Scaffold

Scaffolds are temporary support for tissue formation and are usually seeded with cells and growth factors. Scaffolds are either cultured in vitro which allows the tissues to mature before implantation or they can be directly injected into the injury site to allow the regeneration of tissue by the body’s own mechanisms.

Figure 1: Tissue engineering scheme for articular cartilage injuries. A: A focal articular cartilage injury. B: The lesion is debrided to ensure healthy perimeter for the implant. C: The lesion is filled with biomaterial scaffold to trigger tissue renewal.

Scaffolds are designed to:

• promote cell-biomaterial interaction, cell adhesion, and extracellular matrix (ECM).
• allow sufficient transport of gases, nutrient, and regulatory factors to support cell survival and proliferation.
• enhance removal of waste products.
• biodegrade at controllable rate.
• induce minimal level of inflammation in vivo.

An ideal scaffold should be porous, biocompatible, biodegradable, have mechanical properties appropriate for the intended implantation site, and use cell-friendly manufacturing technologies.

Type of scaffold

• Hydrogels are three dimensional polymer networks swollen in water, is akin to cartilage structure making it a suitable choice as cartilage substitute.

• Solid. Scaffolds from solid inorganic material (hydroxyapatite, tricalcium phosphate) are preferably used in bone tissue engineering.

• Porous scaffolds are mainly used for bone tissue that depends on vascularization for regeneration.