Proliferation of HDFs is induced by CM of M2 macrophages. After 72 h, no differences in cell numbers were seen between HDFs stimulated with CM of M1 polarized, M2 polarized or unstimulated macrophages. After 144 h, stimulation with CM of M2 macrophages increased the dermal fibroblast cell number, exclusively (A). This is due to proliferation of the HDFs as shown by MKI67 protein staining (B). More MKI67 positive nuclei (green) were seen in fibroblasts stimulated with CM of M2 macrophages compared to fibroblasts stimulated with CM of M1 and unstimulated macrophages after 144 h (C). *** p < 0.001, Difference between HDFs stimulated with CM of M1 polarized and CM of M2 polarized macrophages. # p < 0.05, Difference between HDFs stimulated with CM of M2 polarized and CM of unstimulated macrophages. ^ p < 0.05, Difference between 72 h and 144 h after stimulation of HDFs with CM of M2 polarized macrophages. Cell numbers and MKI67 positive nuclei were analyzed using two-way ANOVA followed by Bonferroni’s post-test n = 3. MKI67 protein expression was shown in green, nuclei in blue (DAPI) and original magnification was 200×.