Chitosan/collagen/Mg, Se, Sr, Zn-substituted Calcium Phosphate Scaffolds for Bone Tissue Engineering Applications: A Growth Factor Free Approach

According to the biomimetic bone scaffold design paradigm, a scaffold resembling natural bone tissue with molecular, structural and biological compatibility is needed to allow effective regeneration of bone tissue. Continuing our previous studies regarding scaffolds with chitosan matrix containing Mg, Se, Sr, Zn-substituted calcium phosphates (CaPs), the focus of this work was to further improve the properties of these growth factor-free scaffolds. By addition of collagen into the chitosan matrix at weight ratios of 100:0, 75:25, 50:50, 25:75 and 0:100, we aimed to better resemble natural bone tissue. Highly porous composite scaffolds based on chitosan and collagen, with 30 wt% of Mg, Se, Sr, Zn-substituted CaPs, were prepared by the freeze-gelation method. The scaffolds show a highly porous structure, with interconnected pores in the range of 20-350 mu m and homogeneously dispersed CaPs. The added collagen further enhanced the stability measured during 28 days in simulated biological conditions. Live/dead and CyQUANT assays confirmed good viability and proliferation of human bone marrow-derived mesenchymal stem/stromal cells, while successful osteogenic differentiation was confirmed by alkaline phosphatase quantification and type I collagen immunocytochemical staining. Results indicated that the addition of collagen into the chitosan matrix containing Mg, Se, Sr, Zn-substituted CaPs improved the physicochemical and biological properties of the scaffolds.