The beneficial effect of chitooligosaccharides on cell behavior and function of primary Schwann cells is accompanied by up-regulation of adhesion proteins and neurotrophins.

Chitosan-based tissue engineered nerve grafts are successfully used for bridging peripheral nerve gaps. The biodegradation products of chitosan are water-dissolvable chitooligosaccharides (COSs), which have been shown to support peripheral nerve regeneration. In this study, we aimed to examine in vitro interactions between COSs and Schwann cells (SCs), the principal glial cells in the peripheral nervous system. Treatment of primary SCs with COSs enhanced cell survival and promoted cell proliferation in a dose-dependent manner (0.25-1.0 mg/ml), as determined by real-time cell analyzer-based assay, cell growth assay, cell cycle analysis, and EdU incorporation. Western blot analysis and immunocytochemistry with antibodies against MBP and MAG (two myelin-specific markers) showed that COSs enhanced axonal myelination in a co-culture system consisting of SCs and dorsal root ganglia (DRGs). Furthermore, we observed that COSs enhanced the protein expression of N-cadherin and β-catenin in primary SCs, and also increased the release of BDNF and NGF in co-culture of SCs with DRGs. And we also noted that knockdown of N-cadherin in primary SCs reduced COSs-induced increase in cell proliferation. Our findings suggested that beneficial effects of COSs on cell behavior and functions of primary SCs might be accompanied by up-regulation of adhesion proteins and neurotrophins, thus providing a new insight into the supportive role of COSs during peripheral nerve regeneration.