CD44 and pneumonia: Studies are ongoing to determine if there were any differences in the binding kinetics with CD44 on human monocytes with different MW of HA which may affect phagocytosis; (2) despite the significant effect of MSC EV on bacterial phagocytosis by monocytes in vitro and alveolar inflammation and bacterial load following severe pneumonia in vivo, the target cells of MSC EV are currently unknown.