Tissue and vascular toxicity in healthy tissue after CD34-TRAIL⁺ cell administration. NOD/SCID mice bearing subcutaneous tumor nodules received a single intravenous injection of CD34-TRAIL⁺ cells (3 × 10⁶ cells/mouse) or control vehicle. Forty-eight hours after treatment, lung, liver, spleen, and femur were harvested and analyzed. (A) Hematoxylin and eosin and (B) immunohistochemical staining with anti-CD31 antibody demonstrated the absence of tissue or vascular damage. Representative histologic images are shown. Objective lens, original magnifications: (A) 0.4 NA dry objective, 10×; (B) 0.75 NA dry objective, 20×.