Injectable hydrogels for cartilage and bone tissue engineering

Abstract

Tissue engineering has become a promising strategy for repairing damaged cartilage and bone tissue. Among the scaffolds for tissue-engineering applications, injectable hydrogels have demonstrated great potential for use as three-dimensional cell culture scaffolds in cartilage and bone tissue engineering, owing to their high water content, similarity to the natural extracellular matrix (ECM), porous framework for cell transplantation and proliferation, minimal invasive properties, and ability to match irregular defects. In this review, we describe the selection of appropriate biomaterials and fabrication methods to prepare novel injectable hydrogels for cartilage and bone tissue engineering. In addition, the biology of cartilage and the bony ECM is also summarized. Finally, future perspectives for injectable hydrogels in cartilage and bone tissue engineering are discussed.

Tissue engineering: Optimizing injectable hydrogels to improve bone repair

A review of injectable hydrogels highlights their potential for bone engineering, but stresses the need to optimize their fabrication. Tissue engineering requires a scaffold that encourages cells to grow on it; hydrogels, which are polymeric materials that contain large amounts of water, can form such scaffolds and can be injected, thereby avoiding surgery and easily filling irregularly shaped bone defects. Nongyue He from Southeast University, Nanjing, China and colleagues have reviewed the materials and techniques available to make injectable hydrogels. They conclude that natural materials are biocompatible but lack strength, whereas synthetic materials are strong but not biocompatible. Similarly, physical fabrication is simple but produces hydrogels with low strength, whereas chemical fabrication yields strong hydrogels that are not biocompatible. New approaches and integration of existing methods are needed to produce an injectable hydrogel with ideal properties.

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