Hematopoietic cells expressing NP-1 induce angiogenesis in in vivo Matrigel assay.

(A) Matrigels containing CD45⁺B220⁺ cells from E12.5 fetal liver of wild type (ii,iv,vi) or CD45⁺B220⁺ cells from E12.5 fetal liver of NP-1 mutants (i,iii,v) were injected subcutaneously near the abdominal midline of 8-week-old C57BL mice. (i-ii) Gross appearance of Matrigels on day 5. (iii-vi) Histologic analysis of sections from the Matrigels. ECs were visualized by the staining with anti–PECAM-1 antibody (iii-iv) or anti–VEGFR-2 antibody (v,vi). Scale bar indicates 500 μm (i-ii) and 50 μm (iii-vi). Arrows indicate newly formed vessels in the Matrigel plugs. (B) Values represent the concentration of hemoglobin (g/dL) per Matrigel plug weight (mg) ± SE for 6 assays. “a” is CD45⁺ NP-1⁺ cells with VEGF₁₆₅; “b,” CD45⁺ NP-1^–cells with VEGF₁₆₅.