A reductive amination reaction (N-alkylation) obtained exploiting the aldheyde group of lactose and the amino group of the
glucosamine residues of chitosan (d.a. 89%) afforded a highly soluble engineered polysaccharide (chitlac) for a potential application
in the repair of the articular cartilage. Chitosan derivatives with 9% and 64% of side chain groups introduced have been prepared
and characterized by means of potentiometric titration, 1H-NMR and intrinsic viscosity. Both polymers, with respect to the
unmodified chitosan, induce cell aggregation when in contact with a primary culture of pig chondrocytes, leading to the formation of
nodules of considerable dimensions (up to 0.5–1mm in diameter). The nodules obtained from chondrocytes treated with chitlac with
the higher degree of substitution have been studied by means of optical and electron microscopy (SEM, TEM) and the production of
glycosaminoglycans (GAGs) and collagen has been measured by means of colorimetric assays. The chondro-specificity of GAG and
collagen was determined by RT-PCR. The results show that the lactose-modified chitosan is non-toxic and stimulates the production
of aggrecan and type II collagen.
