We compared the structure and mechanical properties of scaffolds based on pure collagen, pure chitosan, and a mixture of these polymers. The role of the composition and structure of scaffolds in the maintenance of cell functions (proliferation, differentiation, and migration) was demonstrated in two experimental models: homogeneous tissue analogues (scaffold populated by fibroblasts) and complex skin equivalents (fibroblasts and keratinocytes). In contrast to collagen scaffolds, pure chitosan inhibited the growth of fibroblasts that did not form contacts with chitosan fibers, but formed specific cellular conglomerates, spheroids, and lose their ability to synthesize natural extracellular matrix. However, the use of chitosan as an additive stimulated proliferative activity of fibroblasts on collagen, which can be associated with improvement of mechanical properties of the collagen scaffolds. The effectiveness of chitosan as an additional cross-linking agent also manifested in its ability to improve significantly the resistance of collagen scaffolds to fibroblast contraction in comparison with glutaraldehyde treatment. Polymer scaffolds (without cells) accelerated complete healing of skin wounds in vivo irrespective of their composition healing, pure chitosan sponge being most effective. We concluded that the use of chitosan as the scaffold for skin equivalents populated with skin cells is impractical, whereas it can be an effective modifier of polymer scaffolds.

We analyzed viability of mesenchymal stem cells seeded by static and dynamic methods to highly porous fibrous 3D poly-L-lactide scaffolds with similar physical and chemical properties, but different spatial organization modified with collagen. Standard collagen coating promoted protein adsorption on the scaffold surface and improved adhesive properties of 100 μ-thick scaffolds. Modification of 600-μ scaffolds with collagen under pressure increased proliferative activity of mesenchymal stem cells seeded under static and dynamic (delivery of 100,000 cells in 10 ml medium in a perfusion system at a rate of 1 ml/min) conditions by 47 and 648%, respectively (measured after 120-h culturing by MTT test). Dynamic conditions provide more uniform distribution of collagen on scaffold fibers and promote cell penetration into 3D poly-L-lactide scaffolds with thickness >600 μ.

Biocompatibility of film and fibrous scaffolds from polylactide-based polymers and the relationship between their architecture and the functional characteristics of mesenchymal stem cells were studied. Cell culturing on polylactide-based film and fibrous matrixes did not deteriorate cell morphology and their proliferation and differentiation capacities. The rate of cell proliferation and penetration in microporous 3D matrices with the same porosity parameters and pore size depended on their spatial organization. The above materials can be used as scaffolds for mesenchymal stem cells for creation of tissue engineering implants. The scaffold size and structure should be determined by the defects in the organs in which the regeneration processes have to be stimulated.

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