Figure 4

A lack of host immune response of microglia to DAPF. (a–d) Confocal images of Iba-1 labelled microglia (white arrowhead) interacting with DAPF and showing quiescent morphology (bipolar) with no expression of the pro-inflammatory cytokine iNOS in vitro. (e and f) Representative fluorescence images of microglia in the spinal cord dorsal horn in which there was no implantation (e) or where DAPF was implanted for 5 months (f). Resting microglia morphology, or with process length double the soma diameter, is unaltered across the two conditions. (g) Percentage of total microglia with bipolar (non-activated) morphology was increased significantly on cells cultured on DAPF compared to control (no biomaterial) and LPS (positive controls). Percentages of (h) iNOS expression and (i) nitrite release are reduced significantly for DAPF compared to LPS and not significantly different from control. (j) Counts of the number of activated and resting microglia confirms that there were no morphological changes across all three conditions (N = 3 BRs). For g, h, I: ***p < 0.001; N = 9 BRs, n = 3 TRs/BR. Scale bars = 50 µm.