Dependence of SDF-1–induced polarization and directional migration of CD34⁺ cells through ECM on VLA-4 and VLA-5.

(A) Polarization and (B) migration of CD34⁺ cells. The control (□) was done without a gradient of SDF-1; • indicates a gradient of SDF-1. The cells were quantified in 3-D ECM-like gels without or with the following: anti–VLA-4 mAb (○), anti–LFA-1 mAb (◍), or anti–VLA-5 mAb (▵). The average of 3 different experiments plus or minus SD are shown. (C, D) Contribution of β1 and β2 integrins to the engraftment of CD34⁺cells in NOD/SCID mice. Percent engraftment in the murine bone marrow by cord blood CD34⁺ cells pretreated with antibodies to either LFA-1, VLA-4, VLA-5, β1, VLA-6, or CD34, quantified after (C) 6 weeks or (D) 4 weeks by immunostaining with antihuman CD45 mAb. (C) Each point represents 1 mouse. (D) Results were pooled from 3 different experiments.