(A). The injured spinal cord was collected at day 14 post SCI, which was sectioned and subjected to immunofluorescence staining for galectin-3 (red, arrowhead)/HuNu(green, arrow) and Iba-1 (red, arrowhead)/HuNu (green, arrow). The tissue sections were then incubated with DAPI for nuclear counterstain. (B). Microglia-hMSC co-cultures were treated with PACAP (100 nM) for 24 hours, and then subjected to immunofluorescence staining for galectin-3 (green) and HuNu (red). (C). A representative cytogram of microglia and hMSCs was shown in the left and middle panel, respectively. Accordingly, the cytogram of microglia-hMSC co-culture indicates two cell populations (right panel): microglia scattering in R1, and hMSCs appearing in R2. (D) Microglia were treated with PACAP (100 nM), or co-cultured with hMSCs in the absence or presence of PACAP (100 nM). 24 hours later, the relative levels of galectin-3 positive microglia were determined by FACS. The data represent as the relative level of galectin-3 positive microglia by determining the ratio of galectin-3 positive microglia being analyzed in the region of R1 (C) in comparison with that detected in the control culture. The images shown in B and C were taken from confocal microscopy. Data consist of means ± SEM of three independent experiments. Scale bar in A, 50 µm; in B, 40 µm. *p<0.05 versus control.