Glycated chitosan as a new non-toxic immunological stimulant

Abstract

Chitosan is capable of stimulating immune responses. However, because chitosan is not water soluble, it has limited biological applications. By attaching galactose molecules to the chitosan molecules, a new water-soluble compound, glycated chitosan (GC), was synthesized. GC was designed for immune stimulations in combination with phototherapies in the treatment of metastatic tumors. To investigate the possible toxicity of GC, cultures of normal and tumor cells were incubated with GC of different concentrations and the cell viabilities were determined. For in vivo studies, GC solution was fed or injected to animals and its toxicity was determined through observations of animals and histological examinations of vital organs. No toxic effects of GC were observed in cultured cells or in animal studies. In addition, the immunological effect of GC was investigated through its stimulation of TNFα secretion by macrophages in vitro. In vivo studies showed enhancement of the survival of laser immunotherapy-treated rats bearing metastatic mammary tumors. Our in vitro and in vivo results indicated that GC was a strong immunological stimulant. Its non-toxic nature and immunological activity make GC a potential immunoadjuvant for treatment of metastatic tumors.

Keywords::

• Chitosan
• galactose
• glycated chitosan
• toxicity
• TNFα
• macrophages
• immune responses

Acknowledgments

This research was supported by the National Natural Science Foundation of China (30470494; 30627003) and the Natural Science Foundation of Guangdong Province (7117865), and by a grant from the US National Institutes of Health (P20 RR016478 from the INBRE Program of the National Center for Research Resources).

Declaration of interest: The authors report no conflicts of interest.