Extracellular NAD is a regulator for FcgammaR-mediated phagocytosis in murine macrophages.

NAD is available in the extracellular environment and elicits immune modulation such as T cell apoptosis by being used as the substrate of cell surface ADP-ribosyl transferase. However, it is unclear whether extracellular NAD affects function of macrophages expressing cell surface ADP-ribosyl transferase. Here we show that extracellular NAD enhances Fcgamma receptor (FcgammaR)-mediated phagocytosis in J774A.1 macrophages via the conversion into cyclic ADP-ribose (cADPR), a potent calcium mobilizer, by CD38, an ADP-ribosyl cyclase. Extracellular NAD increased the phagocytosis of IgG-coated sheep red blood cells (IgG-SRBC) in J774A.1 macrophages, which was completely abolished by pretreatment of 8-bromo-cADPR, an antagonist of cADPR, or CD38 knockdown. Extracellular NAD increased basal intracellular Ca(2+) concentration, which also was abolished by pretreatment of 8-bromo-cADPR or CD38 knockdown. Moreover, the chelation of intracellular calcium abolished NAD-induced enhancement of phagocytosis of IgG-SRBC. Our results suggest that extracellular NAD act as a regulator for FcgammaR-mediated phagocytosis in macrophages.

Homogeneous chitosan-PLGA composite fibrous scaffolds for tissue regeneration.

Novel chitosan-poly(lactide-co-glycolide) (PLGA) composite fibers and nonwoven fibrous scaffolding matrices were designed for cartilage regeneration. A homogenous one-phase mixture of chitosan and PLGA at a ratio of 50:50 (w/w %) was successfully produced using cosolvents of 1,1,1,3,3,3-hexafluoroisopropanol and methylene chloride. A wet spinning technique was employed to fabricate composite fibrous matrices. Physical characterizations of one-phase chitosan-PLGA composite (C/Pc) matrices were performed for their homogeneity, in vitro degradability, mechanical property and wettability in comparison to two-phase chitosan and PLGA composite fibrous matrices in which PLGA was dispersed in a continuous chitosan phase. The one-phase property of C/Pc matrices was confirmed from thermal analysis. Significantly retarded degradation was observed from the composite C/Pc fibrous matrices in contrast to the PLGA-dispersed chitosan (C/Pd) fibrous matrices due to the effective acid-neutralizing effect of chitosan on acid metabolites of PLGA. The composition of chitosan with PLGA resulted in a characteristic soft and strong mechanical property that could not be retained by either PLGA or the chitosan fibers. In addition, the presence of chitosan in the composite matrices provided proper wettability for cell cultivation. The C/Pc matrices were further investigated for their scaffolding function using chondrocytes for cartilage regeneration. Enhanced cell attachment was observed on the composite matrix compared with the PLGA fibrous matrices. The mRNA expression of type II collagen and aggrecan was upregulated in the composite matrix owing to the superior cell compatibility of chitosan. These results suggest an excellent potential for C/Pc one-phase composite fibrous matrices as scaffolding materials for tissue regeneration.