10 - Collagen–hydroxyapatite composite scaffolds for tissue engineering

Abstract

Advances in tissue engineering and regenerative medicine have provided alternate solutions for providing bone substitutes for bone and joint disease treatment. The tissue-engineering approach involves the seeding of cells onto a 3D scaffold, followed by a culture within a suitable bioreactor, and finally implantation into the body when a mature matrix is formed. Here, the scaffold serves as a physical support structure for cell growth and a template for tissue regeneration. The ideal scaffolds should have an appropriate surface chemistry and microstructures to facilitate cellular attachment, proliferation, and differentiation. It should also possess adequate mechanical strength for handling and a biodegradation rate without any undesirable by-products. Both collagen and hydroxyapatite have been used in bone tissue engineering owing to their excellent osteoconductive property to provide a relatively successful means of augmenting bone growth. The composite scaffold of these two natural materials has been proved to be more useful than a monolithic component. This chapter summarizes some important issues related to collagen–hydroxyapatite composite scaffold development. The scaffold design and fabrication techniques are overviewed, and their advantages and manufacturing feasibility are compared. The scaffold architecture, including pore size and size distributions, and its effects on the cells’ growth are discussed. Emerging scaffold fabricating technique using solid freeform fabrication has been discussed. A strong potential to integrate architecture with surface chemistry of the scaffolds has been shown. In vitro and in vivo performance of collagen–hydroxyapatite composite scaffold has been reported and discussed. It is recommended that collagen–hydroxyapatite composite scaffold used for musculoskeletal tissue engineering should direct 3-D organization of cells in vitro or in vivo. To achieve this, the structural properties of the collagen–hydroxyapatite scaffold should be refined in a way to provide a microenvironment that can control the spatial organization of cells attachment, growth, and differentiation. Such scaffolds will contribute to achievement of the goal of musculoskeletal tissue engineering and regenerative medicine.