Comparative study of bovine, porcine and avian collagens for the production of a tissue engineered dermis

Combining bovine collagen with chitosan followed by freeze-drying has been shown to produce porous scaffolds suitable for skin and connective tissue engineering applications. In this study collagen extracted from porcine and avian skin was compared with bovine collagen for the production of tissue engineered scaffolds. A similar purity of the collagen extracts was shown by electrophoresis, confirming the reliability of the extraction process. Collagen was solubilized, cross-linked by adding chitosan to the solution and freeze-dried to generate a porous structure suitable for tissue engineering applications. Scaffold porosity and pore morphology were shown to be source dependant, with bovine collagen and avian collagen resulting into the smallest and largest pores, respectively. Scaffolds were seeded with dermal fibroblasts and cultured for 35 days to evaluate the suitability of the different collagen-chitosan scaffolds for long-term tissue engineered dermal substitute maturation in vitro. Cell proliferation and scaffold biocompatibility were found to be similar for all the collagen-chitosan scaffolds, demonstrating their capability to support long-term cell adhesion and growth. The scaffolds contents was assessed by immunohistochemistry and showed increased deposition of extracellular matrix by the cells as a function of time. These results correlate with measurements of the mechanical properties of the scaffolds, since both the ultimate tensile strength and tensile modulus of the cell seeded scaffolds had increased by the end of the culture period. This experiment demonstrates that porcine and avian collagen could be used as an alternative to bovine collagen in the production of collagen-chitosan scaffolding materials.