(A) Adhesion of CD34⁺ cells to differentially sulfated GAGs. ⁵¹Cr-labeled CD34⁺ cells (20,000 cells/well) were incubated for 4 hours at 37°C in 48-well plates previously coated with 5% BSA or with 100 μg/mL ovalbumin-conjugated GAGs. The percentage of adhesion was calculated from the proportion of input cpm present in the adherent cells. Numbers within bars indicate the number of experiments. Comparison between O-sulfated heparin and other conditions: *P< .002; §P < .005; ¶P < .05. (B) Binding of ¹²⁵I-HS to CD34⁺ cells. The binding of 10⁶ cpm of ¹²⁵I-HS from the two cells to 0.75 × 10⁶ CD34⁺ cells suspended in 0.5 mL medium was estimated, as described in Materials and Methods. Radioactivity bound to the cells was counted using a gamma counter.