Influence of chitosan concentration on cell viability and proliferation in vitro by changing film topography

Chitosan is a natural polysaccharide which can form gels and scaffolds that support its use as a biomaterial in various tissue engineering applications. A useful feature of chitosan polymer is that you can manipulate its properties easily. Thus, in this work we studied the effect of varying chitosan concentration in the topography and the biological properties of the chitosan films, as well as the effects in the structure of 3D gels in order to be used as nerve bridges.

Analysis of film topographies were addressed by swelling test and atomic force microscopy (AFM). In vitro biological properties were assessed through MTT viability assays on cultures of blood-brain barrier forming endothelial (bEnd5), glioma (C6) and postmitotic neuron (NGF-differentiated PC12) cell lines. The structure of tridimensional gels was studied by environmental scanning electron microscopy.

Topography of 1% chitosan films showed a AFM profile with higher nano-roughness profile than that observed in 2% films, which was smoother. Moreover, swelling rate was not affected. Topography changes affected cell viability as shown by the MTT assays. Our results showed that 2% chitosan films promoted higher proliferation and viability of C6 and PC12 respectively than 1% films. Conversely, neither 1% nor 2% films promoted viability of bEnd5 cells. In order to establish the
feasibility of both type of chitosan solutions as nerve bridges, we constructed 3D gels by alkaline precipitation. Resulting gels showed that only 2% gels were rigid enough to be effectively used as nerve bridges.

These results establish that changes in chitosan concentration affects the polymer surface topography, which has a direct effect in the growing cell behavior. Additionally, higher concentration of chitosan gels are required to be used in neural tissue engineering.