LOW-MOLECULAR-WEIGHT CHITOSAN STIMULATION OF MITOGENIC RESPONSE TO PLATELET-DERIVED GROWTH-FACTOR IN VASCULAR SMOOTH-MUSCLE CELLS

Low molecular weight chitosan (LMWC) (a mixture of chitooligosaccharides with high degrees of polymerization; an average degree of polymerization is 6.8) stimulated mitogenic response to platelet-derived growth factor (PDGF) in a dose-dependent manner in cultured rat vascular smooth muscle cells, and a maximum effect was observed at 100 mu g/ml. However, the mitogenic response was not induced when cells were incubated with LMWC alone, This stimulatory effect of LMWC on the mitogenic response to PDGF (a competence factor) appeared to resemble the effect of insulin as a progression factor. Chitooligosaccharides with higher degrees of polymerization were more effective, but D-glucosamine, chitobiose, and chitotriose were barely active, LMWC as well as PDGF induced protein tyrosine phosphorylation in vascular smooth muscle cells.