Properties of chitosan-collagen sponges and osteogenic differentiation of rat-bone-marrow stromal cells

The aim of this study was to further investigate effects of a combined chitosan and collagen matrix on osteogenic differentiation of rat-bone-marrow stromal cells (BMSCs), including analysis of the physical and mechanical properties of the sponges. There were 4 study groups: collagen, chitosan, 1: 1 chitosan-collagen and 1:2 chitosan-collagen sponges. Chitosan-collagen sponges were fabricated using the freeze-drying technique. BMSCs were seeded on the sponges and cultivated in mineralized culture medium for 27 days. Attachment and growth of cells on the sponges were examined under a scanning electron microscope. Alkaline phosphatase activity and levels of osteocalcin were monitored. Tests of swelling, collagenase and lysozyme enzymatic degradation, and mechanical strength were performed. The BMSCs attached successfully to the structure of the sponges, and expression of ALP and osteocalcin on collagen and chitosan-collagen composite sponges was greater than on chitosan sponges. All sponges showed a high degree of water uptake. Chitosan and chitosan-collagen sponges showed a higher resistance to enzymatic degradation than collagen sponges. A 1:1 chitosan-collagen sponge demonstrated the highest compressive strength. Combined chitosan-collagen matrixes promoted osteoblastic differentiation of BMSCs, and improved the mechanical and physical properties of the sponges.