-2 (Runx2) expression by in situ hybridization, specific for mouse. (D) Osteocalcin (Ocn) expression by in situ hybridization, specific for mouse. (E) Quantitative real-time polymerase chain reaction analysis of RNA derived from cranial defects at 2 weeks postoperatively, specific for mouse genes. A significant induction of mAlp, mCol1a1, and mOcn was observed with hASC engraftment. n = 5 animals per group, *P < 0.05. A one-factor ANOVA was utilized, followed by a post hoc Student's t-test to assess significance. Sagittal suture (ss) and squamosal bone (sb). Color images available online at www.liebertonline.com/scd.