Chitosan surface enhances the mobility, cytoplasm spreading, and phagocytosis of macrophages

A chitosan micropattern was prepared on glass by inkjet printing to visualize and compare in real-time macrophage developments on chitosan versus glass during microfluidic culture. The mobility of macrophages on chitosan was significantly higher, since the cells on glass were anchored by the development of podosomes whereas those on chitosan did not form podosomes. The phagocytosis of bacteria by macrophages was considerably more effective on chitosan because of: (1) the macrophages' higher mobility to scavenge nearby bacteria and (2) their cyotoplasm's ability to spread, re-distribute, and recover more freely to engulf the bacteria. Consequently, bacteria growth on chitosan surface was significantly reduced in the presence of macrophages in comparison to that on glass surface, as measured by surface bacteria density and effluent bacteria concentration. These findings suggest the synergistic effect of chitosan as a potential coating material on biomedical implants in promoting macrophage response upon the arrival of opportunistic bacteria.