Influence of chitosan on cell viability and proliferation in three dimensional collagen gels

The development of suitable three-dimensional matrices for the maintenance of cellular viability and differentiation is critical for applications in tissue engineering and cell biology. The structure and composition of the extracellular matrix (ECM) has been shown to modulate cell behavior with respect to shape, movement, proliferation and differentiation. Although collagen and chitosan have separately been proposed as in vitro ECM materials, the influence of chitosan-collagen composite matrices on cell morphology, differentiation, and function has not been examined. To this end, gel matrices of different proportions of collagen and chitosan were examined ultrastructurally and characterized in terms of tensile and shear mechanical strength and their ability to regulate cellular activity. Mechanical testing of the gels showed that matrix strength increased with chitosan proportion. Gel behavior under fluid force confirmed this result. Scanning and transmission electron microscopy indicated that the addition of chitosan greatly influences ultrastructure and changes collagen fiber crosslinking, reinforcing the structure and increasing pore size. Atomic force microscopy indicated apparent surface modifications induced by chitosan incorporation. K562 cells cultured in three-dimensional gels were examined for cell proliferation and differentiation. While cell proliferation was inhibited with an increasing proportion of chitosan, cell function based on cytokine-release was greatly augmented. Results suggest that a hybrid chitosan-collagen matrix may have potential biological and mechanical benefits for use as a cellular scaffold