Fig. 8. CEPU-1/OBCAM-expressing CHO cells inhibit neurite outgrowth from CGCs. CGCs were seeded at 1x10⁵ cells per well onto confluent CHO cell monolayers growing on coverslips and incubated at 37°C in a 5% CO₂ atmosphere for 28-31 hours. Cells were fixed, permeabilized and stained with chicken-GAP-43 antibody to identify the neurons. (A) At least 100 individual neurons were counted per coverslip, comparing the number with and without neurites. CO-CHO cells inhibited the number of neurons that had extended neurites by 40% (with respect to wild-type CHO cells) and 45% (with respect to the average of the CEPU-1- and OBCAM-expressing cell lines) (n=5). ^*P<0.001 compared with CEPU-1- or OBCAM-expressing CHO cells and P<0.02 compared with wild-type CHO cells. (B) At least 220 random neurites greater than 10 µm long were measured per CHO cell line using Metamorph. Neurites from CGCs seeded on OBCAM-CHO were slightly longer and those on CEPU-1- and CO-CHO slightly shorter, respectively, than those from CGCs seeded on wild-type CHO cells (n=5). (C) CHO cell lines were grown in a 96-well plate and incubated with 1 µg ml^–1 LAMP-Fc. LAMP-Fc bound well to CEPU-1- and OBCAM-expressing CHO cells, but its affinity for CO-CHO cells was comparable to that of the LAMP-CHO cells.